Punching Shear Behavior of Shear Reinforced Slab\u2013Column Connection with Varying Flexural Reinforcement

Jae-Ick Jang,Su-Min Kang

doi:10.1186/s40069-019-0341-4

Abstract

The effects of flexural reinforcement and shear reinforcement on the punching shear strength of slab–column connections are analyzed in this study. For the study, six slab–column connection specimens were constructed with varying flexural reinforcement and shear reinforcement, and were subjected to gravity load tests. Experimental results showed that all specimens were destroyed by punching failure, and that the slab–column connection behaved differently depending on the amount of shear reinforcement and flexural reinforcement. Particularly, the flexural reinforcement in the slab–column connection improved the punching strength of the specimens with or without shear reinforcement. In addition, in this study, a design formula that considers the flexural reinforcement ratio in the calculation of the punching shear strength of the shear reinforced slab–column connection was proposed and was verified using experimental results and existing test data.

Highlights

Flat plate structures consisting of slabs and columns are widely used in apartment houses, offices, and skyscrapers due to their architectural and construction advantages
Relatively thin slabs in the flat plate system are vulnerable to punching shear failure at the slab–column connection; punching shear failure is more dangerous than other ductile failure modes such as flexural failure, as punching shear failure is sudden and may induce collapse of the entire system (Choi and Park 2010; Choi et al 2011, 2012)
SP-3 has a smaller vertical displacement than SP-2 and was destroyed at low load; SP-3 shows better ductility than SP-2. These results show that after the ultimate strength, shear reinforcement affects the ductile behavior of the slab–column connections

Summary

Introduction

Flat plate structures consisting of slabs and columns are widely used in apartment houses, offices, and skyscrapers due to their architectural and construction advantages. In current concrete design codes such as ACI 318 (ACI 2014) and KCI 2012 (KCI 2012), shear reinforcement is adopted to ensure the sufficient strength against punching shear at the slab–column connection. A recent study on the shear reinforcement of slab– column connections proposed that the time at which the maximum punching strength of the slab–column. The current concrete design codes (ACI 2014; KCI 2012) do not consider the difference in the behavior of slab-to-column connections with varying shear reinforcement. They evaluate the punching shear strength by reducing the contribution of the concrete and shear reinforcement according to the design philosophy of each code. Equations (2) and (3) are used to evaluate the punching shear strength for ACI 318 (ACI 2014) and KCI 2012 (KCI 2012), respectively

Objectives

Results

Conclusion