An analytic solution for form finding of GFRP elastic gridshells during lifting construction

摘要

The GFRP elastic gridshell is a type of spatial structure composed of long continuous hollow GFRP members and has been used in large-span roof structures. The elastic gridshell achieves its shape as the result of elastic deformations during the construction process of lifting or pushing. The shape-forming mechanism of such structures is very complicated due to significant geometric non-linearity. This research aims to propose analytic formulations to estimate the structural features of the GFRP elastic gridshell under lifting construction. An analytical theory, considering the large geometric deformations, is first presented for analyzing single lifted member. Based on the given theory and an iteration process, a form-finding method is further proposed for predicting the deformation, nodal forces and bending moment of biaxial symmetrical GFRP elastic gridshells during the lifting construction. The form-finding method is realized on the Matlab platform and a case study is carried out. Finite element analysis is further conducted to validate the accuracy and practicability of the proposed method. Results show that, the analytic theory is highly accurate for the analysis of lifted members, and the proposed form-finding method is applicable in predicting the structural behaviors of GFRP elastic gridshells for which the lifting construction is adopted.