Abstract
This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.
Highlights
Brittle failures, which can occur at the slab-column connection, may typically be prevented through drop panels or by reinforcing the critical region with transverse bars [1,2,3] or structural steel inserts [4,5,6,7,8,9,10,11]
This paper deals with the ultimate behavior of cruciform as well as closed-box shear-head systems fully embedded in RC flat slabs at interior RC columns through threedimensional nonlinear finite element assessments
This paper investigated the ultimate behavior of cruciform and closed-box shear-head systems fully embedded in RC flat slabs at interior RC columns by means of nonlinear finite numerical simulations employing concrete damage plasticity models
Summary
Brittle failures, which can occur at the slab-column connection, may typically be prevented through drop panels or by reinforcing the critical region with transverse bars [1,2,3] or structural steel inserts [4,5,6,7,8,9,10,11]. To avoid previously mentioned mesh-dependency problems the crack band model with constant facture energy in which the tensile response is a function of the characteristic element length, may be considered Models employing such approaches were able to predict the ultimate strength and deformational response of plain and reinforced concrete members (e.g., localized behavior under direct shear and tension [58,59], assessment of a long-term behavior [60], RC flat slabs with and without shear reinforcement under static loading [61,62,63], RC hybrid beams in shear and flexure [64,65,66,67]). After discussing the modeling procedures and constitutive parameters for the concrete, reinforcement and structural steel, validations are carried out against 36 flat slab specimens extracted from three experimental programmes
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