Structural analysis and design of a multistoreyed building with grid slabs

Published on 16 Apr 2022. Written by Nidhi Tiwari

In case when there is a requirement of a structure with a large span without any intermediate column, most engineers resort to the use of grid slabs. Grid slabs are used in many constructions like halls, auditoriums, showrooms, etc.

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The Grid system is constructed by placing beams which cross each other or are perpendicular directions and are monolithic with the slab. These grid frames can support the load of bridges, water tanks, overlying building stories, etc.

The various types of grids commonly used in India and abroad are:

1. Structure Grid – The floor is designed as one integral slab which spans the floor in two directions and is supported by two rectilinear grids of beams.
2. Skewed Structure – If the overall structure of a grid does not appear as a square or a rectangle, it is called a skewed grid.
3. Curved Grid – These grids cover great spans very efficiently giving an overall appearance of a curved surface.

Grids are so popularly employed as they are very efficient in transferring concentrated loads and the entire structure shares the load. If plain beams are used in place of a grid, the depth of the beams will be a great problem to deal with. Grid slabs reduce the depth to span ratio to a great extent. And thus, they also reduce the cost of construction to a good extent. Grid slab is also capable of holding a greater amount of load compared with conventional concrete slabs.

In this project, you will design a multi-storeyed building with grid slabs and do the analysis for both lateral and gravity loads. The results of the analysis can be studied in comparison to a flat slab.

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Project Implementation:

1. As the first step to this project, you need to know the various structural and non-structural components of a building. The structural components like walls, moment-resisting frames, columns, beams, etc. Once you are aware of the various components of the building, you need to specify parameters like the number of storeys, span length, floor to floor height, grid system, etc.
2. The next step includes designing the model of the building on ETABS. On the software, you need to enter the required parameters and prepare the model.
3. Once your model is ready, you need to consider the various forces acting on the given building. The various fundamental loads acting on the structure are :

• Dead load
• Live load
• Wind load
• Snow load
• Earthquake load
• Special loads

There can be other loads on the system according to different IS specifications for various conditions.

4. After knowing the forces, the analysis of the structure has to be done for various values of the above-mentioned parameters and different values of the acting loads.

There are various methods of analysis of any structure. However, you can use the stiffness method or displacement method of structural analysis as it requires minimum input and is much less complex.

5. For the analysis of the structure, you need to study the various factors that can cause deformation on the building under imposed loads. These factors commonly are storey drift, shear force, Storey shear, movement of centre of mass, etc.

Conclusion:

After having done the analysis of the above factors in a structure containing grid slabs, you can compare the results with that of a structure with flat slabs. You can now design a building with a d.l90rproper grid system which will be most suitable in that given situation.

SLDYK
Kit required to develop Structural analysis and design of a multistoreyed building with grid slabs:

• ETABS

Technologies you will learn by working on Structural analysis and design of a multistoreyed building with grid slabs:

• Civil Engineering
• ETABS

Any Questions?