Safety factor calibration for a new model of shear strength of reinforced concrete building beams and slabs

Abstract

When assessing existing structures, the availability of adequate safety factors, calibrated with the most accurate models, and for established target reliability indexes, is of critical importance in order to take the right decision regarding the maintenance/repair/strengthening interventions. In the case of shear resistance in reinforced concrete (RC) structures, when using the current design codes provisions for new constructions in assessment results that, in many cases, existing structures may be considered unsafe, implying large economic costs in strengthening or even dismantling. In this research, a proposal of safety factor relative to a recently developed model for shear strength, for elements with and without transversal reinforcement, based on a reliability-based calibration is presented. A formulation is proposed to determine the adequate strength factor for a selected target reliability index of the existing structure and desired remaining service life by means of a safety factor format, considering the load factors present in the Eurocodes. The calibration is carried out considering typical geometry and load ratios of building floors, as well as normal and high strength concrete. The derived safety factor is almost independent of the chosen remaining service life.