Project-1Fundamental natural periods of buildings

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:

• The column size increases both stiffness and mass of building.When the column size is increase mass of the building is increase,the natural periods reduces,increase in column size
• Buildind E&F are 10storey building with different column size along the column size pf building F is (600x600) fill height,E has a samller column size(400x400) in the upper storey.
• The relative stiffness of building E is small then the building F,when the column size is same efffect on overall natural period is not changed.
• Then building G&H is stiffer.The increasing stiffness the mass is also increased at natural period will increase or decrease when both are changed.

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:

• The increase the mass of building it increase the natural period.Buildings H<,J and K 25 storey same plan and same column size.
• The floors are in different mass.
• Imposed floor mass of building H and that building J and K are 10%and 20% larger respectively.
• Where the Natural period of K and J are larger than building H

3.Effect of mass on T:The fundamental natural periods of buildings A,B,F and H.change with the change in buildings height:

• The height of the building is increase mass of the building and stiffness of the building will be decreases.
• The natural period of the buiding increase with increase height The plan A,B,F,H have different height.
• The tallest building of 25storey are larger natural period compared to other 10storey and 5 storey and 2storey building.

4.Effect of Column orientation on T:The fundamental natural periods of buildings B,C and D.change with the change in Column orientation:

• The column orientation for rectangular farme structure in column along in two directions.
• The orientation of building is change natural period of building will be change.
• The rectangular column orientation is along X-direction and Y-direction,the longer side of the section has a large natural period.
• The cross section of the column orientation where there is a large natural period is large the orientation of column is small the natural period is small.

Efffect of Axial stiffness of vertical members on mode shape:

• When fundamental mode shape of the building H is axial cross-section of column is very small
• The mode shape is perfomance by a axial member of column ans structural wall.
• The axial deformation of this building the fundamental mode shape is change shear type to the flextural type particular in the large storey building.
• The flexural has not apperar purely because of the axial load is large and the member of column is small through the column size is varie.

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

• The rotational fexbility of column is base of building.The building has be design sand detailied rotatioan at these base.
• The Footing of column base sholud be allow the rotation in hinged position.
• The soil condtion and rocky has good fixed they be used column fixity at overall base of the building.
• The rotational fixity of column is restict the rotational in the base and it behave the flexural near the base.