RATIONAL ANALYSIS AND DESIGN OF HIGH RISE BUILDING WITH SOFT STOREY

ABSTRACT:

The buildings with soft storey are very vulnerable under lateral loads and that creates disasters. One of the major problems in present days is severe shortage of parking space in multistorey buildings. Due to accommodation of vehicles and their movements at ground levels infill walls are generally avoided, which creates soft storey effect. It should be noted that 70 to 80 % of buildings of urban areas in India fall under the classification of soft storey according to IS 1893 (2002) Part-I.

For proper assessment of the storey stiffness of such buildings, considerations of infill walls with moment resisting frame is essential. Evaluation of the storey stiffness of high rise building considering various models like bare frame, bare frame with tie beams, frame with infills and frame with infills and tie beams is presented in this paper.

The attempts are made to enhance the stiffness of soft storey considering functional requirements of that storey. Various options like (1) provision of infill walls in soft storey region (2) provision of squat wall in soft storey region (3) provision of shear wall at proper location in building are studied.

Introduction of Soft Storey:

Soft-Storey:-
Generally, the building in which the ground storey consists of open space for parking is called as stilt building and the parking storey is called as stilt Floor or Soft-Storey. When sudden change of stiffness takes place along the building height, the storey of which the drastic reduction of stiffness is observed is called a soft storey.

As per IS 1893 - 2002 (part I)
A Soft Storey is one in which the lateral stiffness is less than 70 percent of that in the storey above or less than 80 percent of the average lateral stiffness of the three storeys above.
Extreme Soft Storey:-
An extreme soft storey is one in which the lateral stiffness is less than 60 percent of that in the storey above or less than 70 percent of the average stiffness of the three storeys above. For example, buildings on STILTS will fall under this category.


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