基于等效结构应力的钢框架焊接梁柱节点低周疲劳评估

在地震作用下钢框架梁柱焊接节点会发生低周疲劳现象，进而导致结构发生破坏。本文基于等效结构应力法提出一种高层钢框架梁柱焊接节点低周疲劳评估方法。首先，结合有限元多尺度模拟方法，建立包含翼缘及腹板焊缝细节的钢框架梁柱焊接节点多尺度模型。其次，利用不同单元尺寸多尺度模型，验证结构应力的网格不敏感特性，进而通过等效结构应力法评估钢框架梁柱焊接节点的疲劳寿命。结果表明，采用等效结构应力法可消除网格的敏感性，在往复荷载作用下，靠近工艺孔焊缝应力水平高于远离工艺孔焊缝，翼缘中心焊缝寿命最低，裂纹最先产生于翼缘焊缝中心处，评估方法为实际工程提供技术支持。

Low-cycle fatigue estimation of welded beam-to-column connection in steel moment resisting frames using equivalent structural stress

Beam-to-column connection (BCC) in steel moment resisting frames (SMRFs) can be susceptible to low-cycle fatigue (LCF) phenomena adjacent to the joint under seismic excitation, which leads to the damage of the structure. This paper presents a low-cycle fatigue assessment method for high-rise steel frame beam-column welded joints based on equivalent structural stress method. Firstly, a multi-scale model of welded joints of steel frame beam-column with flange butt weld and web fillet weld details was established by using finite element multi-scale simulation method to verify the effectiveness of multi-scale interface connection. Secondly, under the multi scale model of different element size, the insensitive characteristics of the grid stress are verified, and the fatigue life of the welded joints of the steel frame beam column is evaluated by the equivalent structural stress method. The results show that the sensitivity of the grid can be eliminated by the equivalent structural stress method. Under the action of reciprocating load, the stress level of the weld seam near the process hole is higher than that of the welding seam away from the process hole. The life of the flange in the center of the flange is the lowest. The crack is first produced at the center of the flange weld, and the evaluation method based on the equivalent structural stress method provides technical support for the actual engineering.