Postbuckling Behavior of FRP Bending-Active Arches Subjected to a Central Point Load

Abstract

A bending-active arch derives its curved shape from elastic bending of an initially straight strut. The recent revival of interest in this special structural form has been largely driven by the use of pultruded hollow-section fiber-reinforced polymer (FRP) profiles. Stability is a crucial concern for bending-active arches, because their unique forming method demands a sufficiently high flexibility (slenderness) to facilitate curvature development. However, previous theoretical results, especially those associated with postbuckling behavior, have not been verified with test results due to the lack of loading tests. To fill this gap, this study conducted central point loading tests on FRP bending-active arches, which successfully captured the full-range postbuckling response. The test data fulfilled the intended goal of verifying a nonlinear load–deflection (equilibrium path) analysis. In this paper, the results of the loading tests are first presented. The differential equations governing the equilibrium path are next formulated and then solved as a boundary value problem (BVP) using a numerical BVP solver. Finally, the results of parametric studies performed using the verified BVP solver are presented. The results show that the effect of gravity on the mechanical behavior of FRP bending-active arches is negligible, whereas the forming-induced prestresses have a negative effect on the buckling load. In the range of practical arch shapes, the loss in buckling load due to this effect is approximately 10%.