索长误差对鞍形膜结构初始形态的影响分析

Effect of cable length error on the initial shape and stress of saddle-shaped membrane structures

针对索长误差会造成膜结构的初始形态产生误差这一问题,基于非线性有限元法,通过对索施加温度作用模拟索长的制作误差,研究了索长制作误差对鞍形膜结构初始形态的影响特性和影响敏感度,其中初始形态包括初始几何形状、膜面初始预应力、索初始预拉力及初始支座反力.并进一步分析了结构参数,如跨度、高跨比、索膜预张力密度比对研究结果的影响.分析得到如下结论:索偏短时,索长误差对初始几何形状、初始膜面应力、初始索力及初始支座反力的影响均成线性关系,也就是影响敏感度为1;索偏长相对较小时,结构各项初始误差仍与索长误差呈线性关系,而索偏长相对较大时,索长误差对结构初始形态的影响表现出了非线性.当结构取不同跨度、矢跨比和索膜预张力比时,仍具有上述规律.本文结论可以为进一步完善膜结构技术规程中的相关规定提供基础材料和依据.

Based on the non-linear FEM and with the method of imposing temperature on cable to simulate the fabrication error of cable length, the affecting characteristics and affecting sensitivity of cable length fabrication error to the initial shape and stress of the saddle-shaped membrane structure is analyzed. The initial shape and stress includes initial geometry, initial stress of membrane element, cable initial pretension and initial support reaction. The influence of structural parameters which includes span, rise- span ratio and pretension ratio of cable-membrane is discussed. Some conclusions are obtained as follows： when the cable length is shorter than the design value, the effect on initial geometry, initial stress of membrane element, cable initial pretension and initial support reaction is linear. When the cable length is a little longer than the design value, the initial errors still varies linearly with cable length error. When the cable length is much longer, the relationship between length error and initial errors become non-linear. Considering different span, rise-span ratio and pretension ratio of cable-membrane, the same laws exist. The conclusions can provide basic information and basis in the perfectionism of the relevant provisions of the technical specification for membrane structure.