Bearing capacity assessment of RC flat slab in frame structures.

After the Ronan Point partial collapse (1968), several design methods have been proposed in Technical Code and Guidelines to mitigate the progressive collapse phenomenon of reinforced concrete structures, such as Tying Force prescriptive rules and Alternative Load Path analysis. The latter is a direct method, where the capacity of the structure to sustain the applied loads after the loss of a load-bearing element is investigated. Two different approaches are used in this study to analyse the ultimate resisting mechanisms of reinforced concrete flat slab in case of a column loss scenario: 1) a simplified approach which consists of an analytical method developed in the framework of the strip method and that takes into the tensile membrane effect, 2) a detailed approach which consists of a finite element analysis using multi-layered shell elements where the nonlinear behaviour is evaluated using the PARC_CL 2.0 crack model, implemented in Abaqus Code as user subroutine. The purpose of this paper is the progressive collapse assessment of a reinforced concrete flat slab frame structure by comparing the simplified and the detailed ap-proaches with experimental data available in literature.