Luca Nardini

Evaluation of Seismic Vulnerability of Santa Maria del Mar in Barcelona by an Integrated Approach Based on Terrestrial Laser Scanner and Finite Element Modeling

Structural assessment of historical constructions is a particular issue as these structures were built with technical knowledge and construction methods based on in-field experience and on the observation of previous failures and successes of similar buildings. Their structural behavior is influenced by numerous aspects, sometimes not completely known (geometry, structural schemes and details, material mechanical properties), which often results in historical structures inadequate to achieve the safety level required for new constructions. In the case of earthquakes, these structures can suffer heavy local or global damages that sometimes lead to collapse. Thus static and seismic vulnerability assessment of historical buildings should therefore be performed by proper methodologies that differ from those used for new constructions. In Italy, an official document (Direttiva del Presidente del Consiglio dei Ministri [DPCM] 2007, revised in 2011) was released, defining a step-by-step procedure for data acquisition and vulnerability assessment of Cultural Heritage buildings. Such procedures can be coupled with new survey technologies such as terrestrial laser scanning (TLS), which, for performing a high-detailed three-dimensional geometrical survey, can provide detailed structural models refining the assessment results. In this study, the DPCM procedure is applied to Santa Maria del Mar Church in Barcelona (Spain) for seismic vulnerability assessment, using TLS three-dimensional survey and finite element analysis.

Dynamical identification and modelling of steel–concrete composite high-speed railway bridges

In the last few years, the construction of new high-speed (HS) railways across Europe, as well as in many other countries, has required many different bridges and viaducts. Together with classical concrete solutions, new steel–concrete composite typologies have been developed, giving light and cheap structures. Despite these studies and applications, some concerns still remain about the definition of reliable models for the evaluation of their actual dynamical behaviour under HS train passage. In particular, the influence of many structural and non-structural components, such as cross-girders and ballast, are still not well recognised. In this paper, open problems related to the dynamical assessment and modelling of new steel–concrete four-parallel-girder and box-girder solutions are exposed and analysed. A suitable procedure, based on operational modal analysis, model updating and train–bridge interaction analysis is applied to two bridges, recently built in the new Italian HS network, in order to assess and verify their dynamic behaviour under operative conditions.

Evaluation of seismic vulnerability of a complex RC existing building by linear and nonlinear modeling approaches

Recent earthquakes, that stroked Italian regions in past decades (Umbria— Marche 1997; Molise 2002; L’Aquila 2009), pointed out the high vulnerability of reinforced concrete existing buildings causing severe damages in the structures and consequently life losses. This is mainly due to the fact that such structures were often built without reference to seismic actions or on the basis of old standard provisions. Nowadays in Italy, Public Authorities are requested to evaluate the seismic vulnerability of their building stock assessing the actual capacity of such structures, as a consequence of new hazard levels and seismic microzonation introduced by new standards. According to Eurocode 8 or Italian standard NTC 2008, the seismic analysis of existing reinforced concrete buildings can be performed by one of the established procedure (i.e. Linear Static Analysis LSA, Linear Dynamic Analysis LDA, Nonlinear Static Analysis NSA, Nonlinear Dynamic Analysis NDA), depending on the achieved knowledge level about the structural system and materials. In order to compare efficiency and differences of previously described approaches, a deep investigation was executed on a reinforced concrete existing building whose dynamic behaviour was evaluated by an experimental dynamic analysis. In such a way, updated models were obtained and adopted for seismic analysis performed by using linear and nonlinear approaches, taking into account the stiffness and strength contribution of masonry infill walls. It was so possible to get useful indications on the reliability and discrepancies of different modelling approaches as well as on the influence of masonry infills on the seismic response of existing r.c. buildings.

Design and Experimental Analysis of an Externally Prestressed Steel and Concrete Footbridge Equipped with Vibration Mitigation Devices

AbstractA 142-m, three-span continuous footbridge over the Esino River (Italy) is considered as a case study to illustrate a number of challenging aspects in its static and dynamic design. The adoption of an optimized steel deck with a variable cross section together with the use of external prestressing tendons in the central span allows a substantial reduction of structural weights. The resulting footbridge requires a proper model for the assessment of its behavior up to the ultimate limit state as well as attention to vibration control under pedestrian loading at the service limit state. The former issue is addressed through the use of a specifically developed material and geometric nonlinear finite-element formulation. Regarding vibration control, an original combination of two different systems is used, i.e., high damping rubber (HDR) stripes and tuned mass dampers (TMDs). The HDR stripes, applied between the steel deck and the concrete floor, increase the overall damping of the footbridge, whereas t...

The Structural Behavior of a Composite Bridge During the Passage of High-Speed Trains

This paper presents the in situ dynamic measurements and the experimental validation of the numerical model for the prediction of the response of a steel–concrete composite railway bridge during the passage of a high-speed train. The dynamic response of the bridge during the passage of high-speed trains is predicted and compared with the experimental data. This study provides a better understanding of the structural behavior of a composite railway bridge under the excitation of high-speed trains.

Characterisation of the mechanical behaviour of the bell tower of the Cathedral of San Miniato (Pisa)

This paper reports the results of a wide-ranging study performed on the Tower of Matilde, the masonry bell tower of the Cathedral of San Miniato (Pisa, Italy). The structure, dating back to the XII century, has been subjected to various modifications over the centuries: from military fortification, to the bell tower incorporated into the church. The research followed a multidisciplinary approach to studying the tower, combining static and dynamic experimental analyses, structural FE modelling and updating through a suitable methodology seldom used in practice on masonry constructions. The aim was to achieve accurate characterization of the overall behaviour of whole masonry construction and the mechanical properties of its constituent materials.