Open Access

ARTICLE

A Coupled 3D Nonlinear Modeling Approach for Evaluating SSI Effects in Large Stepback Buildings on Stepped Slope Site

Jinghao Yang¹, Haitao Yu^2,*, Jian Zhou³, Qingyu Yang¹, Yaokang Zhang³, Hailong Gong³

1 Department of Geotechnical Engineering, Tongji University, Shanghai, China
2 State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai, China
3 East China Architectural Design & Research Institute Co., Ltd., Shanghai, China

* Corresponding Author: Haitao Yu. Email:

Computer Modeling in Engineering & Sciences 2026, 148(2), 23 https://doi.org/10.32604/cmes.2026.086135

Received 25 May 2026; Accepted 22 July 2026; Issue published 28 August 2026

Abstract

Large and complex structures on stepped slope sites are still commonly evaluated using simplified fixed-base assumptions, which may not adequately reflect the effects of soil-structure interaction (SSI). To address this issue, this study develops a coupled three-dimensional nonlinear finite element model in which the surrounding soil domain, foundation system, and superstructure are considered simultaneously, so as to capture soil-structure interaction effects under stepped topographic conditions. A corresponding fixed-base model is further established for comparison, and the approach is applied to the Ground Transportation Center (GTC) at Kunming Airport, a large transportation hub founded on a multi-bench stepped slope. The seismic responses predicted by the two models are compared in terms of slab damage, story drift ratio, story shear force, overturning moment, and energy dissipation characteristics. The results show that the fixed-base model can generally capture the overall response trend, but noticeable differences remain in local response characteristics. Compared with the SSI model, the fixed-base model predicts a wider extent of tensile damage, larger story drift ratios at most middle and upper floors, and larger overturning moments. In contrast, the SSI model shows more unfavorable local responses at lower floors near the soil-contact region, including larger story drift and local story shear force. In addition, SSI changes the energy dissipation pattern by allowing a considerable portion of the input energy to be transmitted into and dissipated through the surrounding soil, thereby reducing the energy demand on the structure and dampers. These results indicate that the effect of SSI should be explicitly considered in the seismic analysis of large irregular structures on stepped slope sites, as relying solely on conventional fixed-base assumptions may lead to inaccurate structural assessments and potential vulnerability at embedded levels.

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Keywords

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