摘要
为了解刚构-连续组合梁合龙段悬臂施工中开裂原因,以某刚构-连续组合梁桥为背景,采用MIDAS Civil建立全桥有限元模型,分析采用劲性骨架合龙法、临时压重合龙法和综合合龙法时合龙段拉应力,以及刚接率、压重率对合龙段下缘最大拉应力的影响。结果表明:劲性骨架合龙法施工中,拉应力分布于合龙段下缘,最大拉应力与刚接率呈指数关系,刚接率不足是导致合龙段下缘初凝或早龄期混凝土开裂主要原因之一;临时压重合龙法施工中,压重率小于(大于)临界压重率时,合龙段下缘(上缘)受拉,合龙段下缘最大拉应力与压重率呈线性关系,压重率不足(过大)是导致合龙段下缘(上缘)初凝或早龄期混凝土开裂的主要原因之一;综合合龙法施工中,合龙段中的应力分布、下缘最大拉应力与压重率关系以及合龙段开裂原因等均与临时压重合龙法的相似,但前者最大拉应力及临界压重率均小于后者。
The cracking of the closure segment of combined rigid-frame and continuous girder bridge is of likelihood during construction.In this paper,the cracking causes are analyzed based on a real bridge of such type.A finite element model of the full bridge was developed by MIDAS Civil to analyze the tensile stresses in the closure segment when different closing methods are used,including the closing with stiffening skeleton,the closing with temporary counterweights and the closing with both stiffening skeleton and temporary counterweights.The influence of rigid connection rate and counterweighting rate on the maximum tensile stress of the closure segment was examined.The results show that when the closing is conducted with the aid of stiffening skeleton,the lower edge of the closure segment is in tension,the maximum tensile stress is in exponential relationship with the rigid connection rate,indicating that the insufficient rigid connection rate is one of the main causes of the initial setting or early-age cracking of the lower edge concrete of the closure segment.When the closing was performed with temporary counterweights,referencing the critical counterweighting rate,the undersized counterweighting rate causes the lower edge of closure segment in tension,while oversized counterweighting rate puts the upper edge of closure segment in tension,implying that the maximum tensile stress in the lower edge of closure segment is in linear relation with the counterweighting rate,and the insufficient counterweighting rate explains the initial setting or early-age concrete cracking of the lower edge of closure segment,while the excessive counterweighting accounts for the initial setting or early-age concrete cracking of the upper edge of closure segment.When the stiffening skeleton and counterweights are used in combination,the relationship between the stress distribution and the maximum tensile stress in the lower edge as well as the cracking causes of the closure segment are similar to those issues when temporary counterweigh
作者
刘东云
李松
王宁
赵莉香
LIU Dong-yun;LI Song;WANG Ning;ZHAO Li-xiang(Xinyu Engineering Co.,Ltd.,China Railway 24th Bureau Group,Xinyu 338000,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《世界桥梁》
北大核心
2022年第5期94-100,共7页
World Bridges
基金
中铁二十四局集团2019年度科技研发项目(科研2019-11)。
关键词
刚构-连续组合梁
悬臂施工
合龙段
合龙措施
早龄期混凝土
开裂原因
有限元法
combined rigid-frame and continuous girder bridge
cantilever construction
closure segment
closure measure
early-age concrete
cracking cause
finite element method
