基于SVM的刚构桥施工期标高控制可靠度研究  

Research on Elevation Control Reliability of Rigid-Frame Bridge at Construction Stages Based on SVM

作　　者：常柱刚 张红显 CHANGZhu-gang;ZHANG Hong-xian(Changsha Planning ＆ Design Institute Co.,Ltd.,Changsha 410007,China)

机构地区：[1]长沙市规划设计院有限责任公司,湖南长沙410007

出　　处：《桥梁建设》2018年第3期73-78,共6页Bridge Construction

基　　金：国家自然科学基金项目(51308056;51678027)~~

摘　　要：为求解PC刚构桥不同施工阶段的标高控制时变可靠度,以云南省怒江州兑房河特大桥为背景进行研究。选取混凝土容重和弹性模量、预应力钢绞线张拉控制应力和弹性模量4种随机因素,利用拉丁超立方抽样法产生随机样本;代入桥梁有限元模型,计算各组样本对应的目标变量;采用遗传算法寻找最优参数,建立该桥各施工阶段的标高控制SVM模型;结合蒙特卡洛法,求解施工期标高控制时变可靠度,并利用正交试验对可靠度灵敏度进行分析。结果表明:PC刚构桥施工期标高控制可靠度指标随悬臂自由端挠度偏差容许值的增大而增大;当结构分别处于短悬臂、中悬臂、最大悬臂阶段时,建议悬臂自由端挠度偏差最大容许值分别取4,10,20mm;影响因素对PC刚构桥施工期标高控制可靠度的影响由大至小依次为混凝土容重、预应力钢绞线张拉控制应力、混凝土弹性模量、预应力钢绞线弹性模量。In order to solve the time-varying elevation control reliability of the PC rigid-frame bridge at different construction stages,the Duifang River Bridge in Nujiang Prefecture,Yunnan Province was taken as example and the relevant study was carried out.Four random factors of the bulk density and elastic modulus of the concrete and the tensioning control stresses and elastic modulus of the prestressing steel strands were selected.The Latin hypercube sampling method was used to generate the random samples,the samples were then substituted into the bridge finite element model and the target variables corresponding to each group of the samples were calculated.The genetic algorithm was used to find the optimal parameters and the SVM model for the elevation control of each construction stage of the bridge was established.With reference to the Monte Carlo method,the time-varying elevation control reliability at the construction stage was solved and the related reliability and sensitivity was analyzed through the orthogonal tests.The results show that the indices of the elevation control reliability of the PC rigid-frame bridge at the construction stages increases with the increase of the allowable values of the deflection deviation of the cantilever free ends.When the structure is at the stages of the short cantilever,medium cantilever and the longest cantilever,it is recommended that the maximum allowable values of the deflection deviation should be respectively 4,10 and 20 mm.The factors having the influence on the elevation control reliability of the PC rigid-frame bridge are successively the bulk density of the concrete,tensioning control stresses of the prestressing steel strands,elastic modulus of the concrete and the elastic modulus of the strands according to the great to the little influence degrees.

关 键 词：刚构桥 悬臂状态 时变效应 标高 挠度偏差容许值 可靠度 灵敏度 

分 类 号：U448.23[建筑科学—桥梁与隧道工程] TB114.3[交通运输工程—道路与铁道工程]