Influence of soil structure interaction effects on the real elastic axis of asymmetric buildings

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 146; p. 106775
• Main Authors: Terzi, Vasiliki G., Athanatopoulou, Asimina
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01-07-2021; Elsevier BV
• Subjects: Asymmetric buildings; Asymmetry; Building codes; Building design; Earthquake analysis; Eccentricity; Flexibility matrix; Matrix methods; Multistory buildings; Real elastic axis; Rigidity; Seismic design; Soil investigations; Soil structure; Soil-structure interaction; Soils; Structural eccentricity; Vectors (mathematics); Soil-structure interaction; Real elastic axis; Asymmetric buildings; Earthquake analysis; Structural eccentricity
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2021.106775

Structural eccentricity plays an important role in the seismic design of buildings. According to various seismic design codes, it is one of the parameters which define whether a building may be considered as regular in plan. Structural eccentricity is defined as the distance between the center of mass and the center of rigidity. However, the center of rigidity is rigorously defined in single story buildings and in some special classes of multi-story buildings, e.g. isotropic ones, under the assumption of fixed based conditions. The present paper deals with single story and multistory asymmetric buildings that possess a real elastic axis under the assumption of fixed base condition and examines the existence or not of an elastic axis under soil structure interaction effects. The flexibility matrix and the loading vector are defined under flexible base assumption and the elastic axis is determined based on the notion of twist center. Mathematical formulas are derived which provide the coordinates of the elastic axis. Numerical examples are presented which investigate not only soil-structure interaction effects but the influence of various loading vectors as well. In general, soil-structure interaction extinct the real elastic axis; hence an optimum torsion axis must be defined. Moreover, soil-structure interaction decreases the structural eccentricity at each story level.
•SSI on the existence of buildings elastic axis.•Derivation of mathematical formulas for elastic axis coordinates under SSI effects.•Investigation of foundation loading on the elastic axis coordinates.•Conditions defined under which an optimum torsion axis must be sought.•Numerical examples demonstrate the multi-parametric nature of the problem.