A unified approach for determining the ultimate strength of RC members subjected to combined axial force, bending, shear and torsion.

Pu Wang,Zhen Huang

doi:10.1371/journal.pone.0175834

Abstract

This paper uses experimental investigation and theoretical derivation to study the unified failure mechanism and ultimate capacity model of reinforced concrete (RC) members under combined axial, bending, shear and torsion loading. Fifteen RC members are tested under different combinations of compressive axial force, bending, shear and torsion using experimental equipment designed by the authors. The failure mechanism and ultimate strength data for the four groups of tested RC members under different combined loading conditions are investigated and discussed in detail. The experimental research seeks to determine how the ultimate strength of RC members changes with changing combined loads. According to the experimental research, a unified theoretical model is established by determining the shape of the warped failure surface, assuming an appropriate stress distribution on the failure surface, and considering the equilibrium conditions. This unified failure model can be reasonably and systematically changed into well-known failure theories of concrete members under single or combined loading. The unified calculation model could be easily used in design applications with some assumptions and simplifications. Finally, the accuracy of this theoretical unified model is verified by comparisons with experimental results.

Highlights

Failure of reinforced concrete (RC) members in extreme loading events is typically caused by different combinations of axial force, bending, shear and torsions, and the failure mechanisms can be highly complex
The theories for RC members subjected to axial forces and bending moments used in various countries are mostly identical, and this theory is widely accepted
This paper focuses on the influence of different loading combinations on the ultimate strength

Summary

Introduction

Failure of reinforced concrete (RC) members in extreme loading events is typically caused by different combinations of axial force, bending, shear and torsions, and the failure mechanisms can be highly complex. Compared to steel structural design and calculation theory, the design and calculation theory of RC members under the combined actions of tensile/compressive axial force, bending, shear and torsion is relatively imperfect and a unified failure theory that can be used worldwide has yet to be developed. A unified approach for determining the ultimate strength of RC members subjected to combined actions. The existing research on the ultimate strength of RC members subjected to a combination of the four loads is far from conclusive, and experimental research is lacking, which makes theoretical research even more difficult

Methods

Discussion

Conclusion