Behavior of two-way RC slab with different reinforcement orientation layouts of tension steel under drop load impact

Abstract

In this research work, dynamic nonlinear incremental finite element analysis is conducted in ABAQUS software with an inbuilt explicit module to study the impact response of a two-way singly reinforced concrete slab, 1000 mm × 1000 mm × 75 mm, with different flexural tension steel reinforcement orientation layouts subjected to low-velocity falling-weight impact loading by cylindroconical impactor with a flat nose of 40 mm diameter having overall mass 105 kg from 2500 mm drop height. Computational findings are found in consonance with experimental results of Sadraie et al. (2019) on an isotopically reinforced concrete slab of the same dimensions with flexural tension steel in two layers i.e., one at 90-degree and the other at 180-degree orientations, subjected to the same impact load. Local damage in the form of punching occurs in the immediate vicinity of the impacted region. Overall deformation and cracking reflect the global behavior of the slab. The slab reinforcement is improvised by providing the same tension steel (0.88 %) in three layers: the first- and third- layer having orientation layouts of (a) 30- & 150-degree, (b) 45- & 135-degree, (c) 60- & 120-degree, and (d) 75- & 105-degree; the second layer is common with 90-degree orientation, and analyses are carried out under the same impact load. The Concrete Damage Plasticity and Johnson-Cook models, respectively, including the strain rate effects, are chosen to define concrete and steel materials’ response under impulsive impact loading. Computational results are discussed and presented in terms of displacement–time plots, stress distribution in the concrete and reinforcing bars, damage dissipation energy, and damage profiles. The tension steel in three layers and its orientation is found to have a noteworthy influence on the response of the slab and reduces the damage severity under impact loading.