ANIDIS - L'ingegneria Sismica in Italia, ANIDIS XIX & ASSISi XVII - 2022

Dimensione del carattere:  Piccola  Media  Grande

Seismic retrofit of reinforced concrete frames using a direct loss-based methodology

Giorgio Rubini, Diego Suarez, Roberto Gentile, Carmine Galasso

Ultima modifica: 2022-10-06


This paper presents a procedure for retrofit design of reinforced concrete (RC) frame buildings to achieve a target level of earthquake-induced loss under a specific seismic hazard profile. The methodology is "direct" because the loss target is specified at the first step of the procedure, and in principle no design iteration is required. The target loss level is defined based on stakeholder preferences and/or external constraints (e.g. foundation capacity). The simplified loss assessment required by the proposed procedure is enabled by using a surrogate model defining the probability distribution of seismic deformation demand estimates of single degree of freedom (SDoF) systems given different ground motion intensity levels. Combined with a hazard curve and a building-level damage-to-loss model, such surrogate model is used to map different candidate SDoF force-displacement curves to their earthquake-induced loss, by assuming a given retrofit strategy. In this case, the considered retrofit strategy consists of changing the frame's local hierarchy of strength to ensure a global plastic mechanism of the structure. Under such assumptions, a designer can select a design force-displacement curve among those that comply with the selected loss target. The detailing of the retrofitted frame is carried out according to the direct displacement-based design principles and the Simplified Lateral Mechanism Analysis (SLaMA). The procedure is applied to an under-designed RC frame building retrofitted with concrete jacketing. A benchmark loss estimate is calculated using non-linear time-history analyses for loss assessment purposes, the proposed procedure showed satisfactory compliance with the benchmark loss.

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