Project 1_Comparative study of different storey buildings for Seismic forces

Aim: To model and analysis the building from A to K with given structure specification and to compare the analysis result.

Model A:

2 story building with the column dimension 400x400

Model B:

5 story building with the column dimension 400x400

Model C:

Bunchmark building with rectangle column oriented along X direction with column dimension of 550x300

Model D:

Bunchmark building with rectangle column oriented along X direction with column dimension of 300x550

Model E:

10 story building with varying column size along the building height

Upper 5 story column dimension 400x400

Bottom 5 story column dimension 600x600

Model G:

25 story building with varying column size along the building height

Upper 5 story 400x400

Middle 10 story 600x600

Bottom 5 story 800x800

Model H:

25 story building with all the columns dimension 800x800

Model J:

25 story building with imposed load mass 10% larger then building H

Model K:

25 story building with imposed load mass 20% larger then building H

Result:

Effect of stiffness on time period:

Building E (10 story with the varying column size): 1.20 s

Building F (10 story with the uniform column size): 1.25 s

Effect of stiffness on time period:

Building G (25 story with the varying column size): 2.99 s

Building H (25 story with the uniform column size): 3.37 s

Time period is directly proportional to mass of the system. So while increasing the mass of the story, it relatively increases the time period of the structure. As we know time period formula.

Effect of mass on time period:

Building H (25 story building with all the 3 KN imposed load): 3.37 s

Building J (25 story building with imposed load mass 10% larger 3.3 KN ): 3.37 s

Building K (25 story building with imposed load mass 20% larger 3.6 KN):3.37 s

Effect of building height on time period:

Building A (2 story): 0.28 s

Building B (5 story): 0.72 s

Building F (10 story): 1.25 s

Building H (25 story): 3.37 s

Time period will increase with respect to increase in height of the building

Effect of column orientation on time period:

Building B (All floor column size are 400x400): 0.72 s

Building C (All floor column size 550x300 oriented in x direction): 0.78 s

Building D (All floor column size 300x550 oriented in Y direction): 0.77 s

Effect of Flexural Stiffness of Structural Elements on mode shapes:

Building B:

Flexural stiffness of the beams (Regular): 0.72 s

Flexural stiffness of the beams close to nil (zero inertia) :1.80 s

Effect of Axial Stiffness of Vertical Members on mode shapes:

Building H:

Axial cross section for the column in close to nil (zero axial area): 4.56 s

Axial cross section for the column (Regular):3.37 s

Effect of Degree of Fixity at column bases on mode shape:

Column support pinned (regular):0.72 s

Column support fixed : 0.65 s

Conclusion:

All the Etabs models with the different structural configuration are analysis and compared