Reliability assessment of robustness for reinforced concrete moment resisting frames

A strain-based 5-step procedure is illustrated for the probabilistic robustness assessment of 2D reinforced concrete moment resisting frames. Considering the central column removal as failure scenario, this study compares three frames, including a code-conforming design (frame 1) and two enhanced designs (frame 2 and frame 3). For the three frames, non-linear finite-element (NLFE) models have been defined including properly calibrated translational springs. By sampling from materials and loads, 300 displacement-controlled pushdown NLFE global analyses have been conducted to determine energy-based dynamic amplification factors (1.02 - 1.75). Next, 300 probabilistic static-equivalent NLFE global analyses, performed by removing the column and amplifying loads, permitted to monitor the aleatory peak strains in any material and point of the frames. This allowed to compute the failure probabilities with respect to the ultimate limit state. Robustness improvements lead to much lower failure probabilities (10−7 - 10−3) in any element with a reduction of damage propagation.