Moment-less arches for reduced stress state. Comparisons with conventional arch forms

This paper presents a study of two-pin arches of constant cross-section that are moment-less under statistically prevalent (permanent) load. The arches are defined by analytical form-finding previously reported in Lewis (2016) [1]. The work provides guidance regarding the solution process, and expressions for reactions and axial forces. New analytical results include the derivation of the arch length, and a method for finding co-ordinates of individual arch segments in pre-fabricated construction. The accuracy of the shape prediction for inextensible moment-less arches is good, compared to the results from elastic models. Case studies report on medium and large-span arches, with the latter resembling the iconic Hoover Dam arch. Comparative studies of the moment-less and conventional arch forms (mostly of parabolic configuration), are carried out using permanent and variable loads. Additionally, the Hoover Dam arch is analysed for a discrete load transfer from the deck. Circular arches are analysed for the permanent load only, and are shown to be extremely inefficient in load resistance. Moment-less arches are found to provide a minimal stress response to loading and require least amount of material - a feature observed in natural objects. These characteristics are important from a durability perspective - a key concern for our future infrastructure. Crown Copyright (C) 2021 Published by Elsevier Ltd. All rights reserved.

Automated summary

This paper studies the characteristics of moment-less two-pin arches of constant cross-section under prevalent load. Analytical form-finding was used to determine the arches' solutions and express reactions and axial forces. The accuracy of shape prediction for moment-less arches was found to be higher compared to elastic models.