Seismic upgrading of existing RC buildings by means of metal shear panels: design models and full-scale tests

In the first Chapter, as a preliminary study phase, the seismic behaviour evaluation of existing RC buildings, with particular reference to the gravity-load designed ones, has been done by means of the analysis of appropriate seismic vulnerability assessment techniques. Then, once the fundamental lacks of such structures have been evidenced, a wide overview on the possible seismic protection systems, starting from conventional methodologies up to the introduction of innovative devices, has been presented. In the second Chapter a complete review of state-of-the-art on steel plate shear walls, with reference to both compact and slender shear panels, has been performed. In particular, for each panel typology, design criteria, theoretical and numerical modelling studies and experimental research activities have been illustrated in detail. Finally, some applications developed worldwide on such systems have been shown. In the third Chapter a wide numerical analysis on both compact and slender shear panels has been developed. Firstly, both parametric studies and numerical simulation of experimental tests on stiffened pure aluminium shear panels have been carried out. Then, in a second investigation phase, the behaviour of slender steel shear panels has been analysed by means of both refined and simplified numerical models and theoretical methods. In particular, a parametric analysis on such systems has been carried out by varying both the aspect ratio and the thickness of the plate and by evaluating the influence provided by intermediate stiffeners. Finally, the obtained results have provided useful information for the correct design of slender steel plates in shear. In the fourth Chapter the experimental campaign developed within the ILVA-IDEM research project, focusing the attention on the sub-structure devoted to the application of metal shear panels, has been presented. After the identification of the mechanical features of structure materials, the dynamic behaviour of the module under study, obtained under experimental way, has been numerically reproduced by means of the calibration of a finite element model. In conclusion, on the basis of a preliminary experimental cyclic test performed on the original RC structure, some pushover numerical analyses have been carried out in order to evaluate the building performance under lateral loads. In the fifth Chapter both the seismic retrofitting methodology and design of existing buildings by means of metal shear panels have been discussed and applied. Based on the provisions given by FEMA 273 and ATC-40 American guidelines, the seismic performance of the building under investigation has been evaluated. Later on, a reliable procedure in the framework of the “performance based design” has been implemented aiming at improving its behaviour by means of the introduction of an appropriate shear panel configuration able to provide the strength and stiffness prerequisites requested for seismic retrofitting design of the original structure. In the sixth Chapter both numerical and experimental activities on the analysed RC structure equipped with metal shear panels have been illustrated. On the basis of the results deriving from seismic retrofitting design, both steel and pure aluminium shear panel configuration arrangements have been defined according to a simplified analytical procedure and then checked by adopting a sophisticated FEM model. Finally, after the global numerical analyses of the whole system, the full-scale test of the upgraded structure has been carried out and the achieved results have been interpreted, confirming the effectiveness of the adopted retrofitting devices. In the seventh Chapter the experimental test results have been compared each other and with the numerical analysis ones. Finally, interesting conclusions on the beneficial effects provided by metal shear panels for the seismic upgrading of existing RC buildings have been drawn.