Analysis of the Via D'Annunzio 24/26 building collapse during the 6.4.2009 L'Aquila earthquake

The thesis analyzes the collapse of the building in “Via D’Annunzio 24/26” during the main shock of L’Aquila earthquake, 6 April 2009. The building in exam was designed in 1961 with a bare frame structure. The collapse of the reinforced concrete building was total and instantaneous and in the downfall 13 people lost their life. Most of the information in the thesis are taken from the report of Prof. Maria G. Mulas presented at the court trial in 2013. “Via D’Annunzio 24/26” building didn’t satisfy many basic principles of seismic engineering. The structure wasn’t regular and uniform. The U-shape plan and the distribution of perimeter walls in basement introduced weaknesses. The structure didn’t provide torsional resistance and stiffness and these facts caused an overload in the perimeter columns. Beams were oversized respect to columns and both of them weren’t provided with adequate transversal reinforcement to resist shear loads. The thesis analyzes the case study with a different approach respect the existing models that were linear and static. The study involved: modal analysis, static adaptive pushover analysis and dynamic time-history analysis. The evaluation are made using SeismoStruct,, a finite element software. The choice of the adaptive forced based pushover analysis was justified by the kind of collapse mechanism. Pushover analysis shows the presence of shear capacity failure in columns, located in the basement, before the chord rotation yielding. The columns of the basement had height 3.3 m but, due to the presence of perimeter walls, the unsupported length of column was reduced up to 0.80 m. In this short columns the increment of shear load was significant. The dynamic analysis was developed to compare the results with the simplified pushover method. The results were in agreement with the adaptive pushover. The limits of the applied methods are that the model cannot reproduce what could happen after the failure of the short columns and the geometry and reinforcement distribution were not known exactly.