含初始损伤的钢筋混凝土结构抗冲击性能评估

Existing concrete structures damaged by cracking and reinforcement corrosion have high risk of shear failure due to the accidental impact loads. Therefore, it is very necessary to assess the impact resistance for the real damaged structures. However, present studies are very limited on the rate-dependent material constitutive models of reinforced concrete, structural damage detection method. This proposal plans to (1) carry out the initial damaging experiments subjected to the coupling effect of environmental action and mechanical loads, and then establish the corrosion detecting method based on the fiber-optic sensing technology and numerical analysis; (2) build the rate-dependent shear transfer model with the shear impact tests on pre-cracked specimen; (3) build the rate-dependent bond models for corroded reinforced concrete with the bond impact tests; (4) develop a nonlinear finite element software for impact resistance assessment on concrete structures, and verify the code through structural impacting tests; (5) apply the analysis to real engineering structures. This research aims to provide a simple and accurate tool for the protection management of existing damaged structures, so as to improve the protection design, ensure the personnel safety and reduce the economic loss. And it will deepen the understanding of the dynamic characteristics of reinforced concrete material, and further extend the theory and method of structural analysis and damage monitoring. It is both practically and scientifically important.

含有混凝土开裂、钢筋锈蚀等初始损伤的实际结构，面临着由于撞击而产生剪切破坏的风险，因此，评价损伤结构的抗冲击性能非常必要。然而，现有研究在钢筋—混凝土材料与率相关模型、结构损伤测量方法等方面研究还不充分。本项目拟(1)开展环境和荷载共同作用下的结构初始损伤实验，研究建立基于光纤传感和数值计算相耦合的钢筋锈蚀率测量方法；(2)开展预制裂缝试件的剪切冲击实验，建立与率相关的裂缝剪力传递模型；(3)开展锈蚀钢筋—混凝土粘结冲击实验，建立锈蚀钢筋—混凝土动力粘结模型，(4)开发结构抗冲击有限元分析程序，并通过损伤结构冲击实验加以验证，(5)将程序用于实际损伤结构抗冲击性能分析。本研究旨在为在役损伤结构的安全防护管理提供简便而准确的分析手段，以便做好防护设计，确保人员安全，减少经济损失；同时加深对钢筋—混凝土材料动力特性的了解，丰富和发展结构分析、损伤监测的理论和方法，具有重要的工程价值和科学意义。

本项目研究将预应力钢筒混凝土管（PCCP管）确定为本项目主要研究对象。该研究对象会承受水锤作用引起的冲击荷载和断丝引起的冲击荷载，研究这一问题对于国内输水工程安全管理具有重要意义。本项目工作包括①研制了腐蚀环境与荷载共同作用下的钢筋混凝土梁慢速重复加载实验装置，并开展了为期长达近2年多的实验研究工作；作为与①的对比，同步开展了钢筋混凝土梁的快速腐蚀疲劳实验研究；②.开展了地面放空PCCP管中预应力钢丝腐蚀断裂引起冲击响应的实验研究，并同步开展分布式光纤应变监测、光纤光栅加速度监测等实验研究，并依据监测结果判断管壁内钢筋腐蚀断裂根数。③.开展了预制裂缝试件的剪切冲击实验；④开展了预应力钢丝在腐蚀环境中的慢应变拉伸实验；研究建立预应力钢丝腐蚀断裂寿命预测模型，以该模型为基础开发了PCCP管寿命预测有限元分析程序。⑤对预应力钢丝腐蚀断裂后钢丝失锚长度问题进行了实验研究，开展了断丝PCCP管的结构承载力有限元分析研究，并应用于实际工程。项目研究工作在原有计划基础上略有调整，达到了预期目标。.