In-Plane Load-Deflection Behavior and Buckling of Pressurized Fabric Arches

Abstract

This study focuses on the in-plane load-deflection and buckling response of pressurized fabric arches of constant circular cross section. These lightweight portable structural members support tents used for temporary medical facilities, disaster-relief shelters, and military applications. A quadratic Timoshenko beam element is developed for materially and geometrically nonlinear analysis based on a virtual work principle that includes work done by internal pressure due to deformation-induced volume changes. The inability of the arch fabric to carry compressive stress is addressed with a nonlinear moment-curvature relationship that captures the effect of fabric tensile stiffness, internal pressure, and axial load. A corotational formulation and cylindrical arc-length solver are used to permit large displacement analysis and the tracking of postbuckling softening response. A convergence study demonstrates the good performance of the element and the solver. Results of laboratory load tests on a 9.5 m-span semicircular inflated fabric arch are presented, and shown to agree well with the model predictions. Parametric studies are conducted to examine the significance of inflation pressure and lateral restraint on arch deflections and buckling under the action of code-specified snow loads. The numerical studies show that the work done by the confined air significantly increases arch load capacity, and that shear deformations of woven fabrics can significantly reduce arch capacity.