张弦梁(桁架)结构的找形方法——分级卸载法

对张弦梁(桁架)结构的找形问题进行了深入研究,根据该类结构的受力特点,提出了分级卸载法。该方法无需假定结构零状态几何,而可以一次得到对应于初状态(即预应力态)几何的结构施工放样尺寸(即零状态几何),并通过分级加载对该方法的精度进行了检验。

Method for form finding of beam string structure:method of offload by steps

In this paper,the issue on the form finding of a beam-string structure is studied and a method named offload by steps is put forward in accordance with the mechanical properties of the structure.Offload the beam-string structure in the pre-stressed state until the cable stress reaches zero,then the form of structure in the unstained state can be obtained.In this process,the offloading step length is very important.And the determination of the step length is also presented in this paper.By this method,the form of unstrained state can be found on the basis of that of pre-stressed state directly,i.e.it needs not to assume the form of unstrained state first.In this paper,the method is applied to a beam-string structure.Thus the form in unstrained state is obtained.After this,the beam-string structure in the unstrained state is loaded by steps until the cable stress reaches the design value,which is another pre-stressed state.Then the form and internal force of the structure in this pre-stressed state reached by loading can be obtained.By comparing the forms and internal forces of the beam-string structure under these two pre-stressed states,the method proposed in the paper is verified.