Coppola, Orsola (2015) INNOVATIVE MATERIALS FOR SEISMIC PROTECTION OF NONSTRUCTURAL COMPONENTS. [Tesi di dottorato]

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Abstract

The role of nonstructural components during a seismic event represents a key issue in the modern performance-based seismic engineering. Nonstructural components are usually defined as secondary structures, since they are not designed to bear horizontal forces or vertical loads. Nevertheless, they must still have suitable features to ensure their integrity in the aftermath of an earthquake. Indeed, the damage of nonstructural components can have significant consequences on the operability of strategic buildings, on the human life safety, but can also have a relevant economic impact related to the post-earthquakes retrofitting actions. The above mentioned motivations highlight that a rational seismic design is required for secondary structures. The modern technical codes should provide appropriate analysis methods to define the seismic capacity of nonstructural components and establish design criteria aimed at protecting the secondary structure from the effects of the earthquakes. The present work focuses on innovative solutions for nonstructural components, namely partition walls and cladding panels, both in residential and industrial buildings. Particular attention is given to the seismic performance assessment of plasterboard panels, nowadays widespread in the European area as internal partition systems. The seismic capacity of such components can be assessed by means of experimental tests or numerical models capable to simulate the real behavior of the analyzed systems. In this work, experimental test performed on high plasterboard partitions, i.e. with height equal to 5 meters, are presented. Ten specimens, representative of the most common plasterboard panels' typology, are subjected to quasi-static cyclic tests in order to evaluate their in-plane seismic behavior. The experimental results show ductile behavior of the tested partitions, which achieve very high inter-story drift at the collapse (usually larger than 1%). On the base of the tests outcomes, a reliable numerical model technique, able to predict the collapse inter-story drift ratio, is proposed and validated. The validated finite element model is then extended to several plasterboard partition typologies whose geometrical features do not allow the experimental assessment. Moreover, a parametric study is carried out in order to identify the influence of some geometrical parameters on the definition of the inter-story collapse drift. To reduce the computational effort in the partitions FEM model definition and analysis, a computer tool, interfacing the SAP2000 finite element structural program and the Matlab platform, is developed. By inserting in the input file the main features of the plasterboard panel to assess, the tool automatically performs the analysis and evaluates the collapse drift. The last part of the work focuses on an experimental test campaign aimed at the mechanical characterization of an innovative material, namely a hybrid cement- polyurethane foam. Compressive, tensile and shear test are carried out on the base of ASTM (American Society for Testing and Materials) standards for rigid cellular plastic materials. The lightweight and the high deformability features of the hybrid foam, joined to sound insulation, fire resistance and water vapor permeability make the material suitable for nonstructural components also in seismic zones.

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