سجاد قشلاقي كازراني

Recent design codes have been developed and investigated individually for the study of buildings under the influence of an earthquake or fire, and have developed guidelines for designing and implementing buildings to control these hazards, but the effect of the sequences of these hazards (pre-damage) have not been cosidered in the codes, also has been seen in recent research that destructive effects of the sequence of hazards on buildings have been of particular importance and therefore can be further investigated. In this research, the effect of the post-fire earthquake on the behavior of steel buildings with rigid frame and moderate ductility with residential occupancy in five and ten storey has been done by finite element modeling in ABAQUS Software. By comparing the results of modeling in this study, with the results of other researchers' work, the adopted approach has been validated and seen that the modeling method is reliable. After verification, according to the nature of the fire, scenarios were defined for the purpose of the survey, in which the fire started at the part of the building, which has the potential for fire, and developed with the assumption that the fire was being extended to other parts, therefore two scenarios fire Differently defined so that in the first and second scenarios, 20 and 60 percent of the lower story were exposed of fire respectively. To investigate the behavior of seismicity of the structure, the nonlinear time-history analysis has been used so that after the structure was exposed fire and then reached to the ambient temperature, an earthquake record scaled was applied and the amount of drift ratio and internal forces of the members were investigated. After modeling and analysis, it was found that under the post-fire earthquake scenario, the drift ratio and seismic performance level of the structure in the five-storey building with the least change were observed, and this difference was small compared to the structure that was only under the earthquake an‎d in the ten-storey building under the first fire scenario, there was no change in the results of the drift ratio but in the second fire scenario, which contained more area than the height of the building, only the exposed stories were slightly increased. This is more evident in the direction that the peak earthquake component is larger, and this increase can not to change the seismic performance level of the structure, so the overall behavior of the structure was not affected by the post-fire earthquake scenario. To investigate the effect of the post-fire earthquake scenario on the behavior of structural elements such as beams and columns, the axial force and bending moment interaction of these members during the earthquake record were investigated. In most cases, depending on the fire scenario and the earthquake record, the level of stresses or internal forces of the elements has increased, which was more evident in the columns.