In urban environments, in many cases, buildings with unequal story plan sizes are desired, resulting in non-uniform mass/stiffness distributions along the buildings’ height. In this study, three groups of 12-story steel buildings with uniform, ascending, and descending story plan size distribution (PSD) along their height, but having the same total architectural space, were investigated to determine how this distribution affects their seismic performance. First, three site conditions—stiff, medium, and soft—were considered, and all buildings were designed by considering moment frames with concentrical bracings as their lateral load-bearing systems. Then, for each site class, seven appropriate sets of accelerograms were selected, and using nonlinear time history analyses, the buildings’ seismic performance levels were compared based on the formation of plastic hinges (PHs). Results show that non-uniform PSD can be quite effective on the seismic performance of buildings’ structures, so that on hard and soft sites, the number of PHs exceeding the collapse prevention performance level in buildings with ascending and descending PSD, respectively, decreases by approximately 30–45% and 20–40% compared with the uniform buildings. Therefore, it is explicitly concluded that employing buildings with uniform plan sizes does not necessarily lead to a higher seismic performance level.

在城市环境中，在许多情况下，需要具有不同楼层平面尺寸的建筑物，从而导致沿建筑物高度的质量/刚度分布不均匀。在这项研究中，我们对三组 12 层钢结构建筑进行了调查，以确定这种分布如何影响其抗震性能，这些建筑沿其高度具有均匀的、上升的和下降的楼层平面尺寸分布 (PSD)，但具有相同的总建筑空间。首先，考虑了三种场地条件——刚性、中等和柔性——并且所有建筑物的设计均考虑采用同心支撑的弯矩框架作为其横向承重系统。然后，对于每个场地类别，选择七组合适的加速度图，并使用非线性时程分析，根据塑性铰链（PH）的形成来比较建筑物的抗震性能水平。结果表明，非均匀PSD对建筑物结构的抗震性能具有相当的效果，在硬场地和软场地上，PSD升高和降低的建筑物超过防倒塌性能水平的PH数分别减少了与统一建筑相比，约 30-45% 和 20-40%。因此，可以明确得出结论：采用统一平面尺寸的建筑并不一定会带来更高的抗震性能水平。