Project 1_Comparative study of different storey buildings for Seismic forces

aim-to have comparative study on

• Factors influencing the dynamic characteristics of a building

• Factors influencing the Natural Period of a building

• Factors influencing the Mode shape of oscillations

Introduction

• every building offers a minimum resistance to the forces industrial by the external effect like earthquake. the important to dynamic characteristic of a building are the modes of oscillation and damping this it has effect of
• flexural stiffness of structural element on mode mood shapes
• axial stiffness of vertical member on mode shapes
• degree of fixity at Colum base on mode shape

Data assumed as per question
structural element size
beams= 300 x400 mm
column =400x400 mm
slab =150 mm thick

material properties
grade of a concrete= M30
grade of a steel and for cement bar =fe 415
loading
dead load on beams from infield wall =10 km per metre
new load on floor= 3 km per metre square

Buildings are assumed to be pined at a base

buildings are considered to illustrate concept of natural period=

General procedure -

• open the tabs software selected new model
• use the built in setting with:
• now at the grids number of storey
• now to add the material selected define then select the material properties and add new material
• now to add the beam property selected define selected the section properties and select the frame section select add new property and insert a concrete
• now select the modify show rebar
• Now to add the column property select the define menu select section properties select frame section add new property
• select the modify rebar and edit
• now to add the slab property again selected the define menu select slab section and add new slab
• now using the quick draw beam columns option draw the beams and columns to the whole structure
• now we need to add the slabs using quick draw floor option
• now selected the base plan and select all the best points
• from the assignment you select the restrain from the joint option does the pin joints are added to the base of structure
• now from the define option select the load pattern and add the dead load live load brick wall load and earthquake load
• now select a and click the modify lateral load and in the new tab periods on factor as per code and select uniform option
• here we consider a new load of 3 kilo Newton per metre square up to the second top most of floor and 1.5 kilo Newton per meter square to the top most of floor
• Now from select menu select to the object type option now a new tab appears and select the beams and click on the select option and close
• now from assignment you select a frame load and select to distributed selected load pattern add brick wall in the new tab and click apply
• now from the define menu select to mass electo modified so much source option and at the load pattern
• again from the define menuu selected the load combination and add default design combination
• now from the select to menu select option and select object type now select the floor and select and close
• now from the assign menu select the shell and select diaphragm
• Now send the new tab appears selected D1 and click on apply and then close
• now from the analyse menu please check model option when the new tab appears select all the option and click okay
• now after checking a warning tab appears and then selector Run analysis
• select to show tables from the display menu and select analysis result select the required tables and now the selected tables will be visible

BUILDING A

BUILDING B

BUILDING C

BUILDING D

BUILDING E

BUILDING F

BUILDING G

BUILDING H

BUILDING J

Imposed load means load as per the question the live load is 10% larger than that imposed in H building therefore live load of 3.3 km per metre square is given

BUILDING K

Imposed load means load as per the question the live load is 20% larger than that imposed in H building therefore live load of 3.6 km per metre square is given

RESULT-

For comparing the fundamental natural period of building E and F as well as G and H

• fundamental natural period of building E is 1.459 second
• fundamental natural period of building F is 1.527second
• the fundamental natural period of a building G is 3.738 sec
  the fundamental natural period of a building H is 4.22 second
  since we used to different colum size in E building and used only one type of column for F building, caused the significant to change in the time period .the same has happened with the case of G and H

For comparing the fundamental natural PERIOD of buiding H, J and K

• when comparing the natural period of a building H,J and K the time period remains constant which means a small increment in the live load causes no change in the stiffness and flexibility of the structure
• while significant change in the structure of flexibility can be expected with greater increment in new load the
• weight of the building is directly proportional to the flexibility of the structure

for comparing the fundamental natural period of a building A, B, F and H change with change in building height

• when observing the height and the natural Period of the building A, B ,F and H it can be observed that with the increase in a height of the structure the natural Period of the building also increases

For comparing the fundamental natural period of a building B,C and D change with change in colume orientation

• 
  with the change in the orientation of the building B C and D a significant change in the fundamental natural period is observed