ABSTRACT

This study investigates the soil–structure interaction (SSI) behavior of low- to medium-rise steel moment-resisting frames (SMRF) resting on loose Ganga sand through a series of resonant vibration tests. Three-dimensional models of a three-story and a six-story structure are used for this purpose. Horizontal harmonic excitations, tuned to the first two natural frequencies of the structures, are applied using a modal mass shaker. Afterwards, a numerical model is developed where the SSI is modeled using discrete Winkler-type springs, and the experimental results are compared with the analytical ones. The study indicates that the floor acceleration and column moment decrease significantly (as much as 50% and 74%, respectively) when the structure is placed on the soil bed compared to the fixed base condition. The estimated energy dissipation is up to 23% through foundation rocking vibration. Furthermore, the deformation and moment distribution profiles are observed to be very sensitive to the exciting frequency, indicating the importance of frequency characteristics of input motions while characterizing the dynamic behavior of multi-story SMRFs.

摘要

本研究通过一系列共振振动测试，研究了搁在松散恒河砂上的中低层钢抗弯框架 (SMRF) 的土壤-结构相互作用 (SSI) 行为。三层和六层结构的三维模型用于此目的。使用模态质量振动器施加水平谐波激励，调谐到结构的前两个固有频率。然后，开发了一个数值模型，其中 SSI 使用离散 Winkler 型弹簧建模，并将实验结果与分析结果进行比较。研究表明，与固定基础条件相比，当结构放置在土床上时，地板加速度和柱力矩显着降低（分别高达 50% 和 74%）。通过基础摇摆振动估计能量耗散高达 23%。此外，观察到变形和力矩分布曲线对激励频率非常敏感，表明输入运动的频率特性在表征多层 SMRF 的动态行为时的重要性。