Project 1_Comparative study of different storey buildings for Seismic forces

To analyze the 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 changes in mass?

Aim:

To Compare. fundamental natural. periods of buildings H, J, and K. using ETABS

Procedure:

Building H:

Step 1:

1) Click the Define tab and click section properties

2) Select Add new property and choose Rectangular

3) Add the new column dimension of 800 x 800

4) click ok

• Click, the Select tab and select the columns
• Click the Assigned tab and choose frame assignment as 800 x 800 dimension column
• Click ok

• After assigning loads of each frame run the analysis
• Click Display and choose the show table option
• The modal participating ratio from Structural output and then click ok

Building J:

• Click, the Edit tab and choose edit story
• Add 25 stories and make 1st story Master and all others similar to 1st story
• Click ok

• Click, the Select tab and select the columns
• Click, the assigned tab and choose frame assignment as an 800 x 800 dimension column
• Click ok

• Click the Select tab and choose Slab
• Click the Assigned tab and choose shell loads then uniform load
• Make live load and load pattern name and input 3.3kn/sq.m for load value
• Click Ok

• Click, the Select tab and choose beams
• Click, the assigned tab and choose frame loads then distribute
• Make, wall load as input 10kn/sq.m for load value
• Click Ok

• After. assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select the Modal participating ratio from the Structural output
• Click ok

Building K:

• Click, the select tab and assign the column dimensions as 800 x 800
• Click, the Select tab and choose floors
• Click, the assigned tab and choose shell loads then uniform load
• Make live load and load pattern name and input 3.6 kN/sq.m for load value
• Click Ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select, Modal participating ratio from the Structural output
• Click ok

Conclusion:

1) For building H, J, and K are the same 25 stories but the load increases gradually like 10% and 20%, because of this the building becomes more

Flexible due to an increase in the weight of the building.

2) time period of H is 4.122, j is 4.137 and k is 4.176.

Comparison 2:

Building A:

• Click the Edit tab and choose edit story
• Add 2 stories and make 1st story Master and all others similar to 1st story
• Click ok

• Click, the Select tab and select the columns
• Click, the assigned tab and choose frame assignment as a 400 x 400 dimension column
• Click ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select the Modal participating ratio from the Structural output
• Click ok

Building B:

1) Click the Edit tab, choose edit story, or use the replicate command.

2) Add 5 stories and make 1st story Master and all others similar to 1st story

3) Click ok

• Click, the Select tab and select the beam and slab
• Click, the assigned tab and choose frame assignment as a 300 x 400 dimension of the beam, and slab one by one after that assign the load

• Click, the select tab and assign the beam dimensions as 300 x 400
• Click, the Select tab and choose floors
• Click, the assigned tab and choose shell loads then uniform load
• Make live load and load pattern name and input 3 kN/sq.m for load value and brick wall load as 10 kN/sq.m
• Click Ok

• After assigning loads of each frame run the analysis
• Click Display and choose the show table option
• Select the Modal participating ratio from the Structural output
• Click ok

Building F:

• Click the Select tab and select the columns
• Click the Assigned tab and choose frame assignment as a 600 x 600 dimension column
• Click ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select the Modal participating ratio from the Structural output
• Click ok

Result:-

Due to the changing in building height the fundamental natural period varies gradually i.e... for A is 76.31% at 0.4, for B is 78% at 0.92, for F is 77% at 0.1.685 and finally for H is 76% is 3.95.

Comparison 3:

Building C:

• Click, the Select tab and select the columns
• Click, assign tab and choose frame assignment as a 550 x 300 dimension column
• Click, ok

• After, assigning loads of each frame run the analysis
• Click Display and choose the show table option
• Select the Modal participating ratio from the Structural output
• click, ok

Building D:

• Click, the Select tab and select the columns
• Click, assign tab and choose frame assignment as a 300 x 550 dimension column
• Click, ok

• Select, the column object
• Click, the Assign tab and choose frame sections then local axes
• Select, the rotation angle and enter the degree of 90
• Click, Ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select, the Modal participating ratio from the Structural output
• Click, ok

Result:-

Due to changing orientation, the fundamental of the natural period varies each building i.e. for C is 0.823 and for D is 1.032 then for B is 0.823

Comparison 4:

For Building E:

• Click, the Edit tab and choose edit story
• Add 10 stories and make 1st story Master and all others similar to 1st story
• Click, ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select, the Modal participating ratio from Structural output
• click, ok

Building G:

• Click the Edit tab and choose edit story
• Add 25 story and make 1st story, 11th story and 21st story as Master and all other as similar to 1st, 11th, 21st story
• Click ok

• Click, the Select tab and select the columns of the 11th story ( make sure story selection must be in similar story mode)
• Click, assign tab and choose frame assignment as a 600 x 600 dimension column
• Click, ok

• Click, Select the tab and select the columns
• Click, assign tab and choose frame assignment as a 400 x 400 dimension column
• Click, ok

• After, assigning loads of each frame run the analysis
• Click, Display and choose the show table option
• Select, the Modal participating ratio from the Structural output
• Click, ok

Result:-

When comparing these buildings there is a significant difference due to different column sizes. The fundamental period of building E is 1.583 and for F is 1.685. similarly for building G is 3.894 and for building, H is 3.95.