Residual Performance and Damage Restorability of Reinforced Concrete Flexural Column after Earthquake

研究了钢筋混凝土柱在受弯屈服后的剪切劣化过程中的轴心受力性能。并对劣化后轴心受力的可恢复性进行了研究。进行了五个相同尺寸、配筋和材料的柱试件的试验。它们被设计成抗剪能力相当于抗弯能力。在相当于0.2σ_B压应力水平(σ_B：混凝土抗压强度)的恒定轴向荷载作用下，它们以循环方式承受横向荷载，产生反对称弯矩分布。通过横向加载修正残余变形后，每个试件均沿轴向加载，得到以下结论：(1)试件的轴向强度劣化是由柱跨中的主要斜向剪切裂缝引起的，且在剪切裂缝出现后立即退化明显。(2)基于桁架和拱形机构的分析很好地预测了轴向强度的劣化，这与桁架机构中支撑混凝土压应力的恶化有很强的相关性。(3)环氧树脂注入斜向剪切裂缝可以有效地恢复横向和轴向强度。

The axial capacity of reinforced concrete columns during shear deterioration after flexural yielding was investigated. The restorability of the axial capacity after the deterioration was also studied. Five column specimens with the same dimensions, reinforcement and materials were tested. They were designed that the shear capacity was equivalent to the flexural capacity. They were subjected to lateral forces in a cyclic manner producing anti-symmetric bending moment distribution under a constant axial load equivalent to 0.2σ_B in the compressive stress level (σ_B : compressive strength of concrete). Each specimen was loaded in the axial direction after corrected the residual deformation by the lateral loading.The following conclusions were obtained.(1) It was observed that the deterioration of the axial strength was caused by dominant diagonal shear cracks in the mid-span of columns, and the deterioration was significantly large immediately after the shear cracks occurred.(2) The analysis based on truss and arch mechanisms well predicted the deterioration of axial strength, which related strongly the deterioration of concrete compressive stress of strut in truss mechanism(3) The injection of epoxy into the diagonal shear cracks was effective to recover the lateral and axial strength perfectly.