Probabilistic Seismic Assessment of Steel Moment Frame by Considering Soil Foundation-Structure Interaction and Moodify Of Conections

Research Aim:The purpose of this study was to investigate the effect of modeling of beam-column connections, the structure height, the type of soil on the seismic response of steel structures. Also Considering that LCC Lifetime Costing is a tool to help select the best and most economical design among design options considering, repair and maintenance. the life cycle cost for the structures designed with two methods of calculating the cost of energy and maintenance and calculating the cost of failure of the structure due to possible earthquakes. For this purpose, the calculation of life-cycle costs, for all models in the 30-year period was performed from the combination of these two methods. Research Method: Structural analysis has significant importance against dynamic and earthquake forces. The responses of structure-foundation and soil to a specified ground motion can be only evaluated using soil-structure interaction. For this purpose, five and ten stories buildings with special steel moment frames and two different soil types (II and IV) have been considered. BFP connections used for these buildings.The models are designed in two ways in terms of the effect of soil - structure interaction and without regard to this effect. Incremental nonlinear dynamic analyses are performed using twelve far-fault ground motion records, and the structural demand is extracted at limit states with 75, 475, 975, 2475 return periods.Their responses are compared with each other using probabilistic seismic analysis.The results of seismic probabilistic analysis of models have been used to calculate the failure. Discount rates of 5, 8, 12 and 15 percent have been used to calculate the life cycle cost. Finding : The results show that the effect of soil-foundation-structure and soil type has a significant effect on the failure probability of the structure. With regard to the effect of connections and soil in models based on type IV soil, the probability of failure of structures 5 and 10 stories reduced, as well as the fall in them occurs in more spectral acceleration and less relative displacement. For models based on type II soil, the effect of the soil increases the likelihood of fracture of the structure and also its collapse in this case in less spatial acceleration and more displacement occurs. According to the resultsin terms of structural failure, and illogical estimated discount rate would reduce life cycle costs and life cycle costs are increasing the discount rate Conclusion: According to the results obtained in soil type II structures, the effect of soil will have a favorable effect on the structure behavior against earthquakes. Since the fracture of the structure when considered the interaction effect is less than the time when this effect is neglected in the design of the structure. But in the structures on the soil type IV, this is true. When the influence of the interaction between the soil and structure is ignored, the structure is better off and the probability of fragility is reduced. Finally, it can be concluded that the actual behavior of the structure is highly dependent on the type of soil that the structure is located on. In calculating the cost of the lifetime of the structure, the effect of soil type and interactions for the structure of the ten classes on the weaker soil is more evident.