全跨荷载作用下内凹式索拱结构受力过程中刚度的变化

针对现有关于全跨荷载作用下内凹式索拱结构受力过程中整体刚度变化规律研究较为缺乏的不足,采用试验验证和有限元分析的方法对其进行深入分析。首先介绍内凹式索拱结构整体刚度的计算原则,然后依据该原则对已完成的模型试验数据进行分析。在此基础上,通过改变某一典型实例中拱和索的矢跨比、截面以及结构初始缺陷等参数,建立不同参数下考虑双重非线性的有限元分析模型,并完成相应的分析工作,证实该类结构的初始刚度主要取决于上弦拱的矢跨比和截面,而受下弦索的影响较小。模型试验和有限元分析结果均表明,当拱索矢跨比差值约小于0.055时,全跨荷载作用下该类结构荷载-位移曲线的弹性段部分将具有较明显的非线性特征。

STIFFNESS CHANGES IN LOADING PROCESS FOR INNER CONCAVE CABLE-ARCH STRUCTURE UNDER FULL-SPAN LOAD

The current research work lacks systematic considerations of stiffness changes in loading process for inner concave cable-arch structure. An intensive study was performed based on the experimental exploration and finite element analysis. Firstly,a principle for calculations of global stiffness was proposed for inner concave cable-arch structure. Then,the testing data obtained from the experimental model were analyzed with that principle. Considering both geometrical and material nonlinear effects,multiple finite element analysis models were built by varying the rise-to-span ratio and cross section of both arch and cable and initial imperfections of a typical inner concave cable arch structure. The corresponding analysis was also completed,which verified that the initial stiffness was mainly dependent on rise-to-span ratio and cross section of arch rather than those of cable. Moreover,the results obtained by both experiment tests and finite element analyses indicated that the load-displacement curve corresponding to elastic stage was obviously nonlinear when the difference between arch rise-to-span ratio and cable rise-to-span ratio was less than 0. 055.