Structural Failure Evaluation of a Substandard RC Building due to Basement Story Short-Column Damage

Abstract

A vast majority of existing substandard reinforced concrete (RC)-framed buildings are prone to seismic damage because of improper design and construction applications as well as poor material properties. In this study, field investigation and analytical research have been conducted for adjacent buildings, which were exposed to an earthquake with a magnitude of 5.0 occurred in Çiçekdağı/Kırşehir/Turkey on January 10, 2016. A building with a basement story was severely damaged following the earthquake and collapsed eight days after the main shock whereas the other building with no basement did not experience significant damage and survived. Except for the presence of the basement in the collapsed building, both buildings have the same structural system and material properties. To let in daylight, ribbon windows were constructed on the partial infill walls adjacent to some of the columns at the basement story level, which resulted in the short-column phenomenon in the collapsed building. Material tests were conducted on the concrete and reinforcing steel samples taken from the collapsed building to determine their mechanical properties. Then, analytical models of both buildings with masonry infill walls were generated based on the information obtained from the site observations, the blueprints of the buildings and the results of material tests. Nonlinear static pushover analyses were performed to obtain the capacity curves of the buildings. Analyses results showed that the formation of short-column damage, which was visually observed in the field, in the basement because of imposed excessive shear demand was found to be the main reason for the total collapse as well as the high axial load level of columns.