Model errors caused by rigid-foundation assumption in soil-structure interaction: a comparison of responses of a soil-structure-flexible foundation system and a rigid foundation system

Chimneys with free-standing liners are often analyzed as fixed base cantilever beams, ignoring the effect of soil-structure interaction on their response. However, soil-structure interaction influences the dynamic response of chimneys in two ways: it alters the natural frequencies, damping ratios, and mode shapes, and it results in coupling of the response of the liner and the shell. In this analysis, the stack was modelled as a continuous cantilever beam with distributed stiffness and mass supported by a flexible foundation. It was found that the relative shell-liner deflection for the flexible foundation case was approximately 35% higher than that for the fixed base case. This increase in deflection may exceed design tolerances for a chimney cap and may lead to liner and (or) shell damage if combined with other adverse conditions such as aerodynamic interference effects with other chimneys. The base forces in the shell decrease significantly due to the foundation flexibility, with values as low as 50% of those of the fixed case. The base forces in the liner were approximately 35% of shell base forces for the fixed base case. These forces are not accounted for in the design of liners using the fixed base assumption. It was concluded that the effects of the foundation flexibility are significant and must be included in the analysis of chimneys with free-standing liners. This is especially true for chimneys in regions with low seismic activity, since the design of the liner would be based on minimal lateral forces.Key words: soil-structure interaction, chimneys, dynamic response, wind.

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Loading Behavior and Soil-Structure Interaction for a Floating Stone Column under Rigid Foundation: A DEM Study

Geofluids ◽

10.1155/2021/9508367 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Feng Liu ◽

Panpan Guo ◽

Haibo Hu ◽

Chengwei Zhu ◽

Xiaonan Gong

Keyword(s):

Radial Stress ◽

Concentration Ratio ◽

Soil Structure ◽

Soft Soil ◽

Soil Structure Interaction ◽

Stone Column ◽

Rigid Foundation ◽

Stress Distributions ◽

Structure Interaction ◽

Stress Concentration Ratio

This paper investigates the loading behavior and soil-structure interaction associated with a floating stone column under rigid foundation by using the discrete element method (DEM). The aggregates and soft soil are simulated by particles with different sizes. The rigid foundation is simulated by two loading plates at the same position with the same velocity. The stress distributions and microscopic interaction between the column and soft soil are investigated. The vertical stress of the column increases with settlement and decreases with the depth. The position of the column with large radial stress also has large deformation, which decreases from top to bottom. The vertical and radial stresses of the soft soil increase with settlement, and the radial stress shows high value in the upper part of soft soil. The stress concentration ratio is obtained by two loading plates, which decreases from 2.5 to 1.55 during loading. The interaction between column and soft soil shows that the column does not penetrate into the underlying stratum but drags the surrounding soil down.

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Seismic Response of Steel Braced Vertically Irregular RC Frame Considering Soil Structure Interaction

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.e6731.018520 ◽

2020 ◽

Vol 8 (5) ◽

pp. 4343-4349

Keyword(s):

Soil Profile ◽

Soil Structure ◽

Response Spectrum ◽

Bending Moment ◽

Soil Structure Interaction ◽

Structural System ◽

Braced Frame ◽

Structure Interaction ◽

Time Period ◽

Flexible Foundation

Bracing system is one of the structural system which forms an integral part of the frame. Steel bracings have been used extensively as a structural system to resist seismic loads in the recent times due to their passive energy dissipation property. Steel bracing being economical and easy to erect assists to enhance the strength and retrofitting properties of a structure and their effective performance in controlling seismic effects on the structures during earthquake. In the present study the effect of soil structure interaction (SSI) on multi-storied vertically irregular RC buildings on a horizontal soil profile with varying underlying soil types using concentric chevron bracing is investigated. A G+4 story vertically irregular building (with bracing and without bracing) is analyzed as per IS 1893:2002 using ANSYS.v19 software with fixed and flexible foundation. The soil structure interaction effects on the flexible foundation are analyzed and the effectiveness of the chevron braced frame on the seismic performance of the building is studied. Two different combination of the soil profile for the same building with bracing and without bracing and for free headed and fixed headed flexible foundation condition has been analyzed in response spectrum method for Winkler theory. The performance of the building is evaluated in terms of displacement, storey drift and bending moment along the pile and time period. It was found that the chevron bracing with fixed headed flexible foundation significantly contributes to the structural stiffness and reduces the displacement compared to the bare frame and also the SSI effect considering the water table showed more displacement when compared to the structure on saturated hard soils. Time period increases when SSI was considered

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Three-dimensional (3D) soil structure interaction with normal-plane P-wave incidence: Rigid foundation

Soil Dynamics and Earthquake Engineering ◽

10.1016/j.soildyn.2017.11.016 ◽

2018 ◽

Vol 105 ◽

pp. 11-21 ◽

Cited By ~ 1

Author(s):

Guanying Zhu ◽

Vincent W. Lee

Keyword(s):

Soil Structure ◽

Three Dimensional ◽

P Wave ◽

Soil Structure Interaction ◽

Rigid Foundation ◽

Structure Interaction ◽

Normal Plane ◽

Plane P Wave ◽

Wave Incidence

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The Effect to Structure due to SSI

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.188.112 ◽

2012 ◽

Vol 188 ◽

pp. 112-118 ◽

Cited By ~ 1

Author(s):

Shou Ping Shang ◽

Wan Ruo Chen ◽

Xi La Liu

Keyword(s):

Dynamic Response ◽

Soil Structure ◽

Steel Frame ◽

Soil Structure Interaction ◽

Rigid Foundation ◽

Vibration Period ◽

Peak Displacement ◽

Structure Interaction ◽

Finite Element Software ◽

Soil Bin

In order to understand the soil-structure interaction, we were doing the excitation test about 1:4 scaled steel frame-raft foundation model in the soil bin. The test was through changing the stiffness of the superstructure respectively. We inputting Gaussian white noise measured vibration period, dynamic response with EL and Taft wave show the shock absorption effect of the soil. Finite element software sap2000 simulated rigid foundation on the dynamic response analysis on the steel frames. We found that there are some differences about the natural period, the upper structural stiffness greater the additional period is longer. Soil has a shock absorbing effect with the steel frame, the effect mainly come from the change of structure stiffness. Because of the soil-structure interaction, peak acceleration of the top storey is reducer when steel framework excitation on the soil bin than on rigid foundation, and peak displacement of the top storey is increased.

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