Simplified moment-curvature relationship in analytical form for circular RC sections

Roberto Gentile,Giuseppina Uva,Domenico Raffaele,Francesco Porco

doi:10.5459/bnzsee.51.3.145-158

Abstract

The behaviour of regular multi-span simply-supported bridges is strongly dependent on the behaviour of its piers. The response of a pier is governed, in general, by different mechanisms: flexure, shear, second order effects, lap-splice of longitudinal bars or their buckling. The flexural behaviour is an important part of the problem, and it can be characterised through the equivalent plastic hinge length and the Moment-Curvature law of the fixed end. In this paper, a procedure to calculate the Moment-Curvature relationship of circular RC sections is proposed which is based on defining the position of few characteristic points. The analytical formulation is based on adjusted polynomial functions fitted on a database of fibre-based analyses. The proposed solution is based on three parameters: dimensionless axial force, mechanical ratio of longitudinal reinforcement, geometrical ratio of transverse reinforcement. A benchmark case is presented to compare the solution to a FEM non-linear analysis. Even if it is based on few input data, this solution allows to have good indicators on the material performances (e.g. yielding, spalling, etc). For these reasons, the proposed approach is deemed to be particularly effective in performing quick yet accurate mechanics-based regional-scale assessment of bridges.

Highlights

The seismic vulnerability of existing structures has become a relevant theme in earthquake engineering, and great attention has been devoted to bridge structures, in order to perform vulnerability inventory at a regional scale
Each of these is defined in analytical form depending on 3 parameters: dimensionless axial force, mechanical ratio of longitudinal reinforcement, volumetric ratio of transverse reinforcement
This paper deals with the development of a polynomial solution for the characterisation of the flexural behaviour of RC circular bridge piers

Summary

Introduction

The seismic vulnerability of existing structures has become a relevant theme in earthquake engineering, and great attention has been devoted to bridge structures, in order to perform vulnerability inventory at a regional scale. A bridge can often be a crucial node of a transport web and its performance should be guaranteed even in the aftermath of an earthquake. Having an inventory of the structural performances of the bridges in a region is crucial in order to plan mitigation actions. This might be needed to quickly assess a large group of damaged bridges in the aftermath of an earthquake. The 2016 Kaikoura Earthquake is a clear example of this situation [1]

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