It is to serve this purpose that IS 1893 : 1962 ‘Recommendations for earthquake resistant design of structures’ was published and revised first time in 1966. In the clauses for design of multi-storeyed buildings, the coefficient of flexibility was given in the form of a curve with respect to period of buildings.

As per IS 1893, Storey drift shall not exceed 0.004 times storey height. If it is exceeded, then how to minimize it for multi storied building.

The allowable drift limits of seismic force-resisting systems are much higher than those permitted for wind force resisting systems. The allowable drift limit for certain seismic systems is about 10 times the drift allowed under wind loading.

IBC sets the maximum drift for normal buildings at between 0.7% and 2.5% of storey height, while Eurocode 8 specifies between 1% and 1.5%.

STORY DRIFT is the lateral displacement of one level relative to the level above or below. STORY DRIFT RATIO is the story drift divided by the story height.

The drift ratio is defined as the ratio of maximum lateral drift to total height of the specimen. The procedure developed by Priestley [4] relies on the ductility ratio (∆ult/∆yield) to calculate the reduction in shear strength that occurs under cyclic loading and lateral drift increase.

Drift shall be caused by the accumulated deformations of each member, such as a beam, column and shear wall. lateral forces due to wind or seismic loading must be considered for tall building design along with gravity forces vertical loads.

The service level wind load is based on a 10-year MRI, instead of a 50-year MRI, which is used to determine the nominal load. The 0.7 factor is approximately equal to the square of the assumed ratio of the 10-year MRI wind speed and the 50-year MRI wind speed.

First, the definitions: Lateral (story) drift is the amount of sidesway between two adjacent stories of a building caused by lateral (wind and seismic) loads (Fig. 11.1). Horizontal deflection of a wall refers to its horizontal movement between supports under wind or earthquake loading.

Storey drift is the lateral displacement of a floor relative to the floor below, and the storey drift ratio is the storey drift divided by the storey height. You can obtain graphs showing the height-wise distribution of displacement, storey drift and storey drift ratio.

Check Design Story Drift: The allowable story drift can be found from Table 12.12-1 of ASCE 7-10 as shown on the figure below. The allowable story drift should be greater than or equal to the design story drifts for each floor level.

7.11.1Storey Drift Limitation The storey drift in any storey due to the minimum specified design lateral force, with partial load factor of 1.0. shallnot exceed0.004 times the storey height, For the purposes of displacement requirements only (see 7.11.1,7.11.2 and

The only way for a design to be in conformance with these wind or seismic requirements is for the designer to check building drift and ensure that the components within the lateral force-resisting system are all compatible and do not exceed the allowable drift.

For seismic load applications, section 12.12.1 of ASCE7-10 states that the design story drift of the structure shall not exceed the allowable drift listed in table 12.12-1. For light-frame buildings, the maximum permitted drift is 2.5% of the story height.