大跨度钢桁梁桥中跨双悬臂施工稳定性研究

Research on the stability of mid span double cantilever construction in large span steel truss bridge

大跨度钢桁架以其材料利用率高、自重轻、跨越能力强等优势被广泛应用在桥梁施工技术中。文章依托夏深铁路某特大桥双悬臂对称施工项目,详细介绍了主桥中跨钢桁架双悬臂架设的总体布置方案和施工方法,通过Midas Civil有限元软件对中跨双悬臂对称施工过程中的稳定性进行了数值分析,研究了最不利荷载下钢桁架的应力、支座反力和节点受力的变化规律。研究结果表明:施工中应采用墩旁托架和临时杆件固定钢梁,注意杆件安装后的吊机迁移、不平衡荷载控制和挠度监测,以确保施工安全。在横向和纵向风荷载作用下,主梁结构应力分布存在明显差异,最大应力出现在上弦杆和下弦杆的特定位置。此外,临时杆和墩旁托架的内力分布表明,无论横向或纵向风载,内力极值总出现在外侧结构处,需要对其进行加固处理。研究结果为大跨度连续钢桁桥主梁悬臂施工提供了理论和实践指导。

Large span steel trusses are widely used in bridge construction technology due to their advantages of high material utilization,light weight,and strong spanning capacity.This article relies on the double cantilever symmetrical construction project of a certain super large bridge on the Xiashen Railway to provide a detailed introduction to the overall layout and construction method of the double cantilever erection of the steel truss in the middle span of the main bridge.The stability of the double cantilever symmetrical construction process in the middle span was numerically analyzed using Midas Civil finite element software,and the variation laws of stress,support reaction force,and node stress of the steel truss under the most unfavorable load were studied.The research results indicate that pier side brackets and temporary rods should be used to fix steel beams during construction.Attention should be paid to crane relocation,unbalanced load control,and deflection monitoring after rod installation to ensure construction safety.Under the action of lateral and longitudinal wind loads,there are significant differences in the stress distribution of the main beam structure,with the maximum stress occurring at specific positions on the upper and lower chords.In addition,the internal force distribution of temporary poles and pier side brackets indicates that regardless of horizontal or vertical wind loads,the maximum internal force always occurs at the outer structure and requires reinforcement treatment.The research results provide theoretical and practical guidance for the cantilever construction of large-span continuous steel truss bridge main beams.