Role and perspective of computational structural analysis for sustainable reconstruction and seismic risk mitigation after an earthquake

The devastating earthquake that on the 6th of April 2009, struck the city of L'Aquila and surrounding villages in the Abruzzo Region represents one of the most damaging natural events which have occurred in Italy in the last century. The causes of structural building failures have constituted a central topic for researchers from different sectors, focusing attention both on the seismic behaviour of structural and non-structural elements, and on the ground role which presented local amplification effects. The investigation presented here aims to achieve an overall comprehension of structural [1] and non-structural vulnerabilities under the seismic input. Starting from a preliminary qualitative survey of damage, developed in the post-event period, the investigation has been deepened through in situ tests [2,3] and numerical analyses. The chapter illustrates the role and the perspective of computational mechanics in different tasks currently under investigation at the new earthquake research centre of the University of L'Aquila (CERFIS). The advances in computing analysis and the need to evaluate the structural elasto-plastic behaviour have introduced several models that are able to reproduce the nonlinear behaviour of the structural elements realized by the different materials using in civil engineering. The extensive scientific literature, available both on nonlinear modelling of reinforce concrete and masonry elements, is discussed here. Preliminary evaluation of the modelling of the seismic action is treated starting from the accelerometer registration, introducing some concepts regarding the possible local effects which characterize the L'Aquila region. Indeed, the observation of the damage scenario distribution provides some evidence of the anomalous effects on the civil structures. Through analyses of the case studies of the Palazzo Camponeschi and Edifice A of the Engineering Faculty Campus of the University of L'Aquila, which represent a particular choice arising from the special and through investigation activities done by different research groups, the models formulated are discussed. In particular, main emphasis is placed on the comparison between the immediate damage scenario and its evolution during the aftershocks with the results obtained by nonlinear structural analyses. The macro element and finite element models used to examine the masonry edifice and the reinforce concrete structure, are fully described, highlighting the role of nonlinear modelling in the final design of the seismic retrofitting of the two buildings.