锈损焊接空心球空间网格结构承载性能评估方法研究

Owing to their excellent mechanical properties and simple construction, space steel structures have been extensively used in civil engineering. However, as the space steel structures entering the aging stage, the corrosion is becoming increasingly prominent. At present, the study on residual mechanical properties of rust space steel structures is still in its early phase. For lack of a systematic and perfect safety assessment method, structure collapse accidents induced by steel corrosion occur frequently, causing serious casualties and economic losses. Taking the welded spatial grid structures as the research objects, this project is intended to study the corrosion morphology of joints and propose the evaluation index of corrosive degree by carrying out the artificial accelerated corrosion tests on welding connection and welded hollow spherical joints. And then, through static experiments on rusty specimens, the parameters influencing residual bearing capacities of the welded hollow spherical joints are studied, such as corrosive degree, material type and joint’s size, and the degradation mechanism of joints is revealed. Combining theoretical and finite element analysis, calculating method of the residual bearing capacities of welded hollow spherical joints will been established. By using time-dependent corrosive models of joints, the patterns of internal force redistribution and residual deformation of welded hollow spherical space grid structures induced by rust is analyzed. Not only the residual static and dynamic behavior, but the capacity of anti-wind and seismic resistance of rust structures is studied, which provides a scientific basis for the safety assessment and restoration of the rust space grid structures.

空间钢结构凭借优良的力学性能和简便的施工方法，在各个领域得到广泛应用；然而，随着空间网格结构老龄化，结构锈蚀问题日益突出。目前，对锈损空间钢结构残余力学性能研究尚处于起步阶段，缺乏系统完善的结构安全评估方法，锈蚀缺陷诱发的空间钢结构坍塌事故时有发生，造成了严重的人员伤亡和经济损失。本项目以焊接空心球空间网格结构为研究对象，拟开展焊缝和焊接空心球节点人工加速锈蚀试验，研究节点腐蚀形貌特征，提出锈损程度评价指标；通过锈损后静力性能试验，研究锈损程度、材料类型、构件尺寸等对锈损焊接空心球节点残余承载力的影响规律，得到节点力学性能退化机理，结合有限元参数分析和理论推导，建立锈损焊接空心球节点的残余承载力计算方法；通过节点时变锈损模型，分析锈损诱发的焊接空心球空间网格结构内力重分布、残余变形的分布规律，研究锈损结构残余静动力性能和抗风、抗震能力，为锈损空间网格结构安全评估与修复加固提供依据。

空间钢网格结构凭借优良的力学性能和简便的施工方法，广泛应用于各领域。然而，空间钢网格结构在服役过程中不可避免的存在锈损问题，削弱结构的承载性能，甚至诱发工程事故，造成严重的经济损失和人员伤亡。因此，针对目前锈损结构评估多忽略了锈蚀后金属材料、焊缝和节点的力学性能退化，未考虑锈蚀后结构内力重分布和残余变形等的影响，通常只对明显变形和破坏的部位补强等问题，以锈损焊接空心球节点空间网格结构为研究对象，采用理论分析、数值模拟和试验研究相结合的方法，研究了锈损焊接空心球空间网格结构承载性能评估方法。主要研究内容从锈损焊缝连接残余力学性能与评估方法研究、锈损焊接空心球节点力学性能退化规律与残余承载力计算方法研究、锈损后焊接空心球空间网格结构承载力退化规律与计算方法研究三方面展开。首先，研究了锈损焊缝的残余力学性能，建立了不同锈蚀程度焊缝连接的残余抗拉承载力计算方法，为锈损焊接空心球节点的残余力学性能评估奠定基础。接着，研究了材料类型、腐蚀时间和腐蚀环境等因素对焊接空心球节点腐蚀形貌特征的影响规律，统计了平均质量损失和点蚀形状参数（平均点蚀深度、最大点蚀深度、等效均匀腐蚀深度）的概率分布模型，建立了焊接空心球锈蚀程度的评价方法和不同锈蚀程度焊接空心球节点承载力的计算方法，为锈损后焊接空心球空间网格结构残余力学性能评估奠定基础。最后，提出了锈损焊接空心球节点精细化模型的参数化建模方法，建立了焊接空心球空间网格结构的考虑随机锈蚀和节点锈蚀影响的数值分析模型；研究了焊接空心球节点和杆件锈蚀引起的空间钢结构内力重分布，以及锈损结构失效机理。此外，还探索了锈蚀后焊接空心球空间网格结构的稳定性能和抗风、抗震性能，构建了锈损焊接空心球节点空间网格结构剩余力学性能评定方法，为锈蚀后结构性能评估与修复加固提供技术支撑。