高强度钢管相贯节点焊缝受力机理与设计方法研究

The use of high-strength steel in structure can reduce the weight of structure and save steel, which has good social and economic benefits. In China Code for Design of Steel Structures（GB50017-2003）, the yield strength of steel material is specified not more than 345 MPa in relevant regulations for the joint of hollow sections. But with the reference of Eurocode 3, the forthcoming specification of China Code for Design of Steel Structures cancels the limit, which pointing out that it is still lack of research. In fact, due to the improvement of the strength, the ductility of high-strength steel decreases, the yield ratio increases, resulting in the tendency to brittle fracture toughness deterioration and making the weld defects more sensitive. The research will be gradually carried out from high-strength steel tubular material, connecting weld and configuration details for tubular joint step by step, with the combination of theoretical analysis, experimental research and numerical simulation method. Upon the accumulation of high strength-steel tubular material and weld mechanical properties test data, two kinds of failure model prediction of high-strength steel tubular joints will be established, and the typical confirmatory test of high-strength steel tubular joints will be carried out. Considering various factors that may affect the mechanical behavior of joints such as material type, connecting weld, local configuration, and geometric parameters, an effective and elaborate finite element model is established for the basis of parameter analysis, and then the regular pattern of influence of the above parameter variation will be found out. The research will put forward the design method of all kinds strength of steel hollow sections, considering the bearing capacity of its connecting welds and then introduce the technical measures to prevent the welds from fracturing. It will provide reliable basis for improving the design theories of such joints.

高强度钢材能减轻结构自重、节约钢材，具有良好的社会经济效益。我国03版《钢结构设计规范》中规定钢管相贯节点条文只适用于屈服强度不超过345MPa的材料，而即将颁布的新版规范借鉴欧洲规范，取消了该限制，但特别指出对高强度钢管相贯节点的受力性能尚缺乏研究。事实上，高强度钢材由于其强度提高，塑性降低，屈强比增大，韧性变差而脆性断裂倾向增大，对焊缝缺陷更为敏感。因此，本项目将采用理论分析、试验研究和数值模拟相结合的方法，从高强度钢管相贯节点的材料、焊缝和构造细节、节点等三个层面开展逐步深入的研究。积累高强度钢管的材料及其焊缝力学性能试验数据，建立预测高强度钢管相贯节点破坏的两类模型，并进行典型节点的验证性试验，进而进行参数分析，得到节点材性、连接焊缝、局部构造、几何参数等对节点性能的影响规律，提出适用于高强度钢材、能准确考虑焊缝承载力的钢管相贯节点设计方法，为完善这类节点的设计理论提供提可靠依据。

高强度钢材能减轻结构自重、节约钢材，具有良好的社会经济效益。我国03版《钢结构设计规范》中规定钢管相贯节点条文只适用于屈服强度不超过345MPa的材料，而2017年颁布的新版规范借鉴欧洲规范，取消了该限制，但特别指出对高强度钢管相贯节点的受力性能尚缺乏研究。事实上，高强度钢材由于其强度提高，塑性降低，屈强比增大，韧性变差而脆性断裂倾向增大，对焊缝缺陷更为敏感。因此，本项目采用理论分析、试验研究和数值模拟相结合的方法，从高强度钢管相贯节点的材料、焊缝和构造细节、节点等三个层面开展逐步深入的研究。积累高强度钢管的材料及其焊缝力学性能试验数据，建立预测高强度钢管相贯节点破坏的两类模型，并进行典型节点的验证性试验，进而进行参数分析，得到了节点材性、连接焊缝、局部构造、几何参数等对节点性能的影响规律，提出了适用于高强度钢材、能准确考虑焊缝承载力的钢管相贯节点设计方法，为完善这类节点的设计理论提供了可靠依据。