Investigation of in-plane stability in bending-active arches.

This article investigates the in-plane instability of bending-active arches—planar arches formed by elastically bending initially straight struts—under hinged and fixed support conditions with mid-span concentrated loads and uniformly distributed loads. Analytical formulations capturing both symmetric and antisymmetric instability modes are derived and validated through finite element simulations using Abaqus. The study reveals that symmetric instability generally exhibits higher peak loads than antisymmetric instability, though antisymmetric modes often develop earlier except in some fixed-support cases. Additionally, under uniformly distributed loads, arches with larger span ratios may initially deflect upward at mid-span, and half-span uniform loading consistently yields higher peak loads than full-span loading. The research also identifies looping behavior in load–deflection responses for hinged arches under concentrated loads, with smaller span ratios corresponding to higher peak loads during these cycles.