A simplified Nonlinear Sway-Rocking model for evaluation of seismic response of structures on shallow foundations

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 81; pp. 14 - 26
• Main Authors: Lu, Yang, Marshall, Alec M., Hajirasouliha, Iman
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2016
• Subjects: Bearing capacity; Coupled sway-rocking response; Earthquake engineering; Foundations; Mathematical analysis; Mathematical models; Nonlinear analysis; Nonlinearity; Seismic phenomena; Simplified model; Soil (material); Soil non-homogeneity; Soil-structure interaction; Soil-structure interaction; Simplified model; Soil non-homogeneity; Coupled sway-rocking response; Nonlinear analysis
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2015.11.002

This paper presents a simplified Nonlinear Sway-Rocking model as a preliminary design tool for seismic soil-structure interaction analysis. The proposed model is intended to capture the nonlinear load-displacement response of shallow foundations during strong earthquake events where foundation bearing capacity is fully mobilised. Emphasis is given to heavily-loaded structures resting on a saturated clay half-space. The variation of soil stiffness and strength with depth, referred to as soil non-homogeneity, is considered in the model. Although independent springs are utilised for each of the swaying and rocking motions, coupling between these motions is taken into account by expressing the load-displacement relations as functions of the factor of safety against vertical bearing capacity failure (FSv) and the moment-to-shear ratio (M/H). The simplified model has been calibrated and validated against results from a series of static push-over and dynamic analyses performed using a more rigorous finite-difference numerical model. Despite some limitations of the current implementation, the concept of this model gives engineers more degrees of freedom in defining their own model components, providing a good balance between simplicity, flexibility and accuracy. •A simplified model is developed to capture nonlinear seismic foundation response.•The effects of soil nonlinearity and heterogeneity are accounted for in the model.•A unique dimensionless backbone is employed for each of sway and rocking motions.•The FLAC3D numerical code is used to calibrate and validate the simplified model.