On the instability of two- and three-pinned circular arches

Absztrakt

Arches are important building blocks that are known for their ability to efficiently distribute loads. That is why they are widely studied. The two-pinned arc has hinges at each end that allow rotation but prevent translation. When loaded on the axis of symmetry, it creates bending moments besides internal forces that affect the stability. The three-pinned arch has an extra inner hinge, this time, at the crown. This hinge allows the moment to relax. However, the inner hinge can introduce additional modes of deformation. Two- and three-pinned slender, circular arches are compared within this work to find out the lowest buckling loads, displacements and inner forces. The external load acts on the axis of symmetry. The span is a fixed value and arches with different angles are placed between the end-supports, starting from very flat (almost straight) to deep geometries. From the selected perspective, it is found that two-pinned arches are stiffer throughout the whole investigated domain. The novel model is also compared with finite element computations and a good correlation can be found.