【摘要】 通过6根钢筋混凝土短柱的低周反复加载试验研究,分离了柱剪切反应和受弯反应。分析结果表明:剪切破坏柱的剪切刚度随剪切裂缝的开展逐渐减小,达到最大剪力时剪切反应骨架曲线进入下降段,剪切滞回曲线具有捏拢效应及刚度退化等特征。达到最大剪力前,柱剪切反应、受弯反应同步发展;达到最大剪力后,对于剪切破坏柱,受弯反应不再发展,剪切反应不断增加,对于受弯破坏柱,两种反应发展趋势相反。对于初始受剪能力小于受弯能力的柱,在剪力达到初始受剪能力时进入剪切破坏阶段;对于初始受剪能力大于受弯能力的柱,塑性铰区的受剪能力会随着弯曲变形的增大而逐渐降低,当受剪能力降至受弯能力以下时进入剪切破坏阶段。在多弹簧模型中引入反映柱平面受剪作用的剪切弹簧,将柱受力机制视为受弯机制与受剪机制的串联,提出了考虑剪切作用的钢筋混凝土柱地震反应分析方法。理论计算结果和试验结果比较表明:考虑剪切作用的多弹簧模型能较好地反映剪切破坏柱的受力性能;未考虑剪切的多弹簧模型会高估剪切破坏柱的延性、耗能能力及抗侧能力,结果偏于不安全。更多还原

【Abstract】 Cyclic loading tests of 6 short columns were conducted.The shearing and bending responses were separated.Analysis results indicated that the shear stiffness of a shear critical column degraded rapidly following the development of shear cracking.The skeleton curve of the shearing response entered the descending branch as the peak shear force was reached.The shear hysteresis shows the characteristics of pinching effect and stiffness degradation.Before the peak shear force is reached,the bending response and the shearing response occur simultaneously.After the peak shear force,if the shear failure is detected,the bending response will not further develop while the shearing response will increase rapidly,and the vice versa for the two responses if the flexural failure occurs.For columns with lower shear strength than the flexural strength,shear failure will be detected as the shear force reached the initial shear strength.For columns with higher shear strength than the flexural strength,the shear strength of the column at plastic hinge zone will decrease with the development of bending deformation and the shear failure will be detected as the shear strength degrades to the value lower than the flexural bearing capacity.A shear spring representing the in-plane shear action was then introduced into the multi-spring model for the seismic analysis of reinforced concrete columns.The load-carrying mechanism of a column was decomposed into bending mechanism and shearing mechanism which were connected in series.Comparing the calculated results with the test results,it was found that the modified multi-spring model provided a good estimation of the seismic behavior of shear-critical columns under earthquakes.The multi-spring model ignoring the shear action overestimates the ductility,energy dissipation and shear strength of the shear critical columns and leads to unsafe evaluation results.更多还原