钢框架新型刚性节点脆断机理及抗断设计理论研究

The steel structure in service under cyclic loading often suffers from the defects and fatigue damage in varying degree, which are liable to brittle fracture under load and erosion environment in critical state, thus resulting in the transformation of failure mode of steel structure from plastic yield into brittle fracture。Therefore, to study the brittle fracture mechanism is of great significance in new rigid joints research field. Through comparing the earthquake disaster data, based on the premise that both the weakness and key parts which are liable to brittle fracture could be identified, this subject will, using non-linear finite element method, simulate transient welding process on the basis of welding residual stress, and evaluate fracture tendency in different types new connections, and subsequently forecast the potential effect of joint behavior for fracture, which helps to theoretically analyze brittle failure mechanism of new rigid joints in steel frame, and finally put forward the design method for avoiding brittle fracture. What this subject involves is of great significance in perfecting aseismic design theory of steel frame, improving abilities of resisting seismic damage and extending the application scope of energy dissipation new rigid joints in practical engineering.

承受反复荷载作用的在役钢结构，通常存在不同程度的缺陷和疲劳损伤,其内部微小缺陷在荷载和侵蚀环境作用下，临界状态时易产生脆性断裂，结构破坏形态也相应的由塑性屈服转变为脆性断裂，故脆性破坏机理是新型抗震节点研究中不可忽视的一个重要内容。本研究拟通过对比震害资料，在找到易发生脆性断裂薄弱环节、关键部位的前提下，利用非线性有限元建模，模拟瞬态焊接过程，在考虑焊接残余应力的基础上，采用断裂性能指标对不同类型新型梁柱连接的断裂倾向作出评估，模拟裂缝动态开展过程，预测可能开裂部分的变形对节点性能的影响，从理论上分析钢框架新强型节点的脆性破坏机理，最终提出能够避免节点脆性断裂的构造设计方法。预期成果对完善钢框架结构体系的抗震设计理论，提高钢框架抵御强烈地震灾害的能力，促进抗震耗能节点在建筑钢结构工程中的推广和应用均有十分重要的意义。

本课题针对承受反复荷载作用的在役钢结构，其内部微小缺陷在荷载和侵蚀环境作用下，临界状态时易产生脆性断裂这一现象，利用非线性有限元模拟瞬态焊接过程，在考虑焊接残余应力的基础上，采用断裂性能指标对梁柱连接的断裂倾向作出评估。课题以避免节点发生断裂为目的，修正了多种节点的设计参数取值范围。本研究模拟了携缺陷工作的节点所对应的裂纹发展趋势，探讨了各类变量对裂纹开展的影响，并对断裂危险点作出预测。项目进行了加强型节点断裂试验研究，通过试验数据和现象的分析对比，明确了节点断裂现象的发生对各类影响因素的敏感程度。成果对完善钢框架结构体系的抗震设计理论，提高钢框架抵御强烈地震灾害的能力，促进抗震耗能节点在建筑钢结构工程中的推广和应用均有十分重要的意义。