Project 1_Comparative study of different storey buildings for Seismic forces

Project 1 - Comparative study of different story buildings for Seismic forces

AIM:- To Compare the results of different - different-story buildings for some given conditions and parameters.

INTRODUCTION:- In the project, we compare the different - different-story buildings for a given condition and try to find out the conclusion.

Given the Parameters of the building:-

Structural Element Sizes

• Beams: 300 × 400 mm
• Columns: 400 × 400 mm
• Slab: 150 mm thick

Material Properties

• Grade of Concrete: M30
• Grade of Steel Reinforcement Bars: Fe 415

Loading

• Dead Load on beams from infill wall: 10 kN/m
• Live load on the floor : 3 kN/m2

(what is the seismic mass?)

• Buildings are assumed to be pinned at the base

Five-storey Benchmark Building: Elevation and plan of benchmark building showing the structural moment frame grid (All dimensions are in mm)

Various Building Description and their conditions:-

List what we try to find out in these analyses and compare these results with each other as per such conditions:

1. Effect of stiffness on T: Compare fundamental natural periods of buildings E & F as well as G & H. Why is there a marginal or significant difference in the fundamental natural periods?
2. Effect of mass on T: Compare fundamental natural periods of buildings H, J and K. Have the buildings become more flexible or stiff due to change in mass?
3. Effect of Building Height on T: How do the fundamental natural periods of Buildings A, B, F, and H change with a change in building height?
4. Effect of Column Orientation on T: How do the fundamental natural periods of Buildings B, C, and D change with a change in column orientation?
5. Effect of Flexural Stiffness of Structural Elements on mode shapes: Compare the fundamental mode shape of Building B in two situations when the flexural stiffness of beams relative to that of adjoining columns is very small versus when it is large.
6. Effect of Axial Stiffness of Vertical Members on mode shapes: Compare the fundamental mode shape of Building H in two situations when the axial cross-sectional area of columns is very small versus when it is large.
7. Effect of Degree of Fixity at column bases on mode shape: Compare the fundamental mode shape of Building B in two situations when the base of columns is pinned versus when it is fixed.

PROCEDURE:-

MODAL-A

First, go to the new model

select parameters

Display units- Metric SI

Default materials - India

Steel section database - Indian

Steel design code - IS-800-2007

Design code - IS-456-2000

Press ok

Custom grid spacing and Story data

Goto Edit Grid data

First Add 5 grids along x-direction @ spacing of 4m

Second Add 4 Grids along the Y-direction @ spacing of 4m

Press ok

Then goto Edit story data

In first project name Model A Is only two stories @ of 3m in Height

And Base to plinth level height is 1.5m

Assign the Master story as Story 1

Assign Similar all story to story 1

Press ok

Everything is done then press ok

Define Materials like concrete grade, Grade of reinforced bars, Loads and Load combination, Slab

Goto to Material properties

Add new materials

Define parameters

Region-India

Material type- Concrete

Standard - Indian

Grade-M20

press ok

Select material type - Concrete

Press ok

Add Another material

Define parameters

Region-India

Material type- Rebar

Standard - Indian

Grade- HYSD-415

press ok

Select Material type- Rebar

press ok

Press ok

Next, Define the Beam and Column

Goto define> section properties> Fame Section

Add new property

Select a rectangular shape section

Define parameters

Property name - C400X400

Material- M20

Depth- 400mm

Width- 400mm

Then to modify rebar

Select parameters

Define type - Column

Rebar materials- Both Longitudinal and ties bars -HYSD 415

Press ok

Press ok

Again Add a new property for the beam

Define parameters

Property name - B300X400

Material-M20

Depth-400mm

Width-300mm

then goto modify the rebar

Define type-Beam

Rebar materials- Both Longitudinal and ties bars -HYSD 415

Press ok

Press ok

Press ok

Next, define slab 150mm thick

Goto Define> section properties> slab section

Add new property

Define parameters

Property name - Slab 150mm

Slab material - M30

Modeling type - Membrane

Thickness - 150mm

press ok

press ok

Then Define loads and combination

Goto define> Load patterns

Add new load

Load - Type - self-weight - Auto lateral load

Dead - Dead - 1 - _

Live - Live - 0 - _

Wall load - super load - 0 - _

EQx - Seismic - 0 - IS 1893-2016

EQy - Seismic - 0 - IS 1893-2016

Modify lateral load

Direction only- X Dr

Seismic zone factor - 0.16(II)

Everything is default

Press ok

Direction only- Y Dr

Seismic zone factor - 0.16(II)

Everything is default

Press ok

Press ok

Check load is defined or not

Goto define> Load case > check ok > press ok

Add load combination

Goto Define> load combination

Select Add default design combos

Select Concrete Frame Design

press ok

The auto combination is created as per IS 1893-2016

Press ok

Define Mass sources

Got to define> Select Mass Sources

Select mass sources > Modify mass Sources

Select the specified load pattern

Add load

Live - 0.25 (Multiplier)

Dead - 1 (multiplier)

Wall load - 1 (Multiplier)

Press ok

Press ok

Now Assign columns, beams, and slabs to their places

Select quick Sketched columns

Select column property -C400X400

The select crosssection of Other direction grids

Select quick Sketched beams

Select Beam property -B300X400

Place beams between columns

Assign slab

Select quick draw floor sketched

Select property- Slab 150mm

Rectangular portions are selected and slabs are defined

Define Slab at Story 1 to Story 2(Select similar story option)

Assign loads in frames

Goto Select by Object type

Select beams

Goto Assign > Frame Loads> Distributed

Select Wall load

Load - 10KN/m

Press Apply

Goto Select by Object type

Select Columns

Goto Assign > Frame Loads> Distributed

Select Live load

Load - 3KN/m

Press Apply

Define Diaphrmgrms

Goto Select by Object type

Select Frames

Goto Assign> select shell> Disphragrms

Select D1 > press apply

The select base of all column's bottom

Assign supports

Goto Assing > joint > Restraints

Select Pin Support> Apply

Run Analysis

Save the Model AS Model A

Results are Available

Model Periods and Frequencies

Modal PArticipating Mass Ratio

Goto Dispaly> Story Response plots

Maximum Story Displacement along EQx

Maximum Story Displacement along EQy

Save Modal A as Modal B (Because Grids, Story Height, load cases, And other parameters are similar)

Change Add 3 more story

Goto Edit> Edit stories and Grid systems

Goto to Modify Story data

Add # story above story 2 and similar to story 2

Select all stories similarly to story 1

And Refresh view

Press ok

Showing load which is already applied and Disphargram

So directly run analysis

Results of modal B

Modal periods and frequencies

Modal participating mass ratios

Maximum story displacement along EQx

Maximum story displacement along EQy

MODAL-C

Save Modal B as Modal C (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes of modal C is only the size of the column is changed -C 550x300 Along X-direction orientation

Define New column size

Goto define> select frame properties

Add new properties

Define Property

Property name - C550X300

Material - M20

Depth-330mm

Width- 550mm

Goto Modify rebar

Select column

Rebar material - Both Longitudinal and ties - HYSD415

Press ok

Press ok

Press ok

Next, assign the column or replace the previous column with new columns

Goto View> Set display options

Deselect beams and floor

press ok

Select entire Columns

Then Goto Assign> select Fram > section property > select C550X300> press ok

In question, Column are oriented along X-direction

So go to Assign > Local axes

Select angle -90 degree

Press Apply

Again open the set view option

select beam and floor

Press Apply

All Live and wall load is already applied

Apply diaphragm

And Run analysis directly

Result of Modal C

Modal period and frequencies

Modal participating mass ratios

Maximum story displacement along EQx

Maximum story displacement along EQy

MODAL-D

Save Modal C as Modal D (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes of modal D is only the size of the column is changed -C 300X550 Along Y-direction orientation

So only we change the orientation of column (i90 degree to 0 degrees)

Goto to Set view options

Deselect Beam and floor

Press Apply

Got assign > Frame > Local Axes> define 0 degree> Press apply

Assign Diaphargram

Run Analysis

Results of Modal D

Modal periods and frequencies

Modal participating mass ratios

Maximum story dispalcement EQx

Maximum story dispalcement EQy

MODAL-E

Save Modal D as Modal E (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal E is S story added and Column size are also change

The upper 5 story is 400x400mm

And Rest of the story is 600X600mm

Goto edit > edit grid and story> select Modify story data

Add 5 stories above the 5th story and similar to story 1

Press ok

press ok

Goto Define > Fram properties> Add new property

Select rectangular section

Define parameters

Property name - C600X600

Material- M30

Depth-600mm

Width-600mm

Goto Modify Rebar

Select design type - Column

Rebar material- Both Longitudinal and ties - HYSD415

Press ok

Press ok

Press ok

Goto set building view limits in the View toolbar

select Top story- Story 10

Base - Story 6

Press ok

Set view option

Deselect beams and floor

Press Apply

Select all columns visible on the screen

Then Assign column size

Goto Frame. section property

Select C400X400

Press Apply

Goto set building view limits

Select Top story- Story 5

Base - Base story

Press ok

Select all columns visible on the screen

Assign Column size C600X600

Press ok

Goto Set view options

Select beam and floor

Press Apply

Set building view limits

Press Show all

Press ok

Rest of things same no need to assign load and diaphragm because it ready to assign

Run Analysis

Result of Modal E

Modal Periods and frequencies

The modal participating mass ratio

Maximum story displacement EQx

Maximum story displacement EQy

MODAL-F

Save Modal E as Modal F (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal E in Column size are also changed

The entire column size is 600X600

Goto to set view options

Deselect beam and floor

Press Apply

Select entire column

Assign Column Size as C600X600(replacing C400x400)

Press Apply

In the previous select beams also doing right (Note: Be careful on selecting the frame and assign members)

Set view options

Select beams

Press Apply

Goto Define frame > Section property

Select B300X400

Press Apply

Now everything is applied already no need to apply or assign

Just goto run the Analysis

Result of Modal F

Modal Periods and Frequencies

Modal Participating mass ratios

Maximum Story displacement EQx

Maximum Story displacement EQy

MODAL-F

Save Modal E as Modal F (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Change as all column size is the same

Goto set view options

Deselect Beams and floor

Press Apply

Select all column

Goto Assign> Frame> section property> select C600X600

Everything is assigned already

just go Run Analysis

Run analysis

Result of Modal F

Modal periods and frequencies

Modal participating mass ratios

Maximum story displacement along EQx

Maximum story displacement along EQx

MODAL-G

Save Modal F as Modal G (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal E in Add 15 more stories and Column size are changed

Goto Edit grids and story

Select Modify story data

Add 15 Stories above Story 12

All story Similar to story 1

Press ok

Press ok

Goto set view options

Deselect beam and floors> press apply

Then goto set building view limits

Top story -story 25

Bottom story- Story-21

press ok

Select all column

Assign >frame> Section property

Select C400X400

Press Apply

Again goto set building view limits

Top Story - Story 20

Bottom story - Story 11

Press ok

Select all columns visible on the screen

Assign C600X600 to select the column

Press Apply

Again goto set building view limits

Top Story - Story 10

Bottom story - Base

Press ok

Goto Define >Frame > Add new property

Select rectangular section

Define Parameters

Property name- C800X800

Material -M30

Depth-800mm

Width-800mm

then Goto Modify rebar

Select Design type- column

Rebar material-both longitudinal and ties bars- HYSD415

Press ok

Press ok

Press ok

Select all columns visible on the screen

Goto Assign >Frame> Select C800x800> Press apply

Goto set view options

Select beam and floor

Press Apply

Goto to set building view limits

select show all

Press ok

Everything is Assign Live and wall load and Diaphragms are already

Just go to Run Analysis

Result of modal G

Modal periods and frequencies

Modal participating mass ratios

Maximum story dispalcement EQx

Maximum story dispalcement EQY

MODAL-H

Save Modal G as Modal H (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal H all columns are in the same size C800X800

Goto set view option

select beam and floor

press apply

Select all column

Goto Assign > frame > section property

Select C800X800
press ok

Everything is assigned already like live and dead load, diaphragms

Just Goto Run Analysis

Result of Modal H

Modal periods and frequencies

Modal Participating mass ratios

Maximum story displacement EQx

Maximum story displacement EQy

MODAL-J

Save Modal H as Modal J (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal J Impose load are increased by 10% of the previous live load

As we see on Floor 3kn/m2 live loads are applied

here we replace that load in 3.3kn/m2

Goto select by object type> Select Floors

Goto Assign > shell loads> uniform

Define load 3.3kn/m2

Select replace existing load

Press Apply

Everything is assigned already Like the wall load and Diaphragms, supports

Just go to Run Analysis

Result of Modal J

Modal periods and frequencies

The modal participating mass ratio

Maximum story displacement EQx

Maximum story displacement EQy

MODAL-K

Save Modal J as Modal K (simply make a copy) (Because Grids, Story Height, load cases, And other parameters are similar)

Changes in modal J Impose load are increased by 20% of the previous live load

Goto Select by slab property

select slab 150mm

Then go to assign uniform load -3.3 to 3.6kn/m2

Select Replace Existing loads

Press Apply

Everything is Already assigned like wall load, Diaphragms, Support

Just Goto Run Analysis

Result of Modal K

Modal periods and frequencies

Modal Participating Mass ratios

MaximumStory displacement EQx

MaximumStory displacement EQy

RESULT:-

1. Effect of stiffness on T: Compare fundamental natural periods of buildings E & F as well as G & H

Criteria	Model	Analysis result
Effect of stiffness on time period	Building E (10 Stories with varying column sizes)	1.73s
	Building F (10 Stories with Uniform column sizes)	1.73s
Effect of stiffness on time period	Building-G (25 stories with varying column sizes)	4.17s
	Building-H (25 stories with varying column sizes)	4.41s

Conclusion:- As we see in varying column sizes and uniform column sizes time periods are not very bigger differences. it is not any concerning point.

2. Effect of mass on T: Compare fundamental natural periods of buildings H, J, and K.

Criteria	Model	Analysis Result
Effect of mass on time period	Building-H (25 stories with 3KN/m^2 imposed load)	4.41s
	Building-J (25 stories with 3.3KN/m^2 imposed load)	4.42s
	Building-K (25 stories with 3.6KN/m^2 imposed load)	4.43s

Conclusion:- As we see changes in imposed load it will change periods of time will also change but the difference is not greater

3. Effect of Building Height on T: How do the fundamental natural periods of Buildings A, B, F, and H change with a change in building height

Criteria	Model	Analysis Result
Effect of building height on time period	Building-A (2 Storey)	0.5s
	Building-B (5 Storey)	1.03s
	Building-F (10 Storey)	1.73s
	Building-H (25 Storey)	4.41s

Conclusion:- As we see No of the story are increase the Time Period of the building also increases

4. Effect of Column Orientation on T: How do the fundamental natural periods of Buildings B, C, and D change with a change in column orientation

Criteria	Model	Analysis Result
Effect of column orientation on Time Period	Building-B (All floors column size 400X400)	1.03s
	Building-C (All floors column size 550X300) oriented in X-direction	1.145s
	Building-B (All floors column size 400X400) oriented in Y-direction	1.12s

Open-C

Goto Deformed shape

Select Mode 1

Press Apply

Deformation will goes along +y-direction

Select Mode-2

Press Apply

Deformation Comes in rotation form about z-axis

Open Model-D

Goto deformed shape

Select Mode-1

Press apply

Deformation goes along -ve X-direction

Select mode-2

Deflection goes to +ve X-direction

5. Effect of Flexural Stiffness of Structural Elements on mode shapes: Compare the fundamental mode shape of Building B in two situations when flexural stiffness of beams relative to that of adjoining columns is very small versus when it is large.

Effect of flexural stiffness of structural element on mode shapes.

Criteria	Model	Case	Analysis Result
Effect of flexural stiffness of structural element on mode shapes.	Building-B	Flexural Stiffness of beam close to nil (Zero inertia)	2.62s
		Full Flexural Stiffness of beam (Regular)	1.03s

Conclusion:- As we see Flexural stiffness of the beam becomes nil(only 10%) time period will be Greater than double the regular building.

Open Model-B

Goto Frame property

Select Beam B300X400

Goto Modify property

Then goto Modifier factor

Give Moment of inertia about 2 axes -0.1

and Moment of inertia about 3 axes -0.1

Press ok

Then go to Run Analysis

See the result

6. Effect of Axial Stiffness of Vertical Members on mode shapes: Compare the fundamental mode shape of Building H in two situations when the axial cross-sectional area of columns is very small versus when it is large.

Effect of axial stiffness of vertical members on mode shapes

Criteria	Model	Case	Analysis Result
Effect of axial stiffness of vertical members on mode shapes	Building-H	The axial cross-section for columns is close to nil(Zero axial areas)(10% assign)	5.99s
		Full Axial cross section for column(Regular)	4.41s

Open Model-H

Goto frame properties

select Column C800X800> select modify Property

Then Goto Modifier >

Give column section axis -0.1

Press ok

Press ok

Then Run analysis

7. Effect of Degree of Fixity at column bases on mode shape: Compare the fundamental mode shape of Building B in two situations when the base of columns is pinned versus when it is fixed

Effect of degree of Fixity at column base on mode shape

Criteria	Model	Case	Analysis result
Effect of degree of fixity at column base on mode shape	Building-B	Column Support pinned (Regular)	1.03s
		Columns support fixed	0.94s

Open model -B

Goto base story

select all column base

Goto restrain> select Fixed support > press ok

Then goto run the analysis