19.1 General
In structural design, account shall be taken of the dead, imposed and wind loads and forces such as those caused by earthquake, and effects due to shrinkage, creep, temperature, etc, where applicable.
19.2 Dead Loads
Dead loads shall be calculated on the basis of unit weights which shall be established taking into consideration the materials specified for construction.
19.2.1
Alternatively, the dead loads may be calculated on the basis of unit weights of materials given in IS 875 (Part 1). Unless more accurate calculations are warranted, the unit weights of plain concrete and reinforced concrete made with sand and gravel or crushed natural stone aggregate may be taken as 24 kN/m³ and 25 kN/m³ respectively.
19.3 Imposed Loads, Wind Loads and Snow Loads
Imposed loads, wind loads and snow loads shall be assumed in accordance with IS 875 (Part 2), IS 875 (Part 3) and IS 875 (Part 4) respectively.
19.4 Earthquake Forces
The earthquake forces shall be calculated in accordance with IS 1893.
19.5 Shrinkage, Creep and Temperature Effects
If the effects of shrinkage, creep and temperature are liable to affect materially the safety and serviceability of the structure, these shall be taken into account in the calculations (see 6.2.4, 6.2.5 and 6.2.6) and IS 875 (Part 5).
19.5.1
In ordinary buildings, such as low rise dwellings whose lateral dimension do not exceed 45 m, the
effects due to temperature fluctuations and shrinkage and creep can be ignored in design calculations.
19.6 Other Forces and Effects
In addition, account shall be taken of the following forces and effects if they are liable to affect materially the safety and serviceability of the structure:
- a) Foundation movement (see IS 1904),
- b) Elastic axial shortening,
- c) Soil and fluid pressures [see IS 875 (Part 5)],
- d) Vibration,
- e) Fatigue, f) Impact [ [see IS 875 (Part 5)],
- g) Erection loads [see IS 875 (Part 2)], and
- h) Stress concentration effect due to point load and the like.
19.7 Combination of Loads
The combination of loads shall be as given in IS 875 (Part 5).
19.8 Dead Load Counteracting Other Loads and Forces
When dead load counteracts the effects due to other loads and forces in structural member or joint, special care shall be exercised by the designer to ensure adequate safety for possible stress reversal.
19.9 Design Load
Design load is the load to be taken for use in the appropriate method of design; it is the characteristic load in case of working stress method and characteristic load with appropriate partial safety factors for limit state design.