Damaging Effects of the Pisco-Chincha (Peru) Earthquake on an Irregular RC Building

This paper presents back-analysis result of a RC building in Ica, Peru which was severely damaged during the Pisco-Chincha Earthquake on 15 Aug 2007. The building was located approximately 120 km from the epicenter. It has 12 spans in E-W direction and 3 spans in N-S direction. It consists of two stories and is separated into two modules at the center which allows independent vibration of each module. During the earthquake, many columns of the building were heavily damaged by shear-flexure-axial interaction. Masonry infill walls shortened the effective length of columns, which resulted in brittle shear failures. Part of the structure was overloaded with partition walls on second floor which might have led to the crushing of columns below. The analytical model of the building is based on the field measurements. Actual size of structural elements, non-structural elements, and exposed reinforcements were measured during field investigation. Unexposed rebars and material properties are determined considering construction practice. Ground motion recorded at a station located at 0.5 km from the building site is used as an input to the structure. To investigate the effect of infill walls on shear force demand, two analyses are conducted; with and without infill walls. The analysis results confirmed that shear force demand on columns with infill walls is significantly higher than those without infill walls. In addition the seismic demand with infill wall is larger than the shear force capacity estimated from design equation. It is anticipated that infill walls in the first floor, overload in the second floor, and inadequate stirrups of the columns resulted in the failure of columns