桁架桥梁节点增强优化方法研究

Research on Reinforcement Optimization Method of Truss Bridge Joints

针对下承式钢管混凝土桁架梁桥拆除过程节点强度不足问题,提出下弦杆翼缘栓接型钢、腹杆补焊槽钢、端部三角区焊接钢板、新增腹杆的综合节点加固方案。基于“整体-局部”分析方法,对比分析3种新增腹杆与原节点连接方案,对加固后的节点构造进行优化设计。结果表明:(1)加固后腹杆应力峰值减小47.6%,下弦杆应力峰值减小44.4%;(2)采用新增腹杆与原节点焊接的连接方案,节点最大应力值均远大于钢材设计强度值,不满足节点受力要求;(3)新增腹杆与原节点外贴节点板连接方案,屈曲荷载约为最大荷载工况对应荷载的5.5倍,但节点最大应力值较大,不满足节点受力要求;(4)采用新增腹杆与原节点焊接并在节点钢管混凝土内部灌浆方案,最大应力值相对较小,原有杆件外侧均采用槽钢加固,节点受力满足要求,推荐采用方案3的连接方式。

In order to solve the problem of insufficient joint strength during the demolition of through concrete-filled steel tubular truss bridge, a comprehensive joint reinforcement scheme of bolted section steel at the bottom chord flange, welded channel steel at the web member, welded steel plate at the end triangle area and new web members is proposed. Based on the “whole-part” analysis method, three connection schemes of new web members and original joints are compared and analyzed, and the joint structure after reinforcement is optimized. The results show that:(1) after strengthening, the peak value of web member stress decreases by 47.6%, and the peak value of bottom chord stress decreases by 44.4%;(2) using the connection scheme of welding the new web member and the original joint, the maximum stress value of the joint is far greater than the design strength value of the steel, which does not meet the stress requirements of the joint;(3) in the connection scheme of the new web member and the original joint pasted to the gusset plate, the buckling load is about 5.5 times of the corresponding load under the maximum load condition, but the maximum stress of the joint is large, which does not meet the stress requirements of the joint;(4) the maximum stress value is relatively small in the scheme of welding the new web member with the original joint and grouting inside the concrete-filled steel tubular at the joint. The outer side of the original member is reinforced with channel steel, so the stress of the joint meets the requirements. The connection method of Scheme 3 is recommended.