Numerical Simulation of Seismic-Induced Failure of a Precast Structure during the Emilia Earthquake

The paper describes the failure scenario of a precast building that collapsed during the 2012 Emilia earthquake. By means of time-history analyses on a detailed finite-element model, the dynamic behavior of the structure was investigated and the most reliable causes producing the seismic collapse were established. All collapse mechanisms (column failures induced by exceeding the shear force capacity, attainment of ultimate chord rotation, equilibrium instability of columns due to second-order effects and loss of support due to sliding at the double-tee slab-beam and beam-column friction-based supports) were monitored for the whole earthquake duration. The collapse scenario obtained from the interpretation of numerical results was compared with that suggested by the in situ inspection, confirming that friction-based supports (with absence of connection mechanical devices), typically adopted in Italy in precast technology when no seismic design provisions were prescribed, are inadequate to carry medium-high horizontal seismic loading. The modeling criteria and the procedure adopted for safety checks until the attainment of a collapse condition are presented and discussed.