Through the test of 8 RC shear wall specimens and computer analysis ofstrains of steel bars with keyways in the specimens,the authors have studied the remains oftensile stress of concrete between cracks after concrete...Through the test of 8 RC shear wall specimens and computer analysis ofstrains of steel bars with keyways in the specimens,the authors have studied the remains oftensile stress of concrete between cracks after concrete cracking and put forward a formulato calculate coefficient Ψ,the ununiform distribution factor of steel strain.This coefficientcan be used to modify the calculated steel strain in cracked zone,so as to make the resultsof using finite clement method to analyze shear walls more accurate.展开更多
This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ducti...This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ductile behavior of UHPC can also be attributed to the steel fiber reinforcement. This feature must be considered to provide rational explanation of the torsional behavior of UHPC structures. In this study, the proposed torsional design adopts a modified thin-walled tube theory so as to consider the tensile behavior of UHPC. And torsion test was conducted on thin-walled UHPC box beams to validate the proposed formula through comparison of the predicted torsional strength with the experimental results. The comparison of the predicted values of the cracking torque and torsional moment resistance with those observed in the torsional test of UHPC verified the validity of the design method. The contribution of the steel fibers to the torsional strength and cracking load was larger than that of the stirrups, but the stirrups appeared to contribute additionally to the torsional ductility. Accordingly, it is recommended that design should exploit effectively the contribution of the steel fiber rather than arrange a larger number of stirrups in UHPC structures subjected to torsion.展开更多
In situ, the changes of temperature, deformation, and stressing of steel bar of C40 reinforced concrete shear wall were measured, respectively. The results are obvious that the temperature change of climate is one of ...In situ, the changes of temperature, deformation, and stressing of steel bar of C40 reinforced concrete shear wall were measured, respectively. The results are obvious that the temperature change of climate is one of the most effective factors which could lead the concrete shear wall to cracking at earlier age. The temperature differences between inside and outside concrete shear wall are so large that the concrete will gain larger shrinkage. This larger shrinkage which is caused by the temperature reducing ratio will gain the strained action of head, end and reinforced steel bar of concrete shear wall. This action can lead to tensile stress on the surface and inside concrete shear wall. If the tensile stress would exceed the pull strength of concrete, the concrete shear wall would crack and cause deterioration. Thus, the enhancing curing of concrete shear wall in suit at earlier age, and controlling temperature reducing ratio and deform caused by shrinkage, will be available treatments which control occurring and developing of cracking on concrete shear wall.展开更多
文摘Through the test of 8 RC shear wall specimens and computer analysis ofstrains of steel bars with keyways in the specimens,the authors have studied the remains oftensile stress of concrete between cracks after concrete cracking and put forward a formulato calculate coefficient Ψ,the ununiform distribution factor of steel strain.This coefficientcan be used to modify the calculated steel strain in cracked zone,so as to make the resultsof using finite clement method to analyze shear walls more accurate.
文摘This study proposed a prediction formula for the torsional strength enabling to reflect the tensile strength of ultra high performance concrete (UHPC) beams based upon the thin-walled tube theory. The remarkable ductile behavior of UHPC can also be attributed to the steel fiber reinforcement. This feature must be considered to provide rational explanation of the torsional behavior of UHPC structures. In this study, the proposed torsional design adopts a modified thin-walled tube theory so as to consider the tensile behavior of UHPC. And torsion test was conducted on thin-walled UHPC box beams to validate the proposed formula through comparison of the predicted torsional strength with the experimental results. The comparison of the predicted values of the cracking torque and torsional moment resistance with those observed in the torsional test of UHPC verified the validity of the design method. The contribution of the steel fibers to the torsional strength and cracking load was larger than that of the stirrups, but the stirrups appeared to contribute additionally to the torsional ductility. Accordingly, it is recommended that design should exploit effectively the contribution of the steel fiber rather than arrange a larger number of stirrups in UHPC structures subjected to torsion.
基金Funded by the National Natural Science Foundation of China (No. 50539010) State High Technic Program "863 Program" (No. 2005AA332010)
文摘In situ, the changes of temperature, deformation, and stressing of steel bar of C40 reinforced concrete shear wall were measured, respectively. The results are obvious that the temperature change of climate is one of the most effective factors which could lead the concrete shear wall to cracking at earlier age. The temperature differences between inside and outside concrete shear wall are so large that the concrete will gain larger shrinkage. This larger shrinkage which is caused by the temperature reducing ratio will gain the strained action of head, end and reinforced steel bar of concrete shear wall. This action can lead to tensile stress on the surface and inside concrete shear wall. If the tensile stress would exceed the pull strength of concrete, the concrete shear wall would crack and cause deterioration. Thus, the enhancing curing of concrete shear wall in suit at earlier age, and controlling temperature reducing ratio and deform caused by shrinkage, will be available treatments which control occurring and developing of cracking on concrete shear wall.
