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 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.

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.

Generalized dynamic Winkler model for nonlinear soil–structure interaction analysis

2008 ◽  
Vol 45 (4) ◽  
pp. 560-573 ◽  
Author(s):  
Nii Allotey ◽  
M. Hesham El Naggar
Keyword(s):  
Soil Structure ◽  
Interaction Analysis ◽  
Soil Structure Interaction ◽  
Winkler Foundation ◽  
Deep Foundations ◽  
Structure Interaction ◽  
Design Engineers ◽  
Winkler Model ◽  
Centrifuge Tests ◽  
Cyclic Degradation

The beam on nonlinear Winkler foundation (BNWF) model is widely used in soil–structure interaction (SSI) analysis owing to its relative simplicity. This paper focuses on the development of a versatile dynamic BNWF model for the analysis of shallow and deep foundations. The model is developed as a stand-alone module to be incorporated in commercial nonlinear structural analysis software. The features of the model discussed are the loading and unloading rules, slack zone development, the modeling of cyclic degradation and radiation damping. The model is shown to be capable of representing various response features observed in SSI experiments. In addition, the predictions of the model for centrifuge tests of piles in weakening and partially weakening soil are shown to be in good agreement with the experimental results. This agreement demonstrates the potential of the model as a useful tool for design engineers involved in seismic design, especially performance-based design.

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.

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.

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.

DIRECT APPROACH TO SEISMIC SOIL – STRUCTURE–INTERACTION ANALYSIS – BUILDING GROUP CASE

2010 ◽  
Vol 2 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Abdelhacine Gouasmia
Keyword(s):  
Structural Analysis ◽  
Soil Structure ◽  
Interaction Analysis ◽  
Soft Soil ◽  
Near Field ◽  
Soil Layer ◽  
Careful Consideration ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Response Amplification

Nowadays, the new and emerging concept of seismic structural design, the so-called performance-based design, requires careful consideration of all aspects involved in structural analysis. One of the most important aspects of structural analysis is soil-structure interaction (SSI). Such interaction may alter the dynamic characteristics of structures and consequently may be beneficial or detrimental to the performance of structures. In order to observe such effects we study the seismic response of an idealized small city composed of five equally spaced, five storey reinforced concrete buildings anchored in a soft soil layer overlaid by a rock half-space. Our results show predict response amplification of the buildings in the near field in accordance with the results observed in similar cases.

scholarly journals Investigation of Soil Structure Interaction and Wall Flexibility Effects on Natural Sloshing Frequency of Vessels

2017 ◽  
Vol 3 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Pouyan Abbasi Maedeh ◽  
Ali Ghanbari ◽  
Wei Wu
Keyword(s):  
Natural Frequency ◽  
Soil Structure ◽  
Direct Method ◽  
Soft Soil ◽  
Soil Structure Interaction ◽  
International Code ◽  
Structure Interaction ◽  
Wall Flexibility ◽  
Sloshing Frequency ◽  
Fixed Base

The main purpose of this study is to establish the effects of vessel walls flexibility on its natural sloshing frequency considering soil-structure-fluid interaction theory. Furthermore, two new efficiently relations to find both of wall flexibility and soil-structure interaction effects on natural frequency are developed. Regarding the aim of current study three different conditions of elevated tanks are applied. Fixed base condition with an emphasis on recommendations of international code ACI-350, analytical FSSI regarding equivalent mass spring method, and the numerical direct method regarding theory of finite element are taken into consideration. Results indicate that there is no significant effect of walls flexibility on natural sloshing frequency regarding fixed base assumptions of vessels. On the contrary, significant effects of wall flexibility are achieved considering SSI theory. Results of international code ACI-350 show that, the international codes assumptions have imprecise estimations of natural sloshing frequency in the range of hard to very soft soil categories.  On the other hand, it is observed that the wall flexibility has a more highlighted effect on natural frequency in soft soils rather than soil-structure interaction. The significance of wall flexibility effect on natural frequency is more than that of SSI considering soil softening.

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