Seismic performance design of the reinforcement of a 60+ year old confined masonry hospital retrofitted with L-shaped end concrete walls

Abstract

The Casimiro Ulloa Hospital is a building more than 60 years old located in a high seismic hazard area such as Lima - Peru. Its construction is based on confined masonry and presents important irregularities in elevation and floor plan, and is susceptible to collapse according to structural evaluations based on the Peruvian seismic code E030. The purpose of this paper is to propose a reinforcement system for this essential infrastructure, increasing its structural capacity such as ductility and ensuring a good seismic performance. This proposal is based on the intervention of specific locations of the infrastructure in order not to stop its use in the rest of the building. This is through 15 cm thick reinforced concrete walls, located at the perimeter corners of the hospital, with variable lengths of 3 m and 3.65 m. The performance design methodology was based on the provisions of the ATC-40, and the nonlinear model according to experimental studies for the masonry and provisions of the ASCE41 for the concrete walls. The As-Built model and the proposed model were subjected to nonlinear Push over analysis in order to determine the capacity curve of both models and therefore qualify the structural performance of the hospital after a seismic event. The resistance when implementing concrete walls increases by 115% and 108% in the longitudinal and transverse directions, respectively. The level of seismic performance achieved by the reinforced model is that of immediate operability, which is due to the increase in ductility, evidencing the release of energy without further damage. By applying this proposed strengthening method, the stability of the structure and the null danger of human life loss after a seismic event are guaranteed.