Nonlinear dynamic analysis of steel buildings subjected to earthquakes

Non-linear dynamic analyses methods generally provide a more adjusted modeling of the structural response for strong seismic events. Such a dynamic seismic nonlinear evaluation took place for six buildings: two 5 story-height, two 12 story-height and two 20 story-high and with a regular configuration. The structural systems of the buildings complied to the NSR-10 (Colombian earthquake resistant standard) and with the seismic microzoning of Bogotá. The analysis done to the previous structures used non-linear methodologies along with two time- histories corresponding to two well recorded earthquakes: Quetame earthquake circa 2008 and the Mesa de los Santos earthquake circa 2015. Said events characterized by records at Bogotá D.C. by the RAB (network of accelerometers of Bogotá). A structural evaluation using the nonlinear approach of a finite element software and following the FEMA 356 guidelines, the structural response to 81 seismic signals from the Mesa de los Santos earthquake and 78 from the Quetame earthquake helped in understanding the simulated behavior. Said signals included three perpendicular ground movements corresponding to the north-south, east-west and vertical directions. With the results of the non-linear dynamic analysis, plastic hinges helped in understanding the nonlinear structural response when the earthquakes hit separately. Based on the results, sway maps showing the results in the Y and X directions, clustered the most affected areas of the city. At the same time, a thorough analysis of moment connections at the first floor, at an intermediate floor and at the last floor of the buildings showed the capacity of the original design. The results suggest that steel buildings have a better structural performance when compared with reinforced concrete buildings that were also analyzed (nonlinear analysis) with real earthquake (in soft soils) in previous investigations.