Load Calculations | Design of Buildings
In our earlier article, we discussed “Different types of loads” and their importance in Structural design.
Now we will move on with our further discussion on the following points:
- Design principle assumption and notation assumed
- Design Constant
- Assumptions regarding Design
- Loads on Beams
- Loads on slabs
Design principle assumption and notation assumed:
The notations adopted throughout are same as given in IS:456:2000
Density of material used in accordance with reference to IS:857-1987s
| Sr.no | Material | Density |
| 1 | Plain concrete | 24 KN/m3 |
| 2 | Reinforced cement concrete | 25 KN/m3 |
| 3 | Flooring material (cement mortar) | 1.00 KN/m3 |
| 4 | Brick masonry | 19 KN/m3 |
Design constant
Using M20 and Fe415 grade of concrete and steel respectively for columns and footings
Therefore:
Fck – i. e. Characteristic strength for M15 – 15 N/mm2
Fck – i. e. Characteristic strength for M15 – 15 N/mm2
Fck – i. e. Characteristic strength for M20 – 20 N/mm2
Fy – i. e. Characteristic strength for steel – 415 N/mm2
Assumption regarding Design
- Slab is assumed to be continuous over interior support and partial fixed on the edge, due to monolithic construction of walls over it.
- Beams are assumed to be continuous over interior support and they frame in to the column at the ends.
Load on Beams
Description of load of slab on beam
The load of slab is dispersed on to the supporting beams in accordance with clause 23.5 of IS:456-1978, which states that the load on beams supporting solid spans, spacing in two directions at right angles and supporting uniformly distributed loads.
Self weight of beams
This load acts on the beams as a UDL, this is calculated after assuming the suitable cross section (by stiffness/deflection consideration) of the beam.
Load due to brick masonry wall
In a framed structure, brick masonry are used to construct curtain walls. They do not carry or transfer any load. Hence, the masonry walls do not have to thick.
Point load from intersecting beam
If there is any beam meeting the beam then the load of that beam is considered as point load.
Loads on slabs
Three types of loads are to be considered for the design of slabs:
- Dead load of the slab
- Live load of the slab
- Floor finish load
Dead load of the slab
Self weight of slab acts:
This load acts as UDL, this is calculated after assuming the 1m wide square strip and suitable thickness consideration.
Floor finish load
This load also acts as UDL and this is calculated after assuming suitable intensity over 1m wide strip.
Live load on the slab
This is the temporary load on its intensity depends on type and occupancy of building.
The intensity can vary with the type of building.