Análise numérica não linear de punção em lajes lisas com armadura de cisalhamento

Abstract

Reinforced concrete flat slabs are widely used in civil construction due to their architectural, constructive and economic advantages. However, the slab-column connection is susceptible to punching shear failure, a brittle failure mode relevant to structural safety. This work aimed to develop and calibrate, using the Finite Element Method (FEM) and the Abaqus software, a threedimensional numerical model capable of simulating the punching behavior of a reinforced concrete flat slab with shear reinforcement and, based on this calibration, to carry out a parametric analysis of variables that influence punching resistance. The experimental slab FS-08 was adopted as reference, measuring 2500 mm × 2500 mm in plan, 180 mm thick, with an internal 300 mm square column and closed stirrups as punching reinforcement. Concrete was represented by the Concrete Damaged Plasticity (CDP) model and the reinforcement by truss elements. Calibration was based on sensitivity analyses of the finite element type, mesh size, dilation angle, viscosity, fracture energy and the constitutive models of concrete and steel, resulting in a model with C3D8R elements, optimized mesh and a 35° dilation angle. The first load reduction occurred at approximately 590 kN, close to the experimental load of 607.8 kN, with a failure mechanism consistent with punching. The main limitation was the inability to reproduce the abrupt post-peak load drop, since the model retained residual load capacity. Parametric analyses then assessed the influence of concrete compressive strength (20 to 50 MPa), slab depth (160 to 270 mm), flexural reinforcement ratio (bar diameters from 10 to 20 mm) and column geometry (square and circular). It is concluded that the model adequately represented the global behavior of the slab-column connection up to the failure region and can be used as a complementary tool to the experimental investigation of flat slabs with punching reinforcement.