网架结构安装应力的影响机理

Impact Mechanism of Member Initial Stress on Space Truss

为研究网架结构杆件安装应力的分布特征,对跨度为4、5、6m各3个,共9个网架模型进行了安装应力试验测量。为说明安装应力对网架极限承载力的影响,对跨度6m的试验模型进行了极限承载力试验,并将结果与基于理想弹塑性、马歇尔压杆模型的Abaqus非线性分析结果进行了对比。安装应力测量结果表明:少数杆件安装应力接近甚至超过稳定应力。承载力对比表明:试验承载力比理论承载力下降了17.9%,结构安全储备仅为1.25。安装应力通过破坏结构原有对称性、产生杆件初弯曲、促使压杆提前失稳等方式影响网架结构性能,危害网架结构的安全。网架设计特别是满应力设计应当充分考虑安装应力的不利影响。

To reveal distribution characteristics of member initial stresses,nine experimental prototypes in span of 4 m,5 m and 6 m were employed.To analyze effects of member initial stresses on ultimate capacity of space truss,a prototype in span of 6m was applied.Meanwhile,the results were compared with those of Abaqus nonlinear FEM which were based on elastic-perfectly plastic model and Marshall Mode.Initial stress test shows that some initial stresses approach or even exceed stability stress.It is shown that the test ultimate capacity decreases by 17.9% than that of Marshall Mode,and the safety margin of structure is just 1.25.The impact mechanism of member initial stress consists in damaging structure initial symmetry,producing member initial bending and prompting press member buckling in advance.Member initial stress must be taken into account when space truss design,especially Fully-Stress design,is conducted.