历经长期持荷后钢骨混凝土柱的抗震试验研究

Experimental Study on Seismic Performance of Steel Reinforced Concrete Columns after Axial Sustained Loading

针对钢骨混凝土柱结构在长期荷载作用下,由于混凝土徐变和收缩引发的与时间相关的力学问题,开展了钢骨混凝土柱及钢筋混凝土柱对比试件历经轴向长期持荷后,在水平低周反复荷载下的抗震性能试验.试验监测了长期持荷期间由徐变和收缩引起的柱试件的轴向长期变形,考察了柱试件在抗震试验中的破坏形态、变形和强度等性能指标.试验结果表明,柱试件在持荷1年后,即已完成大部分徐变变形.抗震试验中,所有试件均发生弯剪破坏,无论其是否经历长期持荷,钢骨配置及试验轴压比对各柱试件的影响规律同以往相关研究所得到的结论基本一致:配置钢骨会提高柱试件的变形和耗能性能;随轴压比的增加,柱试件的变形和耗能性能降低,但抗剪承载力有所提高.长期持载作用使钢筋混凝土柱对比试件的初始刚度减小,屈服位移增大,延性系数减小,但对于钢骨混凝土柱试件,由于配置了核心钢骨,长期持荷的影响被抑制和弱化.因此,相较于钢骨配置及轴压比等重要设计参数,长期持荷对钢骨混凝土柱抗震性能的影响在设计中可以忽略.

In view of the time-dependent behavior of steel reinforced concrete(SRC)columns caused by creep and shrinkage under sustained loading,this paper provides an experimental study on the seismic behavior of SRC columns under low cyclic reversed loading,after they are subjected to axial sustained loading.Long-term axial deformations due to shrinkage and creep of the concrete were recorded,and the failure mode,deformation and strength of these columns in seismic test were analyzed.The test results indicate that the columns develope most of the creep deformation after 1 year of axial sustained loading.All columns fail in flexural-shear failure mode under the cyclic loading test.Whether or not the columns undergo sustained loading,the influence of steel reinforcement configuration and axial compression ratio on their seismic performance is similar to the conclusions drawn by previous studies.The deformation capacity and energy dissipation capacity of columns can be improved by adding steel tube in the columns.With the increase of axial compression ratio,the deformation capacity and energy dissipation capacity of columns decrease,but the shear capacity is improved.Sustained loading can lead to enlargement of yielding displacement,while it can decrease the initial stiffness and ductility coefficient in reinforced concrete columns.However,for the steel reinforced concrete columns,the influence of sustained loading on their seismic performance is restricted and weakened owing to the contribution of steel tube.Therefore,compared with the important design parameters such as steel reinforcement configuration and axial compression ratio,the influence of sustained loading on the seismic performance of SRC columns can be neglected in design.