Evaluation of the Failure Probability of a 2D RC Frame Subjected to Column Loss

This study regards the evaluation of the failure probability of a symmetrical 2D reinforced concrete frame composed of 4 spans and 5 floors, in case of an accidental event which causes the central base column loss. The frame is an internal one of a typical building designed in a highly seismic area, characterised by a high ductility class. The frame is modelled in the non-linear finite elements software Atena 2D, accounting for both geometrical and material nonlinearities. The uncertainties relevant to the problem are included by sampling both material and action variables, adopting the Latin Hypercube Sampling technique. To compute the failure probability associated to the accidental scenario, two sets of analyses are considered: the first set to compute the capacity of the structure against the column removal by means of displacement-controlled pushdown analysis; the second set to evaluate the demand in terms of external loads, properly combined within the accidental combination according to the codes. The external load is then amplified in order to include the dynamic effects characterising a scenario of a structural member loss. Finally, the probability of the demand exceeding the capacity is evaluated.