Equivalent Imperfections In Arched Structures

Marian Dallemule

doi:10.1515/sjce-2015-0012

Abstract

Abstract There are currently three design methods to verify the in-plane buckling of an arched structure: substitute member method, the method of equivalent imperfection with recommendations for arched bridges, and the equivalent unique global and local initial imperfection method (EUGLI), which uses the critical elastic buckling mode as an imperfection. The latter method is included in the EN 1993-1-1 cl. 5.3.2 (11) since 2002; however, to this day it is neither utilized in the design practice nor is it incorporated in ordinary structural analysis software. The main purpose of this article is to show the application of the proposed methods in a step-by-step manner to the numerical example considered and to compare these design methods for various arched structures. Verification of the in-plane buckling of an arch is explained in detail.

Highlights

Arched structures are often used as supporting structures for bridges or other long-span structures
Verification of an in-plane buckling of an arched structure (Fig. 1) is provided, using three different design methods according to the Eurocodes: 1) The substitute member method (SM) according to (STN EN 1993-1-1)
The comparison of these three design methods according to the Eurocodes has been carried out for the spectrum of f / L = 0.1 ~ 0.5 for various arches: hingeless (Fig. 5), 2-hinge (Fig. 6) and 3-hinge (Fig. 7)

Summary

Introduction

Arched structures are often used as supporting structures for bridges or other long-span structures. Verification of an in-plane buckling of an arched structure (Fig. 1) is provided, using three different design methods according to the Eurocodes: 1) The substitute member method (SM) according to (STN EN 1993-1-1). 3) The Equivalent Unique Global and Local Initial imperfection method (EUGLI) according to (STN EN 1993-1-1) cl. Static and buckling analyses were carried out using the 1st order theory for the SM method and the 2nd order theory for TAB. The 2nd order analysis used in this article is not a large deflection analysis – the so-called Newton-Raphson method (in terms of numerical analysis) – but a simplified approach, which only takes into account only the contribution of axial forces on the displacements.

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Conclusion