摘要
为在有限的空间内进行具有足够精度的模型试验以体现斜拉桥整体受力特点,提出了混凝土斜拉桥节段缩尺相似法的模型试验方法。选择主梁塑性最强的跨中附近区域作为试验节段,在节段两端设置无索区并施以弹性支撑,以模拟原结构在边界处的受力状态并消除边界模拟的误差;调整无索区长度和两端弹性支撑刚度,直至试验梁和在外荷载作用下控制截面和控制索的内力增量与原结构保持一致,以正确反映整体结构的受力特征;确定缩尺比例、制作试验梁段和弹簧支座,以混凝土裂缝宽度为控制指标设计了加载工况并完成了加载试验,并对局部节段和整体模型控制截面的计算和实测结果进行对比。试验结果表明:在弹性受力范围内节段模型和实桥受力状态一致,主梁开裂后两者的荷载-挠度曲线和荷载-索力曲线均比较接近,节段模型可较好反映实桥该区域的受力状态;该方法能有效反映大跨径混凝土斜拉桥整体非线性受力特点和内力重分布规律;斜拉桥主梁初裂位置在集中力加载点附近,开裂后裂缝逐渐向加载点周边扩展且最大裂缝宽度增长缓慢,混凝土压应变发展和支撑索的索力增长也比较缓慢;混凝土斜拉桥在主梁开裂后整体刚度下降的幅度并不大,整体结构发生明显的内力重分布使得结构极限荷载加大。
A nonlinear local-global design method test for concrete cable-stayed bridges was proposed, to simulate the spatial structural behavior while considering both the model space and test accuracy, and to reflect the overall mechanical characteristics of cable-stayed bridges. The mid-span region of main girder with the strongest plasticity was selected as the test section. A cable-free zone was set at both ends of the segment, and an elastic support was applied, to simulate the stress states of the original structure at its boundaries and eliminate simulation errors. The length of the cable-free zone and the stiffness of the elastic support at both ends were adjusted, until the control section and the internal force increment of the control cable under external loads of the test beam were consistent with the original structure. This adjustment was made to reflect the mechanical characteristics of the entire structure correctly. The scale ratio was determined, the test beam section and the spring support were constructed, the loading condition was designed, and the loading test was completed with the crack width of the concrete as the control index. Next, the calculation and measurement results for the control sections of the local section and the entire model were compared. The results show that during the elastic period, the segmental model is consistent with the actual bridge. The load-deflection and load-cable force curves of the main girder after cracking are close to each other, and the segmental model better reflects the stress state of the actual bridge in this area. The proposed method effectively simulates the nonlinear character of local cable-stayed bridges as well as their internal force redistribution. The initial crack position on the main beam of the cable-stayed bridge is near the concentrated force loading point. The crack gradually expands to the vicinity of the loading point, and the maximum crack width increases slowly. The development of the concrete compressive strain and the increase in the cab
作者
刘昀
袁明
颜东煌
LIU Yun;YUAN Ming;YAN Dong-huang(School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,Hunan,China;School of Road and Bridge Engineering,Hunan Communication Polytechnic,Changsha 410132,Hunan,China)
出处
《长安大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2019年第5期78-87,共10页
Journal of Chang’an University(Natural Science Edition)
基金
国家重点基础研究发展计划(“973”计划)项目(2015CB057706)
国家自然科学基金项目(51678068)
湖南省自然科学基金项目(2017JJ5029)
湖南省教育厅科学研究项目(18B140)
关键词
桥梁工程
非线性
节段-整体模型
混凝土斜拉桥
无索区
弹性支撑
bridge engineering
nonlinear
local-global model
concrete cable-stayed bridge
cable free zone
elastic supporter
