Assessment of seismic vulnerability of urban areas provides fundamental information for activities of planning and management of emergencies. The main difficulty encountered when extending vulnerability evaluations to urban contexts is the definition of a framework of assessment appropriate for the specific characteristics of the site and providing reliable results with a reasonable duration of surveys and post-processing of data. The paper proposes a new procedure merging different typologies of information recognized on the territories investigated and for this reason called “hybrid.” Knowledge of historical events influencing urban evolution and analysis of recurrent building technologies are used to evaluate the vulnerability indexes of buildings and building stocks. On the other hand, a vulnerability model is calibrated by means of experimental and numerical investigations on prototype buildings representative of the most recurrent typologies. In the final framework, the vulnerability index, calculated through simplified assessment forms, is linked to the seismic intensity expressed by the peak ground acceleration and associated with an index of damage expressing the economical loss. The procedure has been tested on the urban center of Lampedusa island (Italy) providing as the output vulnerability index maps, vulnerability curves, critical PGA maps, and estimation of the economical damage associated with different earthquake scenarios. The application of the procedure can be suitably repeated for medium-to-small urban areas, typically recurring in the Mediterranean by carrying out each time a recalibration of the vulnerability model
Strengthening of concrete columns with fiber reinforced polymer sheets provides a good improvement to the existing structural members in terms of load and strain capacity due to the properties of the composite jacket. A proper knowledge of the load–strain response of the composite members is necessary to design retrofitting intervention of existing structures; however, so far the available design methods do not allow to take into account the effect of the possible presence of service loads on the compressive behavior of the reinforced columns. An experimental investigation on the compressive behavior of preloaded circular concrete columns reinforced with carbon fiber reinforced polymer was carried out to determine the load and deformational capacity of confined concrete subjected to short‐terms loads. Nineteen compression tests were performed to underline the difference respect to the standard compressive stress–strain response of the confined specimens. The results indicate that the compressive behavior seems to be not particularly influenced by the preloading. As the preloading level increases, ultimate axial load and axial strain do not have significant change respect to the test performed without preloading; however, the load–strain response of the confined concrete is affected by a reduction of the secant stiffness.
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