STRUCTURAL PERFORMANCE ASSESSMENT OF EXISTING BRIDGES IN SEISMIC PRONE AREAS

Abstract

For the issue of planning construction areas in order of the prevention and mitigation of seismic risk, in addition to emergency management, the scientific community has for decades studies the identification of tools and methodologies for seismic vulnerability of buildings and infrastructure. In this context it’s very difficult the seismic vulnerability evaluation for existing structures, and especially those distributed. The complexity of the infrastructural vulnerability analysis is represented by the deep interconnection between different features. Several aspects are connected to this problem, from the correct choose of seismic input, structural and geological knowledge, correct modeling and analysis. The process of assessment of structural security conditions therefore must necessarily be dynamic and iterative, depending on the time scale and spatial analysis in the report. The type and quantity of data needed are dependent on the complexity and heterogeneity of both the geological and geotechnical characteristics of the natural system and of the characteristics of structures. So is very important the need for interdisciplinary approach that can integrate organically different methods of investigation related to the different disciplines involved (geology, geotechnical engineering, structural engineering). Structural knowledge refers not only to the geometry structural details, and materials, but also to the state of maintenance of the structure. A careful analysis of conservation state of and degradation of the structure, allows two goals. The first is to ensure that they are not workings special phenomena that may compromise the structural safety of the work, and for which the seismic capacity of the structure can be greatly cut down, the second is related to the observation of the conservation status structure, and quantification of degradation/corrosion due to natural structure working. The attainment of reliable information to study fragility analysis is a complicated and hard work. Still, to obtain hazard and vulnerability structure, it’s need knowledge of site features and geometrical and mechanical structure’s property. The literature on this subject is relatively large but, given the heterogeneity, complexity and scope of works is to be tested is the territory on which they insist, significant progress can be achieved by directing research towards the implementation of strategies and integrated methodologies multi-scale science-engineering. In this context the evaluation of seismic performance of some really existing viaducts are analyzed. The result of the work, is the implementation of global Bridge Management System, useful for global assessment at single structure level, and sufficiently detailed for administration of medium-sized populations, such for example a regional scale. The different sections of BMS, allows the collection and cataloguing of background data and knowledge data, and constitute, the base for performance evaluations in structural perspective, linked to the road network exercise, and in seismic perspective, for seismic vulnerability assessment. A guide for the maintenance program and seismic retrofit is provided, useful for by responsible agencies.