FREE-FORM GRID SHELL STRUCTURES ON RECTANGULAR PLAN WITH SEMI-RIGID SOCKET JOINTS

摘要

To predict the load bearing capacity of single-layered steel grid shell structures, the behavior of the joints need to be considered. A parametric analysis is presented with the aim to decide whether a bolted joint has enough stiffness and strength to be applied in grid shells. Free-form roof structures with rectangular boundary are investigated with different geometrical properties, such as topography and topology. Each structure is designed with rigid and with semi-continuous bolted joints as well, and the smallest possible cross-section sizes are determined. The design method is based on nonlinear finite element analysis considering geometrical and material nonlinearities with imperfections, and the method is validated by analytical and test results. Results are presented for structures spanning 20 meters and using a single-bolted joint system called the socket joint with relatively small rigidity and strength. It is shown, that this free-form shape is highly imperfection-sensitive. Furthermore, the effect of analysis parameters such as imperfection shape or amplitude and simplified moment-rotation characteristics of the joints are presented.