۱- Introduction

۲- Experimental program

۳- Experimental individual behavior of concrete and steel in SCS

۴- The average Poisson effect in core concrete

۵- Constitutive laws of concrete

۶- The solution algorithm

۷- Results and discussion

۸- Conclusion and recommendations

References

Abstract

Steel-Concrete-Steel (SCS) composite wall is being used for different purposes for its improved performances. Some analytical and finite element models have been presented in the past to predict the behavior of such walls. In this paper, an attempt is made to develop an iterative membrane model to analyze SCS wall panels subjected to in-plane membrane forces in the principal directions. The model accounts for the post-cracking Poisson effects of concrete as the Zhu/Hsu ratio.
Individual behaviors of concrete and steel plates in an SCS panel are studied in which confinement in principal tensile direction accompanied by negative uniaxial tensile strain in concrete is observed. To explain this behavior, a detailed perspective for uniaxial strain in principal tensile direction is proposed and the conventional stress-strain trajectory of concrete in tension is extended to incorporate any confinement developed in the concrete. Constitutive law of concrete in compression is also modified to incorporate the observed confining behavior of the concrete.

Introduction

An SCS is a steel plate reinforced concrete in which concrete is sandwiched in between two steel plates. In general, SCS does not have vertical or horizontal rebar reinforcements. Steel face plates are connected with the core concrete by regularly spaced flatheaded shear studs. Face steel plates are also connected with each other by cross tie bars. An SCS structure has improved strength and applicability as prefab over conventional reinforced concrete structures (RC). It was mainly implemented in nuclear power plants during its early development, however, with its popularity, nowadays, high rise buildings, offshore structures [1], and many other structures implement SCS. To analyze an SCS wall, modeling for concrete has always been one of the major tasks. Various approaches have been put forward to predict the behaviors of concrete in RC panels. Softened Membrane Model (SMM) [2], by Zhu and Hsu, is one of the most accurate and efficient iterative models for cracked RC panels under shear. SMM implements a smeared crack concept, in which cracked concrete is treated as a continuous material, to measure the post-cracking Poisson effect of reinforced concrete. Based on the results of 12 full-scale RC panels, Zhu and Hsu proposed a Zhu/Hsu ratio to characterize the Poisson effect after cracking. Zhu/Hsu ratio was observed to reach an unusual value of 1.9 in the post-yield range. Implementation of the Zhu/Hsu enabled prediction of the post-peak shear behavior of RC panels.