考虑时变因素修正的混凝土斜拉桥换索前初态模型

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考虑时变因素修正的混凝土斜拉桥换索前
初态模型
许红
(长沙理
胜，王晟，颜东煌，林呜
工大学土木与建筑学院，长沙 410114)
摘要：为准确掌握混凝土斜拉桥换索施工前的索力和主梁受力状态，建立的换索施工前的初态分
析模型，需要对其运营期间混凝土收缩徐变、预应力索应力松弛、恒载性超载等因素产生的影响进
行评估。而混凝土弹性模量、徐变、收缩及预应力筋松弛等因素具有与时间历程和应力历史紧密关
联的材料非线性特征，采用有限元增量分析是合理的选择。为此，在时间历程划分的基础上，推导
了考虑材料徐变、松弛、收缩影响的弹塑性有限元求解方程，建立了时间增量步内单元计入徐变、收
缩、松弛影响的数值函数表达式，给出了斜拉索损伤刚度修正的具体措施和恒载性超载影响计入的
分析方法，建立的初态模型分析技术进一步改善了混凝土斜拉桥运营期的桥梁状态评估方法。
关键词：桥梁工程；桥梁状态；增量分析；混凝土斜拉桥；收缩徐变；应力松弛；恒载性超载
中图分类号：TU448．27 文献标志码：A 文章编号：1674—4764(2015)04—0045-06
Analysis model before cable replacem ent construction of
stay cable bridge with time’_dependent effects
Xu Hongsheng， W ang Sheng， Yan Donghuang，L『n M ing
(Changsha University of Scinece＆ Technology School of Civil
and Architecture Engineering，Changsha 410114，P．R．China)
Abstract：In order to understand the cables forces and girder forces state of concrete cable—stayed bridge
before the cable replacem ent construction， and to establish the analysis m odel of the bridge，the influence
factors such as concrete creep 8L shrinkage，stress relaxation of prestressing tendons，element damage，
overload of dead need to be evaluated ． Creep， relaxation and shrinkage are closely associated with the
material nonlinearity which dependent on tim e and stress history SO it’S reasonable to adopt the finite
elem ent analysis technology based on elastic—plastic incremental load m ethod． Based on the specified time
intervals，the increm ental elastic—plastic finite element equilibrium equation is deduced which includes the
effect of creep， relaxation and shrinkage． For the tim e increm ent step， numeric expressions of creep，
shrinkage and stress relaxation are established for beam element． M ethods are proposed to analyze the
influence of stay—cables damage and overload of dead．The methods will im prove the structure state analysis