Seismic Assessment of Existing Lowrise and Midrise Reinforced Concrete Buildings Using the 2014 Qatar Construction Specification

Abstract

Qatar is considered to have predominantly low seismic activity despite being close to some of the most active seismic zones in the world, including the Zagros thrust belt. However, the strong earthquakes that have recently taken place in Iran (213) and Afghanistan and Pakistan (215) were felt in Qatar, highlighting the fact that the country is not immune to earthquakes. Until recently, no seismic design criteria had been established for Qatar. The only horizontal load the designers had considered was wind loading. Although national construction standards established in 21 for Qatar did not mandate seismic requirements, a 214 update included some seismic accelerations to be adopted for the design of new buildings, which brought up the need for examining the status of existing buildings with respect to these new requirements. This paper presents the investigation into the performances of existing RC buildings in Qatar that were not originally designed for the seismic loads associated with the 214 criteria. The study covered low- and midrise RC buildings because they represent the majority of buildings in Qatar. For the first time in Qatar, a number of existing buildings were selected and analyzed for both wind and seismic loads in accordance with the ACI and ASCE standards with the accelerations from the 214 Qatar construction standards update. The results showed that the 214 seismic loads were usually more critical than the wind loads for low- and midrise RC buildings, which led to a significant increase in the demand: capacity ratios for the lateral force-resisting system members originally designed per the 21 standards. The four buildings analyzed in this study had sufficient margins to accommodate the increase in the design forces per the 214 update; however, other existing buildings in Qatar may not meet these standards. Also, results revealed that the lateral movements of the structures under seismic loads were significantly greater than the movements under wind loads, which may be the result of the previous building separation requirements, specified by ASCE standards, not being satisfied. If movement joints were designed for only wind or thermal loads, then adjacent buildings may collide during earthquakes.