Study On Seismic Behavior Of Reinforced Concrete T-shaped Column Under Compression-Flexure-shear And Torsion Combined Action

In order to reveal the seismic behavior of reinforced concrete T-shaped column under compress-flexure-shear-torsion combined action,a total of six specimens of reinforced concrete T-shaped column are designed for the constant compress and reversed cycle flexure-shear-torsion loading test.The vary parameters of torsion-bending ratio and axial compression ratio and ratio of highness and thickness level are considered in the experiment.The failure process and failure pattern are observed;the hysteretic curves of torque-torsion angle and loading-displacement,the character results of crack,yield,peak,and failure point are obtained.Based on the test data,the seismic indexes,such as bearing capacity,ductility,energy dissipation,strength and stiffness degradation are analyzed deeply.The ABAQUS finite element software is used to analyze the experimental model,with the comparison of the hysteretic curves and the moment-displacement curves of experiment and those of finite element model,verifying that the finite element simulation can meet the general precision requirement.a total of fifteen specimens are designed under various conditions on the basis of this model.The vary parameters of torsion-bending ratio and axial compression ratio and the diameter of longitudinal bar and the diameter of stirrup are considered in the finite element model.the influence of different parameters on hysteretic curves,moment-displacement curves,ductility,and original stiffness are analyzed.Based on the experimental results and finite element results,the main conclusions from this dissertation are shown below(1)According to difference of torsion-bending ratio,the failure pattern translates from bending to bend-torsionand torsional shear.When the specimen is destroyed,the concrete at the bottom of the web of the T-section is crushed,the concrete on both sides of the web is damaged because of shear and the oblique crack is "X" shape.(2)The hysteretic curves is "S" shape and pinch obviously.The ductility of specimens are weakened under the action of torque;The elastic lateral displacement angle and the elastic-plastic lateral displacement angle are greater than the China code for seismic design of buildings requirements;the action of torsion can accelerate the emergence of cracks,to some extent,it can enhance the seismic energy dissipation capacity of the specimens;the increase of axial compression can improve the initial stiffness and cracking load of the specimens;the increase of limb thickness ration can improve the torsion strength and ductility of specimens,but it has less influence on the stiffness.(3)The ABAQUS finite element model can simulate the performance of T-shaped column under compression-flexure-shear and torsion combine action effectively.The accuracy of model can meet the general requirements.By adding analyzing,it is conclude that increasing the diameter of longitudinal steel bars can effectively improve the energy dissipation capacity of the specimens,but it contribute the flexural bearing capacity and ductility of specimen finitely,The increase of stirrup diameter cause the improvement of ultimate flexural capacity,but the effect is not obvious.