Abstract

This paper studies the flexural and shear performance of steel-concrete-steel (SCS1) sandwich slabs. Six simply supported slabs with different shear spans, section depths and steel configurations were tested under concentrate loads applied at the center. After the tests parts of the steel plates were taken off to observe the crack distribution. The observed modes of failure included flexural yielding and shear punching. The former was initiated by tensile yielding of the bottom steel plate, while the latter was primarily due to punching shear failure of the concrete core. After flexural yielding or concrete punching, the carrying capacities could further increase under large deflections, owning to the shear stiffening of the top steel plate and the membrane action of the bottom steel plate. The top steel plate showed significant shear contribution after concrete punching. A theoretical model is developed to predict the resistance of SCS slabs under concentrate loads. The flexural capacity is calculated with the yield-line method, and the punching shear resistance is analyzed with the radial sector model. The shear contribution of the tie bars is also analyzed experimentally and theoretically.

Introduction

۱٫۱٫ Development of SCS structures

Steel-concrete-steel (SCS) sandwich structures are constructed with the outer steel skins and the concrete core. Composite action is achieved through headed studs, tie bars and other mechanical connectors like angle steel, channel steel, J-hook, etc. [1]. They comprise the advantages of both reinforced concrete (RC) and steel structures, including high bearing capacity, good ductility and integrity, as well as excellent performance in impact resistance and leakage prevention [2]. The steel skins act as both longitudinal reinforcement and permanent formwork, promoting the construction efficiency. In recent years SCS structures have been used in off-shore constructions, submerged tube tunnels, nuclear facilities, bridges, and the application field is still expanding.