The current paper focuses on calculation of the seismic fragility curves for steel structures representing special moment frames conventionally used in highly seismic regions. To be able to draw results more resembling the reality, flexibility of the underlying soil is taken into account. Moreover, since soft soils exhibit variations and uncertainties in their mechanical characteristics, their properties are assumed to be probabilistic parameters in this study. For this purpose, 4, 8, and 12-srory special moment frame steel structures are adopted. The collapse spectral acceleration of the buildings is calculated using the incremental dynamic analysis under concurrent horizontal components of 11 consistent earthquakes. Assuming a Log-Normal distribution, the probability of exceedance of the collapse threshold is calculated at each spectral acceleration value, as a fragility curve. The soil-structure interaction is modelled using the theory of beam on the nonlinear Winkler foundation. Using the Tornado analysis, the most influencing soil parameter on collapse is identified to be its shear modulus. The Monte Carlo analysis is utilized to account for uncertainty of the soil characteristics. It is shown that variation of the soil parameters affects the collapse behavior of shorter buildings more considerably both in terms of relative variability and amplitude. The relative difference between the 16 and 84 fragility percentiles reduces from 14% for the 4-story to 6% for the 12-story building. Soil-structure interaction increases the collapse probability at the same spectral acceleration between 11 and 21% for the shorter structure and between 3 and 13% for the taller building.

目前的论文集中在钢结构的地震脆性曲线的计算上，这些曲线代表了在高地震地区常规使用的特殊矩框架。为了能够得出与实际情况更相似的结果，要考虑下层土壤的柔韧性。此外，由于软土在其机械特性方面表现出变化和不确定性，因此在本研究中假定其性质为概率参数。为此，采用了4、8和12种特殊力矩框架钢结构。在11个一致地震的同时水平分量下，使用增量动力分析来计算建筑物的倒塌谱加速度。假设对数正态分布 在每个频谱加速度值上计算脆性曲线超过崩溃阈值的概率。利用非线性Winkler地基上的梁理论对土壤-结构相互作用进行建模。使用龙卷风分析，对塌陷影响最大的土壤参数被确定为其剪切模量。蒙特卡洛分析用于解释土壤特征的不确定性。结果表明，土壤参数的变化在相对变化和幅度方面都对短建筑物的倒塌行为产生更大的影响。16和84易碎百分位数之间的相对差异从4层建筑的14％降低到12层建筑的6％。