Seismic Performance Comparison Between Structure-Improvement Techniques and Ground-Improvement Techniques: Application to a Reinforced Concrete School Building

Abstract

The seismic retrofitting of reinforced concrete (RC) buildings has been widely analysed. Most of the solutions proposed are focused on the building's structure improvement. However, the effects of ground-improvement techniques combined with the building's structure-improvement techniques have not been usually analysed. Therefore, this paper aims to assess the seismic performance of a building by adding different seismic retrofitting techniques in the structure and the ground. A RC school building is proposed in this work. This has been selected because it was constructed prior to the current seismic code. Schools are some of the buildings most vulnerable to earthquakes. This is due to the low adult/child ratio. This paper is framed within the PERSITAH project (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva, in Portuguese). The main goal of the project is to analyse the seismic vulnerability of schools' buildings located in the Algarve-Huelva region. This area is characterized by earthquakes of long-return period and large magnitude. Therefore, the population is not aware of the seismic hazard of the area. Different seismic retrofitting techniques have been added to the building and they have been compared and analysed. The techniques have consisted of the addition of X-bracings within the buildings' bays, steel jackets in columns and soil injection grouting. These solutions have been added both individually and combined to generate hybrid models. Nonlinear static analyses have been carried out to determine the seismic performance of the building including each technique. The N2-method has been considered to obtain the performance displacement. Moreover, the damage level probability and the mean damage index have been determined for each retrofitting technique. Results have shown that the addition of X-bracings is the most efficient solution. However, this solution causes a great architectural impact. Therefore, the solution of steel jackets and/or injection grouting emerges as an interesting alternative.