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.
DESIGN OF CONTINUOUS MEMBERS IN PRESTRESSEDLOGESH S
• A continuous beam is having more than one span is carried by several supports.
• It is mainly used in bridge construction.
• Simple beam cannot be used for large spans, as it requires more strength and stiffness.
• But continuous PSC beam not only provides adequate strength and stiffness, but also provides sufficient ductility.
This document discusses the design of steel beams. It describes how to account for local buckling in thin-walled beams by limiting the compressive stress. Failure modes like web crushing and shear buckling are also addressed. For lateral buckling, the effective length method is used to determine the elastic lateral buckling moment capacity based on the beam's geometry and support conditions. Modifications to the capacity are needed to account for imperfections and other effects.
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.
This document discusses short compression members under axial load with uniaxial bending. It describes the behavior of such columns and their three modes of failure: balanced failure, compression failure, and tension failure. Balanced failure occurs when the outermost longitudinal steel yields simultaneously with maximum concrete compression. Compression failure happens with a neutral axis outside the section. Tension failure occurs when the neutral axis is inside the section, developing tensile strains. An interaction diagram plots load versus moment pairs that cause failure. The behavior and failure modes depend on the neutral axis location and load eccentricity.
Pile cap two pile laod 50 t desigh and drawingRAJESH JAIN
A pile cap is a reinforced concrete structure that interconnects a group of piles and transfers loads from columns or walls to the piles. It is designed to distribute forces equally to the piles. Pile caps are designed using truss theory for closely spaced piles or beam theory for widely spaced piles. Key aspects of pile cap design include ensuring adequate size, depth, reinforcement, and structural strength to resist bending moments, shear forces, and punching shear from supported loads. Pile cap design involves checking capacities of individual piles and reinforcement requirements to achieve strength and serviceability limits stated in design codes.
This document provides information on the design of reinforced concrete beams, including:
1. It outlines the three basic design stages: preliminary analysis and sizing, detailed analysis of reinforcement, and serviceability calculations.
2. It describes how to calculate the lever arm, depth of the neutral axis, and required area of tension and compression reinforcement for singly and doubly reinforced beams.
3. It discusses considerations for preliminary sizing of beams, including required cover, breadth, effective depth, shear stress limits, and span-depth ratios. Trial calculations are suggested to determine suitable beam dimensions.
The document discusses ACI reinforcement limits for flexural members, including:
- ACI 318-02 provides a unified procedure for reinforced and prestressed concrete design.
- Beams must be designed as either tension-controlled or in the transition between tension and compression-controlled to ensure sufficient under-reinforcement.
- Strength reduction factors vary between 0.81-0.90 for beams depending on reinforcement strain, with more brittle compression-controlled sections having lower factors of 0.70.
The document discusses the strut-and-tie model approach for analyzing and designing concrete structures. It provides an overview of the strut-and-tie model methodology, including key concepts such as struts, ties, nodes, and modeling techniques. Examples are given to illustrate strut-and-tie models for different structural elements like beams, slabs, corbels, and joints. Design considerations such as limiting stresses and reinforcement details are also covered.
DESIGN OF CONTINUOUS MEMBERS IN PRESTRESSEDLOGESH S
• A continuous beam is having more than one span is carried by several supports.
• It is mainly used in bridge construction.
• Simple beam cannot be used for large spans, as it requires more strength and stiffness.
• But continuous PSC beam not only provides adequate strength and stiffness, but also provides sufficient ductility.
This document discusses the design of steel beams. It describes how to account for local buckling in thin-walled beams by limiting the compressive stress. Failure modes like web crushing and shear buckling are also addressed. For lateral buckling, the effective length method is used to determine the elastic lateral buckling moment capacity based on the beam's geometry and support conditions. Modifications to the capacity are needed to account for imperfections and other effects.
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.
This document discusses short compression members under axial load with uniaxial bending. It describes the behavior of such columns and their three modes of failure: balanced failure, compression failure, and tension failure. Balanced failure occurs when the outermost longitudinal steel yields simultaneously with maximum concrete compression. Compression failure happens with a neutral axis outside the section. Tension failure occurs when the neutral axis is inside the section, developing tensile strains. An interaction diagram plots load versus moment pairs that cause failure. The behavior and failure modes depend on the neutral axis location and load eccentricity.
Pile cap two pile laod 50 t desigh and drawingRAJESH JAIN
A pile cap is a reinforced concrete structure that interconnects a group of piles and transfers loads from columns or walls to the piles. It is designed to distribute forces equally to the piles. Pile caps are designed using truss theory for closely spaced piles or beam theory for widely spaced piles. Key aspects of pile cap design include ensuring adequate size, depth, reinforcement, and structural strength to resist bending moments, shear forces, and punching shear from supported loads. Pile cap design involves checking capacities of individual piles and reinforcement requirements to achieve strength and serviceability limits stated in design codes.
This document provides information on the design of reinforced concrete beams, including:
1. It outlines the three basic design stages: preliminary analysis and sizing, detailed analysis of reinforcement, and serviceability calculations.
2. It describes how to calculate the lever arm, depth of the neutral axis, and required area of tension and compression reinforcement for singly and doubly reinforced beams.
3. It discusses considerations for preliminary sizing of beams, including required cover, breadth, effective depth, shear stress limits, and span-depth ratios. Trial calculations are suggested to determine suitable beam dimensions.
The document discusses ACI reinforcement limits for flexural members, including:
- ACI 318-02 provides a unified procedure for reinforced and prestressed concrete design.
- Beams must be designed as either tension-controlled or in the transition between tension and compression-controlled to ensure sufficient under-reinforcement.
- Strength reduction factors vary between 0.81-0.90 for beams depending on reinforcement strain, with more brittle compression-controlled sections having lower factors of 0.70.
The document discusses the strut-and-tie model approach for analyzing and designing concrete structures. It provides an overview of the strut-and-tie model methodology, including key concepts such as struts, ties, nodes, and modeling techniques. Examples are given to illustrate strut-and-tie models for different structural elements like beams, slabs, corbels, and joints. Design considerations such as limiting stresses and reinforcement details are also covered.
04-LRFD Concept (Steel Structural Design & Prof. Shehab Mourad)Hossam Shafiq II
The document discusses load and resistance factor design (LRFD) methods for structural design. It provides information on:
1) Types of loads that must be considered in design like dead, live, and environmental loads. Load factors are used to increase calculated loads to account for uncertainties.
2) Resistance factors are used to reduce nominal member strength to account for variability in material strength and dimensions.
3) The LRFD method aims for a 99.7% reliability target where factored resistance must exceed factored loads based on load combinations outlined in codes.
This document discusses the computation of parameters for designing reinforced concrete beams and one-way slabs. It outlines six assumptions made in the limit state design approach, including that plane sections remain plane after bending and concrete strain is limited to 0.0035. Three types of beams are described - rectangular, T, and L-beams. Equations of equilibrium are presented, including equations to calculate the total compression and tension forces, C and T. Parameters like the area of tension steel, effective depth, and neutral axis depth are also defined.
This document discusses various mechanical properties that are important for selecting materials for structural components. It describes different types of mechanical tests like tension, compression, torsion, bending, impact and fatigue tests that are conducted on metal specimens to determine properties like strength, ductility and toughness. Specifically, it outlines the process for a uniaxial tension test including the equipment used, steps to conduct the test, and how to analyze the stress-strain diagram produced. It also discusses factors that influence mechanical properties like temperature, notches, grain size and hardness tests.
The origin of the word 'Glulam' comes from the words 'glue' and 'laminated'. Glulam is manufactured by gluing together layers of dimensional lumber or timber boards with structural adhesives to form a structural laminated beam or column. One structural advantage Glulam has over conventional solid timber is that it allows for the manufacture of larger and longer structural members than what could be produced from a single piece of solid timber. An example of a type of structural form that can be constructed from Glulam in buildings is glulam arches.
This document discusses the analysis and design of one-way and two-way concrete slabs. It describes how one-way slabs transfer loads in one direction while two-way slabs transfer loads in two perpendicular directions. The coefficient method is presented for analyzing bending moments in two-way slabs using moment coefficients from tables based on support conditions and span ratios. An example is provided to calculate moment coefficients and design a two-way slab using working stress and ultimate strength design methods.
Shear Force And Bending Moment Diagram For FramesAmr Hamed
This document discusses analyzing shear and moment diagrams for frames. It provides procedures for determining reactions, axial forces, shear forces, and moments at member ends. Examples are given of drawing shear and moment diagrams for simple frames with different joint conditions, including pin and roller supports. Diagrams for a three-pin frame example are shown.
This section will introduce how to solve problems of axially loaded members such as stepped and tapered rods loaded in tension. The concept of strain energy will also be introduced.
The document summarizes a numerical analysis of fatigue for a connecting rod in an internal combustion engine. It describes the finite element analysis methodology, including defining the 3D model, loads, meshing, and solving. Stress results are presented for two load cases: maximum compression at 1800 RPM and maximum tension at 2625 RPM. A fatigue life prediction is performed using the stress-life method and Goodman diagram. The lowest fatigue factor of 1.32 was above the acceptable limit of 1.3, indicating no expected fatigue failures under these loads.
The document discusses the design of compression members according to IS 800:2007. It defines compression members as structural members subjected to axial compression/compressive forces. Their design is governed by strength and buckling. The two main types are columns and struts. Common cross-section shapes used include channels, angles, and hollow sections. The effective length of a member depends on its end conditions. Slenderness ratio is a parameter that affects the load carrying capacity, with higher ratios resulting in lower capacity. Design involves checking the member for short or long classification, buckling curve classification, and calculating the design compressive strength. Examples are included to demonstrate the design process.
This document discusses structural theory related to simple beams. It defines different types of beams like simply supported beams, cantilever beams, and continuous beams. It explains failure of beams due to bending, shear, and deflection. It discusses bending moments, shear forces, and laws of bending. Examples are provided to illustrate how to draw bending moment and shear force diagrams for beams under different loading conditions. Exercises are included for the reader to practice drawing bending moment and shear force diagrams.
The document discusses concepts related to stress analysis and design of structures including:
- Normal stress, shear stress, and bearing stress
- Stress analysis using statics to determine internal forces and stresses
- Design considerations like material selection and sizing based on allowable stresses
- Examples calculating stresses in rods, pins, and connections of a structure under a load.
SEISMIC DESIGN OF COMPOSITE SHEAR WALLS & FRAMES - مقاومة الرياح والزلازل جد...Dr.Youssef Hammida
The document discusses different types of composite structural systems that combine steel and concrete elements. It describes composite slabs made with metal decking and concrete topping that act as diaphragms transferring shear forces. It also discusses composite girders that use shear stud connectors to increase the moment of inertia of the beam and girder, and composite columns with a steel core encased in concrete or steel tubes filled with concrete. The document emphasizes that composite systems allow for more efficient use of the dissimilar properties of steel and concrete in buildings.
This document contains 9 problems related to calculating stresses in mechanical components and structures. Problem 1 asks to calculate normal stresses in two cylindrical rods welded together. Problem 2 asks to determine minimum diameters for the rods given a stress limit. Problem 3 asks to calculate maximum stresses in links connecting points of a structure. Problem 4 asks to determine the minimum length of cuts in a glued wooden joint given a shear stress limit.
A Study of Reduced Beam Section Profiles using Finite Element AnalysisIOSR Journals
Abstract: Reduced beam section (RBS) is one of the several connection types, which is economical and
popular for use in new steel moment frame structures in seismic zone. To form RBS connection, some portion of
the beam flanges at a short distance from column face is purposefully trimmed so that the yielding and plastic
hinge occurs within this area of flanges. Use of RBS connection is found advantageous due to: a) the shear
force in the panel zone is reduced; b) the force demand in column continuity plates i.e. stiffeners are reduced;
and c) strong-column – weak-beam requirement is satisfied. Although, radius cut RBS is qualified by
ANSI/AISC, FEMA codes, various flange cut shapes like constant, tapered, radius cut, drilled holes are possible
to reduce the cross sectional area of beam flanges. The purpose of this study is to understand behavior of RBS
beam-to-column moment connections for various flange cut geometries. This document represents nonlinear
finite element analysis of the connection models performed using the computer program, ANSYS/Multiphysics
Keywords - Steel structures, steel connections, reduced beam section, RBS profiles
Design methods for torsional buckling of steel structuresBegum Emte Ajom
The document discusses methods for designing steel structures to resist torsional buckling. It summarizes clauses from Eurocode 3 that provide equations for calculating the elastic critical buckling moment and determining the reduction factor used to calculate the design bending strength. It also presents simplified equations that can be used to calculate the elastic critical buckling moment for common steel beam sections. Additional guidance is provided for calculating the critical buckling moment for non-symmetric sections and when bending occurs about the major axis.
Prestress loss due to friction & anchorage take upAyaz Malik
This document provides a detailed procedure for calculating prestress loss due to anchorage take-up. Prestress Loss due to friction is also discussed in detail.
IMPROVING THE STRUT AND TIE METHOD BY INCLUDING THE CONCRETE SOFTENING EFFECTIAEME Publication
Strut and tie model approach evolves as one of the most useful analysis methods for shear critical structures and for other disturbed regions in concrete structures. The main objective of this research is modified the strut and tie method. As especially of the softening strut and tie method, the following work concern for determining a new factor (named-correction factor λ), and the formulation is based on the failure criterion from the Mohr Coulomb Theory for nodal zones (tension-compression stress state).
This document discusses two approximate methods for analyzing building frames subjected to loads: the portal method and cantilever method. The portal method assumes inflection points at midpoints of beams and mid-heights of columns, and that interior columns carry twice the shear of exterior columns. The cantilever method assumes inflection points at beam midpoints and column mid-heights, and that column axial stresses are proportional to their distance from the storey's centroid. Examples demonstrate applying each method to determine member forces in frames.
The document discusses stress, which is the first step in analyzing the strength of materials. Stress is defined as the internal force distribution on an imaginary cut surface within a material. There are two types of stress: normal stress, which acts perpendicular to the cut surface, and shear stress, which acts parallel to the cut surface. Normal stress is calculated by taking the normal force on the cut surface and dividing by the cross-sectional area. Shear stress is calculated by taking the shear force and dividing by the cross-sectional area. Understanding stress allows engineers to relate the internal forces and stresses in materials to the external forces applied to structures.
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.
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.
04-LRFD Concept (Steel Structural Design & Prof. Shehab Mourad)Hossam Shafiq II
The document discusses load and resistance factor design (LRFD) methods for structural design. It provides information on:
1) Types of loads that must be considered in design like dead, live, and environmental loads. Load factors are used to increase calculated loads to account for uncertainties.
2) Resistance factors are used to reduce nominal member strength to account for variability in material strength and dimensions.
3) The LRFD method aims for a 99.7% reliability target where factored resistance must exceed factored loads based on load combinations outlined in codes.
This document discusses the computation of parameters for designing reinforced concrete beams and one-way slabs. It outlines six assumptions made in the limit state design approach, including that plane sections remain plane after bending and concrete strain is limited to 0.0035. Three types of beams are described - rectangular, T, and L-beams. Equations of equilibrium are presented, including equations to calculate the total compression and tension forces, C and T. Parameters like the area of tension steel, effective depth, and neutral axis depth are also defined.
This document discusses various mechanical properties that are important for selecting materials for structural components. It describes different types of mechanical tests like tension, compression, torsion, bending, impact and fatigue tests that are conducted on metal specimens to determine properties like strength, ductility and toughness. Specifically, it outlines the process for a uniaxial tension test including the equipment used, steps to conduct the test, and how to analyze the stress-strain diagram produced. It also discusses factors that influence mechanical properties like temperature, notches, grain size and hardness tests.
The origin of the word 'Glulam' comes from the words 'glue' and 'laminated'. Glulam is manufactured by gluing together layers of dimensional lumber or timber boards with structural adhesives to form a structural laminated beam or column. One structural advantage Glulam has over conventional solid timber is that it allows for the manufacture of larger and longer structural members than what could be produced from a single piece of solid timber. An example of a type of structural form that can be constructed from Glulam in buildings is glulam arches.
This document discusses the analysis and design of one-way and two-way concrete slabs. It describes how one-way slabs transfer loads in one direction while two-way slabs transfer loads in two perpendicular directions. The coefficient method is presented for analyzing bending moments in two-way slabs using moment coefficients from tables based on support conditions and span ratios. An example is provided to calculate moment coefficients and design a two-way slab using working stress and ultimate strength design methods.
Shear Force And Bending Moment Diagram For FramesAmr Hamed
This document discusses analyzing shear and moment diagrams for frames. It provides procedures for determining reactions, axial forces, shear forces, and moments at member ends. Examples are given of drawing shear and moment diagrams for simple frames with different joint conditions, including pin and roller supports. Diagrams for a three-pin frame example are shown.
This section will introduce how to solve problems of axially loaded members such as stepped and tapered rods loaded in tension. The concept of strain energy will also be introduced.
The document summarizes a numerical analysis of fatigue for a connecting rod in an internal combustion engine. It describes the finite element analysis methodology, including defining the 3D model, loads, meshing, and solving. Stress results are presented for two load cases: maximum compression at 1800 RPM and maximum tension at 2625 RPM. A fatigue life prediction is performed using the stress-life method and Goodman diagram. The lowest fatigue factor of 1.32 was above the acceptable limit of 1.3, indicating no expected fatigue failures under these loads.
The document discusses the design of compression members according to IS 800:2007. It defines compression members as structural members subjected to axial compression/compressive forces. Their design is governed by strength and buckling. The two main types are columns and struts. Common cross-section shapes used include channels, angles, and hollow sections. The effective length of a member depends on its end conditions. Slenderness ratio is a parameter that affects the load carrying capacity, with higher ratios resulting in lower capacity. Design involves checking the member for short or long classification, buckling curve classification, and calculating the design compressive strength. Examples are included to demonstrate the design process.
This document discusses structural theory related to simple beams. It defines different types of beams like simply supported beams, cantilever beams, and continuous beams. It explains failure of beams due to bending, shear, and deflection. It discusses bending moments, shear forces, and laws of bending. Examples are provided to illustrate how to draw bending moment and shear force diagrams for beams under different loading conditions. Exercises are included for the reader to practice drawing bending moment and shear force diagrams.
The document discusses concepts related to stress analysis and design of structures including:
- Normal stress, shear stress, and bearing stress
- Stress analysis using statics to determine internal forces and stresses
- Design considerations like material selection and sizing based on allowable stresses
- Examples calculating stresses in rods, pins, and connections of a structure under a load.
SEISMIC DESIGN OF COMPOSITE SHEAR WALLS & FRAMES - مقاومة الرياح والزلازل جد...Dr.Youssef Hammida
The document discusses different types of composite structural systems that combine steel and concrete elements. It describes composite slabs made with metal decking and concrete topping that act as diaphragms transferring shear forces. It also discusses composite girders that use shear stud connectors to increase the moment of inertia of the beam and girder, and composite columns with a steel core encased in concrete or steel tubes filled with concrete. The document emphasizes that composite systems allow for more efficient use of the dissimilar properties of steel and concrete in buildings.
This document contains 9 problems related to calculating stresses in mechanical components and structures. Problem 1 asks to calculate normal stresses in two cylindrical rods welded together. Problem 2 asks to determine minimum diameters for the rods given a stress limit. Problem 3 asks to calculate maximum stresses in links connecting points of a structure. Problem 4 asks to determine the minimum length of cuts in a glued wooden joint given a shear stress limit.
A Study of Reduced Beam Section Profiles using Finite Element AnalysisIOSR Journals
Abstract: Reduced beam section (RBS) is one of the several connection types, which is economical and
popular for use in new steel moment frame structures in seismic zone. To form RBS connection, some portion of
the beam flanges at a short distance from column face is purposefully trimmed so that the yielding and plastic
hinge occurs within this area of flanges. Use of RBS connection is found advantageous due to: a) the shear
force in the panel zone is reduced; b) the force demand in column continuity plates i.e. stiffeners are reduced;
and c) strong-column – weak-beam requirement is satisfied. Although, radius cut RBS is qualified by
ANSI/AISC, FEMA codes, various flange cut shapes like constant, tapered, radius cut, drilled holes are possible
to reduce the cross sectional area of beam flanges. The purpose of this study is to understand behavior of RBS
beam-to-column moment connections for various flange cut geometries. This document represents nonlinear
finite element analysis of the connection models performed using the computer program, ANSYS/Multiphysics
Keywords - Steel structures, steel connections, reduced beam section, RBS profiles
Design methods for torsional buckling of steel structuresBegum Emte Ajom
The document discusses methods for designing steel structures to resist torsional buckling. It summarizes clauses from Eurocode 3 that provide equations for calculating the elastic critical buckling moment and determining the reduction factor used to calculate the design bending strength. It also presents simplified equations that can be used to calculate the elastic critical buckling moment for common steel beam sections. Additional guidance is provided for calculating the critical buckling moment for non-symmetric sections and when bending occurs about the major axis.
Prestress loss due to friction & anchorage take upAyaz Malik
This document provides a detailed procedure for calculating prestress loss due to anchorage take-up. Prestress Loss due to friction is also discussed in detail.
IMPROVING THE STRUT AND TIE METHOD BY INCLUDING THE CONCRETE SOFTENING EFFECTIAEME Publication
Strut and tie model approach evolves as one of the most useful analysis methods for shear critical structures and for other disturbed regions in concrete structures. The main objective of this research is modified the strut and tie method. As especially of the softening strut and tie method, the following work concern for determining a new factor (named-correction factor λ), and the formulation is based on the failure criterion from the Mohr Coulomb Theory for nodal zones (tension-compression stress state).
This document discusses two approximate methods for analyzing building frames subjected to loads: the portal method and cantilever method. The portal method assumes inflection points at midpoints of beams and mid-heights of columns, and that interior columns carry twice the shear of exterior columns. The cantilever method assumes inflection points at beam midpoints and column mid-heights, and that column axial stresses are proportional to their distance from the storey's centroid. Examples demonstrate applying each method to determine member forces in frames.
The document discusses stress, which is the first step in analyzing the strength of materials. Stress is defined as the internal force distribution on an imaginary cut surface within a material. There are two types of stress: normal stress, which acts perpendicular to the cut surface, and shear stress, which acts parallel to the cut surface. Normal stress is calculated by taking the normal force on the cut surface and dividing by the cross-sectional area. Shear stress is calculated by taking the shear force and dividing by the cross-sectional area. Understanding stress allows engineers to relate the internal forces and stresses in materials to the external forces applied to structures.
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.
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.
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.
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 the design of pipe support structures for structural engineers. It discusses loads on the structures from pipe expansion and contraction due to temperature changes. Frictional forces between pipes and supports are small compared to expansion forces. Stability bracing is required to prevent structural instability. Key details include avoiding oversized holes, providing expansion joints over 500 feet, and bracing T-supports in both axes by connecting flanges.
1) The document discusses torsion of non-circular and thin-walled sections, including rectangular, narrow rectangular, thin-walled open, thin-walled split tube, and other solid cross sections.
2) It presents equations for calculating maximum shear stress and angle of twist for each type of cross section. These equations involve constants that depend on the cross-sectional geometry.
3) Methods are described for approximating cross-sectional properties like shear stress and angle of twist by assuming an equivalent circular or elliptical cross section.
The document proposes a redesigned carding cylinder with a staggered, layered structure to improve fiber separation and drafting. It consists of an inner core with high mass density, followed by shells of decreasing density. This staggered structure causes:
1. Energy from the core's rotation to deflect at boundaries between layers, displacing air and transmitting energy more gradually across the cylinder surface.
2. Changing packing densities and surface curvatures between layers to further disrupt energy trajectories, gradually separating fibers along the cylinder.
3. A reduced carding zone thickness and delayed rate of normal vector change along the cylinder to improve fiber gripping over a longer length.
A pile cap is a reinforced concrete slab that connects a group of piles and transfers load from structures like walls or columns to the piles. It is designed to distribute load equally to the piles. This document discusses design considerations for pile caps including shape, depth, reinforcement, assumptions in design, and design methods. Pile caps can be designed using truss theory for closely spaced piles or beam theory for piles spaced further apart. Reinforcement is proportioned to resist bending moments, shear forces, and prevent bursting. Pile cap size depends on pile diameter and spacing to accommodate piles within a tolerance.
A pile cap is a reinforced concrete slab that connects a group of piles and transfers load from structures like walls or columns to the piles. It is designed to distribute load equally to the piles. This document discusses design considerations for pile caps including shape, depth, reinforcement, assumptions in design, and design methods. Pile caps can be designed using truss theory for closely spaced piles or beam theory for piles spaced further apart. Reinforcement is proportioned to resist bending moments, shear forces, and prevent bursting. Pile cap size depends on pile diameter and spacing to accommodate piles within a tolerance.
A reinforced concrete slab or block which interconnects a group of piles and acts
as a medium to transmit the load from wall or column to the Piles is called a Pile
Cap. The Pile cap should normally be rigid so as to distribute the forces equally on
the piles of a group. In general it is designed like a footing on soil but with the
difference that instead of uniform reaction from the soil, the reactions in this case
are concentrated either point loads or distributed.
A pile cap is a reinforced concrete slab that connects a group of piles and transfers load from structures like walls or columns to the piles. It is designed to distribute load equally to the piles. This document discusses design considerations for pile caps including shape, depth, reinforcement, assumptions in design, and design methods. Pile caps can be designed using truss theory for closely spaced piles or beam theory for piles spaced further apart. Reinforcement is proportioned to resist bending moments, shear forces, and prevent bursting. Pile cap size depends on pile diameter and spacing to accommodate piles within a tolerance.
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.
The document discusses concepts of stress, including:
1. Stress is defined as the force per unit area acting on a surface or section. There are two main types: normal stress and shear stress.
2. To determine if a structure can safely support a load, both the internal forces and the material properties must be considered.
3. Allowable stress values lower than the actual failure stress are used in design, with factors of safety typically between 1-3 depending on the application. This ensures the structure does not fail under expected loading conditions.
This document discusses an ab initio density functional theory study of structural transitions and pseudoelastic behavior in copper nanowires under tensile strain. The study finds that for nanowires with diameters below 1.38 nm, surface stresses alone can cause the structure to transition from an initial face-centered cubic structure to a body-centered tetragonal structure. Under loading and unloading conditions, the structure reversibly transitions between body-centered tetragonal and face-centered tetragonal structures, explaining the observed pseudoelastic behavior. The mechanical properties of copper nanowires depend not only on diameter size but also on surface orientation.
This document provides instructional objectives and content on bond, anchorage, development length, and splicing of reinforcement. It discusses:
- The importance of bond between steel and concrete to allow them to act together without slip.
- Development length, which is the length required to develop full bond.
- Design bond stress, which is the average shear stress along the reinforcement.
- Values of design bond stress in tension and compression for plain and deformed bars.
- Equations to calculate the development length of a single bar or bundled bars.
- Requirements for checking development lengths of bars in tension.
Deflections in PT elements pt structure for all pt slabs in civil industry.pdfvijayvijay327286
The document discusses factors that influence deflections in prestressed concrete members and methods for predicting deflections. It covers:
- Short term deflections of unracked members which can be estimated using Mohr's theorem.
- How the tendon profile affects deflections, providing formulas for straight, trapezoidal, parabolic, and other tendon types.
- Downward deflections due to self-weight and imposed loads that can be calculated using formulas provided.
- Estimation of long-term deflections accounting for creep and shrinkage effects, discussing various methods like those of Busemann, McHenry, and Neville.
Modeling and Optimization of Cold Crucible Furnaces for Melting MetalsFluxtrol Inc.
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Cold Crucible Furnaces (CCFs), widely used in multiple special applications of
melting metals, oxides, glasses and other materials [1], are essentially 3D devices and their modeling is a complicated task. Multiple studies of CCFs have been made for their
optimization, but their electrical efficiency is still low; for metals approximately 25-30% andeven lower. Fluxtrol, Inc., made an extensive study of electromagnetic processes of CCFs using computer simulation and laboratory tests. This study showed that electrical efficiency of CCFs may be strongly improved by means of optimal design of the whole system with use of magnetic flux controllers. Theoretical results had been confirmed by laboratory tests on mockups and by industrial tests with real melting processes. The presentation contains a description of the computer modeling procedure and major findings. They form a basis for optimal design of electromagnetic systems of CCFs.
1. The document discusses the design of various welded joints, including butt joints, transverse and parallel fillet joints, and circular fillet joints subjected to torsion. It provides the equations to calculate the permissible load or torque based on the weld material properties and joint geometry.
2. Examples of design calculations are provided for parallel fillet joints subjected to load and transverse fillet joints. Design stresses for welds using bare and covered electrodes are also tabulated.
3. Review questions at the end test the understanding of welded joint design, and examples are worked out for fillet joints subjected to load and a circular fillet joint subjected to torque.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
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1. 1 INTRODUCTION
An efficient seismic force resisting system should
possess enough strength such that member forces are
lower than the factored resistance, supply adequate
stiffness to limit the system’s deformation, and
should exhibit sufficient ductility. Thus, concentri-
cally braced frames (CBF) are characterized by a
very high stiffness-to-weight ratio and limited ductil-
ity. As stated in the Canadian standard CSA/S16-
2009, the dissipative zones of the classical CBF sys-
tems are located in the brace members which are de-
signed to yield in tension and buckle in compression.
However, during the hysteresis response, braces on
the verge of buckling lose their buckling strength
and drive the system to behave asymmetrically.
To overcome this deficiency, authors relayed on
the statement given in Eurocode 8, where it is sug-
gested that the location of dissipative zones may be
placed in “the structural members or in the connec-
tions”. In addition, it is stated that “the overstrength
condition for connections need not apply if the con-
nections are designed to contribute significantly to
the energy dissipation capability” of the system.
Thus, in this paper, a CBF system with dissipative
single-pin brace-to-column connections is consi-
dered for seismic simulation and design.
Initially, this innovative structural system was
proposed and experimentally tested during the Euro-
pean INERD project (Plumier et al. 2005). The sin-
gle-pin connection consists of two outer-plates
welded or bolted to the flanges of CBF’s columns,
two inner-plates welded to the brace member and a
single-pin running through the four plates as shown
in Figure 1a. The dissipative zone is located in the
pin, which yields in bending, while the remaining
connection components are designed to respond in
elastic range. Thus, under earthquake loads, braced
frames equipped with dissipative pin connections al-
low braces to develop their full compressive strength
and are able to avoid an asymmetrical response. In
addition, when dissipative zones are located in the
connections, adjacent members shall be designed
with sufficient overstrength, to allow the develop-
ment of cyclic yielding of the pin.
To emphasize the seismic response of low-rise
CBF buildings with dissipative connections, a 2-
storey structure located in a high risk seismic zone
was selected and analysed against a limited ductile
CBF system, by means of the OpenSees framework.
2 OPENSEES MODEL AND DESIGN OF CBF
SYSTEM EQUIPPED WITH PIN DEVICES
2.1 Preliminary design of single-pin device
The behavior of the single-pin connection, corres-
pondingly, its capacity to dissipate energy is influ-
enced by the length of the pin, L, its cross-sectional
size and shape as well as the distance between the
inner-plates (L-2a) as illustrated in Figure 1b. Re-
garding the shape of the pin, researchers have con-
cluded that a rounded pin can resist larger forces due
to a reduced effect of torsion, while a rectangular pin
with rounded corners possesses a larger moment of
inertia (Vayas & Thanopoulos 2005). Concerning
the distance between the inner-plates (L-2a), it was
concluded that the maximum energy is dissipated
when a larger distance is provided. However, this
configuration depends on the size and depth of the
column’s cross-section, which governs the pin’s
length. The pin behaves as a four-point loaded beam.
Seismic Simulation and Design of Low-Rise CBF Buildings with and
without Dissipative Connections using OpenSees
L.Tirca, C. Caprarelli and N. Danila
Dept. of Building, Civil and Environmental Eng., Concordia University, Montreal, Canada
ABSTRACT: In this study, the performance of a low-rise CBF building with dissipative single-pin connec-
tions is analysed against the classical CBF building with limited ductility. The two seismic resistant braced
frames located in Victoria, B.C., Canada, were modeled using the OpenSees framework. From the time-
history analysis, it is concluded: CBFs with pin connections experience a longer fundamental period, develop
approximately half of the classical CBF’s base shear, exhibit similar interstorey drift and higher ductility.
2. The axial tension/ compression force developed in
the brace, P is transferred to the pin through two-
point loads located at the intersection of the inner-
plates and the pin. When the yielding moment My =
WyFy is reached, the pin starts to yield in bending
under the point load Py/2 = My/a. At this stage, cha-
racterized by the yielding of the extreme fibers of the
pin’s cross-section, the static deflection of the pin is:
δy = (My/6EI)aL(3 - 4aL) (1)
where EI is the flexural stiffness, Wy is the section
modulus and Fy is the yield strength of the pin.
Figure 1. Single-pin connection: a) a 3-D view of the single-pin
brace-to-column connection; b) Pin member and its geometry.
By considering the small deflection theory, the
pin’s deflection at strain hardening is δsh =fa, where
f is the plastic rotation. By definition, f = kstlp,
where kst is the curvature at strain hardening com-
puted as kst = 2εsh /h and lp is the length of the plastic
hinge which may be approximated with the height of
the pin’s cross-section, h. In general, the average
strain hardening is estimated as: εsh = 10εy, where εy
is the strain at yield. Therefore, the pin reaches its
plastic moment Mp = WpFy under the two point-
loads Pp/2. The maximum value of the total force is
given in Eq. (2), while the corresponding deforma-
tion is shown in Eq. (3).
PI = Pp = 2Mp/a (2)
δI = (kstlp)a = (20εy)a (3)
After the attainment of Mp, under the tow point-
loads, same clamping is developed at the pin’s ends
and end bending moment is generated (Fig. 2a). By
equating the external work Pδ/2 = Pfa/2 with the
internal work (M1 +M2)f, the ultimate load of the
beam is given in Eq. 4. Herein, Mu = WpFu is the ul-
timate flexural capacity of the pin computed with the
steel yielding strength Fu.
PII = Pu = 2(M1 +M2)/a ~ 4Mu/a (4)
Under the two-point forces Pu/2, the ultimate strain
εu is estimated as being approximately equal to εu=
0.1, the corresponding value of the ultimate plastic
rotation fu becomes fu= 0.2 radians and the esti-
mated ultimate deflection is:
δII = δu = 1.15(0.2a) (5)
In Eq. (5), the numerical coefficient 1.15 symbolises
the difference between the length of the plastic hinge
lp and the dimension of the pin’s cross-section, h.
The above equations have been derived and vali-
dated against experimental test results provided by
Plumier et al. (2005). By employing Eqs. (2) to (5),
the pin response follows a tri-linear curve, which is
shown in Figure 2b. The slope of the first segment
defines the elastic modulus of elasticity E, while the
second slop defines the tangent modulus, Et.
Figure 2. Pin response: a) Pin mechanism; b) Tri-linear curve.
Furthermore, the ultimate deformation of the pin
influences the interstorey drift of the structure which
is limited by the current NBCC code to be 2.5%hs,
where hs is the storey height. When a brace is
equipped with dissipative single-pin connections at
both ends, the diagonal line will elongate with two
times the ultimate pin deformation estimated at 2δu
= 2[1.15(0.2a)]. The horizontal projection of the ul-
timate pin deformation is Δ = 2δu/cosϕ where ϕ is
the angle between the brace member and a horizon-
tal line. To ensure that the lateral drift is less than
2.5%hs, the following equation must be satisfied:
2δu/cosϕ < 2.5%hs. It is implied that the distance be-
tween the outer-plate and the inner-plate, a, should
be in agreement with the following equation:
a < 0.054hscosϕ (6)
Therefore, the pin should be calibrated to satisfy
both strength and deformability criteria. Regarding
strength, the pin should resist the axial force devel-
oped in the brace and be design to yield before the
brace reaches 80% of its compressive strength. With
regards to deformability, Eq. (6) must be satisfied.
2.2 OpenSees model
The OpenSees pin model, shown in Figure 3, was
built to simulate the behavior of a four-point loaded
beam, as previously described, and demonstrated the
seismic response of the pin member. It consists of
eight nonlinear beam-column elements and four in-
tegration points per element. The pin’s cross-section
is made up of 60 fibers. Among them, 12 fibers were
a) b)
a) b)
3. -80 -40 0 40 80
Displace m ent [m m ]
-800
-400
0
400
800
Force [k N]
Ex pe rimental res ult
Pinchin g
Sk eleton curve
assigned along the depth of the cross-section and 5
along its width. The length of the pin, Lpin is the
clear span between the outer-plates which act as
supports. Herein, the pin’s supports are modeled as
rigid links with a length equal to the thickness of the
outer-plate, top. To allow rotation between the pin
member and the support (rigid link), a zero-length
rotational spring is added at both ends. The material
assigned to the pin model is Steel02 which is known
also as Giuffre-Menegotta-Pinto material. A cali-
brated Pinching4 material, explained below, is as-
signed to springs and rigid links to simulate the de-
formation of the pin in the outer-plate supports. In
this pin model a very small strain hardening value of
0.0005 was considered. The computations con-
ducted for a 40x60mm pin member, made up of steel
with the following properties: Fy=396MPa and Fu=
558MPa, are detailed in Tirca et al. (2011).
Figure 3. OpenSees pin model.
As mentioned above, the Pinching4 material was
calibrated against experimental data obtained from a
full scale single-storey CBF frame in X-bracing con-
figuration, where braces were equipped with single-
pin brace-to-column connections at both their ends.
The experimental test was conducted at Polytechnic
of Milano, while the OpenSees model simulated by
authors is shown in Figure 4. In this regard, beams
and columns are modeled using one beam-with-
hinge element per member and the length of the
plastic hinge was set to be equal to the depth of the
member. Each column cross-section was defined as
fiber section with 5 fibers along the flange width and
6 fibers along the depth of the web. The beam was
connected to the column with a zero-length rotation-
al spring, C1. Each of the four brace segments were
modeled with 8 nonlinear beam-column elements
and 4 integration points per element. As per the
aforementioned figure, the tensile brace was defined
to work as one element using 16 sub-elements and
the compressive brace was defined as two half-brace
connected to the tensile brace by very stiff rotational
springs, C4. In the experimental test, W-shape was
used for all members including braces. The cross-
section of each brace was defined with 5 fibers along
the flange width and 6 fibers along the web’s depth.
A section aggregator was used to assign a torsional
stiffness to each cross-section of brace.
In order to connect braces to columns, 4 rigid
links, defined as elastic beam-columns were used.
These rigid links represent the part of the brace, or
brace connectors (outer-plates) that are rigidly fas-
tened to the column. A zero-length spring element
was inserted between the end node of the brace and
the rigid link. The properties of these springs C2 and
C3 were set for two different situations: one was to
model the single-pin connection and the other was to
model a gusset plate. In the case of modeling the
gusset plate, stiffer properties were set in order to
simulate its rigid behaviour. The Giuffré-Menegotta-
Pinto material was assigned to all members.
Figure 4. OpenSees model of a CBF system with pin devices.
The pin connection, represented by zero-length
elements deforming in x and y translations, was de-
fined using the Pinching4 material. The pinching
that is exhibited is the loss of resistance during un-
loading of the pin after a tensile force was applied
and reloading it after the point force has changed di-
rection. As shown below in Figure 5, a skeleton
curve was built to encompass the total force defor-
mation shape, where the displacement accounts for
two pins located at the ends of each brace.
Figure 5. Calibration of the Pinching4 material.
The three points defined in the skeleton curve
represent the tri-linear curve of the pin stiffness as
discussed in Fig. 2b. The first slope would define the
elastic stiffness of the pin while the second slope de-
fines the plastic stiffness and the third represents
some overstrength of material. The pinched shape of
the curve is defined by specifying three floating
point values in tension and three floating point val-
ues in compression. The first floating point value,
both in tension and compression is defined by the ra-
tio of the deformation at the point of reloading to the
total hysteretic deformation demand. The second
4. floating point value, again in both tension and com-
pression, is the ratio of the force at the point of re-
loading to the force corresponding to the total hyste-
retic deformation demand. The third floating point
value is a ratio of the strength developed upon un-
loading to the maximum strength developed in the
monotonic loading stage.
3 NUMERICAL ANALYSES
3.1 Design and analytical procedure
The plan view and elevation of the studied 2-storey
CBF office building with and without dissipative
brace-to-column connections is shown in Figure 6.
The studied building is classified in the normal
building category with the importance factor IE=1
and is located on a firm ground site in Victoria, B.C.,
Canada that qualifies for Fa= Fv=1 (NBCC 2010),
where Fa and Fv are the acceleration and velocity-
based site coefficient, respectively. The design was
performed according to the NBCC 2010 and
CSA/S16-2009 standard, assuming the braced
frames were classified in the Limited Ductile catego-
ry. The specified gravity (dead and live) loads are
shown in Figure 6c and the seismic weight of the en-
tire building is 13312kN. Accidental in-plan torsion
was omitted in both directions.
The design seismic load for the 2-storey CBF
building with tension-compression X-bracing was
determined using the period obtained from the empi-
rical equation to which a factor of 2 was assigned
(NBCC 2010). The obtained period Temp = 0.38s
leads to base shear V = 0.38W. However, according
to NBCC 2010, the maximum earthquake force V
Figure 6. Building studied: a) Plan view; b) Elevation; c) Speci-
fied loads.
needs not to exceed Vlim = 0.31W = 4100kN. This
value was obtained by scaling down the spectral ac-
celeration magnitude by a factor of 2/3S(0.2). From
OpenSees analysis, the computed fundamental pe-
riod is T1= 0.45s which implies a base shear slightly
larger than 0.31W. Thus, each one of the two CBF
systems located in the same direction was designed
to carry a lateral earthquake force Vframe = 2048kN
which corresponds to Rd = 2.0, Ro = 1.3, where Rd
and Ro are the ductility and the overstrength factors,
respectively. All members are made of steel with Fy
= 350MPa and their sizes are shown in Figure 6b.
The braces are square hollow structural sections,
HSS, whereas W-shapes were used for beams and
columns.
The same member sizes were considered for the
CBF structure with dissipative pin connections, in-
corporated at each brace’s end. As mentioned above,
the pin has to yield in bending before the brace
reaches 80% of its buckling strength, Cr. Thus, for
the brace HSS 127x127x8, the Cr is 907kN and for
the brace HSS 127x127x8 it is Cr = 1320kN. In this
light, at the 2nd
floor, the size of the pin is 40x60mm
and at the 1st
floor is 55x65mm. In this design, all
pins are made of steel with the following properties:
Fy = 396MPa and Fu = 586MPa. By employing eq-
uations (2) to (5), the tri-linear curve for both pins is
shown in Figure 7. In the same figure, the buckling
strength of braces computed with the resistance fac-
tor =1.0 and the probable yield strength RyFy,
where the factor Ry = 1.1, is also depicted.
Figure 7. Pin’s response.
At the bottom floor, the width of the inner- and
outer plates was considered to be 280mm. To assure
that the tensile capacity of the plates is larger than
the ultimate capacity of the pin, the thickness of the
outer-plates is 28mm and that of the inner-plates is
22mm, while the length of the pin is 310mm. The
distance between the inner- and the outer-plate as il-
lustrated in Figure 1b is a = 100mm which also veri-
fies with Eq. (6). At the 2nd
floor, the plates’ widths
are 250mm; the thickness of the outer-plates is
22mm, while that of the inner-plates is 15mm. In
both cases Fy= 350MPa.
By considering the characteristics of pin members
as given in the tri-linear curve illustrated in Figure 7,
a
)
c
)
b
)
5. the Pinching4 material was calibrated as described
above (Fig. 5). For the Opensees model of the CBF
system, the same procedure as detailed above was
considered. A 2% damping was applied in the first
and the second vibration mode; damping was consi-
dered proportional to the initial stiffness and for the
CBF structure it was assigned to all members ex-
cluding braces, while for the CBF (pin) to all mem-
bers excluding the pin connections. In this analysis,
the Newton algorithm was employed. It was found,
that the fundamental period of the CBFs equipped
with dissipative connections elongates to 0.82s and
the seismic demand per frame computed base on the
equivalent static method with Rd = 2 and Ro = 1.3 is
V = 1382kN.
3.2 Ground motions
In general, the seismic hazard for a given location is
characterized by uniform hazard spectral ordinates,
Sa, that are specified at periods of 0.2, 0.5, 1.0, and
2.0s for a return period of 2% in 50 years or 2475
years. For Victoria, the spectral ordinates in units of
ground acceleration are: 1.2, 0.82, 0.38, and 0.18g.
The uniform hazard spectrum (UHS) is constructed
based on a conservative method of combining the
spectral accelerations at all aforementioned periods
that are exceeded with a specified rate. Thus, in this
study, the ground motions were selected so that their
spectra matched the design UHS in the range deli-
mited by the following period of interest: 0.2T1 and
1.5T1. In this study, for the analysis of the sample
structure, seven crustal ground motions, which are
shown in Table 1, were selected to match the magni-
tude scenarios for Victoria: Mw6.5 at an epicentral
distance of 20-30km and Mw7.2 at larger epicentral
distances. Although, the seismic hazard for Victoria
is affected by the Cascadia subduction zone, this
scenario is not covered.
In this study, the method proposed by Reyes &
Kalkan (2011) was employed in order to scale the
selected ground motions. Regarding this, the mean
Table 1. Characteristics of selected ground motions
*) peer.berkeley.edu/peer_ground_motion_database
of seven ground motions has to match the UHS in
any period belonging to the range of interest: 0.2T1-
1.5T1. This requirement complies with ASCE/SEI-7
provisions. The scaling factor computed for both
structures with and without dissipative connections
is shown in Table 2. In addition, Table 2 contains the
value of peak ground acceleration, PGA, peak
ground velocity, PGV, the Trifunac td duration and
the total duration, t. The scaled records for time-
history analyses, of the building with pin connec-
tions (T1 = 0.82s), the UHS and the mean of C1 to
C7 records is depicted in Figure 8.
Table 2. Characteristics and scaling factor of ground motions
Figure 8. Scaled acceleration spectrum for CBF with devices.
3.3 Seismic response
The mean response of the structure, with and with-
out dissipative connections, subjected to seven
ground motions, is analysed in terms of base shear
and lateral deformation. Thus, Figure 9a illustrates
the mean time-history base shear against the design
base shear as computed according to the static
equivalent procedure. From this example, it is ob-
served that the 2-storey structure with pin devices
develops a base shear corresponding to a ductility
factor Rd = 3. Furthermore, by studying the mean re-
sponse in terms of ductility, μ, defined as the ratio
Δ/Δy (interstorey drift over interstorey drift at yield),
it results a ductility of μ = 3 (Fig. 9b). However, the
corresponding interstorey drift value, as shown in
Figure 9c, is less than 2.5%hs or 95mm. For both
braced frames, this mean value is lower because
each one of the seven accelerograms (C1 to C7)
reached its PGA at different time step which are:
8.1; 4.59; 9.92; 8.27; 1.09; 6.69 and 19.62s. For both
CBF structures with and without pin devices, the
maximum interstorey drift is below 2.5%hs, while
No Event/Station Comp Mw R
km
C1 Oct 18, 1989 Loma Prieta,
(739)*, Anderson Dam
2500
6.93 19.9
C2 Jan. 17, 1994, Northridge,
(954), Big Tujunga, Angeles N
3520
6.7 19.1
C3 Jan. 17, 1994, Northridge,
(1077), St. Monica City Hall
3600
6.7 17.3
C4 Jan. 17, 1994, Northridge,
(963), Castaic Old Ridge Rout
900
6.7 20.1
C5 Feb. 9, 1971, San Fernando,
(57), Castaic Old Ridge Route
2910
6.6 19.3
C6 Feb, 1979, Imperial Valley,
(164) Cerro Prieto
147 6.53 15.2
C7 Apr. 13, 1949, Western Wash.
Olympia, Test Lab.
860
7.1 76.0
No PGA PGV td t SF SF
(g) (m/s) (s) (s) T1=0.45s T1=0.82s
C1 0.244 0.203 10.51 40.00 2.00 1.82
C2 0.325 0.127 9.44 30.00 2.20 2.00
C3 0.369 0.253 10.72 40.00 2.02 1.83
C4 0.568 0.520 9.10 40.00 1.10 0.92
C5 0.268 0.259 15.04 30.00 2.15 1.95
C6 0.170 0.120 29.70 63.74 2.20 2.00
C7 0.280 0.170 18.80 89.06 2.30 2.10
6. the maximum demand was imposed by the C3 and
C4 records. Thus, in Figure 10, the seismic response
of the dissipative members: braces for CBF and pin
device for CBF (pin) are illustrated when subjected
to the C4 record. The hysteresis loops resulting from
the first floor brace (CBF) in terms of axial force
versus axial displacement is shown in Figure 10a.
Figure 9. Seismic response (Mean): a) base shear; b) ductility
demand; c) interstorey drift.
Figure 10. Hysteresis loops of dissipative members: a) brace;
b) pin device; c) accelerogram C4.
The brace reaches its buckling strength at 5.9s and in
the next cycle its tensile strength at 6.3s. In this case,
some overstrength was developed and a maximum
tensile deformation was reached at 8.26s which cor-
responds to the attainment of the PGA of 0.63g (Fig.
10c). A similar hysteresis response is shown in Fig-
ure 10b for the CBF structure with dissipative pin-
connections. Herein, the figure depicts the axial
force transferred from the brace to the pins, 55x65,
against the cumulative deformation experienced by
both pins attached at the same brace.
4 CONCLUSIONS
From this analysis, it can be concluded that low-rise
buildings with single-pin devices provides the re-
quired resistance and have minor overstrength. Al-
though, there is no weight reduction in the structure,
the foundation cost is reduced, because the lateral
force transferred to the foundations is half than that
transferred by a limited ductile CBF structure.
A CBF structure with pin devices prevents braces
from buckling and it eliminates the uncertainty of
modeling the brace’s plastic zone. By considering
the pin connection as a calibrated device, the model-
ing in plastic range can be accurately controlled. To
better assess the ductility of CBF with pin devices,
an incremental dynamic analysis is required.
5 ACKNOWLEDGMENTS
The authors gratefully acknowledge the financial
support provided by the Natural Sciences and Engi-
neering Research Council of Canada (NSERC) and
also thank researchers: Plumier, Castiglioni, Vayas
and Calado for providing experimental test results.
6 REFERENCES
CSA. 2009. Design of Steel Structures, CSA-S16-09, Canadian
Standards Association, Toronto, ON.
EUROCODE 8, 2004. Design of structures for Earthquake Re-
sistance, EN1998-1, EU Standardization Committee.
NRCC. 2010. National Building Code of Canada 2010, 13th
ed., National Research Council of Canada, Ottawa, ON.
Plumier, A., Castiglioni, C., Vayas, I., Calado, L. 2005. Beha-
viour of seismic resistant braced frame with innovative dis-
sipative connections, EUROSteel Conf., Maastricht, 2005.
Reyes., J.C., Kalkan, E. 2011. Required Number of Records for
ASCE/SEI 7 Ground Motion Scaling Procedure,
http://pubs.usgs.gov/of/2011/1083/of2011-1083.pdf.
Tirca, L., Caprarelli, C., Danila, N. 2011. Behavior of a Low
Rise Concentrically Braced Frame Building with and with-
out Dissipative Pin Connections, Proc. CSCE Annual Conf.,
Ottawa, ON, 14-17 June 2011.
Vayas, I., Thanopoulos, P. 2005. Innovative Dissipative (IN-
ERD) Pin Connections for Seismic Resistant Braced
Frames, International Journal of Steel Structures, Vol. 5.
a) b)
c)
a)
b)
c)