The document discusses numerical modeling of dissipative pin devices used in brace-column connections in concentrically braced frames (CBF). It analyzes the behavior of single-pin and double-pin connection devices under monotonic and cyclic loading through theoretical models and an OpenSees beam model. The single-pin model is calibrated against experimental test data. The double-pin connection, with pins arranged in parallel or in-line configurations, is also studied through numerical modeling. The purpose of the pin connections is to preserve the elastic behavior of brace members while maintaining their buckling resistance by dissipating energy through the pins.
IRJET- Impact Resistances of Hybrid Steel Truss BeamsIRJET Journal
1) The document investigates the impact resistance of hybrid steel truss concrete beams (HSTCBs) under three-point loading using finite element analysis.
2) Nine HSTCB models with varying truss configurations and impact velocities were analyzed. The model with a cover plate and no confinement had the lowest displacement and highest stiffness, indicating better impact resistance.
3) Analysis of load-deflection graphs and maximum deformation showed that the HSTCB model with a cover plate and no confinement performed best in resisting impact across different velocities tested.
Assessment of Combinatorial Support Assemblies and Their Energy Matrixes in H...IOSR Journals
The bolt and nut coupling are fundamental design requirement for machines and steel structures and
their relevance and utilization are of topmost priority in the areas of their application. The paper viewed the
component parts and dimensions of this coupling from the perspective of energy content delivery, balancing and
equilibrium. This result from the fact that the supply of compression torque on the coupling converts ingrained
residual energy in the individual parts into utility energy assets for the support and sustenance of structures of
interest. The mechanics and practicality of this energy matrix theory has been investigated using congruent
scientific analysis, conventional tables, lab test data and graphics which depicts boundary behavioral
tendencies resulting from structural realignments in the face of increasing load value. The extreme limit of this
realignments, culminate in varying degrees of yield conditions particular viewed as deformation, which occurs
at the point of lowest energy availability in the coupled system.
This document summarizes research on modelling and designing dissipative connections for brace-to-column joints. The behaviour of single-pin and double-pin connection devices is emphasized through theoretical beam models and OpenSees models under monotonic and cyclic loading. The proposed models are calibrated against experimental test results from two specimens. The single-pin device consists of inner and outer plates with a pin running through, while the double-pin device has two pins. The models match the experimental hysteresis loops and energy dissipation, validating the numerical modelling approach.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document presents a monolithic bistable mechanism that does not rely on residual stress. It consists of two curved beams clamped at the center.
Analytic and finite element modeling is used to predict and design the bistable behavior. The modeling shows that for a single curved beam to be bistable, its second buckling mode must be constrained. A double curved beam structure satisfies this requirement through mutual cancellation of twisting modes.
Microfabricated double curved beam tests match the analytic predictions well. The design allows tailoring of the bistable behavior without needing residual stress or complex structures.
The document presents a novel set of Multiscale Periodic Boundary Conditions (MPBCs) that enable two-scale (solid-to-shell) numerical homogenization of periodic structures using reduced Unit Cells (rUCs), including their bending and twisting response. The MPBCs are formulated and their derivation is provided in an appendix. Details on their implementation in finite element analysis and application to the homogenization of a periodic pin-reinforced sandwich structure are discussed. The MPBCs allow accurate determination of the fully-populated shell constitutive matrix using rUCs, providing significant reductions in modeling and computation times compared to full Unit Cells.
Design of short sstt confined circular hsc columnseSAT Journals
Abstract Steel-straps tensioning technique (SSTT) has been proven to be an effective mean to confined High-strength concrete (HSC). The pre-tensioned force offers by this confining method can significantly restraint the small lateral dilation of HSC. However, most of the design guidelines only concerned with FRP-confined columns subjected to concentric compression. The direct application of these design guidelines on the SSTT-confined HSC column is being questioned due to different material and confining method adopted. Hence, a numerical study was carried out in the view of developing a simple design equation for HSC column confined with SSTT. The parameters such as SSTT-confinement ratio, load eccentricities and slenderness ratio were tested. Based on the numerical results, design equations based on regression analysis were proposed to determine the ultimate load and bending moment of SSTT-confined HSC columns. Index Terms:Confinement, Steel Straps, Eccentric loads, and Theoretical Model.
Analysis of Behaviour of U-Girder Bridge DecksIDES Editor
The concept of U-shaped bridge girder is now being
increasingly adopted in urban metro rail projects and for
replacing old bridges where there is a constraint on vertical
clearance. These bridge decks are commonly designed in
practice using simplified methods that assume beam action of
the webs in the longitudinal direction and similar flexural
action of the deck slab in the transverse direction. However,
such assumptions can lead to errors. This paper attempts to
assess the extent of error in the simplified analysis, by
comparing the results with a more rigorous three-dimensional
finite element analysis (3DFEA). A typical prototype railway
bridge girder has been taken as a case study. The results of
the 3DFEA, in terms of load-deflection plots, have been
validated by field testing.
IRJET- Impact Resistances of Hybrid Steel Truss BeamsIRJET Journal
1) The document investigates the impact resistance of hybrid steel truss concrete beams (HSTCBs) under three-point loading using finite element analysis.
2) Nine HSTCB models with varying truss configurations and impact velocities were analyzed. The model with a cover plate and no confinement had the lowest displacement and highest stiffness, indicating better impact resistance.
3) Analysis of load-deflection graphs and maximum deformation showed that the HSTCB model with a cover plate and no confinement performed best in resisting impact across different velocities tested.
Assessment of Combinatorial Support Assemblies and Their Energy Matrixes in H...IOSR Journals
The bolt and nut coupling are fundamental design requirement for machines and steel structures and
their relevance and utilization are of topmost priority in the areas of their application. The paper viewed the
component parts and dimensions of this coupling from the perspective of energy content delivery, balancing and
equilibrium. This result from the fact that the supply of compression torque on the coupling converts ingrained
residual energy in the individual parts into utility energy assets for the support and sustenance of structures of
interest. The mechanics and practicality of this energy matrix theory has been investigated using congruent
scientific analysis, conventional tables, lab test data and graphics which depicts boundary behavioral
tendencies resulting from structural realignments in the face of increasing load value. The extreme limit of this
realignments, culminate in varying degrees of yield conditions particular viewed as deformation, which occurs
at the point of lowest energy availability in the coupled system.
This document summarizes research on modelling and designing dissipative connections for brace-to-column joints. The behaviour of single-pin and double-pin connection devices is emphasized through theoretical beam models and OpenSees models under monotonic and cyclic loading. The proposed models are calibrated against experimental test results from two specimens. The single-pin device consists of inner and outer plates with a pin running through, while the double-pin device has two pins. The models match the experimental hysteresis loops and energy dissipation, validating the numerical modelling approach.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document presents a monolithic bistable mechanism that does not rely on residual stress. It consists of two curved beams clamped at the center.
Analytic and finite element modeling is used to predict and design the bistable behavior. The modeling shows that for a single curved beam to be bistable, its second buckling mode must be constrained. A double curved beam structure satisfies this requirement through mutual cancellation of twisting modes.
Microfabricated double curved beam tests match the analytic predictions well. The design allows tailoring of the bistable behavior without needing residual stress or complex structures.
The document presents a novel set of Multiscale Periodic Boundary Conditions (MPBCs) that enable two-scale (solid-to-shell) numerical homogenization of periodic structures using reduced Unit Cells (rUCs), including their bending and twisting response. The MPBCs are formulated and their derivation is provided in an appendix. Details on their implementation in finite element analysis and application to the homogenization of a periodic pin-reinforced sandwich structure are discussed. The MPBCs allow accurate determination of the fully-populated shell constitutive matrix using rUCs, providing significant reductions in modeling and computation times compared to full Unit Cells.
Design of short sstt confined circular hsc columnseSAT Journals
Abstract Steel-straps tensioning technique (SSTT) has been proven to be an effective mean to confined High-strength concrete (HSC). The pre-tensioned force offers by this confining method can significantly restraint the small lateral dilation of HSC. However, most of the design guidelines only concerned with FRP-confined columns subjected to concentric compression. The direct application of these design guidelines on the SSTT-confined HSC column is being questioned due to different material and confining method adopted. Hence, a numerical study was carried out in the view of developing a simple design equation for HSC column confined with SSTT. The parameters such as SSTT-confinement ratio, load eccentricities and slenderness ratio were tested. Based on the numerical results, design equations based on regression analysis were proposed to determine the ultimate load and bending moment of SSTT-confined HSC columns. Index Terms:Confinement, Steel Straps, Eccentric loads, and Theoretical Model.
Analysis of Behaviour of U-Girder Bridge DecksIDES Editor
The concept of U-shaped bridge girder is now being
increasingly adopted in urban metro rail projects and for
replacing old bridges where there is a constraint on vertical
clearance. These bridge decks are commonly designed in
practice using simplified methods that assume beam action of
the webs in the longitudinal direction and similar flexural
action of the deck slab in the transverse direction. However,
such assumptions can lead to errors. This paper attempts to
assess the extent of error in the simplified analysis, by
comparing the results with a more rigorous three-dimensional
finite element analysis (3DFEA). A typical prototype railway
bridge girder has been taken as a case study. The results of
the 3DFEA, in terms of load-deflection plots, have been
validated by field testing.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Design for crash injuries mitigation using magnesium alloyeSAT Journals
Abstract This paper describes a computational investigation on the response of thin wall structures due to dynamic compression loading. In this paper, the tubes subjected for both direct and oblique loading. Several different cross-sectional structures have been studied to specify the best one. Initially the tubes were subjected to direct loading, and then the tubes were subjected to oblique loading. After that, the tubes were compared to obtain the cross section which fulfills the performance criteria. The selection was based on multi criteria decision making (MCDM) process. The performance parameters taken in this study are the specific energy absorbed by the tube for both direct and oblique, crush force efficiency and the ratio between the energy absorbed by direct and oblique loading. Trigger and foam filled are implemented to study their effects on the parameters used. The study used the magnesium alloy as a material to study potentially the possibility and ability of using the magnesium alloy in the energy absorber parts since the magnesium has lighter weight. Index Terms: dynamic compression, thin wall, energy absorption, direct oblique loading
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document contains a multiple choice quiz on concepts related to stress and strain in materials. There are 40 questions covering topics like:
- The relationships between elastic modulus, shear modulus, and Poisson's ratio for materials
- Calculating stresses and strains in loaded structures
- Principal stresses and maximum shear stress
- Mohr's circle representation of stresses
- Elastic properties like modulus of elasticity, modulus of resilience
- Stresses in loaded bars, beams, and other basic structural elements
The questions require applying stress/strain and material property equations to calculate values or identify correct statements regarding stresses and deformations in loaded materials and structures.
This document presents a finite element model of chain-link wire nets used in rockfall protection barriers. Chain-link nets have loose connections that allow for flexibility but make modeling the contact interactions complex. The study develops an improved finite element model that uses a general contact algorithm to model the complex contact between chain-link elements. Laboratory tensile tests on chain-link nets are performed and used to calibrate the model parameters. The calibrated model is shown to accurately simulate a full-scale rockfall barrier test, demonstrating the model's ability to realistically simulate the mechanical behavior of chain-link wire nets.
Parameter identification of rockfall protectionJuan Escallón
This document presents a numerical approach to parameterize macroscopic finite element models of rockfall protection barrier components through an inverse formulation. The components modeled include wire-ring nets and spiral cables, which are key flexible elements in rockfall barriers. Laboratory tests are used to characterize the highly nonlinear force-displacement behavior of these components under tension. Macroscopic finite element models of the components are developed using beam elements to represent the wires and cables. Additional parameters are included to simulate the nonlinear response. An inverse optimization process using a multi-island genetic algorithm is employed to determine the model parameters that best match the laboratory test data. The accuracy of the approach is then verified by simulating a full-scale rockfall barrier prototype test.
Fabrication and Analysis of Tensegrity Based Prism structureIRJET Journal
This document discusses the fabrication and analysis of a tensegrity-based prism structure. It begins with an introduction to tensegrity structures, which are composed of both compressive struts and tensile cables. The authors then describe how they fabricated a Class-I tensegrity model using UPVC pipes as struts and nylon rope as cables in the shape of a triangular prism. They performed material testing on the UPVC and nylon to characterize their properties. Finally, the authors discuss their methodology for designing the tensegrity prism and conclude that these structures have potential applications in construction due to their flexibility, economic efficiency, and light weight.
Numerical and Theoretical Analysis for Investigation of Shear strength of A J...ijsrd.com
This document presents a numerical and theoretical analysis of the shear strength of an adhesive joint used in an automotive application. Finite element analysis was conducted using ABAQUS software to determine the shear stresses induced in two adhesive materials joining a brake shoe assembly under an applied torque load. Shear stress values from the finite element analysis were validated using theoretical calculations. The results showed that one of the adhesive materials (Material 2) produced lower shear stresses than the other (Material 1) according to both the numerical and theoretical analyses. The study aimed to determine the optimal adhesive material and joint design to maximize shear strength for the automotive application.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Prediction of Ultimate Shear Strength of Moderate Deep Concrete Beam Includin...IRJET Journal
The document discusses predicting the ultimate shear strength of moderate deep concrete beams. It begins by defining shallow, moderate deep, and deep beams based on their span-to-depth and shear span-to-depth ratios. It then discusses how the stress distribution in moderate deep beams is non-linear and more complex than in shallow beams. The document proposes modifying an existing equation for predicting ultimate load by incorporating a size effect factor related to effective depth and compressive strength. The modified equation is checked against test data from 54 beams and shows good agreement compared to other code provisions and formulas.
This document summarizes research on the buckling failure of compressed cellular steel members. Cellular members have large circular openings in their web which makes them more efficient in material use than plain members, but also alters their failure behavior when loaded axially and in bending. Through finite element analysis of various geometries, the authors developed a design approach to calculate the ultimate failure load based on the member's weak-axis flexural buckling capacity. Preliminary results found the approach provides acceptable but conservative estimates of failure load compared to simulations. Further study of residual stresses is still needed to fully validate the design approach.
APPLYING DIFFERENT DECENTRALIZED LOADINGS ON RC CONTINUOUS DEEP BEAMS USING STMIAEME Publication
This research presents strut and tie modeling for the reinforced concrete
continuous deep beams that are subj
The different types of loadings area single concentrated force, two concentrated
forces, and a uniformly distributed load.
internal shear span to the effective depth r
current questions are presented besides the detailed numerical examples. It is
concluded that, in case of single concentrated force, reducing a/d from 1.36to 1.09,
0.81, and then to 0.54, increased the ultimate
respectively. It is also concluded that, in cases of two concentrated forces and
uniformly distributed load, reducing a/d from 1.09 to 0.81, 0.54 and then to 0.27,
increased the ultimate capacity by about 12%, 17% and 21
increment in the ultimate capacity occurred because upon moving the load from span
center toward the inner support, the length of the inner strut shortens and the
dimensions of its section increase significantly which leads to more str
that, in contrast, the length of the external strut increases and its dimensions decrease,
but this decrease in its dimensions is slight, making the weakness cause is due to that,
ineffective and therefore, indecisive.
Experimental study on bending behaviour of triangular web profile steel beam ...eSAT Journals
Abstract A triangular web profile (TRIWP) steel section is a section made of two flanges connected to a slender web. The web and the flanges can be produced from different steel grades depending on design requirements. The flanges width and thickness is determined based on the depth of the section. The web is corrugated at regular interval into triangular shape along the length of the beam. This paper describes an experimental study on the bending behavior in major (Ix) and minor (Iy) axes of Triangular Web Profile (TRIWP) compared to flat web (FW) steel sections. Two types of sizing involved which is 200×100×6×3mm and 180×75×5×2mm section. Each of beam section was modeled using several spans such as 3m, 4m and 4.8m. It was observed that the TRIWP section had a higher stiffness about minor axis compared to that of FW steel section but has lower stiffness about major axis. The analyses results show that the flexural stiffness for TRIWP1 is 0.794 times the Ix of the flat web steel section (FW1). Meanwhile, the flexural stiffness for TRIWP1 is 1.429 times the Iy of the flat web steel section (FW1). The findings for section TRIWP2 found to be similar to that of TRIWP1. For the section TRIWP2, it was observed that the value of Ix of TRIWP is 0.780 times the Ix of FW steel section which is less than that of FW. The Iy of TRIWP is 1.393 times the Iy of FW steel section which is more than that of FW steel section. Keywords: Flexural stiffness, Bending, Triangular web profile.
The relationship between stress and deformation will be covered in this section, and some of the important elastic material properties such as Young’s modulus and the modulus of rigidity will be defined.
Effect of lamination angle on maximum deflection of simply supported composit...RAVI KUMAR
In this project a composite laminated beam is studied with glass-epoxy and graphite-epoxy combination. The beam is composed of four layers of different combination of composite material (glass epoxy and graphite epoxy composite). The beam is simply supported at both the ends and is subjected to uniformly distributed load along the length. Transverse deflection is computed for different lamination angle (0^0-〖90〗^0) by using Euler- Bernoulli’s theory (or CLPT). Maximum transverse deflection analysis is carried out using derived analytical expressions. The research carried out in this project will enable to determine the beam strength due to bending loads. The importance of fibre reinforcement in the manufacturing of the beam is studied in terms of bending strength of the beam. MATLAB codes are generated to implement analytical expiations of the composite beam.
The main objective of the paper is to find out the lamination angle at which minimum deflection is obtained & to find out the effect of lamination angle on maximum transverse deflection of the beam.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Optimization of Tie rod using FEAIJERD Editor
Structural performance of any mechanical component is measured basically in terms of its natural frequency, deformation, stiffness, maximum stress level, fatigue life etc. In case of vehicle suspension system; however tie rod is mainly under compressive and fluctuating forces encounter from steering and bumping of vehicle. When steering acts to turn the vehicle, tie rod comes under compressive load. And when vehicle running on rough road condition, fluctuating forces.
The document discusses the analysis and design of beams subjected to bending. It provides examples of how to:
1) Determine shear and bending moment diagrams by drawing free body diagrams and applying equilibrium equations.
2) Calculate maximum shear forces and bending moments.
3) Relate loads, shears, and bending moments.
4) Select beam cross sections based on required section modulus to limit normal stresses to below allowable values.
1. The document presents research on predicting the ultimate shear strength of reinforced concrete deep beams of varying web reinforcement.
2. A new effectiveness coefficient (g) is introduced to understand the contribution of steel reinforcement during failure of deep beams under concentrated loads.
3. Based on a database of experimental beam tests, the proposed model is found to predict shear strength with good correlation, especially for beams with shear strengths over 500 kips.
This document outlines Renew GR's business ethics policy, which applies to all employees and volunteers. It addresses appropriate use of funds, compensation, computer/internet usage, social media, behavior at events and outside of work, political affiliations, whistleblowing procedures, and recycling/composting expectations. The policy is intended to ensure ethical conduct, prevent corruption, and have all staff represent Renew GR's mission.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Design for crash injuries mitigation using magnesium alloyeSAT Journals
Abstract This paper describes a computational investigation on the response of thin wall structures due to dynamic compression loading. In this paper, the tubes subjected for both direct and oblique loading. Several different cross-sectional structures have been studied to specify the best one. Initially the tubes were subjected to direct loading, and then the tubes were subjected to oblique loading. After that, the tubes were compared to obtain the cross section which fulfills the performance criteria. The selection was based on multi criteria decision making (MCDM) process. The performance parameters taken in this study are the specific energy absorbed by the tube for both direct and oblique, crush force efficiency and the ratio between the energy absorbed by direct and oblique loading. Trigger and foam filled are implemented to study their effects on the parameters used. The study used the magnesium alloy as a material to study potentially the possibility and ability of using the magnesium alloy in the energy absorber parts since the magnesium has lighter weight. Index Terms: dynamic compression, thin wall, energy absorption, direct oblique loading
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document contains a multiple choice quiz on concepts related to stress and strain in materials. There are 40 questions covering topics like:
- The relationships between elastic modulus, shear modulus, and Poisson's ratio for materials
- Calculating stresses and strains in loaded structures
- Principal stresses and maximum shear stress
- Mohr's circle representation of stresses
- Elastic properties like modulus of elasticity, modulus of resilience
- Stresses in loaded bars, beams, and other basic structural elements
The questions require applying stress/strain and material property equations to calculate values or identify correct statements regarding stresses and deformations in loaded materials and structures.
This document presents a finite element model of chain-link wire nets used in rockfall protection barriers. Chain-link nets have loose connections that allow for flexibility but make modeling the contact interactions complex. The study develops an improved finite element model that uses a general contact algorithm to model the complex contact between chain-link elements. Laboratory tensile tests on chain-link nets are performed and used to calibrate the model parameters. The calibrated model is shown to accurately simulate a full-scale rockfall barrier test, demonstrating the model's ability to realistically simulate the mechanical behavior of chain-link wire nets.
Parameter identification of rockfall protectionJuan Escallón
This document presents a numerical approach to parameterize macroscopic finite element models of rockfall protection barrier components through an inverse formulation. The components modeled include wire-ring nets and spiral cables, which are key flexible elements in rockfall barriers. Laboratory tests are used to characterize the highly nonlinear force-displacement behavior of these components under tension. Macroscopic finite element models of the components are developed using beam elements to represent the wires and cables. Additional parameters are included to simulate the nonlinear response. An inverse optimization process using a multi-island genetic algorithm is employed to determine the model parameters that best match the laboratory test data. The accuracy of the approach is then verified by simulating a full-scale rockfall barrier prototype test.
Fabrication and Analysis of Tensegrity Based Prism structureIRJET Journal
This document discusses the fabrication and analysis of a tensegrity-based prism structure. It begins with an introduction to tensegrity structures, which are composed of both compressive struts and tensile cables. The authors then describe how they fabricated a Class-I tensegrity model using UPVC pipes as struts and nylon rope as cables in the shape of a triangular prism. They performed material testing on the UPVC and nylon to characterize their properties. Finally, the authors discuss their methodology for designing the tensegrity prism and conclude that these structures have potential applications in construction due to their flexibility, economic efficiency, and light weight.
Numerical and Theoretical Analysis for Investigation of Shear strength of A J...ijsrd.com
This document presents a numerical and theoretical analysis of the shear strength of an adhesive joint used in an automotive application. Finite element analysis was conducted using ABAQUS software to determine the shear stresses induced in two adhesive materials joining a brake shoe assembly under an applied torque load. Shear stress values from the finite element analysis were validated using theoretical calculations. The results showed that one of the adhesive materials (Material 2) produced lower shear stresses than the other (Material 1) according to both the numerical and theoretical analyses. The study aimed to determine the optimal adhesive material and joint design to maximize shear strength for the automotive application.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Prediction of Ultimate Shear Strength of Moderate Deep Concrete Beam Includin...IRJET Journal
The document discusses predicting the ultimate shear strength of moderate deep concrete beams. It begins by defining shallow, moderate deep, and deep beams based on their span-to-depth and shear span-to-depth ratios. It then discusses how the stress distribution in moderate deep beams is non-linear and more complex than in shallow beams. The document proposes modifying an existing equation for predicting ultimate load by incorporating a size effect factor related to effective depth and compressive strength. The modified equation is checked against test data from 54 beams and shows good agreement compared to other code provisions and formulas.
This document summarizes research on the buckling failure of compressed cellular steel members. Cellular members have large circular openings in their web which makes them more efficient in material use than plain members, but also alters their failure behavior when loaded axially and in bending. Through finite element analysis of various geometries, the authors developed a design approach to calculate the ultimate failure load based on the member's weak-axis flexural buckling capacity. Preliminary results found the approach provides acceptable but conservative estimates of failure load compared to simulations. Further study of residual stresses is still needed to fully validate the design approach.
APPLYING DIFFERENT DECENTRALIZED LOADINGS ON RC CONTINUOUS DEEP BEAMS USING STMIAEME Publication
This research presents strut and tie modeling for the reinforced concrete
continuous deep beams that are subj
The different types of loadings area single concentrated force, two concentrated
forces, and a uniformly distributed load.
internal shear span to the effective depth r
current questions are presented besides the detailed numerical examples. It is
concluded that, in case of single concentrated force, reducing a/d from 1.36to 1.09,
0.81, and then to 0.54, increased the ultimate
respectively. It is also concluded that, in cases of two concentrated forces and
uniformly distributed load, reducing a/d from 1.09 to 0.81, 0.54 and then to 0.27,
increased the ultimate capacity by about 12%, 17% and 21
increment in the ultimate capacity occurred because upon moving the load from span
center toward the inner support, the length of the inner strut shortens and the
dimensions of its section increase significantly which leads to more str
that, in contrast, the length of the external strut increases and its dimensions decrease,
but this decrease in its dimensions is slight, making the weakness cause is due to that,
ineffective and therefore, indecisive.
Experimental study on bending behaviour of triangular web profile steel beam ...eSAT Journals
Abstract A triangular web profile (TRIWP) steel section is a section made of two flanges connected to a slender web. The web and the flanges can be produced from different steel grades depending on design requirements. The flanges width and thickness is determined based on the depth of the section. The web is corrugated at regular interval into triangular shape along the length of the beam. This paper describes an experimental study on the bending behavior in major (Ix) and minor (Iy) axes of Triangular Web Profile (TRIWP) compared to flat web (FW) steel sections. Two types of sizing involved which is 200×100×6×3mm and 180×75×5×2mm section. Each of beam section was modeled using several spans such as 3m, 4m and 4.8m. It was observed that the TRIWP section had a higher stiffness about minor axis compared to that of FW steel section but has lower stiffness about major axis. The analyses results show that the flexural stiffness for TRIWP1 is 0.794 times the Ix of the flat web steel section (FW1). Meanwhile, the flexural stiffness for TRIWP1 is 1.429 times the Iy of the flat web steel section (FW1). The findings for section TRIWP2 found to be similar to that of TRIWP1. For the section TRIWP2, it was observed that the value of Ix of TRIWP is 0.780 times the Ix of FW steel section which is less than that of FW. The Iy of TRIWP is 1.393 times the Iy of FW steel section which is more than that of FW steel section. Keywords: Flexural stiffness, Bending, Triangular web profile.
The relationship between stress and deformation will be covered in this section, and some of the important elastic material properties such as Young’s modulus and the modulus of rigidity will be defined.
Effect of lamination angle on maximum deflection of simply supported composit...RAVI KUMAR
In this project a composite laminated beam is studied with glass-epoxy and graphite-epoxy combination. The beam is composed of four layers of different combination of composite material (glass epoxy and graphite epoxy composite). The beam is simply supported at both the ends and is subjected to uniformly distributed load along the length. Transverse deflection is computed for different lamination angle (0^0-〖90〗^0) by using Euler- Bernoulli’s theory (or CLPT). Maximum transverse deflection analysis is carried out using derived analytical expressions. The research carried out in this project will enable to determine the beam strength due to bending loads. The importance of fibre reinforcement in the manufacturing of the beam is studied in terms of bending strength of the beam. MATLAB codes are generated to implement analytical expiations of the composite beam.
The main objective of the paper is to find out the lamination angle at which minimum deflection is obtained & to find out the effect of lamination angle on maximum transverse deflection of the beam.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance Optimization of Tie rod using FEAIJERD Editor
Structural performance of any mechanical component is measured basically in terms of its natural frequency, deformation, stiffness, maximum stress level, fatigue life etc. In case of vehicle suspension system; however tie rod is mainly under compressive and fluctuating forces encounter from steering and bumping of vehicle. When steering acts to turn the vehicle, tie rod comes under compressive load. And when vehicle running on rough road condition, fluctuating forces.
The document discusses the analysis and design of beams subjected to bending. It provides examples of how to:
1) Determine shear and bending moment diagrams by drawing free body diagrams and applying equilibrium equations.
2) Calculate maximum shear forces and bending moments.
3) Relate loads, shears, and bending moments.
4) Select beam cross sections based on required section modulus to limit normal stresses to below allowable values.
1. The document presents research on predicting the ultimate shear strength of reinforced concrete deep beams of varying web reinforcement.
2. A new effectiveness coefficient (g) is introduced to understand the contribution of steel reinforcement during failure of deep beams under concentrated loads.
3. Based on a database of experimental beam tests, the proposed model is found to predict shear strength with good correlation, especially for beams with shear strengths over 500 kips.
This document outlines Renew GR's business ethics policy, which applies to all employees and volunteers. It addresses appropriate use of funds, compensation, computer/internet usage, social media, behavior at events and outside of work, political affiliations, whistleblowing procedures, and recycling/composting expectations. The policy is intended to ensure ethical conduct, prevent corruption, and have all staff represent Renew GR's mission.
This document summarizes a case study of a 52-year-old man with treatment-refractory mood lability and aggression due to traumatic brain injury. He responded well to two separate trials of amantadine, with remission of symptoms during both trials. Amantadine is not commonly used but may be effective for these symptoms where other medications have failed or caused intolerable side effects. The case suggests amantadine should be considered more for treatment-refractory behavioral issues following traumatic brain injury.
This document summarizes and reviews a book about the lives of Indian women. It provides an introduction to the book and its author, a brief summary of the book's content and perspective, and reviews some of the most important chapters. The book uses case studies and research to examine issues facing Indian women like dowry deaths, female infanticide, and arranged marriages from a observational, non-stereotypical lens. It aims to provide insight into the lives and roles of women across India from various perspectives.
This document summarizes research on a low-rise concentrically braced frame building equipped with dissipative pin connections. It describes:
1) Experimental testing of a single-pin connection that dissipates energy through flexure of the pin, allowing braces to behave elastically.
2) Computer modeling using OpenSees of a one-story braced frame with these connections, validated against experimental results.
3) A comparative study of the braced frame's seismic response with and without dissipative connections.
The document summarizes the political history and conflicts in Egypt since the 1950s. It discusses Egypt's transition from a British colony to a republic led by Nasser and various other presidents. It then focuses on the Arab Spring protests that overthrew Mubarak in 2011, the subsequent election of Morsi, and his eventual overthrow by the military. It concludes by noting Egypt has essentially returned to square one with an interim government and plans for new elections.
The document discusses how wealthy philanthropists in Grand Rapids, Michigan have sparked a modern Renaissance by funding the arts, education, and culture over several generations, similar to wealthy families during the Italian Renaissance like the Medicis. It provides examples of philanthropists like Peter Wege, Frederik Meijer, Richard DeVos, Jay Van Andel, and Peter Cook who have donated billions to organizations, buildings, and attractions in Grand Rapids that have elevated the city's reputation and quality of life through supporting areas like the arts, gardens, hospitals, and more. Their generous contributions have transformed Grand Rapids into a cultural and economic center much like cities during the original Renaissance.
This document describes a study analyzing the seismic performance of a 2-story concentrically braced frame (CBF) building with and without dissipative single-pin connections using OpenSees software. It first provides details on the design and modeling of the single-pin connection, which is intended to improve the seismic response of CBFs by allowing full development of brace compressive strength. It then describes the OpenSees model of the connection and calibration against experimental data. Finally, it outlines the numerical analysis conducted, including design of the CBF building based on Canadian standards and comparison of the seismic response of the building with and without pin connections.
The document discusses biometrics and lists several group members. It describes two types of biometric recognition - identification and verification. Some common biometric traits are fingerprints, face recognition, iris scans, and hand geometry. Biometrics work by recording and comparing unique human characteristics digitally. Popular applications include security access, law enforcement, banking, and time/attendance systems. Common biometric devices include iris scanners, fingerprint scanners, and facial recognition systems. Both advantages and disadvantages of different biometric traits are outlined.
Numerical modeling on behaviour of reinforced concrete exterior beam column j...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Paper " STRUT-AND-TIE MODEL AND 3-D NONLINEAR FINITE ELEMENT ANALYSIS FOR THE...Waleed E. El-Demerdash
This document discusses the use of strut-and-tie modeling and 3D nonlinear finite element analysis to predict the behavior of reinforced concrete shallow and deep beams with openings. It presents the development of strut-and-tie models based on experimental results for selected beams. Finite element analysis using ANSYS is also employed for selected beams to complement the strut-and-tie model results. A parametric study investigates factors affecting beam behavior. Comparisons are made between finite element results, strut-and-tie model results, and experimental data.
IRJET-Cyclic Response of Perforated Beam in Steel Column JointsIRJET Journal
This document summarizes a study on the cyclic response of perforated steel beams in column joints under finite element analysis. The study analyzed the effect of various web opening parameters on the energy dissipation capacity of beams with circular and elongated circular openings. A finite element model was validated against experimental data and then used to conduct a parametric study. The study found that energy dissipation increased as opening size and dimensions increased, with maximum dissipation achieved when the opening depth was 80% of the beam depth. Openings with an elongated circular shape oriented across the beam depth also dissipated more energy than other orientations. In general, beams with larger perforations performed better in dissipating energy during cyclic loading.
2001 iabse - Reliability Assessment of Cable-Stayed BridgesFranco Bontempi
IABSE Conference on Cable-Supported Bridges
June 12–14, 2001, Seoul, Korea
The paper deals with the reliability assessment of P.C. cable-stayed bridges, but it is thought that the presented methodology is generally applicable. Due to several sources of uncertainties, the geometrical and mechanical properties which define the structural problem cannot be considered as deterministic quantities. In this work, such uncertainties are modelled by using a fuzzy criterion which considers the model parameters bounded between minimum and maximum suitable values.
The reliability problem is formulated in terms of safety factor and the membership function over the failure interval is derived for several limit states by using a simulation technique. In particular, the strategic planning of the simulation is found by means of a genetic optimisation algorithm and the structural analyses are carried out by taking both material and geometrical non-linearity into account. An application to a cable-stayed bridge shows the effectiveness of the proposed procedure.
Reliability Assessment of Cable-Stayed BridgesFranco Bontempi
The paper deals with the reliability assessment of P.C. cable-stayed bridges, but it is thought that
the presented methodology is generally applicable. Due to several sources of uncertainties, the
geometrical and mechanical properties which define the structural problem cannot be considered as deterministic quantities. In this work, such uncertainties are modelled by using a fuzzy criterion which considers the model parameters bounded between minimum and maximum suitable values. The reliability problem is formulated in terms of safety factor and the membership function over the
failure interval is derived for several limit states by using a simulation technique. In particular, the strategic planning of the simulation is found by means of a genetic optimisation algorithm and the structural analyses are carried out by taking both material and geometrical non-linearity into
account. An application to a cable-stayed bridge shows the effectiveness of the proposed procedure.
Reliability Assessment of Cable-Stayed BridgesFranco Bontempi
This document discusses a methodology for reliability assessment of cable-stayed bridges that considers uncertainties in geometric and material properties. A case study application to a cable-stayed bridge in Brazil is presented. Non-linear structural analyses are performed through simulation to derive membership functions for safety factors associated with limit states of failure. An optimized sampling method using genetic algorithms is proposed to refine the simulation results and provide more accurate minimum safety factors.
The document describes an extension to the brittle cracking concrete material model in ABAQUS. The extension adds nonlinear compressive behavior using a user subroutine. The extended model is validated by comparing it to the original brittle cracking model and damaged plasticity model under uniaxial loading. The extended model is also shown to capture strain rate effects observed in experiments. Finally, the extended model is used to simulate benchmark cases including a notched concrete beam, demonstrating its ability to model tensile failure of concrete structures.
Implementation of a tension-stiffening model for the cracking nonlinear analy...Luis Claudio Pérez Tato
The development of a smeared-crack model offers a general crack-modeling method that is independent of the structural configuration. It treats cracking as a constitutive material behaviour rather than a geometric discontinuity and lends itself well to implementation in large finite element codes. This paper deals with the implementation in XC of a constitutive model for reinforced concrete elements that takes into account the increase in stiffness of a cracked member due to the development of tensile stresses in the concrete between the cracks, effect known as tension-stiffening. The nonlinear analysis in XC of fiber-like sections with this constitutive model allows for a more general, direct and intuitive evaluation of the crack amplitude than applying the mostly specific formulae developed in the standards. The numerical results obtained by the program compare extremely well with existing designing results issued by other applied methods.
Finite Element Modeling of RCC voided Beam and it’s comparison with conventio...inventionjournals
This document presents a finite element analysis of reinforced concrete beams both with and without transverse web openings. The analysis models the beams in ANSYS and validates the results against experimental testing. It finds that beams with circular or rectangular openings experience higher stresses and deflections compared to conventional solid beams without openings. Additional reinforcement is needed around openings to reduce stresses. The maximum stresses occur near openings. This paper compares the performance of beams with openings to solid beams to determine how openings affect behavior and appropriate reinforcement design.
Construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the type of Reinforced Concrete (RC) beams with transverse web openings. Various design approaches and strengthening techniques are also presented.
Probabilistic Design of Hollow Circular Composite Structure by using Finite E...IJERA Editor
This document summarizes a study that uses finite element analysis to analyze the bending stress of a hollow circular composite beam under static loading conditions while accounting for uncertainty in design variables. A probabilistic design system is used to simulate the effects of varying the beam's length, radius, material properties, ply angles, thickness, and applied load on the bending stress. The results identify that variation in load, radius, modulus, ply thickness, and angles have the most significant effect on bending stress. The analysis finds the bending stress can range from 104 to 392 MPa with a 90% probability of being below 250 MPa. Improving the robustness of the design may require addressing variables with the highest sensitivity on bending stress.
This paper presents a model for calculation of torsion capacity of the reinforced concrete beams using the artificial neural network. Considering the complex reaction of reinforced concrete beams under torsion moments, torsion strength of these beams is depended on different parameters; therefore using the artificial neural network is a proper method for estimating the torsion capacity of the beams. In the presented model the beam's dimensions, concrete compressive strength and longitudinal and traverse bars properties are the input data, and torsion capacity of the reinforced concrete beam is the output of the model. Also considering the neural network results, a sensitivity analysis is performed on the network layers weight, and the effect of different parameters is evaluated on the torsion strength of the reinforced concrete beams. According to the sensitivity analysis, properties of traverse steel have the most effect on torsion capacity of the beams.
Design and analysis of stress ribbon bridgeseSAT Journals
Abstract
A stressed ribbon bridge (also known as stress-ribbon bridge or catenary bridge) is primarily a structure under tension. The tension cables form the part of the deck which follows an inverted catenary between supports. The ribbon is stressed such that it is in compression, thereby increasing the rigidity of the structure where as a suspension spans tend to sway and bounce. Such bridges are typically made RCC structures with tension cables to support them. Such bridges are generally not designed for vehicular traffic but where it is essential, additional rigidity is essential to avoid the failure of the structure in bending. A stress ribbon bridge of 45 meter span is modelled and analyzed using ANSYS version 12. For simplicity in importing civil materials and civil cross sections, CivilFEM version 12 add-on of ANSYS was used. A 3D model of the whole structure was developed and analyzed and according to the analysis results, the design was performed manually.
Keywords: Stress Ribbon, Precast Segments, Prestressing, Dynamic Analysis, Pedestrian Excitation.
Design and analysis of stress ribbon bridgeseSAT Journals
Abstract
A stressed ribbon bridge (also known as stress-ribbon bridge or catenary bridge) is primarily a structure under tension. The tension cables form the part of the deck which follows an inverted catenary between supports. The ribbon is stressed such that it is in compression, thereby increasing the rigidity of the structure where as a suspension spans tend to sway and bounce. Such bridges are typically made RCC structures with tension cables to support them. Such bridges are generally not designed for vehicular traffic but where it is essential, additional rigidity is essential to avoid the failure of the structure in bending. A stress ribbon bridge of 45 meter span is modelled and analyzed using ANSYS version 12. For simplicity in importing civil materials and civil cross sections, CivilFEM version 12 add-on of ANSYS was used. A 3D model of the whole structure was developed and analyzed and according to the analysis results, the design was performed manually.
Keywords: Stress Ribbon, Precast Segments, Prestressing, Dynamic Analysis, Pedestrian Excitation.
This document discusses the results of an investigation into splitting of timber dowel joints. It summarizes the following key points in 3 sentences:
The document critiques the empirical methods used in previous studies, arguing they do not fit theoretical models and have high variability. It then precisely fits the experimental data from one study to limit analysis theory, demonstrating a 10% coefficient of variation. The analysis shows the empirical data can be trusted but that exact theory, not empirical approaches, provides the proper design rules for timber dowel joints.
Bolted Joints Analysis Methods and EvaluationIJMER
Calculation of accurate bolt forces is the primary requirement in many industries. All the
theoretical calculations for bolt forces, includes many significant assumption based on idealized
mechanical models. In this paper two models of flange joints were taken and analyzed
forpretensionvariation due to internal temperature changes, And for theForces induced in the bolt due to
the combined effect of external forces applied and internal temperature change. The results were utilized
to gain insight into joint softening that arises from gradual, nonlinear opening of flange gap under
external tension. Later these results were compared with the theoretical calculations, and our models
allow relaxations for many assumptions in theoretical calculations
This document provides information on the design and behavior of eccentrically braced frames (EBFs). The key points are:
(1) EBFs resist lateral loads through a combination of frame and truss action, with inelastic behavior restricted to links.
(2) Links are designed to have high ductility and act as "fuses" that develop plastic hinges. Other members remain elastic.
(3) Link behavior depends on its length. Short links undergo shear yielding while long links undergo flexural yielding. Intermediate links experience both.
(4) Experimental tests show short links have the highest ductility capacity followed by intermediate then long links. Designs aim to match link
Numerical study on behaviour eccentrically loaded double circular steel tubul...IRJET Journal
This document presents a numerical study on the behavior of eccentrically loaded double circular steel tubular short columns filled with concrete. An Abaqus finite element model was developed and validated against experimental results from literature. The model considered material nonlinearities, confinement effects, and bond. Comparisons showed good agreement between experimental and numerical load-displacement curves, capacities, and failure modes. Parametric studies were then conducted using the model to analyze the performance of columns with varying geometries, materials, and loading conditions. The research aims to enhance understanding and modeling of these composite columns to inform design practices.
Comparative Study on Anchorage in Reinforced Concrete Using Codes of Practice...IJERA Editor
This paper (Part II) reports a comparative study for BS8110 and EC2 of practice and those expressions by Batayneh and Neilsen on tests from literature. These have been treated under straight bar anchorages with transverse pressure. The aim of this study is to evaluate the reliability of the existing equations for bond strength of straight bars by applying to the available tests in the literature .The most important parameters were examined in these tests are concrete strength, anchorage length, concrete covers, bar diameter and transverse pressure. 264 tests from the literature have been chosen, which are all for straight bars with transverse pressure. The specimens are pull-out specimens with small concrete covers, beams ends and slabs. For both comparative studies in Part I and Part II, the conclusions and recommendations are presented here together.
2. project [12]. The brace-column pin connection consists of two outer-
plates welded or bolted to column flanges, two inner-plates welded to
the brace and a rectangular pin member with rounded corners running
through the four plates. As illustrated in Fig. 1a, the configuration of pin
device depends on the size and depth of the CBF column's cross-section
that governs the pin's length, Lpin, while the size of the pin member de-
pends on the probable compressive resistance of the connected brace,
Cu, and the distance between the inner-plates (Lpin-2a). As illustrated
in Fig. 1b, parameter a is the distance between the outer-plate and the
centerline of the inner-plate. The pin element is proportioned to yield
in flexure under a force equating 60% Cu of the attached hollow structur-
al section brace, HSS [10].
In this study, the behaviour of single-pin device is analysed through
numerical modelling, developed in the OpenSees framework version
2.2.0 [11]. Then, the single-pin connection model is calibrated against
results obtained from experimental tests, conducted at Technical Uni-
versity of Lisbon, Portugal [12]. When large axial forces need to be trans-
ferred from braces to CBF columns through connections, the available
sizes of single-pin member may not be sufficient. To overcome this
limit, the authors proposed an innovative double-pin connection with
pins displaced either in-parallel or in-line, as illustrated in Fig. 2. By
employing the same design approach as that used for the single-pin de-
vice, the proposed double-pin connection is analysed in both configura-
tions through theoretical and numerical modelling with the aim of
sizing the specimens and preparing the upcoming experimental tests.
3. Design and behaviour of single-pin connection device
To validate the design method for the single-pin connection device,
two numerical models are employed and defined as follows: the theo-
retical beam model and the OpenSees beam model. Regarding the the-
oretical beam model, the same approach considered by Vayas and
Thanopoulos [13] and refined by Tirca et al. [8] is used to size the pin
cross-section and the connection's components. Then, the theoretical
beam model was replicated in the OpenSees framework with the aim
of investigating the stress versus strain development along the pin
cross-section, as well as the length of plastic zone resulted under incre-
mental static loading up to failure. By using data from both theoretical
and OpenSees beam models, the authors replicate two experimental
tests conducted at the Technical University of Lisbon under quasi-
static displacement loading. The calibration of the model is validated
when both the experimental and simulated models match in terms of
hysteresis loops generated from plotting the force versus displacement
and the cumulative dissipated energy.
3.1. Theoretical beam model
The behaviour of the single-pin device in terms of its capacity to dis-
sipate energy under cyclic loading is influenced by the following param-
eters: the length of the pin, Lpin, its cross-sectional shape and size, as
well as the distance between the inner-plates (Lpin-2a). As illustrated
in Fig. 1, the axial force developed in the brace, P, is transferred to the
pin through the two inner-plates as uniformly distributed loads which
act along the thickness of the plates. For simplicity, the pin is considered
to behave as a four-point loaded beam, where the concentrated load P/2
is the resultant of the uniformly distributed force, as is shown in Fig. 3a.
When the yielding moment My = WyFy is reached, the pin starts
to yield in bending under the applied point load Py/2, where Py/2 =
My/a. By employing Hooke's law, yielding of pin is initiated when the
maximum normal strain that is developed at the top and bottom fiber
of the rectangular pin's cross-section (bp x hp) is εy = Fy/E, where bp
and hp are the dimensions of pin's cross-section and E is the modulus
of elasticity. Thus, the applied Py/2 loads bent the simply supported
beam in single curvature as illustrated in Fig. 3c. It is noted that 1 mm
clearance was provided between the pin and the outer-plate hole [14],
which meets the requirements of the current standard [1]. The
deflection required to produce material's yielding at the pin's mid-
span is δy = ρ(1 − cos(Lpin/2ρ)), where ρ is the radius of curvature
and the curvature is defined as ky = 1/ρ = 2εy/hp. However, the strain
corresponding to the static yield stress may be two to five times the
yield strain εy [15]. At this stage, the strain considered to compute the
static yield stress, εI, is expressed as: εI = 1.5εy and the corresponding
curvature becomes kI = 2(1.5εy)/hp and ρI = hp/(3εy). The maximum
deflection computed at the pin's mid-span is given by Eq. (1) and the
maximum deflection under the point of loading may be obtained by
multiplying δy with the ratio 2a/Lpin. Although the provided deflection
equation applies rigorously for the case of pure bending, as is the seg-
ment between inner-plates, the assumption that cross-sections remain
plane and perpendicular to the deformed axis leads to expressions for
normal strain ε and stress σ that are quite accurate in the elastic range
even in the case of non-uniform bending (dM/dx = V(x) ≠ 0), as are
the segments between outer- and inner-plate [16]. The yielding mo-
ment, My = WyFy, is reached under the application of two Py/2 loads
that are defined in accordance with Eq. (2).
δy ¼ δI ¼ hp=3εy
1– cos 1:5Lpinεy=hp
ð1Þ
PI ¼ Py ¼ 2My=a ð2Þ
For a rectangular cross-section, the ratio between the plastic mo-
ment Mp and My equates the shape factor given by Wy/Wp = 1.5.
After the attainment of My, some clamping forces start developing at
the pin's ends and in consequence the boundary conditions gradually
allow the development of end bending moment (Fig. 3b). By equating
the external work, Pδ/2 = P(φa)/2, with the internal work,
(M1 + M2)φ, where φ is the rotation as illustrated in Fig. 3c, the magni-
tude of the ultimate load carried by the beam, PII, is given in Eq. (3). It is
estimated that the ultimate flexural capacity of the pin member, Mu, is
computed as: Mu = WpFu, where Fu is the steel ultimate strength.
Under the two-point loads Pu/2, the ultimate strain, εII, is approximated
as being equal to εII = 50εy = 0.1 and the corresponding curvature is
kII = 2εII/hp = 0.2/hp. The value of the ultimate plastic rotation, φu,
b)a)
Fig. 1. Dissipative single-pin connection: a) 3-D view; b) detail.
Fig. 2. Dissipative double-pin connections: a) pins in-paralel; b) pins in-line.
138 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
3. becomes φu = kIIlp = lp(0.2)/hp radians. Herein, the length of the plas-
tic hinge, lp, is anticipated as being 1.25 times the height of the pin's
cross-section, hp. As presented hereafter, the development of the plastic
hinge length may vary with the distance between the inner-plates and
the magnitude of the applied forces. The ultimate deflection, δII, at dis-
tance a from the pin's support is given in Eq. (4).
PII ¼ Pu ¼ 2 M1 þ M2ð Þ=a e 4Mu=a ð3Þ
δII ¼ φIIa ¼ δu ¼ lp=hp
0:2að Þ ¼ 1:25 0:2að Þ ð4Þ
During the incursions in plastic range, the magnitude of load PII may
slightly increase due to material strain hardening to a value PIII, while
the maximum deflection of pin at failure is estimated to be δIII = 0.4a
[13,14]. The failure mechanism is depicted in Fig. 3d and is formed
when plastic hinges are developed at the location where maximum
bending moment is reached. By employing Eqs. (1) to (4) and the pa-
rameters at failure: PIII and δIII, the pin response follows a tri-linear
curve as illustrated in Fig. 3e.
3.2. OpenSees beam model
The purpose of developing the OpenSees beam model is to simulate
the behaviour of the pin in its outer-plate supports and to measure the
developed strains, stresses, and deformations. Thus, until the yielding
moment is reached, the pin behaves as a simply supported beam.
Then, by increasing the applied loads, the pin member behaves in the
plastic range and its deformed shape causes bearing pressure to the con-
tact surface of the outer-plate hole, which is the pin's support. In this
stage, bending moment is generated at both pin ends and its magnitude
is incremented until the pin reaches its failure mechanism. The develop-
ment of bending moment diagram across the pin's length depends on
the pin-to-outer-plate stiffness ratio, (Ipin/Lpin)/(Iop/Hop). When the
aforementioned ratio approaches zero, the pin member imposes no re-
straint on joint rotation and it behaves as a pure fixed–fixed member,
while it triggers the largest axial compression force. It is desirable to
optimize the size of outer-plates such that the mid-span bending mo-
ment to be slightly larger than that developed at the pin's support. To
satisfy this demand, the outer-plate should be sized to comply with
the following expression: (Ipin/Lpin)/(Iop/Hop) = 0.5. The OpenSees
beam model simulates the behaviour of the pin member acting in elastic
range as a four-point loaded beam and in the non-linear range as a
clamped–clamped member, as previously described.
The model shown in Fig. 4 consists of eight nonlinear beam-
column elements with distributed plasticity and four integration
points per element. The pin's cross-section is made up of 60 fibers.
Among them, 12 fibers are assigned along the height of the cross-
section, hp, and 5 along its width, bp, as illustrated in Fig. 4. The length
of the pin, Lpin, is the clear span between the outer-plates, which act
as supports. Herein, the pin's supports (outer-plates) are modelled
as rigid links of length Hop, which represents the free length. When
the applied forces increase, large bearing stresses develop in the
pin's hole support. Further, due to the enlargement of these holes
pinching occurs. To simulate this behaviour, a zero-length element
object that is defined between two nodes generated at the same loca-
tion is added at the connection between pin and outer-plates, as il-
lustrated in Fig. 4. These nodes of identical coordinates are
connected by springs, with the aim to represent the force–deforma-
tion relationship exhibited by the pin in the outer-plate supports.
The uniaxial material assigned to the pin member and rigid links is
Steel02, which is also known as Giuffre-Menegotto-Pinto material.
It is recommended that the steel strength of plates to be the same
with that of the pin. Nonetheless, the length and thickness of the
outer-plates influence the behaviour of the connection, while the de-
flection of the pin controls the transversal deflection of outer-plates.
When the pin member behaves elastically, both links (outer-plates)
act as cantilever members with a stiffness Kop = 3EopIop/Hop
3
, where
EopIop is the flexural stiffness of the link. To simulate the non-linear
behaviour of pin member in the outer-plate supports, two transla-
tional springs were added in the zero-length element, in the x-
direction and one is the y-direction. Among them, one spring is
made of Steel02 material and others of Pinching4 material that is de-
fined in the OpenSees library [17]. The Pinching4 material represents
a)
b) d)
c) e)
Fig. 3. Theoretical beam model: a) elastic; b) plastic; c) deformed shape; d) plastic mechanism; e) tri-linear curve.
139L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
4. a pinched force-deformation response and it allows users to simulate
the deformed shape of the pin in the outer-plate's hole support after
the pin member is loaded below its elastic bending capacity.
The OpenSees beam model was developed by using data from two
experimental tests conducted at the Technical University of Lisbon,
and the employed specimens, PA-9 and P-3, are shown in Fig. 5.
The pin member considered in the experimental test has a solid rect-
angular shape with rounded corners and was mounted in the weak
axis as illustrated in Fig. 1. The difference between PA-9 and P-3
specimen is only the distance between the inner-plates. In both
cases, the pin is made of steel with the following characteristics:
Fy = 396 MPa and Fu = 558 MPa, while the pin's cross-sectional di-
mensions are 60 × 40 mm. The tri-linear curves of both specimens,
PA-9 and P-3, are built by using the theoretical values computed
with Eqs. (1) to (4) and are plotted in Fig. 6a.
To investigate the correlation between the theoretical tri-linear
curve and that resulted from the OpenSees beam model, an incremental
analysis is performed. Pairs of applied forces and deflections recorded
under the point of loading are plotted in Fig. 6b together with the theo-
retical tri-linear curve. In addition, at each incremental loading applica-
tion, the strain and stress corresponding to each one of the 12 fibers are
recorded at beam's mid-span of specimen PA-9 and are plotted in Fig. 7.
Thus, when both forces Py/2 are applied to the OpenSees beam model, as
illustrated in Fig. 4, the strain recorded in the extreme fibers of the mid-
span cross-section is εy and the associated stress is Fy. By using the ge-
ometry of PA-9 specimen, the force Py computed with Eq. (2) is
145 kN. As depicted in Fig. 7, under PII forces, the numerical model
shows a slight difference in strain and stress recorded at the extreme
tension and compression fiber of the pin's mid-span length. Herein,
the strain in the tensile fibers is about 12% larger than that in compres-
sion fibers, while the variation of stresses in fibers is between Fy and Fu.
Thus, the analytical and the OpenSees beam models show a good corre-
lation and the stress and strain diagrams validate the theoretical equa-
tions previously devised.
To analyse the propagation of plasticity along the pin's length under
incremented static loads, the strain time-history series, developed in the
extreme fibers, is investigated. In this numerical model, the pin member
is divided in eight force-based beam-column elements, rigidly connect-
ed, as illustrated in Fig. 8a. These beam-column elements are made of
cross-sections based on fiber formulation, while the depth of pin's
cross-section is divided in 12 fibers, in conformity with Fig. 4. Each
fiber made of Steel02 material is defined by an area and a location (x,
y). As shown in Fig. 8a, four Gauss-Lobatto integration points are placed
along each element and the force-deformation response at each integra-
tion point is recorded at the defined section.
To define the length of the developed plastic zone exhibited by the
pin member, the values corresponding to the strain — deflection curve
are recorded at the upper and lower fiber (1 and 12, respectively) of sec-
tions belonging to the integration points of elements number 3 and 4
(Fig. 8a). As shown in Fig. 8b, when the applied force increases above
the elastic range, the portion of the pin between the inner-plates de-
forms in the non-linear range under the developed constant bending
moment. The larger deflection is recorded at the pin's mid-span, while
the larger strain is recorded at the location of inner-plates. Fiber 12 be-
longing to the tension surface shows a slightly larger strain than fiber 1,
located at the compression surface. This difference increases with the
magnitude of applied forces. For the modelled PA-9 specimen, the
strain-deflection curves of extreme fibers located between the inner-
plates show a linear relationship. In this example, the left inner-plate in-
tersects the pin member in the vicinity of section 4 of element 3
(Fig. 8a). For the half-length pin, it is observed that the plastic region
length ends close to section 2 of element 3, which corresponds to a dis-
tance of hp/2 measured from the inner-plate, where hp is the depth of
the pin member. As illustrated in Fig. 8b, the maximum deflection at
pin's mid-span is 36 mm.
Similarly, Fig. 9 illustrates the strain and stress diagram of the P-3
specimen model that is measured in each one of the 12 fibers located
at the pin's mid-span. The difference between the P-3 and PA-9 speci-
mens was set by the distance a, which in case of P-3 was reduced by
13%. Thus, the pin of the P-3 specimen is able to transfer a force that is
113% larger (690 kN versus 612 kN), while exhibiting lower strain. As
depicted in Fig. 9, the strain recorded in the extreme fibers at the pin's
mid-span length displays values that are lower by 13%. A schematic rep-
resentation of the pin member of the P-3 specimen model is shown in
Fig. 4. OpenSees beam model of single-pin device.
50
15
80
40
80
30
P-A9
15
40
70
P-3
7070
30
60 60
PA -9 P-3
Fig. 5. The geometry of specimens P-A9 and P-3.
140 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
5. Fig. 10a and the time-history series of strain-deflection curves of the ex-
treme tension and compression fibers (12 and 1) are depicted in
Fig. 10b. In the case of P-3 specimen model, the strain-deflection curves
show a weaving behaviour with a sharp increasing in strain for forces
larger than 612 kN. The maximum strain is experienced by fiber 12 of
element 3, section 4, located in vicinity of inner-plate. It displays a defor-
mation of 20 mm for a tensile strain of 0.08 or 40εy and 30 mm at failure
when the associated strain is about 0.12. In comparison with the PA-9
pin model, the fiber 12 of element 3, section 4 of both pin specimens ex-
perienced the same strain for a 20 mm deflection, but at the state of fail-
ure, the corresponded strain and deflection value experienced by the
same fiber of pin P-3 have dropped by 13%. In addition, by comparing
the tensile and compression strain recorded at pin's mid-span (fibers
12 and 1 of element 4, section 4) the P-3 pin developed lower strain
values (Fig. 10b).
The difference in behaviour is due to a/Lpin ratio. In the case of P-3
specimen, a/Lpin = 0.323 where a = 77.5 mm and Lpin = 240 mm. By
considering the pin and outer-plate cross sections 60 × 40 mm and
180 × 30 mm, respectively, the computed pin-to-outer-plate stiffness
ratio is (Ipin/Lpin)/(Iop/Hop) = 0.5, where Ipin = 60 × 403
/12, Iop =
180 × 303
/12 and Hop = 150 mm. When the point of applied force
moves toward the middle of the pin (PA-9 specimen), slightly larger
outer-plate stiffness is required to sustain the same applied force. In
the case of PA-9, a = 87.5 mm, a/Lpin = 0.365 and the change in the
a/Lpin ratio with respect to the previous case is 113% (e.g., 0.365/
0.323 = 1.13). As noted above, the ratio between the maximum force
carried by P-3 specimen and PA-9 specimen is 1.13 (692 kN versus
612 kN). In addition, from previous studies [13,14] it was found that
clamping effect increases until the thickness of outer-plates reaches
0.75 hp.
In the nonlinear range, axial compression force is developed in addi-
tion to bending moment which magnitude is slightly larger at pin's mid-
span than at its support. The compression force developed between the
inner-plates is smaller than that developed between the inner-plate and
outer-plate due to the tangential component of applied load that acts in
opposite direction. Failure of pin occurs under the combined effect of
axial force and bending moment. From data collected for both speci-
mens P-3 and PA-9 it was found that the normalized bending moment
component has the largest weight in the interaction equation while
the normalized axial force component is less than 10% in the mid-span
segment and less than 15% at pin's support.
To summarize, the behaviour of pin member is influenced by the dis-
tance between the inner- and outer-plate that is expressed by parame-
ter a, as well as by the dimensions of outer-plates. When the distance
between inner-plates (Lpin-2a) increases (e.g. P-3 specimen vs. PA-9),
the portion of pin that is subjected to plastic deformation expands
across the pin's length, while the maximum strain decreases. From nu-
merical computations, the length of plastic hinge developed over the
pin member is approximated as being: (Lpin-2a + hp). However, both
PA-9 and P-3 pins experience the same deflection at the mid-span
a) b)
Fig. 6. Tri-linear curve of the PA-9 and P-3 devices: a) theoretical, b) OpenSees model.
a) Strain b) Stress
Fig. 7. Strain and stress diagram of the PA-9 pin recorded at the pin's mid-span length.
141L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
6. length and display larger strain in tension than in compression. The
OpenSees beam model was used to emphasise the distribution of strain
and stress across the pin's length.
3.3. Validation of the OpenSees model of PA-9 and P-3 joints against exper-
imental test results
The two selected specimens PA-9 and P-3 were tested on a box stand
under the ECCS cyclic quasi-static loading protocol [18]. The displace-
ment loading applied to the PA-9 sample has 25 cycles with a rate of
loading of 0.45 mm/s and a maximum displacement in the last cycle
of 40 mm. The displacement loading protocol applied to the P-3 sample
has 21 cycles, a rate of loading 0.33 mm/s and a maximum displace-
ment of 45 mm. In both cases, three consecutive cycles reaching
the same displacement amplitude were considered. The force-
displacement hysteresis loops that characterize the behaviour of speci-
mens PA-9 and P-3 are shown in Fig. 11. In both cases, the failure of the
pin occurred at one of the two points of load application, when it was
reloaded in tension [12], as illustrated in Fig. 11. Thus, in the case of
specimen PA-9, when the distance between the outer- and inner-plate
is larger than the distance between inner-plates, the failure occurs in
the longer pin segment at the external face of the inner-plate which ro-
tates in the direction of the radius of curvature (Fig. 12a). In the case of
specimen P-3, the failure occurred in the middle segment at the internal
face of the inner-plate as showed in Fig. 12b. For both specimens, the
same stiffness degradation occurred during reloading. Although both
specimens reached approximately the same magnitude of maximum
deformation in bending, 37 mm, the corresponding ultimate tensile
forces of PA-9 (615 kN) is lower than that recorded for P-3 (694 kN).
On the other hand, for both specimens the capacity in tension is larger
than that in compression by 13%. This difference in strength is due to
the out-of-plane bending of outer-plates, which implies an increased
distance between the pin's supports in the outer-plate hole. In this
case, the outer-plates deflect toward the exterior, as is shown in
Fig. 12b. As a result, the stiffness and the thickness of outer-plates influ-
ence the behaviour of pin connection. As discussed above, it is recom-
mended that the stiffness of the outer-plate to be two times larger
than the stiffness of the pin and top ≥ 0.75hp.
The purpose of developing the OpenSees model for pin connections
is to study the behaviour of CBFs equipped with pin devices placed in-
EL1 EL2 EL3 EL4
2 3 41 2 3 4 1
Fiber 1
Fiber 12
P/2
44
P/2
El 3/4 Fiber 12
El 4/1 – 4/4 Fiber 12 El 4/4 – 4/1
Fiber 1
El 3/4 Fiber 1
El 3/2 Fiber 1
El 3/2 Fiber 12
El 3/3 Fiber 1
b)
a)
Fig. 8. Numerical modelling of the PA-9 specimen: a) schematic representation of pin member in OpenSees; b) strain-deflection curves.
a) Strain b) Stress
Fig. 9. Strain and stress diagram of the P-3 pin recorded at the pin's mid-span length.
142 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
7. line with brace members. In this light, the rigid link (outer-plate) is
fixed to the column's flange at the level of column-to-beam intersection
and is connected by means of zero-length element to brace member.
Pinching4 material is assigned to translational springs and was
employed in this study with the aim of simulating the changes in pin
member behaviour, while undergoing different degrees of fixity when
changing from a pinned to a clamped support. To simulate the hysteret-
ic response of specimens P-3 and PA-9, the unloading stiffness degrada-
tion model for a hardening-type response envelope is used and
calibrated against experimental test results.
The hysteresis shape defined by the Pinching4 uniaxial material
model is illustrated in Fig. 13 and it corresponds to that provided in
the OpenSees manual [17]. The coordinates of force-deformation corre-
sponding to a hardening-type response envelop are those computed for
the tri-linear curve (e.g., Fig. 6) and are depicted in Fig. 13: (ePf1, ePd1),
(ePf2, ePd2) and (ePf3, ePd3). However, the hysteresis shape may not be
symmetric when the outer-plates behave in tension or compression as
shown in Fig. 11. To define pinching, three additional floating points
(rForceP•ePf3, rDispP•ePd3 and uForceP•ePf3) are required to be identified
in tension and three in compression. Points involving these coordinates
are symbolized with “X” in Fig. 13. For example, in the case of PA-9 spec-
imen depicted in Fig. 11a, the floating point rForceP•ePf3 represents the
ratio of the force at which reloading occurs, 291 kN, to the total hyster-
etic force demand, 615 kN. Similarly, the second floating point
rDispP•ePd3 represents the ratio of displacement where reloading be-
gins, 24 mm, to the total hysteretic displacement demand, 37 mm. In
this light, the computed ratios are 0.47 and 0.65, respectively. The
third floating point uForceP•ePf3 is the ratio of force at negative
unloading, 17 kN, to the total load during monotonic testing,
615 kN, resulting in a value of 0.03. Therefore as is shown above,
the pinching envelope is built by multiplying certain values of the
skeleton curve, better known as the tri-linear curve, with the above
floating point values, defined for the tension side. For the compres-
sive side, the floating points are reported to a total compressive
force of 549 kN.
To validate the OpenSees model that is simulated for specimens PA-
9 and P-3, the normalized cumulative energy, E/Pyδy, illustrated in
Fig. 14, is computed as the summation of the normalized energy dissi-
pated per cycle, Ecycle/Pyδy. Herein, the energy dissipated per cycle is cal-
culated as the area enclosed by the associated cycle over the energy at
yield, Pyδy. The difference between the numerical model and physical
test increases significantly for the last cycle prior failure. The hysteresis
response of both specimens shows the occurrence of failure when the
specimen is reloaded in tension.
1
EL1 EL2 EL3 EL4
2 3 41 2 3 4
P/2P/2
Fiber 1
Fiber 12
22 33 41 3
El 4/1 –El 4/4
Fiber 12
El 4/1 – 4/4
Fiber 1
El 3/4 Fiber 12
El 3/3 Fiber 12
El 3/2 Fiber 12
El 3/1 Fiber 12
El 2/4 Fiber 12
El 3/3 Fiber 1
El 3/2 Fiber 1
Deflection (mm)
Strain
Strain-deflection curves:
b)
a)
Fig. 10. Numerical modelling of the P-3 specimen: a) schematic representation of pin member in OpenSees; b) strain-deflection curves.
a) b)
Fig. 11. Hysteresis loops of the OpenSees model vs. experimental test: a) PA-9, b) P- 3.
143L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
8. Thus, the OpenSees model is able to replicate the global behaviour of
single-pin connection. The P-3 specimen was subjected to 21 cycles,
while the PA-9 specimen to 25 cycles. To summarize, under similar condi-
tions (equal number of cycles), the single-pin connection with larger dis-
tance between inner-plates possesses a larger dissipative energy capacity.
4. Numerical modelling of double-pin connection device
When concentrically braced frames are designed to withstand earth-
quake forces computed for moderate to high seismic areas, a large shear
force demand is expected to develop at the lower part of multi-storey
P - A9
Failure
of pin
Failure
of pin
Inflection point
P - 3
a) b)
Fig. 12. Failure mechanism of specimens PA-9 and P-3 (Courtesy of Prof. Luis Calado).
(rForceP•ePf3, rDispP•ePd3)(uForceP•ePf3,*)
Fig. 13. Pinching4 material definition.
Fig. 14. Normalized cumulative dissipated energy of numerical model versus physical test: a) PA-9 specimen, b) P-3 specimen.
144 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
9. Equivalent pin
PI = 74 kN
δI = 1.18 mm
PIII = 319 kN
δIII = 35 mm
PII = 312 kN
δII = 21 mm
PIII = 638 kN
δIII = 35 mm
PII = 624 kN
δII = 21 mm
PI = 148 kN
δI = 1.18 mm
a) b)
Fig. 15. Double-pin connection with pins placed in-parallel: a) tri-linear curve; b) three- dimensional model.
b) Stressa) Strain
Fig. 16. Stress and strain diagram of one of the two pins placed in-parallel, recorded at pin's mid-span length.
El 3/4 Fiber 12
El 4/1 -4/4 Fiber 12
El 4/4-4/1
Fiber 1
El 3/3 Fiber 1
El 3/2 Fiber 12
Deflection (mm)
Strain
Strain-deflection curves: Pins placed in parallel
Fig. 17. Strain-deflection curves of one of the two pins placed in-parallel.
145L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
10. buildings. Thus, to transfer large axial force triggered in brace members to
brace-column connections, the capacity of the single-pin device may not
satisfy the demand. For this case, authors proposed the double-pin con-
nection device, whereas the pin member may be displaced either in-
parallel or in-line, as illustrated in Fig. 2. To prepare further experimental
tests, the double-pin connection is analysed through numerical models by
following the same approach that was used for the single-pin. In this
study, only the case with a larger outer- to inner-plate distance is consid-
ered (a = 87.5 mm). For comparison purposes, two small pins of rectan-
gular shape 40 × 35 mm that possess an equivalent flexural stiffness
with that of single-pin 60 × 40 mm are selected for investigation.
4.1. Modelling and behaviour of double-pin connection with pins placed in-
parallel
As illustrated in Fig. 2a, the double-pin connection with pins placed in-
parallel (DP-PP) has a symmetrical geometry. Due to its symmetry, the
study can be conducted for half of the device and its behaviour is expected
to be similar with that for a single-pin. Thus, each pin must be propor-
tioned to carry half of the force triggered in the brace, while undergoing
the same deflection that is expected to be experienced by an equivalent
single-pin device. In this example, the same geometry of pin's length,
outer- and inner-plates as that illustrated for the specimen PA-9 is consid-
ered and used in the single-pin OpenSees beam model depicted in Fig. 4.
The theoretical tri-linear curve computed for each pin displaced in-
parallel may be plotted similarly with that developed for a single-pin.
The tri-linear curve and three-dimensional model of the DP–PP connec-
tion are illustrated in Fig. 15. The strain and stress diagram corresponding
to each one of the two pins subjected to incremental static loading, is
shown in Fig. 16. Data was recorded for each one of the 12 fibers
(Fig. 4) that represent the pin's cross-section located at pin's mid-span
length. From Fig. 16, it is observed that slightly larger strain is developed
in tension than compression upon failure. The values of strain and stress,
recorded for one of the two pins when subjected to half of the force ap-
plied to PA-9 specimen, show almost the same values with those plotted
in Fig. 8. The 40 × 35 pin member is subdivided in 8 elements as depicted
in Fig. 8a. Similarities in the strain-deflection time-history series depicted
for the 40 × 35 pin and shown in Fig. 17 were also observed.
As illustrated, the maximum strain is recorded in the extreme tensile
fiber (fiber 12) at the location of section 4 that belongs to element 3. In
addition, the length of plastic region is similar with that illustrated for
PA-9 pin model, while the time-history strain-deflection curves show
a linear relationship for fibers located between the inner-plates. Thus,
by doubling the pin member, the load-carrying capacity of connection
increases two times, while the deflection remains the same as that ex-
perienced by an equivalent single-pin device.
4.2. Modelling and behaviour of double-pin device placed in-line
The three-dimensional scheme of double-pin connection with pins
placed in-line (DP–PL) is shown in Fig. 18 and the OpenSees model is il-
lustrated in Fig. 19. Each one of the two pins is composed of 8 force-
based nonlinear beam-column elements with distributed plasticity
along the member length and four integration points per element as
depicted in Fig. 8a. Pins cross-sections are made of 60 fibers distributed
as illustrated in Fig. 4. Steel02 material was assigned at all fibers. A zero-
length element is placed at each pin ends in order to simulate the com-
plexity of pin's support in the outer-plate hole. In addition, zero-length
elements are placed at the connection between pin members and inner-
plates. Through design, the pin members of the DP-PL connection are
assumed to dissipate energy in flexure, while the remaining compo-
nents such as the outer- and inner-plates behave elastically. In this
model, both outer- and inner-plates were made of fibers and Steel02
material was assigned. Due to the large stiffness of the inner-plate in
the plane of loading, both pins are subjected to equal deformation,
while the system composed of two pins connected by the two inner-
plates behaves as an equivalent W-shape beam where both flanges
are supported in the four outer-plates holes. In this example, the dis-
tance between the centerline of the two pins is 2.5 hp (100 mm) and
it can be increased to 3 hp, the thickness of the outer-plates is 30 mm
(top ≥ 0.75 hp), while that of inner-plate is 20 mm (tip ≥ 0.5 hp). The
net area of outer-plate across the pin hole, normal to the axis of the
member, shall be at least 1.33 times the cross-sectional area of the pin
member. In the same time, the distance from the edge of the pin hole
to the edge of the outer-plate member, measured transverse to the
axis of the member, shall not exceed four times the thickness of the ma-
terial at the pin hole (e.g., the width of outer-plate is bop = 180 mm and
(180 − 40)/2 ≤ 4top where top = 30 mm). This verification is applied
to inner-plates as well (e.g., for bip = 180 mm it results (180 − 40)/
2 ≤ 4tip where tip = 20 mm).
To simulate the connection between the pin member and the outer-
plate support, three translational and one torsional spring are assigned
Lower pin
Upper pin
Fig. 18. Three-dimensional scheme of double-pin connection device with pins placed in-
line.
x
y
z
pin
Outer-plates
Inner-plates
Upper Pin
Lower Pin
Fig. 19. The OpenSees model of double-pin connection with pins placed in-line.
146 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
11. in the zero-length element illustrated in Fig. 19. Among them, two
translational springs are placed in the x-direction and one in the y-
direction, while the torsional spring assures that no twist occurs in the
z-axis. One of the two translational springs, made of Steel02 material
and assigned in the x-direction, simulates the effect of the outer-plate.
The second translational spring, assigned in the x-direction, is made of
Pinching4 material and represents the pinched force–deformation rela-
tionship that controls the pin behaviour. On the other hand, between
the inner-plate and the pin member is a pinned connection that is sim-
ulated by two translational and one torsional spring, assigned in the
zero-length element. Among the two translational springs, made of
Steel02 material, one is placed in the x- and the other in the y-
direction, while the torsional spring is added to restrain torsion about z.
However, in the plastic range, there is a difference in the develop-
ment of strain in the upper versus the lower pin. The strength of pin
connection is larger when outer plates are in tension due to transverse
bending in opposite direction of the plates that fallow the curvature of
the pin which magnify the distance between outer-plates. In addition,
the deformation of the two pins is controlled by the force–deformation
relationship exhibited by the inner-plates in the process of transferring
the axial force from the brace to the column. Thus, the two pins experi-
ence equal deformation in bending, although the pin located toward the
brace (lower pin) is subjected to larger stress and strain than that on the
above (upper pin), as shown in Fig. 20. In this light, the maximum strain
that is developed in the lower pin is about 40εy in both tension and com-
pression. This maximum strain value is smaller than that shown for the
same pin's size displaced in-parallel (Fig. 16). To summarize, dissipative
connection with pins in-line shows lower demand in strains and stress-
es than the equivalent connection with pins in-parallel, while carrying
the same magnitude of forces.
To analyse the undergoing deformation of the pin members, the
time-history series of strain-deflection of the extreme pin's fibers are
plotted in Fig. 21. Herein, the maximum tensile strain recorded in
fiber 12 of element 4, section 4 (mid-span length) of the upper pin is
0.06 versus 0.072 of the lower pin. However, for the same section loca-
tion, the maximum compressive strain developed in fiber 1 of the lower
pin is double than that developed by the upper pin. Meanwhile, the
lower pin shows a linear strain–deformation relationship, while the
upper pin shows a parabolic relationship. Each pin is made of eight
non-linear beam-column elements as illustrated in Fig. 8a. The length
of the plastic region is similar with that illustrated in Fig. 8b, while the
maximum bending deformation is slightly reduced.
5. Conclusions
In this paper, the concept of incorporating dissipative brace-
column connection devices in CBF systems is proposed in order to
protect braces against buckling. Pin connection devices are classified
a)
c)
b)
d)
Fig. 20. Stress and strain diagram of pins placed in-line, recorded at pins mid-span length: a) strain of upper pin; b) stress of upper pin, c) strain of lower pin; d) stress of lower pin.
147L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
12. as single- and double-pin and the computation is carried out using
the theoretical beam model and the OpenSees beam model under
monotonic loading and cyclic quasi-static displacement loading.
The proposed model for the single-pin connection device was cali-
brated against experimental test results. From this study, the result-
ed recommendations are:
• The theoretical beam model is recommended for preliminary design
of dissipative pin connections.
• The OpenSees beam model employs the Pinching4 material which rep-
resents a pinched force-deformation response and it allows users to
simulate the deformed shape of the pin member in the outer-plate's
hole support after it is loaded below its elastic bending capacity.
• The dissipative energy capacity of connection devices, computed for
the same number of cycles, increases if larger distance between the
inner-plates, (Lpin-2a), is provided. When the distance between
inner-plates increases, the portion of pin experiencing plastic defor-
mation expands across the pin's length, while the maximum stress
and strain decrease.
• In all cases, the larger deformation was recorded at the pin's mid-span,
while the larger strain was recorded in the vicinity of inner-plates that
transfer the axial forces from the brace to the pin member. The tensile
fibers show a slightly larger strain than the compression fibers. This
difference increases with the magnitude of applied forces. By numer-
ical studies, the distribution of plastic strains over the pin's length was
recorded and in this light, the plastic hinge length is approximated as
being: (Lpin-2a + hp), where hp is the depth of the pin member.
• The length and thickness of the outer-plates influence the behaviour
of the dissipative pin connections and the deflection of the pin con-
trols the transversal deflection of outer-plates.
• When the distance between the outer- and inner-plate is larger than
the distance between inner-plates, the failure of the pin member occurs
in the longer pin segment at the external face of the inner-plate due to
the rotation of inner-plate in the direction of the radius of curvature. In
the case showing larger distance between inner-plates, the failure oc-
curs in the middle segment, at the internal face of the inner-plate.
• A double-pin connection device with pins displaced in-parallel and in-
line is proposed in this study. This connection is studied through nu-
merical models and is projected to replace the single-pin connection
in the case when larger axial forces are developed in braces of CBFs lo-
cated in seismic areas. A similar design and modelling approach with
that used for single-pin connection is employed.
• By doubling the pin member and employing the parallel configuration,
the load-carrying capacity of connection increases two times, while the
deflection is similar to that experienced by an equivalent single-pin de-
vice.
• The double-pin connection with pins displaced in-line shows lower
strains. Due to the large stiffness of the inner-plate in the plane of load-
ing, both pins displaced in-line are subjected to equal deformation. In
addition, the double-pin connection device with pins in-line has large
redundancy while displaying lower deflection, stresses and strains
than an equivalent single-pin device.
• To validate the performance of single- and double-pin devices, addi-
tional experimental tests are required.
Deflection (mm)
StrainStrain
Deflection (mm)
El 4/4 – 4/1
Fiber 1
El 3/4 Fiber 12
El 3/3 Fiber 12
El 4/1 – 4/4 Fiber 12
El 3/2 Fiber 12
El 3/2 Fiber 1
Strain-deflection curves: Upper Pin
El 4/4 – 4/1
Fiber 1
El 3/3 Fiber 1
El 4/1 – 4/4 Fiber 12
El 3/4 Fiber 12
Strain-deflection curves: Lower Pin
a)
b)
Fig. 21. Strain-deflection curves of both pins placed in-line: a) upper pin; b) lower pin.
148 L. Tirca et al. / Journal of Constructional Steel Research 94 (2014) 137–149
13. Acknowledgements
Financial support from the Natural Sciences and Engineering Re-
search Council of Canada (NSERC) is gratefully acknowledged. Authors
express their gratitude to Prof. Luis Calado for providing experimental
test results.
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[4] Constantinou MC, Symans MD. Seismic response of structures with supplemental
damping. Struct Des Tall Build 1993;2:77–92.
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