Long term strain gage monitoring was conducted on the reconstructed silo PC1 to track stress changes in the walls from variations in clinker loading levels and temperatures. Over one year, 16 strain gages at different heights measured stresses as the silo was filled from 5 to 47 meters and discharged. Results showed stresses increased with filling from -52 to 85 MPa and decreased from -29 to -59 MPa with discharge. Stresses also varied by height. Finite element modeling in ANSYS generally matched measured stresses but showed higher dispersion at greater heights. Monitoring provided data to evaluate stresses in the reconstructed silo under working conditions.
This document presents the results of a study comparing the abilities of ABAQUS and OpenSees finite element software to model the pinching and softening behavior observed in an experimental cyclic loading test of a reinforced concrete frame. The test was conducted on a full-scale frame in India. Both software were able to generally capture the strength envelope, but OpenSees was better able to model the pinching effect and strength/stiffness degradation seen in the experimental hysteretic curves. The pinching material model in OpenSees accounted for unloading, reloading and strength degradation in a way that improved the accuracy of the numerical simulation results compared to the experimental data.
Experimental Evaluation of Fatigue Performance of Steel Grid Composite Deck J...IJERDJOURNAL
ABSTRACT:- The steel grid composite deck is a composite structure made of a concrete slab disposed over a steel grid. The joints of the deck segments precast with regular width can be designed by means of lap-spliced rebar or mechanical connection composed of concrete shear key and bolts. This study intends to evaluate comparatively the fatigue performance with respect to the type of joint based upon the results of fatigue tests conducted on deck specimens equipped with such joints. The evaluation reveals that there is practically no change in the stiffness regardless of the type of joint even after 2 million loading cycles and that the safety and serviceability are secured under cyclic loading since the maximum crack widths remained below the allowable values.
#2 2006 improving seismic performance of concrete filled tube to base connec...jothi boominathan
The document summarizes an experimental study on improving the seismic performance of concrete-filled tube (CFT) column base connections. Seven CFT column specimens with varying embedded depths (0.5D, 1.0D, 1.5D) and stiffener configurations were tested under combined axial and lateral loads. It was observed that adding stiffeners to the embedded portion of the CFT columns increased the rigidity of the base connections and allowed the critical section to shift from the column bottom to the top of the foundation. Specimens with stiffeners developed their full strength even at an embedded depth of 0.5D, while an unstiffened specimen required a greater embedded depth of 1D to prevent premature concrete
This paper involves an experimental investigation on the flexural behaviour of curved beams and comparison of its results with conventional beams. Curved beams of size 1200 x 150 x 100 mm with varying initial curvature as 4000mm, 2000mm and the concrete strength as M40 is considered. Various reinforcement are provided in the curved beams to predict which reinforcement detail would give more resistant over maximum loading. The material properties of cement, fine aggregate, coarse aggregate and the compressive strength of concrete cube were found out. A total of 12 specimens of curved beams were casted with various combination of reinforcement along with three control specimens. The beams are tested under two point loading both horizontally and vertically. The deflection and maximum moment carrying capacity are investigated to understand its strength. Also analytical modelling is done to determine the ultimate moment carrying capacity using Finite Element Software ABAQUS to compare with the experimental model.
This document summarizes a study that tested reinforced concrete beam-column connections under cyclic loading to evaluate their seismic performance. A 1/3 scale beam-column specimen was designed and constructed based on analysis of a 4-story building frame. The specimen was tested under reversed cyclic loading with increasing displacements up to failure while monitoring response through instruments. Cracks initially formed in flexure and progressed to shear cracks. Analysis of load-displacement hysteresis loops provided information on ductility, energy dissipation, strength degradation, and stiffness degradation to evaluate the seismic performance of the connection.
Effect of prism height on strength of reinforced hollow concrete block masonryeSAT 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.
Experimental shear testing was conducted on eight unreinforced masonry wall panels with varying mortar and brick strengths to determine the failure mode transition point. Two failure modes were observed: stair-step cracking through mortar joints and diagonal cracking through bricks and mortar. It was found that the transition between modes occurs when the mortar to brick strength ratio is approximately 0.4. Additionally, three repaired wall panels that had previously failed were tested with steel wire rope reinforcement, which improved shear strength and displacement capacity up to double and fifty times respectively compared to the original panels.
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 the results of a study comparing the abilities of ABAQUS and OpenSees finite element software to model the pinching and softening behavior observed in an experimental cyclic loading test of a reinforced concrete frame. The test was conducted on a full-scale frame in India. Both software were able to generally capture the strength envelope, but OpenSees was better able to model the pinching effect and strength/stiffness degradation seen in the experimental hysteretic curves. The pinching material model in OpenSees accounted for unloading, reloading and strength degradation in a way that improved the accuracy of the numerical simulation results compared to the experimental data.
Experimental Evaluation of Fatigue Performance of Steel Grid Composite Deck J...IJERDJOURNAL
ABSTRACT:- The steel grid composite deck is a composite structure made of a concrete slab disposed over a steel grid. The joints of the deck segments precast with regular width can be designed by means of lap-spliced rebar or mechanical connection composed of concrete shear key and bolts. This study intends to evaluate comparatively the fatigue performance with respect to the type of joint based upon the results of fatigue tests conducted on deck specimens equipped with such joints. The evaluation reveals that there is practically no change in the stiffness regardless of the type of joint even after 2 million loading cycles and that the safety and serviceability are secured under cyclic loading since the maximum crack widths remained below the allowable values.
#2 2006 improving seismic performance of concrete filled tube to base connec...jothi boominathan
The document summarizes an experimental study on improving the seismic performance of concrete-filled tube (CFT) column base connections. Seven CFT column specimens with varying embedded depths (0.5D, 1.0D, 1.5D) and stiffener configurations were tested under combined axial and lateral loads. It was observed that adding stiffeners to the embedded portion of the CFT columns increased the rigidity of the base connections and allowed the critical section to shift from the column bottom to the top of the foundation. Specimens with stiffeners developed their full strength even at an embedded depth of 0.5D, while an unstiffened specimen required a greater embedded depth of 1D to prevent premature concrete
This paper involves an experimental investigation on the flexural behaviour of curved beams and comparison of its results with conventional beams. Curved beams of size 1200 x 150 x 100 mm with varying initial curvature as 4000mm, 2000mm and the concrete strength as M40 is considered. Various reinforcement are provided in the curved beams to predict which reinforcement detail would give more resistant over maximum loading. The material properties of cement, fine aggregate, coarse aggregate and the compressive strength of concrete cube were found out. A total of 12 specimens of curved beams were casted with various combination of reinforcement along with three control specimens. The beams are tested under two point loading both horizontally and vertically. The deflection and maximum moment carrying capacity are investigated to understand its strength. Also analytical modelling is done to determine the ultimate moment carrying capacity using Finite Element Software ABAQUS to compare with the experimental model.
This document summarizes a study that tested reinforced concrete beam-column connections under cyclic loading to evaluate their seismic performance. A 1/3 scale beam-column specimen was designed and constructed based on analysis of a 4-story building frame. The specimen was tested under reversed cyclic loading with increasing displacements up to failure while monitoring response through instruments. Cracks initially formed in flexure and progressed to shear cracks. Analysis of load-displacement hysteresis loops provided information on ductility, energy dissipation, strength degradation, and stiffness degradation to evaluate the seismic performance of the connection.
Effect of prism height on strength of reinforced hollow concrete block masonryeSAT 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.
Experimental shear testing was conducted on eight unreinforced masonry wall panels with varying mortar and brick strengths to determine the failure mode transition point. Two failure modes were observed: stair-step cracking through mortar joints and diagonal cracking through bricks and mortar. It was found that the transition between modes occurs when the mortar to brick strength ratio is approximately 0.4. Additionally, three repaired wall panels that had previously failed were tested with steel wire rope reinforcement, which improved shear strength and displacement capacity up to double and fifty times respectively compared to the original panels.
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.
IRJET- Study & Improvement of Design and Construction Methodology of Precast ...IRJET Journal
The document studies the design and construction methodology of precast concrete segmental box culverts. It analyzes 6 alternative design modules for single and double box cells using different end conditions. Finite element analysis is conducted to determine the optimal section dimensions that result in minimum bending moments, shear forces, and principal stresses. Transportation cost is found to be lowest for a double box cell design with hinge joints at the top and bottom.
1. The document discusses applying the convergence-confinement approach to analyze rock-lining interaction in tunnels using the Shimizu Tunnel case study.
2. It constructs ground reaction and support characteristic curves for different support systems - steel ribs, shotcrete, and rock bolts used in Shimizu Tunnel.
3. By intersecting the curves, it determines the design load carried by each support system when the ground and lining reach equilibrium after tunnel excavation.
CONCRETE FILLED STEEL TUBULAR COLUMNS USING GS SHEETAL AMIN AZIZ
1) The document presents the findings of an experimental investigation on concrete filled steel tubular columns using galvanized steel sheet strengthened with self-compacting concrete.
2) The investigation found that confined columns exhibited less axial deformation than unconfined columns under the same loads and failed initially at the top and bottom before failing in the middle.
3) It was concluded that confined columns provided higher strength than unconfined columns and failed due to shear stresses, while further research is needed on casting methods and numerical modeling to better understand column behavior.
Experimental study on shear behavior of the interface between old and new dec...Fakhruddin Muchtar
The document describes an experimental study that tested the shear behavior of the interface between old and new concrete deck slabs under different conditions. Nine specimens were tested that varied the initial prestressing level, connection method of steel bars across the interface, reinforcement ratio, and surface roughness of the interface. The specimens were subjected to double-shear testing and the shear capacity, cracking patterns, joint openings, load-displacement responses, and stress in prestressing rods were examined. The experimental results were then compared to code design provisions.
Evaluation of concrete spall repairs by pullout testfrank collins
This document summarizes a study that evaluated concrete spall repairs using pullout tests. Concrete specimens were damaged via an initial pullout test, repaired with epoxy mortar, and subjected to a second pullout test. The tests showed that:
1) Pullout force of repaired specimens was linearly correlated with concrete cylinder compressive strength up to around 45 kN/2.26 MPa, but diminished at higher strengths.
2) Pullout force/stress of repaired specimens increased similarly to concrete specimens as age increased up to 90 days, but was lower than unrepaired concrete.
3) Higher initial pullout damage forces resulted in higher pullout forces for repaired specimens, up to around 43
This document summarizes a master's thesis that experimentally and numerically studied the pull-out behavior of steel fibers in concrete. Experiments were conducted on straight and hooked steel fibers under various lateral pressures. The experiments showed large variations in results partly due to local crushing of the cement matrix. A numerical model was developed using an interface damage model and contact simulation to model fiber-concrete bonding. The model studies the influence of heterogeneous concrete properties on hooked fiber pull-out behavior by varying cement, aggregate, and interface strengths and toughnesses. Simulated results agreed with experiments, showing local concrete fracture influences pull-out behavior.
Comparison of performance of lateral load resisting systems in multi storey f...eSAT Journals
Abstract This paper introduces the comparison between lateral load resisting systems in multi storey building. Multi storey building
composed of very special class of structure and therefore require special treatment. Hence to overcome the effects of seismic
forces, Flat slab system in which slab rests on drop or capital which is connected to column is induced with different load
resisting systems. The combined systems which is used to withstand seismic forces in this study are 1. Flat slab without lateral
load resisting system, 2. Flat slab with shear wall, 3. Flat slab with infill wall, 4. Flat slab with bracings, 5. Flat slab with shear
wall and bracings. ETABS software version is used to accomplish dynamic analysis and also building is investigated for nonlinear
static analysis in order to identify seismic demands. From the obtained results conclusions are drawn.
Keywords: Capital, Bracings, Dynamic, and Treatment etc…
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences 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
The document presents a finite element analysis of concrete filled steel tube (CFT) beams subjected to flexure. A numerical model was developed using ANSYS to predict the flexural behavior and moment capacity of circular and rectangular CFT beams. The model considered the material properties of steel and concrete, and incorporated the interaction between concrete and steel. Results of the numerical analysis for moment capacity were compared to experimental data. For circular CFT beams, the predicted capacities matched well with experimental values. The analysis showed rectangular CFTs can provide good confinement of the concrete core.
Stiffness degradation behavior of retrofitted rc infilled frame under cyclic ...eSAT Journals
Abstract The present study was to evaluate the load carrying capacity of retrofitted 3-bay 4-storey brick infill R.C frame using Ferro cement under cyclic loading. Generally bricks will not be considered as a structural element, but by an effective strengthening technique infill walls and RC frame elements can be kept together and forcing them to work as a whole until the end of the ground motion. The effectiveness of the retrofitted frame under cyclic load was investigated in terms of displacement, stiffness and load carrying capacity. Keywords: Retrofit, Ferro cement, R.C frame, brick infill, cyclic loading, stiffness degradation
1) The study tested 4 reinforced self-compacting concrete beams to analyze the effect of construction joints on structural performance.
2) The beams included a reference beam without a joint, and beams with horizontal, vertical at mid-span, and vertical at 1/4 span joints.
3) Test results showed construction joints had a more significant effect on ultimate load than first crack load. The horizontal joint beam performed best with a 6.7% reduction in first crack load and 26.7% reduction in ultimate load compared to the reference beam. The vertical 1/4 span joint beam performed worst with reductions of 16.7% and 56.2% respectively.
Dynamic Analysis of Soft Storey Frame with IsolatorsIJMTST Journal
Soft storey buildings are very common in Indian housing construction and the bottom storey is left open without walls for car parking. Past earthquakes showed that these kinds of buildings performed poor and the damages are also heavy. As the base isolation is a technique developed to prevent or minimize damage to building during an earthquake, this study focuses on the time history analysis of a soft-storey building with and without lead rubber isolator. The soft-storey building with and without isolator is analysed using Elcenrto earthquake data and the dynamic characteristics are compared.
Parametric Study of Square Concrete Filled Steel Tube Columns Subjected To Co...IJERA Editor
The Concrete Filled Steel Tube (CFST) member has many advantages compared with the conventional concrete structural member. This study presents on the behaviour of concrete-filled steel tube (CFST) columns under axial load by changing parameters. The parameters are thickness of steel tube, Grade of concrete and length of column. The study was conducted using ANSYS 13 finite element software. All the columns are 60 X 60 mm in size. The thickness of the tube is taken as 2, 3, 4, 5 and 6 mm for thickness variation. The grades of concrete infill are M25, M30, M40, M50, M60 and M70 used for grade variation. Lengths of columns are taken as 900, 1200, 1500, 1800, 2100, and 2400 mm for length variation. Buckling load is compared with Euro code 4 (1994).
This document presents a numerical analysis of high strength concrete beams using ABAQUS finite element software. An M60 concrete beam was modeled in ABAQUS with different reinforcement configurations. The beam models were analyzed under static loading and the results were verified against experimental data. The failure loads, deflections, and load-deflection behaviors obtained from ABAQUS analysis matched closely with the experimental values, with errors of less than 10% in most cases. Stress contours from the ABAQUS models also agreed well with the failure patterns observed in experiments. The study demonstrated that ABAQUS can accurately simulate the behavior of reinforced high strength concrete beams.
Cyclic Load Test on Beam-Column Behavior of Portal Frame Strengthening by Mic...Md. Sajjak Hosain
I am Md. Sajjak Hosain. This is my undergraduate thesis program for retrofitting of existing structure with local material available in Bangladesh. This thesis highlights the behavior of RCC structure after and before strengthening.
This document summarizes analytical studies on concrete filled steel tubes. A finite element model of a rectangular concrete filled steel tube short column was created using ANSYS software. The model was validated against experimental data. Both eigenvalue and nonlinear buckling analyses were performed to determine the ultimate axial load capacity of the column. The eigenvalue analysis provides the theoretical buckling strength, while the nonlinear analysis is more accurate as it considers factors like imperfections and plastic behavior. The results from the ANSYS model were used to develop an approximate formula for calculating the ultimate load of rectangular concrete filled steel tube short columns based on material properties.
The document presents a finite element analysis of reinforced concrete beam-column connections under monotonic loading using ABAQUS. Two experimental specimens were modeled - a control specimen (J0) with joint reinforcement and a specimen (JI0) without joint reinforcement. The models showed good agreement with experimental load-deflection curves and failure modes. A parametric study then investigated the effects of column width, axial column load, and concrete compressive strength. It was found that increasing these parameters increased the connection capacity. The finite element analysis provided an accurate way to study beam-column connection behavior without the cost and time of physical testing.
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.
IRJET- Study & Improvement of Design and Construction Methodology of Precast ...IRJET Journal
The document studies the design and construction methodology of precast concrete segmental box culverts. It analyzes 6 alternative design modules for single and double box cells using different end conditions. Finite element analysis is conducted to determine the optimal section dimensions that result in minimum bending moments, shear forces, and principal stresses. Transportation cost is found to be lowest for a double box cell design with hinge joints at the top and bottom.
1. The document discusses applying the convergence-confinement approach to analyze rock-lining interaction in tunnels using the Shimizu Tunnel case study.
2. It constructs ground reaction and support characteristic curves for different support systems - steel ribs, shotcrete, and rock bolts used in Shimizu Tunnel.
3. By intersecting the curves, it determines the design load carried by each support system when the ground and lining reach equilibrium after tunnel excavation.
CONCRETE FILLED STEEL TUBULAR COLUMNS USING GS SHEETAL AMIN AZIZ
1) The document presents the findings of an experimental investigation on concrete filled steel tubular columns using galvanized steel sheet strengthened with self-compacting concrete.
2) The investigation found that confined columns exhibited less axial deformation than unconfined columns under the same loads and failed initially at the top and bottom before failing in the middle.
3) It was concluded that confined columns provided higher strength than unconfined columns and failed due to shear stresses, while further research is needed on casting methods and numerical modeling to better understand column behavior.
Experimental study on shear behavior of the interface between old and new dec...Fakhruddin Muchtar
The document describes an experimental study that tested the shear behavior of the interface between old and new concrete deck slabs under different conditions. Nine specimens were tested that varied the initial prestressing level, connection method of steel bars across the interface, reinforcement ratio, and surface roughness of the interface. The specimens were subjected to double-shear testing and the shear capacity, cracking patterns, joint openings, load-displacement responses, and stress in prestressing rods were examined. The experimental results were then compared to code design provisions.
Evaluation of concrete spall repairs by pullout testfrank collins
This document summarizes a study that evaluated concrete spall repairs using pullout tests. Concrete specimens were damaged via an initial pullout test, repaired with epoxy mortar, and subjected to a second pullout test. The tests showed that:
1) Pullout force of repaired specimens was linearly correlated with concrete cylinder compressive strength up to around 45 kN/2.26 MPa, but diminished at higher strengths.
2) Pullout force/stress of repaired specimens increased similarly to concrete specimens as age increased up to 90 days, but was lower than unrepaired concrete.
3) Higher initial pullout damage forces resulted in higher pullout forces for repaired specimens, up to around 43
This document summarizes a master's thesis that experimentally and numerically studied the pull-out behavior of steel fibers in concrete. Experiments were conducted on straight and hooked steel fibers under various lateral pressures. The experiments showed large variations in results partly due to local crushing of the cement matrix. A numerical model was developed using an interface damage model and contact simulation to model fiber-concrete bonding. The model studies the influence of heterogeneous concrete properties on hooked fiber pull-out behavior by varying cement, aggregate, and interface strengths and toughnesses. Simulated results agreed with experiments, showing local concrete fracture influences pull-out behavior.
Comparison of performance of lateral load resisting systems in multi storey f...eSAT Journals
Abstract This paper introduces the comparison between lateral load resisting systems in multi storey building. Multi storey building
composed of very special class of structure and therefore require special treatment. Hence to overcome the effects of seismic
forces, Flat slab system in which slab rests on drop or capital which is connected to column is induced with different load
resisting systems. The combined systems which is used to withstand seismic forces in this study are 1. Flat slab without lateral
load resisting system, 2. Flat slab with shear wall, 3. Flat slab with infill wall, 4. Flat slab with bracings, 5. Flat slab with shear
wall and bracings. ETABS software version is used to accomplish dynamic analysis and also building is investigated for nonlinear
static analysis in order to identify seismic demands. From the obtained results conclusions are drawn.
Keywords: Capital, Bracings, Dynamic, and Treatment etc…
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences 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
The document presents a finite element analysis of concrete filled steel tube (CFT) beams subjected to flexure. A numerical model was developed using ANSYS to predict the flexural behavior and moment capacity of circular and rectangular CFT beams. The model considered the material properties of steel and concrete, and incorporated the interaction between concrete and steel. Results of the numerical analysis for moment capacity were compared to experimental data. For circular CFT beams, the predicted capacities matched well with experimental values. The analysis showed rectangular CFTs can provide good confinement of the concrete core.
Stiffness degradation behavior of retrofitted rc infilled frame under cyclic ...eSAT Journals
Abstract The present study was to evaluate the load carrying capacity of retrofitted 3-bay 4-storey brick infill R.C frame using Ferro cement under cyclic loading. Generally bricks will not be considered as a structural element, but by an effective strengthening technique infill walls and RC frame elements can be kept together and forcing them to work as a whole until the end of the ground motion. The effectiveness of the retrofitted frame under cyclic load was investigated in terms of displacement, stiffness and load carrying capacity. Keywords: Retrofit, Ferro cement, R.C frame, brick infill, cyclic loading, stiffness degradation
1) The study tested 4 reinforced self-compacting concrete beams to analyze the effect of construction joints on structural performance.
2) The beams included a reference beam without a joint, and beams with horizontal, vertical at mid-span, and vertical at 1/4 span joints.
3) Test results showed construction joints had a more significant effect on ultimate load than first crack load. The horizontal joint beam performed best with a 6.7% reduction in first crack load and 26.7% reduction in ultimate load compared to the reference beam. The vertical 1/4 span joint beam performed worst with reductions of 16.7% and 56.2% respectively.
Dynamic Analysis of Soft Storey Frame with IsolatorsIJMTST Journal
Soft storey buildings are very common in Indian housing construction and the bottom storey is left open without walls for car parking. Past earthquakes showed that these kinds of buildings performed poor and the damages are also heavy. As the base isolation is a technique developed to prevent or minimize damage to building during an earthquake, this study focuses on the time history analysis of a soft-storey building with and without lead rubber isolator. The soft-storey building with and without isolator is analysed using Elcenrto earthquake data and the dynamic characteristics are compared.
Parametric Study of Square Concrete Filled Steel Tube Columns Subjected To Co...IJERA Editor
The Concrete Filled Steel Tube (CFST) member has many advantages compared with the conventional concrete structural member. This study presents on the behaviour of concrete-filled steel tube (CFST) columns under axial load by changing parameters. The parameters are thickness of steel tube, Grade of concrete and length of column. The study was conducted using ANSYS 13 finite element software. All the columns are 60 X 60 mm in size. The thickness of the tube is taken as 2, 3, 4, 5 and 6 mm for thickness variation. The grades of concrete infill are M25, M30, M40, M50, M60 and M70 used for grade variation. Lengths of columns are taken as 900, 1200, 1500, 1800, 2100, and 2400 mm for length variation. Buckling load is compared with Euro code 4 (1994).
This document presents a numerical analysis of high strength concrete beams using ABAQUS finite element software. An M60 concrete beam was modeled in ABAQUS with different reinforcement configurations. The beam models were analyzed under static loading and the results were verified against experimental data. The failure loads, deflections, and load-deflection behaviors obtained from ABAQUS analysis matched closely with the experimental values, with errors of less than 10% in most cases. Stress contours from the ABAQUS models also agreed well with the failure patterns observed in experiments. The study demonstrated that ABAQUS can accurately simulate the behavior of reinforced high strength concrete beams.
Cyclic Load Test on Beam-Column Behavior of Portal Frame Strengthening by Mic...Md. Sajjak Hosain
I am Md. Sajjak Hosain. This is my undergraduate thesis program for retrofitting of existing structure with local material available in Bangladesh. This thesis highlights the behavior of RCC structure after and before strengthening.
This document summarizes analytical studies on concrete filled steel tubes. A finite element model of a rectangular concrete filled steel tube short column was created using ANSYS software. The model was validated against experimental data. Both eigenvalue and nonlinear buckling analyses were performed to determine the ultimate axial load capacity of the column. The eigenvalue analysis provides the theoretical buckling strength, while the nonlinear analysis is more accurate as it considers factors like imperfections and plastic behavior. The results from the ANSYS model were used to develop an approximate formula for calculating the ultimate load of rectangular concrete filled steel tube short columns based on material properties.
The document presents a finite element analysis of reinforced concrete beam-column connections under monotonic loading using ABAQUS. Two experimental specimens were modeled - a control specimen (J0) with joint reinforcement and a specimen (JI0) without joint reinforcement. The models showed good agreement with experimental load-deflection curves and failure modes. A parametric study then investigated the effects of column width, axial column load, and concrete compressive strength. It was found that increasing these parameters increased the connection capacity. The finite element analysis provided an accurate way to study beam-column connection behavior without the cost and time of physical testing.
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.
La Web 2.0 permite a los usuarios crear y compartir contenido de manera colaborativa, convirtiéndose en contribuidores activos. Facilita la publicación y distribución abierta de información de forma interactiva. Para el periodismo, la Web 2.0 ofrece nuevas formas de comunicar las noticias de manera participativa, donde las audiencias ayudan a construir los contenidos.
La alumna Lilia Bacilia Carrizales Ibarra presentó un ejercicio de la unidad 2 de Investigaciones y Actividades Prácticas de la materia de Mercadotecnia Electrónica ante su maestra María Guadalupe Navarro Torres en septiembre de 2014.
El documento describe las actividades para crear un curso en línea que incluyen diseñar un curso en Canvas con temas y subtemas, crear un video en CamStudio y publicarlo en YouTube, incrustar el video en Canvas, diseñar 5 diapositivas en SlideShare.net y compartirlas, y crear una presentación del curso en HaikuDeck y incrustarla en Canvas. El documento fue elaborado por Jorge Quiroz Díaz.
Este documento presenta los resultados de evaluación de 26 estudiantes de enfermería de la Universidad Técnica de Machala. Incluye las calificaciones de cada estudiante en trabajos autónomos de investigación, prácticas, evaluaciones parciales y la evaluación final, así como su promedio general y posición en la clase. La estudiante Katherine Ochoa obtuvo la calificación más alta con un promedio general de 10, mientras que Sara Nagua obtuvo la calificación más baja con un promedio de 7.
Flor Oliver Plata presenta a su familia y comparte algunos detalles sobre su vida. Creció con su hermana y padre, a quien extraña desde que falleció. Actualmente está casada con Erick Monroy y tienen un hijo, Irving Santiago. Flor y Erick bailan en un grupo de danza universitario llamado Yeyecatl. Flor cursa el sexto semestre de la licenciatura en educación mientras cría a su familia y trabaja como maestra.
El Ministerio de Finanzas de Indonesia ofrece varias becas para estudios de posgrado en el extranjero. Las becas incluyen programas de maestría y doctorado en universidades de alto nivel en varios países. Los solicitantes deben cumplir con los requisitos académicos y de idioma especificados para cada programa de becas.
O documento discute vários aspectos do trânsito no Brasil, incluindo as datas comemorativas, os órgãos responsáveis, as leis e regulamentações, infrações e o Departamento Nacional de Trânsito.
La cibernética se refiere al estudio del control y la regulación en sistemas complejos, ya sean biológicos, sociales o tecnológicos. Su propósito es desarrollar lenguajes y técnicas para abordar problemas de control y comunicación que permitan a los sistemas mantener su equilibrio a pesar de variaciones ambientales. La cibernética fue introducida por Norbert Wiener para referirse a la ingeniería de sistemas de control humanos.
Stress ribbon bridges stiffened by arches or cablesMasum Majid
The document summarizes research on developing new stress-ribbon pedestrian bridges that are stiffened by arches or cables. It describes two types of structures being studied: 1) A two-span stress-ribbon deck supported and stiffened by a central arch. 2) A suspension structure formed by a straight or arched stress-ribbon fixed at the abutments and stiffened by external bearing cables. The paper presents the structural solutions, analysis methods, and some preliminary results from testing scale models.
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1. Long term strain gage monitoring of the cylindrical construction of the silo PC1
Lukáš Kowalski1
Annotation
Thin walled steel shell structures have considerable utilization in various industrial
applications – pipelines, various chemical applications, tanks, silos, etc. In ideal state of loading and
ideal geometry without any dents, shell theory can be applied – in construction occur only axial
forces. With increasing slenderness, problems of losing the stability come to prior. Usage of
various stiffening systems is one of the possibilities how to increase buckling resistance of the
structure. Among mentioned constructions belongs even construction of the silo PC1 in company
Holcim. Construction of the silo PC1 (serves for storing clinker) is the main subject of the article.
On originally not stiffened construction of the silo were noticed various failures that led to, at the
first stage to repair of the failures, in the second step led to overall reconstruction of the silo
structure through application of the orthotropic stiffeners. Article is focused on experimental
monitoring using the strain gages of the walls of the silo construction. Results of the monitoring are
being compared with results of the mathematical modeling of the construction using finite element
method in program ANSYS.
Introduction
In past years, significant number of silo failures was noticed. This fact raises serious concerns about
safety and reliability of the silo constructions. From research, common behavior of the collapsed
constructions was noticed, in most cases, wrong usage of the constructions was set as a origin of the
failures. Among such a reasons belong nonsymmetrical filling/discharge, wrong estimation of the
material characteristics (flow properties) of the stored material, the other utilization errors and poor
quality workmanship, unauthorized design changes, etc.. During usage of the silo PC1 serious
1
Kowalski, Lukáš, Ing., Department of steel and timber structures, Faculty of civil engineering, Slovak university of
technology, Radlinského 11, 813 68, Bratislava, e-mail: lukas.kowalski@stuba.sk, 00 421 903 719 302
2. deformations even with the fracture of the bearing horizontal foundation stiffening ring occurred.
Application of the various types of the stiffeners is one of the possibilities of reconstruction of the
silo structures and of the increasing of the buckling resistance of the thin walled shell structures. In
the set of standards and in the literature, formulas and processes just for some basic types of
geometry and loading states are mentioned. General recommendations for design of the stiffeners
are not presented; just appeal to solution using FEM is mentioned. In recent years, research was
focused on the impact of the imperfections on the construction (Singer, Abramovic, 1995), buckling
of the not-stiffened cylinder shells (Galletly, 1987, Shen, Chen, 1991), stiffened cylindrical shells
(Agelidis, 1982, Miller, Vojta, 1984, Croll 1985). Impact of the discrete vertical restraints was
researched by Eggwertz and Samuelson (1991), impact of local imperfections as a consequence of
the hit was researched by Krishnakumar, Foster (1991).
Object: Silo PC1 in Holcim, Rohožník
In site Holcim, 2 same silos that serve for storage clinker, PC1 and PC2, are placed. Silos
were designed by PIO Keramoprojekt in 1973. Diameter of the silo PC1 is 36m, height of the
cylindrical part is 41,4m and overall height to the top of the silo is 50,525m. Storage capacity of the
silo is 60 000t of clinker. Constructional material of the silo walls with variable thickness (design
thickness 33mm – 13mm, real thickness from diagnostic overview 29mm – 10mm) is steel S275.
Construction of the silo is bolted to the foundation through welded T restraint (T330x70-250x25).
On the east side of the silo is lift to top of the silo. 8 hoppers are placed in two rows (2x4). Improper
use of the silo (nonsymmetrical charge, discharge) led to significant failure of the construction
(deformations, fracture of the bottom bearing ring), therefore resolution about upcoming
reconstruction were done. In the first stage, fractures were fixed, in the second stage system of
orthotropic restraints were designed and applied.
3. Fig. 1 View at the reconstructed structure of the silo PC1 with installed strain gage aparature
Experiment: long term strain-gage monitoring of the silo PC1
In 2009 was determined to examine an experimental long term strain gage monitoring of the
reconstructed construction of the silo PC1. Aim of the experiment was to track changes of the
stresses on silo walls from the change of the loading state (height of the clinker, change of the
temperature of the wall). Minimal length of duration of the experiment was set to 1year due to
lasting of the one cycle between ordinary shut down of the clinker furnace. Minimum height of the
storage clinker in the silo was reached on measurement no. 35 (3.12.2010, 4,995m). Before shut
down, silo was fully filled (measurement no. 40, 28.1.2011 approximately 46,59m). Measured
stresses serve as a basement for comparison with numerical results (ANSYS) of calculation of the
stresses on construction of the silo.
4. On silo was planned to install 16 strain gages, linear HBM LY11 and T rosettes HBM XY11. Strain
gages LY11 are placed near restraints and on the “L” shaped restraint. Strain gages XY11 are
placed between restraints. Horizontally, strain gages were placed in 3 sets – A, B, C. Vertically,
strain gages are glued at heights: +1,000m, +5,525m, 6,675m, +8,025m, +10,525m. Height of the
filling by storied clinker was measured by two radar rangefinders Siemens Sitrans LR400.
Measurement of the temperature of the silo wall was done from measurement no. 30 by non-contact
thermometer CEM DT-812 (1.10.2010).
Outputs of strain gage measurement are noticed in diary of the experiment. In diary are stored data:
change of the stress for appropriate strain gage, change of the height of the filling, weather
conditions, date and time of the measurement, progress of the work on long term monitoring. On
additional list are tracked data about temperature of the silo walls.
Then data from linear strain gages are calculated through formula
εσ E= (1)
Data from T rosette strain gages are calculated to planar state of loading through formulas
)(
1 2 yxx
E
νεε
ν
σ +
−
= (2)
)(
1 2 xyy
E
νεε
ν
σ +
−
= (3)
Fig. 2 Schematic position of the strain-gage device
6. height of the filling of the silo PC1
0
5
10
15
20
25
30
35
40
45
50
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
number
heightofthefilling[m]
Fig. 7 Height of the filling of the silo PC1
Finite element method simulation (model) of the silo PC1
Finite element method simulation (model) is part of theoretical analysis of the silo
construction. Model was created in FEM program ANSYS. In analysis, quadratic approximation
elements are used:
SHELL93 (8 node shell element) for silo walls
BEAM189 (3 node beam element) for restraints
SOLID95 (20 node volume element) for volume of storage clinker
Fig. 8 Elements used in
analysis, SHELL93, SOLID95, BEAM189
Interaction between construction of the silo and storage clinker was created through pair of
the surface contact elements TARGET170 (silo wall)/CONTACT174 (storage clinker). Mass of the
clinker is modeled as cylinder with appropriate height ranged from 5m (cylinder) to 47m (cylinder
+ cone) with step of 5m. Steel is described by bilinear model with stiffening. Value of yield stress is
fy=275MPa, modulus of elasticity E=210.109
Pa for primary wave, E=210.107
Pa for secondary
7. wave. For clinker, Drucker-Prager model for particle materials was used. Input data for clinker was
taken from standards STN (r=1500 kg/m3
, f=30°) and EC (r=1800 kg/m3
, f=40°). Modulus of
elasticity of clinker is E=10MPa. Coefficient of friction is m=0.56, cohesion is c=0kPa. System is
loaded by self weight of the construction and storaged material. In analysis, non uniform
diskretisation to final elements is used with increased density at lower part if the construction.
Connection of the silo to the foundation is pinned. Solution was done using small deformations
method.
Fig. 9 Cross section of the silo structure and
storied clinker
Fig. 11 von Mises stresses on the silo
structure from loading of the self weight of
the storied material, height of the filling 5m
Fig. 10 Mass of the clinker, filling height 47m
Fig. 12 von Mises stresses on the silo
structure from loading of the self weight of
the storied material, height of the filling 47m
9. Graph on Fig. 19 represents change of the meridional stress during increase of the filling
height from 4995mm to 46590mm (increase 41595mm). During that period, meridional stresses
were increased in range from 52,450MPa to 85,300MPa. Maximum amplitude of the measured
meridional stress was 105,400MPa. Output data from strain gage device are displayed as a square
marks (linear strain gage) and cross marks (T rosette). Lines (dot, solid) represent outputs from the
FEM analysis. Dot lines describe stresses from the filling the silo to
0
5
10
15
20
25
30
35
40
-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120
change of the meridional stresses while filling of the silo structure [MPa]
height[m]
A B C cross A cross B cross C EC stiff 47m
EC stiff 5m EC stiff 47-5m EC wall 47m EC wall 5m EC wall STN stiff 47m STN stiff 5m
STN stiff STN wall 47m STN wall 5m STN wall
Fig. 19 Comparison of measured changes of meridional stresses and data from FEM analysis
during filling process
10. Graph on Fig. 20 represents change of the meridional stress during discharge (change of the
filling height from 46590mm to 16140mm (decrease 30340mm). During that period, meridional
stresses were increased in range from -29,290MPa to -59,300MPa. Maximum amplitude of the
measured meridional stress was -69,000MPa.
From the graphs on Figures 19, 20 is obvious dispersion of the measured data of the changes of the
meridional stresses with increasing height of the installed strain gages. This effect is caused
probably due to decreasing of the stiffness with increasing height from the supports. On the strain
gages near horizontal “L” restraint was tracked the smallest dispersion of the measured data. It has
to be mentioned that input data of the loading for FEM analysis are characteristic values.
0
5
10
15
20
25
30
35
40
-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120
change of the meridional stresses while discharge of the silo structure[MPa]
height[m]
A B C cross A cross B cross C
EC stiff 47m EC stiff 15m EC stiff EC wall 47m EC wall 15m EC wall
STN VYSTUZ 47m STN VYSTUZ 15m STN VYSTUZ STN wall 47m STN wall 15m STN wall
Fig. 20 Comparison of measured changes of meridional stresses and data from FEM analysis
during discharge process
11. 0
5
10
15
20
25
30
35
40
-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120
amplitudes of the tracked meridional stresses [MPa]
height[m]
A B C cross A cross B cross C
Fig. 21 Changes of the stresses on strain-gage devices during shut down of the clinker furnace,
measurements 40-43, 28.1.2011-25.2.2011
On Fig. 21 measured data during shut down of the clinker furnace are shown. During that
period were noticed only minor changes of the stresses on the silo walls. That measurement proved
sufficient stability of the strain-gage devices in rather long period. Again, dispersion of the
measured data was increasing with increasing height of the installed strain gages. Strain gages
installed near horizontal restraint proved the smallest dispersion of the measured data.
12. Lessons learned from usage of the long-term strain gage monitoring
During overall long term monitoring was strain-gage device working and react properly on
changes of usage conditions (height of filling, temperature of the wall, outside temperature). Usual
problem was that strain gage was not able to maintain “zero” reference value in long term period.
Mostly, this problem was dominant on strain gages installed on the “L” restraint. On these strain
gages, values of the changes of the circumferential stresses lowered down to the value
approximately -400MPa. Trends of behavior of the installed strain gages are similar.
-500
-450
-400
-350
-300
-250
-200
-150
-100
-50
0
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
number
changeofstress[MPa]
Fig. 22 Output from strain gages “L” restraint, circumferential stresses
Measurement in short time period proved that strain gages were working properly and
outputs from the strain gages followed data of the filling the silo (vertical channel) and data
describing the temperature of the environment and temperature of the walls of the silo (horizontal
channel).
-80
-70
-60
-50
-40
-30
-20
-10
0
25.0 25.2 25.4 25.6
number
changeofstress[MPa]
-140
-130
-120
-110
-100
-90
-80
-70
-60
26.0 26.2 26.4 26.6 26.8
number
changeofstress[MPa]
Fig. 23 Output from strain gages “L” restraint, circumferential stresses, 1.7.2010, 25.7.2010
13. Application of the strain gages is strongly recommended when temperature exceed at least
15°C. By lower temperatures were noticed problems with setting of the glue that led to
impossibility of application of the strain gages. It is necessary to take special care about isolation of
the strain gage device against weather conditions, humidity, water, dust, etc.. Installation of the
strain gages in required quality were time consuming, therefore were maximum 4 strain gages
installed in one day (2-3 workers). Generally, it is possible to validate used strain gages as
conditionally sufficient for long term exterior monitoring of the construction that are exposed to
difficult weather conditions. It is recommended to install several strain gages to provide possibility
of comparing results.
References
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technickej normalizácie, 2006
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