张拉成形曲面的应力松弛分析  

Stress relaxation analysis of membrane structures in actual equilibrium state

作　　者：孟雷[1] 吴明儿[2] 

机构地区：[1]鲁东大学土木工程学院,山东烟台264025 [2]同济大学建筑工程系,上海200092

出　　处：《建筑结构学报》2015年第5期81-87,共7页Journal of Building Structures

基　　金：国家自然科学基金项目(50778129);鲁东大学博士科研启动基金项目(LY2014029)

摘　　要：对膜结构施工中由裁剪片拼接张拉形成的膜面进行应力松弛分析,考察膜面应力随时间逐渐减小的变化规律。考虑膜材材料和几何双重非线性,采用广义Maxwell黏弹性模型建立积分型本构方程,推导增量本构方程,编制非线性有限元程序实现成形曲面的应力松弛数值分析过程。对聚氯乙烯(PVC)膜材进行了不同初始应力水平下的单轴应力松弛试验和不同应力比下的双轴应力松弛试验,用5单元的广义Maxwell黏弹性模型对试验数据拟合,确定了膜材本构方程的黏弹性参数。进行十字形膜片的加载及应力松弛试验,对其试验过程进行数值分析,结果表明试验结果与数值分析结果基本一致,验证了成形曲面黏弹性数值分析方法的可行性。对PVC膜材马鞍形曲面算例进行黏弹性分析,结果表明,马鞍形曲面在张拉完成4 d后,膜面平均应力降低了44%。The actual equilibrium surface of membrane structure,which was formed through assembling the plane cutting strips and stretching them to a frame on the construction site,was analyzed by considering stress relaxation.The membrane stresses decreasing over time were obtained. By considering material nonlinearity and geometric nonlinearity of membrane materials,the incremental constitutive equations were derived from the integral constitutive equations of the generalized Maxwell model,and a program based on the nonlinear finite element method was developed to achieve the stress relaxation analysis of membrane structures. In order to determine viscoelastic parameters of the constitutive equations,the uniaxial stress relaxation tests under different initial stresses and biaxial stress relaxation tests under various stress ratios of polyvinyl chloride( PVC)-coated fabrics were carried out and simulated by the five-element generalized Maxwell model. The cruciform membrane loading and stress relaxation tests were conducted,and the numerical analysis showed a good agreement with the tests indicating the reliability of the suggested numerical method. By taking the saddle curved surface of PVC-coated fabrics as a numerical example,it is found that the average membrane stress reduces by 44% in four days.

关 键 词：张拉成形曲面 广义Maxwell模型 PVC膜材 黏弹性 模型 应力松弛 

分 类 号：TU38[建筑科学—结构工程]