体内张拉成形屋架垂跨比和矢跨比影响分析

Analysis on ISFRT affected by sag-span ratio and rise-span ratio

为了改善体内张拉成形屋架受力性能,根据结构张拉成形后的矢跨比和垂跨比组合的不同,建立了20个计算模型.选用APDL参数化设计语言编程分析垂跨比及矢跨比对结构受力特点的影响.研究表明:随着结构矢跨比的增加和垂跨比的减小,上弦中间单元成形轴力、弯矩和截面应力逐渐增大,而受荷状态则是在此基础上叠加相应轴力;成形阶段以弯曲应变为主,截面拉应力和压应力较为接近,表现为轴压力很小,受荷阶段以轴向压应变的增加为主,表现为轴压力很大.选取适宜的矢跨比和垂跨比组合可以改善体内张拉成形屋架受力性能.

In order to improve mechanics performance of the internal stretch forming roof truss （ ISFRT）, twenty computation models with different sag-span ratios and rise-span ratios were built. The influence of sag-span ratio and rise-span ratio on mechanics performance was analyzed using parametric design language APDL programming analysis. Study shows that with the increase of rise-span ratio and the decrease of sag-span ratio of ISFRT, the axial force, the bending moment and the cross-section stress of upper chord middle elements in the forming process increase gradually, and the ISFRT state in the loading process is formed by subjoining special axial force to the state in the forming process. Additionally, bending strain is the main mechanics performance in the forming stage, in which cross-section tension stress is close to compressive stress, so the axial force of ISFRT is small. And the increase in axial compressive strain is the main mechanics performance in the loading stage, so the axial force of ISFRT is great. Selecting appropriate sag-span ratio and rise-span ratio can improve mechanics performance of ISFRT.