On the Influence of Geometric Boundary Conditions on the Form Finding of Funicular Shells
摘要
The statics of funicular shells is governed by Pucher’s theory. When external loads are known in advance, the horizontal equilibrium of a membrane shell can be fully handled through the Airy stress function and then decoupled from its vertical equilibrium leading to the form-found geometry. Apart from limiting the solution space investigated during the search, the manual prescription of the potential field tends to become cumbersome when either relatively elaborate free-form shell planar footprints are addressed or functional requirements are considered. In this work, a recently formulated isogeometric form-finding strategy is employed to study the effect of different kinematic boundary conditions on the shape of funicular shells made of a unilateral material. The procedure benefits from a nonlinear programming routine to automatically determine a feasible Airy stress function fulfilling concurrent static and functional constraints. Further, use is made of spline technology allowing for smooth surface modelling and enhanced computational efficiency.