Improving Seismic Performance of Existing Schools: Design and Analysis of Steel Exoskeleton Systems

Recent earthquake events are highlighted the significant seismic vulnerability of public structure not only related to collapse of building but also hazardous falling architectural component, that can endanger the lives of the occupant. This study presents a comprehensive study on the seismic strengthening of an existing steel school located in Italy, employing parallel steel exoskeletons as the primary retrofitting technique. The approach adopted to assess the current structural deficiencies, seismic vulnerabilities, and performance objectives of the school building are outlined. Subsequently, the proposed exoskeleton systems were designed according to displacement-based step-by-step procedure which aims to enhance the structural safety and seismic performance of the investigated structure. The use of steel members strategically positioned on the outer perimeter of the existing building allows to distribute lateral loads effectively without disrupt the structural grid and non-structural architectural elements such as exterior partitions. Moreover, during the exoskeleton design process, key considerations for the connection between the external exoskeleton and the existing structure are emphasized. These considerations encompass load transfer mechanisms, compatibility of materials, and integration of the retrofit with the original architecture. The study involves 3D finite element numerical modelling and non-linear static analyses to compare the seismic performance of the as-built and strengthened structures verifying the adequacy of the exoskeleton-to-existing structure connection.