6 Storied Building

Problem Statement:

A six storey building for a commercial complex has plan dimensions as shown in Figure 

1. The building is located in seismic zone III on a site with medium soil. Design the building for seismic loads as per IS 1893 (Part 1): 2002.

General 1. The example building consists of the main block and a service block connected by expansion joint and is therefore structurally separated (Figure 1). Analysis and design for main block is to be performed. 

2 The building will be used for exhibitions, as an art gallery or show room, etc., so that there are no walls inside the building. Only external walls 230 mm thick with 12 mm plaster on both sides are considered. For simplicity in analysis, no balconies are used in the building. 

3. At ground floor, slabs are not provided and the floor will directly rest on ground. Therefore, only ground beams passing through columns are provided as tie beams. The floor beams are thus absent in the ground floor. 4. Secondary floor beams are so arranged that they act as simply supported beams and that maximum number of main beams get flanged beam effect.

5. The main beams rest centrally on columns to avoid local eccentricity. 6. For all structural elements, M25 grade concrete will be used. However, higher M30 grade concrete is used for central columns up to plinth, in ground floor and in the first floor.

7. Sizes of all columns in upper floors are kept the same; however, for columns up to plinth, sizes are increased. 8. The floor diaphragms are assumed to be rigid. 9. Centre-line dimensions are followed for analysis and design. In practice, it is advisable to consider finite size joint width.

10. Preliminary sizes of structural components are assumed by experience. 11. For analysis purpose, the beams are assumed to be rectangular so as to distribute slightly larger moment in columns. In practice a beam that fulfils requirement of flanged section in design, behaves in between a rectangular and a flanged section for moment distribution.

12. In Figure 1(b), tie is shown connecting the footings. This is optional in zones II and III; however, it is mandatory in zones IV and V. 13. Seismic loads will be considered acting in the horizontal direction (along either of the two principal directions) and not along the vertical direction, since it is not considered to be significant. 14. All dimensions are in mm, unless specified otherwise.