Project 1_Comparative study of different storey buildings for Seismic forces

AIM

TO create the Comparative study of different storey buildings for Seismic forces.

INTRODUCTION

This project 1 is created using ETABS and the procedure are explained in detail.

PROCEDURE

• Open the etabs software.
• create a new model.
• create a grid system and teh storey hesight of the building according the questions given
• define the frame section of column and beam.
• select the column size and beam sizes of the building
• and define then slab section.
• assign the prroperties according to the grid system
• slect the load patterns in the building.
• select the load cases and load combination of the building.
• after assign the properties of the slab section
• select the mass of the building.
• and select the modal diagrham of the building
• after all done RUN THE ANALYSIS.
• the time period of the effect of stiifness ,dynamic chateristic of the building,natural period of time, factors infuencing the mode shape of the building.
• the images shows the step by step procedure of analysisng in the ETABS.

set the metric conversion as per the indian standard.

then click ok.

select the grid system as siven in the qusetion spacing of 4m distance.

and select the storey height of the building

and select the pilnt level as 1.5m

select the height of the building as 3m

each 25 storey has 3m height of the building as shown in the fig below.

after selecting ok the grid system of plan and 3d plan is visible as shown in the fig below.

select DEFINE in the ribbon bar and select and add the properties of column and beam.

select the depth and width of beam.

and select the column 800mm x800mm

afetr completing column and beam select the slab properties in the define ribbon bar.

and select the slab section.

A tab appears of slab properties as shown in the fig below.

after completing slab propeties and now the assign the load properties as shown in the fig below.

select the mass propeties.

select the cente of mass of structure.

assign the load cases and load combination of the properties

MODEL A

MODEL B (ZERO INERTIA)

MODEL-B ( REGULAR)

MODEL-C

MODEL-D

MODEL-E

MODEL-F

MODEL-G

MODEL-H

MODEL J

MODEL-J(ADDING 10% LIVE LOAD)

MODEL-K (REGULAR)

MODEL-K(ADDING 20% OF LIVE LOAD)

MODEL-B (FIXED)

RESULT ; the following models are created and completed and analysed, explained in detail below.

CRITERIA	MODEL	ANALYSIS	CONCLUSION
EFFECT OF STIFFNESS ON TIME PERIOD	BUILDING-E (10 Storey with varying column size)	1.73 s	If the storey are minimum no significant difference in the mode 1
	BUILDING-F (10 Storey with varying column size)	1.73 s
EFFECT OF STIFFNESS ON TIME PERIOD	BUILDING-G (25 Storey with varying column size)	4.16 s	If the storey height of the building is high the varying column is more stabe than the uniform column sizes With the uniform column size the mass of the building is lumped on the top more lateral load acting on the building leading to more time period.
	BUILDING-H (25 Storey with uniform column size)	4.40 s
EFFECT OF MASS ON TIME PERIOD	BUILDING-H (25 Storey with 3KN/Sq.m imposed load)	4.40 s	There is no big diffrence in the lateral load of the building .
	BUILDING-J (25 Storey with 3KN/Sq.m imposed load)	4.41 s
	BUILDING-K (25 Storey with 3KN/Sq.m imposed load)	4.42 s
EFFECT OF BUILDING HEIGHT ON TIME PERIOD	BUILDING-A (2STOREY)	0.5 S	There is a time difference in according to the storey height of the building.
	BUILDING-B (5STOREY)	1.03 s
	BUILDING-F (10STOREY)	1.73 S
	BUILDING-H (2STOREY)	4.40 s
EFFECT OF COLUMN ORIENTATION ON TIME PERIOD	BUILDING-B (All floors column size 400x400)	1.03 s	Efffect of column is flexibe is according to the storey height.
	BUILDING-C (All floors column size 550x300) oriented in x axis	1.14 s
	BUILDING-D (All floors column size 300x500) ) oriented in y axis	1.12 s	The deflection of the building D is higher in the x direction for the lateral case load
EFFECT OF FLEXURAL STIFFENESS OF STRUCTURAL ELEMENTS ON MODE SHAPES	BUILDING-B Flexural stiffeness of beam close to nil ( zero inertia)	2.62 s
	Full Flexural stiffeness of beams ( regular)	1.03 s
EFFECT OF AXIAL STIFFENESS OF VERTICAL MEMBERS ON MODE SHAPES	BUILDING-H Axial cross section for column is close to nil (Zero axial area)	5.98 s	Column play a vital role in the time period gravity load should also be controlled.
	Full Axial cross section for column (regular)	4.41 s
EFFECT OF DEGREE OF FIXITY OF COLULMN BASE ON MODE SHAPE	BUILDING-B Column support pinned(regular)	1.03 s	More fixidity of column lesser its gets deflected.
	Column support fixed	0.94 s