In this Article:
Learn Types of loads on R.C.C. Structures, Dead loads, Live loads or imposed loads, Wind loads, Snow Loads,Earthquake loads.
TYPES OF LOADS ON R.C.C. STRUCTURES
Structures are designed to withstand various types of loads. The various types of loads expected on a structure are as follows :
(i) Dead loads
(ii) Live loads or imposed loads
(iii) Wind loads
(iv) Snow loads
(v) Earthquake loads
Dead loads are due to self weight of the structure. Dead loads are the permanent loads which are always present. Dead loads depends upon the unit weight of the material. Dead loads includes, the self weight of walls, floors beams, columns etc. and also the permanent fixtures present in the structure.
The unit weight of commonly used building materials are given in the code IS 875 (part-I)-1987. The unit weights of important building materials are given in Table 1.11.
Unit Weights of Common Building Materials
|S.No.||Material||Unit Weight kN/m3|
|1.||Plain Cement Concrete||24|
|2.||Reinforced Cement Concrete Steel||25|
|4.||Brick Masonry (Cement Plaster)||20|
|5.||Stone Masonry Granite||24|
|6.||Asbestos Cement Sheets||0.13|
(i) Ordinary Portland
(ii) Rapid Hardening
|9.||Mortar (i) Cement
|12.||Timber (i) Chir
|14.||Surkhi (Brick dust)||9.9|
Live loads on floors and roofs consists of all the loads which are temporarily placed on the structure, For example, loads of people, furniture, machines etc. Live loads keep on changing from time to time. Live loads are also called as imposed loads. Various types of imposed loads coming on the structure are given in IS 875 (Part-2): 1987. The imposed loads depend upon the use of building. Some of the important values of live loads are given in Table 1.12.
TABLE 1.12. Minimum Live Loads to be Considered
|1.||Bath rooms and toilets in all types of building||2 kN/m2|
|2.||Living and bed rooms||2 kN/m2|
|3.||Office rooms in :
(i) Hostels, hotels, hospitals and business building with separate store
(ii) In assembly buildings
|4.||Kitchens in : (i) Dwelling houses
(ii) Hostels, hotels and hospitals
|5.||Banking halls, class rooms, X-ray rooms, operation rooms||3 kN/m2|
|6.||Dining rooms in : (i) educational buildings, institutional and mercantine buildings
(ii) Hostels and hotels
|7.||Corridors, passages, stair cases in:
(i) Dwelling houses, hostels and hotels
(ii) Educational institutional and assembly building
(iii) Marcantine buildings
|8.||Reading rooms in libraries :
(i) With separate storage
(ii) Without separate storage
|9.||Assembly areas in assembly buildings :
(i) With fixed seats
(ii) Without fixed seats
|10.||Store rooms in educational buildings||5 kN/m2|
|11.||Store room in libraries||6 kN/m2 for a height of 2.24+2 kN/m2 for every 1 m additional height|
|12.||Boiler rooms and plant rooms in :
(i) Hostels, hotels, hospitals, mercantine and industrial buildings
(ii) Assembly and storage buildings
|13.||Roof loads (Flat, sloping with slopes upto 10 degrees):
(i) Access provided
(ii) Access not provided
|14.||Sloping roof with slope greater than 10 degree||For purlins – 0.75 kN/m2 less 0.02 kN/m2 for every degree increase in slope over 10 degrees|
The force exerted by the horizontal component of wind is to be considered in the design of building. Wind loads depends upon the velocity of wind, shape and size of the building. The method of calculating wind loads on structure is given in IS 875 (Part-3):1987.
The building which are located in the regions where snowfall is very common, are to be designed for snow loads. The code IS 875 (Part-4):1987 deals with snow loads on roofs of the building.
Earthquake loads depend upon the place where the building is located. As per IS 1893-2002 (Part-I) (General Provisions for Buildings), India is divided into four seismic zones. The code gives recommendations for earthquake resistant design of structures. Now, it is mandatory to follow these recommendations for design of structures.