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Summary It is desirable that nonlinear dynamic analyses for structural fragility assessment are performed using unscaled ground motions. The widespread use of a simple dynamic analysis procedure known as Cloud Analysis, which uses unscaled records and linear regression, has been impeded by its alleged inaccuracies. This paper investigates fragility assessment based on Cloud Analysis by adopting, as the performance variable, a scalar demand to capacity ratio that is equal to unity at the onset of limit state. It is shown that the Cloud Analysis, performed based on a careful choice of records, leads to reasonable and efficient fragility estimates. There are 2 main rules to keep in mind for record selection: to make sure that a good portion of the records leads to a demand to capacity ratio greater than unity and that the dispersion in records' seismic intensity is considerable. An inevitable consequence of implementing these rules is that one often needs to deal with the so‐called collapse cases. To formally consider the collapse cases, a 5‐parameter fragility model is proposed that mixes the simple regression in the logarithmic scale with logistic regression. The joint distribution of fragility parameters can be obtained by adopting a Markov Chain Monte Carlo simulation scheme leading directly to the fragility and its confidence intervals. The resulting fragility curves compare reasonably with those obtained from the Incremental Dynamic Analysis and Multiple Stripe Analysis with (variable) conditional spectrum–compatible suites of records at different intensity levels for 3 older reinforced concrete frames with shear‐, shear‐flexure‐, and flexure‐dominant behavior.

SUMMARYThe behaviour of the EPP-SDOF model under seismic actions is analysed herein by different 'damage functionals' to define collapse under cyclic loading. In particular, the damage functionals based on the concept of maximum ductility and dissipated plastic energy are first compared. Afterwards the methods of Banon and Veneziano, Park and Ang and the linear cumulative law of plastic fatigue are reviewed and extensively analysed. Comparisons in the case of simple cyclic histories and in terms of acceleration collapse spectra are carried out with reference to significant earthquake records. In particular, it is shown in which cases the damage functionals of Banon and Veneziano, Park and Ang and the linear cumulative law of plastic fatigue, completely defined by the value of a single parameter, degenerate in the limit methods of ductility or dissipated energy and in which cases they provide similar results.

The reconstruction process of residential buildings severely damaged by the 06 April 2009 L’Aquila earthquake, the so called “heavy damage” reconstruction, started after the “light damage” reconstruction process. The “heavy damage” reconstruction involved buildings outside the historical centres assessed as unusable due to high structural and/or non-structural risk. The costs of repair and strengthening of both the “light damage” and the “heavy damage” were directly funded by the State. The procedures to deal with funding applications made by private owners were similar to those related to the “light damage” reconstruction, but specific regulations were issued to regulate the public contributions of severely damaged buildings in L’Aquila and other municipalities. The paper describes such regulations and the data collected during the approval process of funding applications. In particular, the discussion focuses on: the time for the approval of funding applications; the types and costs of the different repair and strengthening interventions designed by practitioners to attain the usability recovery of buildings; the State funding for repair works, strengthening works, tests on material for their mechanical characterization, energy efficiency upgrading, and, in several cases, for demolition and reconstruction; the correlation between structural types of buildings and costs. The process of assessment and State funding of repairs and upgrading of residential buildings outside historical centres that were damaged by the L’Aquila earthquake took less time than past Italian earthquakes with similar or even lower impacts. The data presented may help, inform and encourage decision makers to establish priorities and reconstruction policies for use in the aftermath of future earthquakes. Being prepared for destructive earthquake impacts requires identification of the procedures and tools required to quickly start the reconstruction phase. © 2016 Springer Science+Business Media Dordrech

Assessment of the seismic damage and usability of the building stock started a few days after the L’Aquila earthquake in order to evaluate the safety conditions of the buildings concerned. Several ordinances of the Prime Minister were issued to regulate the reconstruction process. In particular, based also on damage level, the procedures for repair, strengthening or demolition/reconstruction of residential buildings were established with the definition of relevant state funding. For each damaged building, practitioners engaged by property owners designed repair and strengthening interventions and then computed the corresponding costs. These projects were the technical basis for funding applications that owners submitted to the government. Technical and financial information collected during the approval procedure of such applications allowed compilation of a database regarding 5775 residential buildings damaged by the L’Aquila earthquake. The present study examines the restoration policy and the procedures regulating the reconstruction process of residential property outside city centres. In particular, the data related to the first phase of the reconstruction process (the so-called “light damage” reconstruction) to recover the usability of slightly damaged buildings are illustrated. The discussion focuses on the time-to-approval of funding applications and on the public contributions granted for repair and local strengthening works. © 2016 Springer Science+Business Media Dordrech