Simulation Methods for the Erection of Strained Grid Shells Via Pneumatic Falsework

Abstract

The practical benefits of strained (a.k.a. ‘elastic’) grid shells, such as low material usage and fabrication simplicity, are undermined by the methods typically used for their erection. Established erection methods for strained grid shells (‘lift up’, ‘push up’ and ‘ease down’) can be time-consuming, costly and can overstress the system locally (Harris et al. in Build Res Inf 31:427–454, 2003; Quinn and Gengnagel in Mob Rapidly Assem Struct IV 136:129, 2014). The feasibility of and methodology for using inflated pneumatic cushions for the erection of strained grid shells (Otto et al. 1987) is investigated based on geometrically non-linear FE simulations and a scaled physical model for a case study of a dome with a 30 m span, 10 m pitch and constant double curvature. This paper provides a detailed write-up of the scaled physical experiment as well as the developed FE method. A detailed comparison is carried out between different erection methods for strained grid shells in order to evaluate key performance criteria such as bending stresses during erection and the distance between shell nodes and their spatial target geometry. The risk of beam-overstressing for existing erection methods along with challenges caused by modern safety restrictions, scaffolding costs and build duration can be drastically reduced or even eliminated by making use of inflated pneumatic falsework for the erection of strained grid shells. Finally it is argued that the use of pneumatic falsework has the potential to once again facilitate large-span $\left( {L \ge 30\,{\text{m}}} \right)$ strained grid shell structures such as have not been realised since the likes of the extraordinary “Multihalle Mannheim” (Happold and Liddell in Struct Eng 53:99–135, 1975).