钢筋混凝土梁冲击损伤后剩余抗弯承载力试验及评估方法研究

结构在遭受爆炸冲击荷载后，对其进行性能评估十分必要。就钢筋混凝土梁（简称“梁”）而言，爆炸冲击造成强惯性与应变率效应，使其开裂机理及材料冲击损伤后的力学性能与静载下完全不同，故其冲击损伤后性能评估不能采用受静载结构的性能评估方法。然而国内外对梁及钢筋、混凝土冲击损伤后的力学性能及评估方法研究甚少。因此，本项目采用试验和数值分析方法，研究梁冲击损伤后抗弯承载力及其评估方法。首先，开展钢筋与混凝土冲击损伤后本构行为试验与数值研究，以及冲击回波法检测混凝土剩余强度的测强曲线试验研究。然后，开展梁冲击损伤后的抗弯承载力试验及数值分析，进行参数分析及冲击对剩余抗弯承载力的影响机理研究，并对试验梁冲击损伤后的压区混凝土与钢筋强度进行评估。最后，根据冲击影响机理推导极限状态剩余抗弯承载力计算公式，并根据试验梁的材料强度评估数据与承载力验证和修正公式。本研究为梁冲击损伤后的修复加固和结构安全评估提供基础。

It’s very necessary to evaluate the behavior of structures damaged induced by blast and impact loading. For reinforced concrete (RC) beams, strong inertia effect and strain rate effect caused by blast and impact loading make the cracking mechanism in beam and the mechanical behaviors of materials damaged induced by impact very different from those under static load. So, it is infeasible to evaluate the behaviour of impact-damaged RC beam by using the evaluation method of behaviour of damaged structure under static loading. However, there is little research on the residual mechanical behavior of impact-damaged steel rebar, concrete and RC beam and their evaluation. Therefore, based on the experiment method and numerical analysis, the residual flexural capacity of impact-damaged RC beam and its evaluation method are investigated in the project. Firstly, the residual constitutive behaviors of impact-damaged steel rebar and concrete are investigated by experimental and numerical method, and the strength curve based on impact-echo method for evaluation of residual strength of concrete damaged induced by impact is experimentally studied. Secondly， experiment and numerical analysis of the residual flexural capacity of impact-damaged RC beam are conducted， including the parametric analysis and the mechanism of influence of impact loading on the residual flexural capacity, also the residual strength evaluation of steel rebar and concrete in tested beams after impact.Finally, based on the mechanism of influence of impact loading on the residual flexural capacity, the formulation of residual flexural capacity at ultimate state is derived，and the formulation is validated and modified by the experimental result. The achievements can provide a basis for repairing, strengthening and reasonable safety assessment of impact-damaged RC structures.