A Study on Soil Structural Interaction of Multi Storied Framed Structure with Different Support Cond

IJIRST –International Journal for Innovative Research in Science & Technology| Volume 3 | Issue 04 | September 2016 ISSN (online): 2349-6010

A Study on Soil Structural Interaction of Multi Storied Framed Structure with Different Support Conditions K. S. Sai Kumar PG Student Department of Civil Engineering DNR College of Engineering & Technology Bhimavaram, Andhra Pradesh, India

Mr. M. K. M. V. Ratnam Assistant Professor Department of Civil Engineering DNR College of Engineering & Technology Bhimavaram, Andhra Pradesh, India

Dr. U. Ranga Raju Professor Department of Civil Engineering DNR College of Engineering & Technology Bhimavaram, Andhra Pradesh, India

Abstract The response of a structure to earthquake shaking is affected by interactions between three linked systems: the structure, the foundation, and the soil underlying and surrounding the foundation. Soil structure interaction analysis evaluates the collective response of these systems to a specified ground motion. The terms Soil-Structure Interaction (SSI) and Soil-Foundation-Structure Interaction (SFSI) are both used to describe this effect in the literature. In this report, the foundation is considered part of the structure, and the term SSI has been adopted. The present study provides systematic guidelines for determining the natural periods of frame buildings due to the effect of soil-flexibility and identification of spring stiffness for different regular and irregular story buildings. Specific techniques are described by which SSI phenomena can be simulated in engineering practice, and recommendations for modelling seismic soil-structure interaction effects on building structures are provided. The study is carried out by considering high raised building of about G+19 storied considering all the basic parameters like stiffness factors, base shear, wind forces etc., It also studies on seismic analysis of buildings in which the stiffness is reduced for time being.

Keywords: Base Shear, Soil Structural Interaction, Displacement, Wind Forces, Relative Stiffness _______________________________________________________________________________________________________ I.

INTRODUCTION

Soil-structure interaction (SSI) analysis evaluates the collective response of three linked systems: the structure, the foundation, and the soil underlying and surrounding the foundation. Problems associated with practical application of SSI for building structures are rooted in a poor understanding of fundamental SSI principles. Implementation in practice is hindered by a literature that is difficult to understand, and codes and standards that contain limited guidance. This report represents an advancement in the state of SSI knowledge for practicing engineers. It provides a synthesis of the body of SSI literature, distilled into a concise narrative, and harmonized under a consistent set of variables and units. Techniques are described by which SSI phenomena can be simulated in engineering practice, and specific recommendations for modelling seismic soilstructure interaction effects on building structures are provided. The resulting recommendations are illustrated and tested, in detail, on realistic example buildings.

II. LITERATURE REVIEW Koushik Bhattacharya et.al (2006), Studied the effect of soil structure interaction which was ignored in the design of a low rise building resting on shallow foundation, ignoring such effects it may create an unsafe seismic design. Later the effect of soil structure interaction is considered for low rise building to conducted the investigation for formulating direct design guidelines, calculated the design spectrum based on code specified for the elastic domain. Dynamic characteristic of the building with various numbers of storeys, bays, etc. are computed to seismic vulnerability of low rise building with isolated footing and Mat foundation. The study attempts to identify the influence of various parameter effects to regulating the SSI of base shear and torsional to lateral period ratio for low rise building. A number of curves forming a variation of these two parameters, these curves help with evaluation of the effect of SSI and important to dynamic characteristic parameters for designers, at least preliminary seismic design identify the expected vulnerability by ignoring the influenced SSI in the process of design.

Ravikumar C M et.al (2012), Addressed many buildings have irregular configurations in both plan and elevation. This in a future earthquake subjected to devastating such type of buildings. In case, it identifies the necessary performance of the new and

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A Study on Soil Structural Interaction of Multi Storied Framed Structure with Different Support Conditions (IJIRST/ Volume 3 / Issue 04/ 028)

existing structure to withstand against disaster. This paper studid the two kinds of irregularities in the structure, namely plan irregularity with diaphragm and geometric discontinuity and vertical irregularity with sloping ground and setback. This irregularity is framed as per IS 1893 (part 1), class 7.1 code. The considered in identifying the most vulnerable buildings, in both linear and nonlinear seismic demands to identify the performed various analytical approaches. It is also tested by different lateral loads for various irregular buildings with the performance of pushover analysis. Finally, the result shows that the building capacity may be significant, but the seismic demand differs with respect to the configuration. The eccentricity between centre of rigidity and centre of mass is differ in the absence of dual system. This study generates the awareness of seismic vulnerability in practicing engineering.

III. EXPERIMENTAL ANALYSIS Modeling and Analysis The soil Flexibility effects on Frame building resting on different types of soils, viz Hard, Medium, Soft is also trying to be studied in the present work.

Main Design Parameters of the Structure are as follows: Soil Parameters Type of Soil Medium

Table - 1 Soil Parameters Mass Density (Kn/m3) 18.5

N Value 20

Vs(m/sec) 83

Poissions Ratio (v) 0.33

Wind Parameters Table - 2 Wind Parameters Wind zone Terrain Category Class of the Structure Topography Life of the Structure

2 3 A Float that is Upward slope < 3o 100 Years

Physical Building Parameters Table - 3 Physical Building Parameters Length 17 m Width 13 m Height 15 m

Design Wind Pressure (Pz) The designed Wind Pressure at any height above mean ground level shall be obtained by following relationship.

Pz = 0.6 Vz2 No. of Floors 5 10 15 20

Table - 4 Design Wind Pressure Height of Floor(m) Designed Wind Pressure( PZ) in N/m2 15 1646.1 30 1966 45 2194.7 60 2395

Load Combinations According to IS Code, the Combination of loads has been taken in to Consideration: Table - 5 Load Combinations Factor

Load Combination

1.5

(D.L + L.L)

1.2

(D.L + L.L + WL X)

1.2

(D.L + L.L + WL - X)

1.2

(D.L + L.L + WL Z)

1.2

(D.L + L.L + WL - Z)

1.2

(D.L + L.L + SL X)

1.2

(D.L + L.L + SL Z)

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A Study on Soil Structural Interaction of Multi Storied Framed Structure with Different Support Conditions (IJIRST/ Volume 3 / Issue 04/ 028)

Base Shear Calculation Table - 6 Base Shear Calculation Description G +4 G +9 Effective Weight(Kn) 10445.06 22005.75 Base Shear(Kn) 334.24 484.12

G +14 33501.8 536

G +19 45065.3 540

IV. EXPERIMENTAL RESULTS AND DISCUSSIONS Since the thesis studied by considering different types of Support Conditions as like Fixed Support, Pinned Support and Fixed but Support The following are the graphs which are developed after final calculations: Conclusions Fixed Supports: Displacements Table - 7 Fixed Supports: Displacements Fixed Supports Storeys G+4 G+9 G+14 Displacement(MM) 3.721 12.04 24.43

G+19 105.345

Fig. 1: Displacement v/s Floods

Fixed but Supports: Displacements Table - 8 Fixed but Supports: Displacements Fixedbut Supports Storyes G+4 G+9 G+14 Displacement(MM) 7.77 29.83 50.801

G+19 187.154

Fig. 2: Displacement v/s Floods

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A Study on Soil Structural Interaction of Multi Storied Framed Structure with Different Support Conditions (IJIRST/ Volume 3 / Issue 04/ 028)

Pinned Supports: Displacements Table - 9 Pinned Supports: Displacements Pinned Supports Storeys G+4 G+9 G+14 Displacement(MM) 4.003 12.04 24.431

G+19 105.345

Fig. 3: Displacement v/s Floods

Base Shear Graphs : Table - 10 Load Combinations Storyes Base Shear(Kn) 5 334.24 10 484.12 15 536 20 540.78

Fig. 4: Displacement v/s Floods

REFERENCES [1] [2] [3] [4] [5] [6]

Bhattacharya. K, and Dutta, S.C and Rana Roy, “Seismic Design Aids for Buildings incorporating Soilflexibility”, Journal of Asian Architecture and Building Engineering, November 2006, pp 341-348..

Elements of Earthquake Engineering by Jai Krishna, A.R. Chandra Shekaran, Brijesh Chandra From University of Roorkie IS Code 456:2000 of Plain and Reinforced concrete. Bureau of Indian Standards ,New Delhi IS 1893 (Part 1) :2002 “Criteria for Earthquake Resistant Design of Structures”, part 1-General provisions and buildings, fifth revision, Bureau of Indian Standards, New Delhi, India IS 875 Part-3 -1987 Code of Practice for Design Loads for Buildings and Structure, Bureau of Indian Standards, New Delhi, India Sekhar Chandara Dutta and Rana Roy (2002), A Critical Review on Idealization and Modeling for Interaction among Soil-Foundation-Structural System.

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