平转桥梁施工阶段主梁应力与转体过程动力特性  

Stress of Main Beam and Dynamic Characteristic of Swivel Process in Construction Stage of Horizontal Swivel Bridge

作　　者：谭生永 TAN Shengyong(Railway-related Engineering Office,China Railway Jinan Group Co.,Ltd.,Jinan Shandong 250000,China)

机构地区：[1]中国铁路济南局集团有限公司涉铁工程办公室,山东济南250000

出　　处：《中国铁路》2023年第5期66-71,共6页China Railway

摘　　要：某T型刚构桥采用支架法分段现浇,并在落架后进行平面转体,此种施工方法桥梁直接由支架支撑状态转为最大悬臂状态,靠近悬臂中墩位置处的梁体应力会在短时间内急剧增大,且在转体过程中梁体振动会加剧梁内应力,对桥梁施工安全造成不利影响。因此,在中墩两侧主梁断面安装应变计,对转体前主要测点各施工阶段的应变与应力进行记录和分析,在悬臂端部布置振动传感器,对转体过程进行模态分析与振动监测,从而对桥梁施工安全做出判断。结果表明:0#块浇筑之后,顶、底板测点应力值均增大,0#块浇筑后直至2#块预应力钢筋张拉完成,顶板应力在整体上呈下降趋势,拆架过程中顶板测点应力持续增大;0#块浇筑后直至拆架完成,底板应力在整体上呈减小趋势;第1阶模态为主梁对称弯曲,第2阶与第3阶模态均为主梁反对称弯曲。转体过程中振动对梁体产生的不利影响有限,不会对梁体安全造成威胁。A T-shaped rigid frame bridge is cast in situ in sections by the support method,and plane swivel is carried out after the frame is erected.This construction method directly changes the bridge from the support state to the maximum cantilever state.The stress of the beam near the cantilever intermediate pier will increase sharply in a short time,and the vibration of the beam will aggravate the stress in the beam during the swivel process,which will have an adverse impact on the safety of bridge construction.Therefore,strain gauges are installed on the main girder sections on both sides of the intermediate pier to record and analyze the strain and stress at each construction stage of the main measuring points before the swivel,and vibration sensors are arranged at the cantilever ends to carry out modal analysis and vibration monitoring of the swivel process,so as to judge the safety of bridge construction.The results show that after 0#block is poured,the stress values of the top and bottom plate measuring points increase.After 0#block is poured until the prestressed reinforcement of 2#block is tensioned,the top plate stress shows a downward trend on the whole,and the stress of the top plate measuring point continues to increase during the removal process.After 0#block is poured until the removal is completed,the bottom plate stress shows a downward trend on the whole;the first-order mode shows symmetrical bending of the main beam,and the second-order and third-order modes show antisymmetrical bending of the main beam.The adverse effects of vibration on the beam body during the swivel process are limited,which will not threaten the safety of the beam body.

关 键 词：水平转体 应力监测 振动监测 动力响应 模态分析 

分 类 号：U445[建筑科学—桥梁与隧道工程]