Significance Of Soil-structure Interaction Research Articles

The Effect of Soil-Structure Interaction (SSI) on Structural Stability and Sustainability of RC Structures

The issue of SSI involves how the ground or soil reacts to a building built on top of it. Both the character of the structure and the nature of the soil have an impact on the stresses that exist between them, which in turn affects how the structure and soil beneath it move. The issue is crucial, particularly in earthquake regions. The interaction between soil and structure is an extremely intriguing factor in increasing or reducing structural damage or movement. Structures sitting on deformable soil as opposed to strong soil will experience an increase in static settlement and a decrease in seismic harm. The engineer must take into account that the soil liquefaction problem occurs for soft ground in seismic areas. A reinforced concrete wall-frame dual framework's dynamic reaction to SSI has not been sufficiently studied and is infrequently taken into consideration in engineering practice. The structures’ seismic performance when SSI effects are taken into account is still unknown, and there are still some misconceptions about the SSI idea, especially regarding RC wall-frame dual systems. The simulation study of the soil beneath the foundations significantly impacts the framework's frequency response and dynamic properties. Therefore, the overall significance of SSI in the structural aspect and sustainability aspects will be reviewed in this research.

Seismic Response of RC Frame Buildings: Theoretical Formulation and Modeling with Soil-Structure Interaction Analysis

"Seismic Response of RC Frame Buildings: Theoretical Formulation and Modeling with Soil- Structure Interaction Analysis," offers a comprehensive exploration of the seismic response of reinforced concrete (RC) framed structures, with particular emphasis on soil flexibility. Through a meticulous response spectrum analysis, the study delves into the influence of soil flexibility on buildings of varying heights, ranging from five to nine storeys, considering both fixed and flexible support conditions across diverse soil types. The research draws the following significant conclusions: Significance of Soil-Structure Interaction (SSI): Incorporating soil-structure interaction (SSI) into the analysis leads to a noteworthy extension of the natural time period of the structure. This parameter stands as a linchpin in grasping the lateral response of framed structures, underlining its pivotal role in the precision of seismic design calculations. Soil Flexibility and Amplified Base Shear: Enhanced soil flexibility is found to correlate with a proportional increase in base shear. This phenomenon is most pronounced in soft soil conditions, where base shear experiences substantial escalation, particularly in taller buildings. Roof Displacement as a Performance Indicator: Roof displacement, a crucial indicator of structural performance, exhibits an upward trajectory owing to the cumulative effects of SSI. Notably, soft soils manifest higher roof displacements, with these variations becoming more pronounced as the building's height increases. The insights garnered from this analysis underscore the profound influence of SSI on a building's seismic response. Furthermore, the study highlights that advancements in finite element methods (FEM) and computer technology have significantly facilitated the integration of SSI into structural analysis. Therefore, it is imperative to harness these advancements fully to enhance our comprehension of structural behavior and to promote the adoption of secure construction practices in seismic-prone regions.

Effect of foundation embedment on the response of a multi-story building to earthquake excitation

During an earthquake, the behaviour of any structure is affected not only by the superstructure response, but also by the response of the soil beneath. Recent structural failure patterns have indicated the significance of soil-structure interaction (SSI) effects. The present study focuses on SSI analysis considering the embedment depth of the foundation of a symmetric six stories reinforced concrete (RC)space bare frame building resting on stiff soil and subjected to seismic loading. The finite element analysis software ANSYS v17.2 is used. Time history (TH) analysis has been adopted. The Response in terms of lateral displacements, base shear forces, base moments and variation in natural time periods are calculated from the analysis of the soil foundation structure interaction (SFSI) model. Results are compared with that obtained from conventional method assuming rigid support at the base (fixed base) of the structure. The results show that the SFSI considering different embedment depths are significant in altering the seismic response of the multi-story building (MSB).

Analysis of Foundation of Tall R/C Chimney Incorporating Flexibility of Soil

Three dimensional Finite Element (FE) analysis was carried out for 100 and 400 m high R/C chimneys having piled annular raft and annular raft foundations considering the flexibility of soil subjected to across-wind load. Stiffness of supporting soil and foundation were varied to evaluate the significance of Soil-Structure Interaction (SSI). The integrated chimney-foundation-soil system was analysed by finite element software ANSYS based on direct method of SSI assuming linear elastic material behaviour. FE analyses were carried out for two cases of SSI namely, (1) chimney with annular raft foundation and (2) chimney with piled annular raft foundation. The responses in raft such as bending moments and settlements were evaluated for both the cases and compared to those obtained from the conventional method of analysis of annular raft foundation. It is found that the responses in raft vary considerably depending on the stiffness of the underlying soil and the stiffness of foundation. Piled raft foundations are better suited for tall chimneys to be constructed in loose or medium sand.

The Incorporation Of Soil-structure Interaction Into Performance-based Design

A performance-based design is aimed at controlling the structural damage relying on-precise estimations of proper response parameters. This is possible if more accurate analyses are carried out, including all potentially important factors involved in the structural behaviour, as is the case of soil-structure interaction. This paper presents a simplified procedure for practical damage analysis of structures elastically supported, with potential application to performance-based design. The damage model proposed here is based on maximum displacement and dissipated energy under monotonic loading, with the effects of cyclic behaviour and load reversals being estimated using a modified Park-Ang index. Analyses are made for a single elastoplastic structure with embedded foundation in a stratum over rigid bedrock. This is done by using an analogy with an equivalent fixed-base oscillator defined by the coupled period and damping of the system and its global ductility. Selected numerical results are presented in terms of dimensionless parameters, the significance of soil-structure interaction in the structural performance is elucidated and the adequacy of the approach presented is examined.

ANÁLISIS DE DAÑO EN ESTRUCTURAS CON APOYO FLEXIBLE

Se presenta un enfoque de diseño por desempeño encaminado a controlar el daño estructural a partir de estimaciones precisas de la respuesta sísmica del sistema completo cimentación-edificio. Se trata de un procedimiento simplificado para el análisis práctico de daño en estructuras considerando los efectos de interacción suelo-estructura, con aplicaciones potenciales para el diseño por desempeño de nuevos edificios así como para la evaluación por desempeño de edificios existentes. Se propone un modelo de daño basado en desplazamientos máximos y energía disipada bajo carga monotónica, con efectos de inversiones de carga cíclica estimados mediante un índice de Park y Ang modificado. Para simplificar la consideración de los efectos de interacción suelo-estructura, se hace uso de un oscilador con base rígida equivalente, con la resistencia de fluencia y capacidad de disipación de energía del sistema real con base flexible. Para asegurar la generalidad de las conclusiones, se presentan resultados numéricos en términos de parámetros adimensionales obtenidos con un conjunto de movimientos sísmicos apropiados. En este trabajo se esclarece la importancia de la interacción suelo-estructura en el desempeño estructural y se examina la aplicabilidad del enfoque propuesto.

Significance of SSI and nonuniform near-fault ground motions in bridge response I: Effect on response with conventional expansion joint

This paper studies the influence of spatially varying near-source ground motions and soil–structure interaction (SSI) on the relative response of two bridge frames. The spatial ground motions are simulated according to a near-fault ground motion model with different wave apparent velocity and a coherency loss function. Numerical calculations of bridge structure responses including pounding and SSI effect to a number of simulated spatially varying ground motions are carried out. The study reveals that the assumption of uniform ground excitation and fixed base in the analysis and design might not provide a realistic estimation of the pounding responses of bridge frames. The consequence of adjusting bridge fundamental frequency ratio towards unity to minimize relative response and consequently girder pounding potential as recommended by current design regulations is also evaluated.

Significance of SSI and non-uniform near-fault ground motions in bridge response II: Effect on response with modular expansion joint

This is the second part of the study of soil–structure interaction (SSI) and ground motion spatial variation effects on bridge pounding responses. The first part [Chouw N, Hao H. Significance of SSI and non-uniform near-fault ground motions in bridge response I: Effect on response with conventional girder gap. J Eng Struct. [in press]] concentrated on studying the responses of bridges with a traditional expansion joint between adjacent girders. The main objective of this second paper is to investigate the influence of spatial variation of ground motions and SSI on the minimum total gap that a modular expansion joint system (MEJS) between two bridge frames must have to prevent any pounding between the adjoined girders. This minimum total gap is critical in a MEJS design because it ensures intact expansion joint and adjacent girders. Additional investigations of pounding response with a large total gap of a MEJS are performed to study the characteristics of pounding responses when collision does occur e.g. due to unintended underestimation of the ground excitation magnitude, which may be different from the pounding responses between bridge girders with a small gap of a conventional expansion joint. The spatially varying ground excitations are simulated stochastically based on an empirical near-source response spectrum and an empirical coherency loss function. The investigation reveals that neglecting spatial variation of ground motions and SSI can significantly underestimate the total gap of a MEJS required to avoid pounding between the adjacent bridge girders. The results also show that pounding between girders with a large gap of a MEJS in general causes stronger impact forces. Compared with the results reported in the first part of this study, using a MEJS with a large gap is likely to completely preclude bridge girder pounding, and consequently to prevent local damage at the girder ends. However, a large girder movement results in large bending moment in bridge piers, which compensates the advantages of using MEJS in bridges to resist earthquake loading.

Incorporation Of The Soil-structure InteractionInto Performance-based Design

A performance-based design is aimed at controlling the structural damage based on precise estimations of proper response parameters. This is possible if more accurate analyses are carried out, including all potential important factors involved in the structural behaviour, as is the case of soil-structure interaction. This paper presents a simplified procedure for practical damage analysis of structures elastically supported, with potential application to performance-based design. The damage model proposed here is based on maximum displacement and dissipated energy under monotonic loading, with the effects of cyclic behaviour and load reversals being estimated by using a modified Park-Ang index. Analyses are made for a single elastoplastic structure with embedded foundation in a stratum over rigid bedrock. This is done by using an analogy with an equivalent fixed-base oscillator defined by the coupled period and damping of the system and its global ductility. Selected numerical results are presented in terms of dimensionless parameters, the significance of soil-structure interaction in the structural performance is elucidated and the adequacy of the approach presented is examined.