scholarly journals Revisions to Soil-Structure Interaction Procedures in NEHRP Design Provisions

2003 ◽  
Vol 19 (3) ◽  
pp. 677-696 ◽  
Author(s):  
Jonathan P. Stewart ◽  
Seunghyun Kim ◽  
Jacobo Bielak ◽  
Ricardo Dobry ◽  
Maurice S. Power
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Damping Ratio ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Structure Interaction ◽  
Fixed Base ◽  
Flexible Base ◽  
New Buildings ◽  
Base Structure

The NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures have contained procedures for soil-structure interaction analysis that were originally developed between 1975 and 1977 by the Applied Technology Council Committee on Soil-Structure Interaction (ATC3 Committee 2C). These procedures affect the analysis of seismic demand in structures by modifying the base shear for a fixed-base structure to that for a flexible-base structure with a longer fundamental mode period and a different (usually larger) system damping ratio. In the 2000 NEHRP Provisions and Commentary, several changes were made to these procedures that affect the analysis of foundation stiffness, and in turn affect the SSI adjustment to base shear. In this paper, SSI analysis procedures in the pre-2000 and 2000 NEHRP Provisions are examined relative to a database of “observed” SSI effects previously evaluated using system identification analyses. Through this calibration exercise and focused numerical analyses, we discuss the motivation and justification for the modifications to the NEHRP SSI analysis procedures.

Equivalent Fixed-Base Model for Soil-Structure Interaction Analysis

2006 ◽  
Vol 22 (3) ◽  
pp. 167-180 ◽  
Author(s):  
C.-H. Chen ◽  
S.-Y. Hsu
Keyword(s):  
Soil Structure ◽  
Simple Structure ◽  
Interaction Analysis ◽  
Damping Ratio ◽  
Elastic Half Space ◽  
Soil Structure Interaction ◽  
Rigid Base ◽  
Test Results ◽  
Structure Interaction ◽  
Fixed Base

AbstractThis paper is to investigate the effects of Soil-Structure Interaction (SSI) on the dynamic response of a soil-structure system. An ideal model with a simple structure supported on elastic half space is utilized to derive the factor FSSI that can completely represent the effects of SSI. This factor is able to characterize both the change of predominant frequency and damping ratio of the system when compared to the conventional rigid-base type structural analysis. Based on that, an Equivalent Fixed-Base (EFB) model, which takes the effects of SSI into account, can be constructed. The Hualien field test results are then used to verify the applicability of the proposed EFB model.

Free Vibration Analysis of Building Considering Soil Structure Interaction

2016 ◽  
Vol 857 ◽  
pp. 125-130 ◽  
Author(s):  
Thaiba T. Beegam ◽  
Tissa Sebastian
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Soft Soil ◽  
Free Vibration Analysis ◽  
Soil Structure Interaction ◽  
Soil Stiffness ◽  
Structure Interaction ◽  
Winkler Model ◽  
Fixed Base ◽  
Flexible Base

Modeling and design of foundation are always done without considering the effect of stiffness of the soil. In the conventional non-interaction analysis of building frame settlements are calculated without considering the influence of the structural stiffness. Therefore a modeling and interaction analysis of soil structure interaction will help to find soil stiffness and effects of soil structure interaction on structure. In this paper, soil structure interaction analysis of a symmetric space frame of 2 bays in both x and y direction are assessed with SAP 2000 software. The frame is modeled with different storey resting on raft foundation with fixed base and flexible base. Three types of soil, i.e. hard, medium, and soft soil are used for Soil Structure Interaction (SSI) study. MODAL analysis is carried out to illustrate the effects of soil-raft-structure interaction on the response of structures. The Soil is considered as Winkler model and elastic continuum model. The developed methodology is validated with results available in the literature. The effects of SSI on frequency of modal are studied. The comparison is carried out the frame with different base conditions.The frequency of the building was found to be decreased when SSI was considered.

scholarly journals Effect of Soil-Structure Interaction on the Seismic Response of Existing Low and Mid-Rise RC Buildings

2020 ◽  
Vol 10 (23) ◽  
pp. 8357
Author(s):  
Ibrahim Oz ◽  
Sevket Murat Senel ◽  
Mehmet Palanci ◽  
Ali Kalkan
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Soil Structure ◽  
Soft Soil ◽  
Soil Structure Interaction ◽  
Soil Conditions ◽  
Existing Buildings ◽  
Structure Interaction ◽  
Fixed Base ◽  
New Buildings

Reconnaissance studies performed after destructive earthquakes have shown that seismic performance of existing buildings, especially constructed on weak soils, is significantly low. This situation implies the negative effects of soil-structure interaction on the seismic performance of buildings. In order to investigate these effects, 40 existing buildings from Turkey were selected and nonlinear models were constructed by considering fixed-base and stiff, moderate and soft soil conditions. Buildings designed before and after Turkish Earthquake code of 1998 were grouped as old and new buildings, respectively. Different soil conditions classified according to shear wave velocities were reflected by using substructure method. Inelastic deformation demands were obtained by using nonlinear time history analysis and 20 real acceleration records selected from major earthquakes were used. The results have shown that soil-structure interaction, especially in soft soil cases, significantly affects the seismic response of old buildings. The most significant increase in drift demands occurred in first stories and the results corresponding to fixed-base, stiff and moderate cases are closer to each other with respect to soft soil cases. Distribution of results has indicated that effect of soil-structure interaction on the seismic performance of new buildings is limited with respect to old buildings.

Seismic behavior of structures considering uplift and soil–structure interaction

2017 ◽  
Vol 20 (11) ◽  
pp. 1712-1726
Author(s):  
Farhad Behnamfar ◽  
Seyyed Mohammad Mirhosseini ◽  
Hossein Alibabaei
Keyword(s):  
Seismic Behavior ◽  
Soil Structure ◽  
Nonlinear Dynamic Analysis ◽  
Steel Structures ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Nonlinear Seismic Response ◽  
Tensile Forces ◽  
Fixed Base ◽  
Flexible Base

A common assumption when analyzing a structure for earthquake forces is that the building is positively attached to a rigid ground so that it can sustain possible tensile forces without being detached, or uplifted, from its bearing points. Considering the facts that almost no tension can be transferred between a surface foundation and soil and soft soils interact with the supported structure during earthquakes, in this research, the effects of uplift and soil–structure interaction on nonlinear seismic response of structures are evaluated. Several reinforced concrete and steel structures under different suits of consistent ground motions are considered. The base of the buildings is modeled with vertical no-tension springs being nonlinear in compression. The total soil–structure interaction system is modeled within OpenSees, and the seismic behavior is evaluated using a nonlinear dynamic analysis. The nonlinear responses of buildings are determined and compared between three cases: fixed base, flexible base without uplift, and flexible base with uplift. The cases for which uplift in conjunction with soil–structure interaction should be considered are identified.

Seismic Response of Multistoried Building with Different Foundations Considering Interaction Effects

2018 ◽  
Vol 877 ◽  
pp. 276-281
Author(s):  
Shreya Sitakant Shetgaonkar ◽  
Purnanand Savoikar
Keyword(s):  
Seismic Response ◽  
Soil Structure ◽  
Response Spectrum ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Foundation Soil ◽  
Soil Medium ◽  
Structure Interaction ◽  
Raft Foundation ◽  
Fixed Base

Current seismic design practice assumes the base of the building to be fixed and does not consider the flexibility of foundation and soil. This assumption is realistic only when the structure is founded on solid rock or when the relative stiffness of the foundation soil compared to the superstructure is high. Whereas, in reality due to natural ability of soil to deform, supporting soil medium modifies the response of the structure during earthquake to some extent. In this work the effect of soil structure interaction on seismic response of building resting on different types of foundation was studied. Present work aims to study the effect of soil structure interaction on seismic response of building resting on fixed base, pile foundation, raft foundation and combined pile-raft foundation. G+9 RCC building is analyzed for earthquake loads considered in zone III by response spectrum method and storey displacement and base shear force of building by considering and without considering SSI effect is found out by using MIDAS GEN software.

scholarly journals Soil-pile-structure interaction effects on high-rise building under seismic shaking

2019 ◽  
Vol 2 (1) ◽  
pp. 153-164
Author(s):  
Umesh Jung Thapa ◽  
Ramesh Karki
Keyword(s):  
Soil Structure ◽  
Seismic Analysis ◽  
Time History ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Structure Interaction ◽  
High Rise ◽  
High Rise Building ◽  
History Analysis ◽  
Fixed Base

In this paper, study of the response (base shear, time period, storey drift, storey displacement) of a structure is done for the tall building including basement with fixed base and with pile foundation considering Soil Structure Interaction (SSI). Finite element based program ETABS2016 v16.1.0 is used for the analysis of the superstructure. Seismic analysis is done to get the dynamic response of superstructure for two types of model,one model is with fixed baseand second is Model with Winkler spring for Chhaya Center, Thamel, a high rise building with 14 story including double basements. Itisobserved with the consideration of Soil Structure Interaction (SSI). The soil is replaced by spring and assigned at joints. El Centro earthquake (1940) is used for time history analysis. The response obtained due to SSI effect is compared with fixed based model. Results of analysis presented include the comparison of natural periods, base shears, displacements and overturning moment. It is observed that the natural periods increase and the base shears decrease as the base become more flexible.

scholarly journals Comparative Study of Soil Structure Interaction Analysis of Building on Clayey and Sandy Soil

2021 ◽  
Vol 9 (9) ◽  
pp. 57-65
Author(s):  
Payal Jain
Keyword(s):  
Soil Structure ◽  
Clay Soil ◽  
Seismic Analysis ◽  
Soil Structure Interaction ◽  
Base System ◽  
Base Shear ◽  
Structure Interaction ◽  
Time Period ◽  
Natural Time ◽  
Flexible Base

Abstract: Present days the analysis of structure with seismic design is more popular. because the first priority of the engineer is effective and durable structure. There are two type of base system first is rigid and second is flexible. In case of flexible base structure, only seismic analysis is not give very effective results. In this condition the SSI effect is more significant and give effective results for flexible base system. The term Soil Structure Interaction (SSI) means interaction between soil to the substructure. This effect give more accurate results after consider in the seismic analysis. If a structure is design according to the seismic analysis with SSI effect than structure could get more durability and safety against earthquake as compare to seismic analysis without SSI effect condition. So the SSI effect can change response of the seismic very significantly. The present study aim is based on seismic analysis of building with Soil Structure Interaction effect on two different soil. A frame rectangular building of G+6 storey has analyzed for flexible base simulating sand and clay soil conditions The software is used SAP2000. Raft foundation has been modeled also. Analysis is made with the response spectrum of IS 1893 2016 code. Seismic response of SSI analysis results are compare in terms of lateral storey displacement, base shear and modal behavior of natural time period on different type of soil ( clay and sand). and conclude that the lateral storey displacement, base shear and natural time period values in SSI analysis with sand soil is maximum as compare to clay soil.

scholarly journals Assessment of Soil-Structure Interaction in Seismic Bridge Pier Analysis Using Force and Displacement Based Approaches

2015 ◽  
Vol 10 (2) ◽  
pp. 113-126
Author(s):  
R N P Singh ◽  
Hemant Kumar Vinayak
Keyword(s):  
Soil Structure ◽  
Seismic Analysis ◽  
Soft Soil ◽  
Bridge Pier ◽  
Soil Structure Interaction ◽  
Base Shear ◽  
Structure Interaction ◽  
Capacity Spectrum ◽  
Fixed Base ◽  
Displacement Based

Abstract The seismic analysis carried out assuming foundation to be perfectly rigid and bonded to the soil underneath is far from truth and therefore, the soil-structure interaction effect on the dynamic behavior of the bridge pier should be considered. The assessment of soil-structure effect on the design force generated has been estimated using Force based, Capacity Spectrum and Direct Displacement based methods considering fixed and flexible foundations. For this purpose a single cantilever bridge pier of constant diameter with varying heights has been considered for the analysis in different type of soils and earthquake zones. The study has revealed that soil-Structure Interaction index is negative in some cases, especially in soft soil, implying base shear demand being greater than that of fixed base contrary to the traditional views.

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