Seismic Analysis of A Multi-Storeyed Building With Floating Columns using ETABS

Seismic Analysis of A Multi-Storeyed Building With Floating Columns using ETABS

Teena Tara Tom

Student

Dept.of Civil Engineering

Mangalam College of Engineering, Ettumanoor,India

Meenu Madhu

Student

Dept.of Civil Engineering

Mangalam College of Engineering, Ettumanoor,India

V.P Akhil

Student

Dept.of Civil Engineering

Mangalam College of Engineering, Ettumanoor,India

Richu Varghese Renji

Student

Dept.of Civil Engineering

Mangalam College of Engineering,Ettumanoor,India

Gokul P.V

Assistant Professor Dept. of Civil Engineering

Mangalam College of Engineering Ettumanoor,India

AbstractFloating columns are a type of column constructed over beams or slabs of any intermediate floors of a multistoreyed building.They are not attached to any footings or pedestal and is also called hanging column.The present study investigates the effect of floating column upon the storey shear,displacement and storey drift using ETABS software.Static analysis and dynamic analysis using response spectrum method is done for multi storeyed building with and without floating columns.

KeywordsFloating columns,static analysis,dynamic analysis,response spectrum analysis.

1.INTRODUCTION

Today many multistoreyed buildings have floating column.This is provided generally to provide more space in ground floor for accomodation of parking and for aesthetic beauty.Floating column in a building may may result in concentration of forces,or deflection in the undesirable load path in vertical laretal force resisting system.Building with hanging column at an intermediate storey have discontinuities in the load transfer path.This paper presents the results of investigation of structural response quantities of a multi storeyed building with floating column provided at outer corners and inner corners.

building in asystematic process

1. To study the structural responseof the building models withrespect to

   • Base shear

   • Storey displacement

   • Storey drift

   • Fundamental time period of the building

III. MODEL STUDIES

A 24 m x 24 m multi storeyed building (G+6) is selected forstudy.The details of bare frame is given in Table.1.

Building Type	G+6 RC building
Plan	24 mx 24m
No. of bays	5
Bay width	4.8m
Total building height	24 m
Each storey height	3 m
Beam	300mm x 400mm
Column	400mm x 500mm
Slab Thickness	150 mm
Exterior wall thickness	230 mm
Interior Wall Thickness	155 mm
Materials used	Fe415 rebars M25 grade concrete
Load combinations	Based on IS 875-1987,IS 456- 2000
Earthquake load	based on IS 1893-2002
Live Load	2 kN/m2
Floor Finish load	1 kN/m2
Wall load	13.66 kN/m

TABLE1. BUILDING DATA

II. OBJECTIVES

The primary objectives of this study are

1. To ensure safety against earthquake forces of tall structures

2. To reduce irregularity introduced by floating columns

3. To produce good structural work for performing analysisand design for a building.

4. To predict the responses of different structural componentsdue to effect of loads.

5. To design and analyse multi-storeyed

   The modelling of a bare frame is done as the first step.The model details and their details are shown in the figures given below.The plan,elevation,3D view are shown below.

   Fig.1 Plan view

   Fig.2.Elevation view

   Fig.3 3D view of building

   Fig.4 Rendered 3D View

   After modelling completed,analysis of this bare frame is carried out.When the loads are applied,we get the mode shapes during a particular time interval.The first mode shape obtained is shown below.It shows the deformation of the building due to the loading.

   Fig.5 First mode shape

   FLOATING COLUMN

   The same building is modelled with floating columns provided at the inner and outer corners of the building.The variation in the behaviour and the displacements are necessary to analyse the effect of floating column in buildings,especially in earthquake prone areas like seismic zones IV and V.

   The model of the building with floating column at inner corners is shown below.

   Fig.6 a)Plan of the building with infill wall at inner corners

   Fig6 b) Elevation of building

   Fig 6 c) 3D view

   Similiarly,the ground soft storey building with floating columns are provided at the outer corners of the building.The model details are shown in Fig.7

   Fig..7a) Plan of the building with infill wall at outer corners

   Fig7 b) Elevation of building

   Fig 7 c) 3D view

   1. METHOD OF ANALYSIS

      Seismic analysis is an important tool in earthquake engineering which is used to invvestigate the response of buildings in a simpler manner due to seismic forces.It is a part of structural design where earthquake is prevalant.

      Response Spectrum Analysis (RSM) permits a multiple modes of response of a building to be taken into account.Computer analysis can be done to determine these modes of structure.For each mode,a response is obtained from the design spectrum ,corresponding to modal frequency and modal mass,and they are combined to estimate the total response of the structure.In this,the magnitude of forces in all directions are calculated and then effects on the building are observed.

   2. RESULTS AND DISCUSSIONS

   In the present study,the effect of varying the location of floating columns is studied.The results are compared in graphical form for analysis of building with floating column at inner,outer corners and without floating column.

   Fig.8a)Base shear for bare frame

   Fig.8b) storey displacement for bare frame

   Fig.8c) storey drift for bare frame

   Fig.9a) Base shear for building with floating column at inner

   corners

   Fig9b)storey displacement for building with floating column at inner corners

   Fig.9c) storey drift for building with floating column at innercorners

   Fig.10a) Base shear for building with floating column at outercorners

   Fig.10b) storey dislacement for building with floating column atouter corners

   Fig.10c) storey drift for building with floating column at outercorners

   1. CONCLUSIONS

      The present studt investigated the effect og structural response quantities of building due to presence of floating columns.Analytical study was carried out on a building by comparing the cases when floating column absent,provided at inner corner and outer respectively.Following are the conclusion that are drawn on the basis of study.

      • By introduction of floating columns, the base shear decreases about 51.38% that of building with infill walls at all stories. Thus it has technical and functional advantage over conventional construction

      • Storey displacements increase about 12.5 % when floating columns are introduced in the building

      • Buildingswith floating column can be adopted for getting more space for parking or entrancecorridors.

      • Floating column buildings are safe under gravity loads and designed only for those loads.

1. REFERENCES

[1] Promodini Naik,Satish Annigeri| Performance Evaluation of a 9Storey RC building located in North Goa (2017) | Procedia Engineering 173 1841 1846

[2] Maruthi T, Pruthvi Raj, Pramod, Raghavendra & Krishnamurthy|Analysis and Design of Commercial Building Using ETabs(2019)|International Journal of Engineering Sciences

& Research Technology

[3] P. Guruswamy Goud| Analysis and Design of Hostel Building (G+4) using ETabs(2020)|International Journal of Engineering Applied Sciences and Technology, Vol. 4|Issue 12

[4] Chinmay Padole, Samiksha Bansod, Taniya Sukhdeve, Abhishek Dhomne, Maheshwari Nagose, Pratik Hanwate| Analysis and design of G+4 Residential Building using ETabs(2021)|International Journal of Engineering Applied Sciences and Technology|Vol. 5|Issue 12

[5] Sayyed Feroz Sikandar, Shaikh Zameeroddin, Prof. Agrawal|Analysis and Design of Multistory Building using ETABS 2017(2019)|Volume 9| Issue No. 6

[6] Mastan Shereef|Analysis & Design of Residential Buildings Using E-TABS(2019)|International Journal of Advanced Scientific Technologies in Engineering and Management Sciences|Volume.5|Issue.1