SEISMIC ASSESSMENT OF THE PRECODE HIGH RISE BUILDING FRAME USING THE PUSHOVER ANALYSIS

A large part of the housing stock of the Republic of Croatia consists of buildings that were built in the first half of the 20th century, when seismic regulations were poorly developed. Such buildings do not have quality details and have a high seismic risk. In this work it a pushover analysis of a reinforced concrete historic high rise building in Zagreb was carried out in order to assess its seismic resistance. Given that the building is symmetrical in plan and has a frame structural system, one planar multi-story frame in week direction was chosen for analyses. The quality of materials, dimensions of the cross-sections, and position of reinforcement in the elements were obtained from the building’s archival documentation, along with non-destructive tests that were carried out on the building. A numerical model was established, and plastic hinges were defined for the columns and beams of the observed frame, with corresponding load-bearing capacity curves based on Eurocode 8-3. The analyses were carried out using the nonlinear static pushover analysis method (N2) in the ETABS software. The capacity curves of the structure and the significant structural damage index (SDI) were obtained for the observed direction of the building. At the end, a critical review of the analysis method and the original conception of the historical high rise building construction was made, and a proposal for strengthening the building was provided.