3 Important Types of Loads on Foundations – Building and Other Structure
Anything that is built with walls and roofs is termed as building and society requires the building for various activities ,but before construction of a building you need to know the loads which impact a lot on the buildings,
So today in this article we discuss in a details the 3 Important types of loads on foundation – Building and Other Structure.
Following are the 3 Important types of loads on foundations – building and other structure
1). Dead Load
2). Live load
3). Wind load
1). Dead Load :-
Dead load is 1st type of Loads on Foundation ,the load of the materials used for the various components Of a building such as walls,floors,roofs etc. All permanent loads are thus included in that loads. Sometimes the provision for the future construction of a partition wall is made by allowing a dead load of 0.10 KN/m 2 of the floor area.
it should be seen that the dead load of partitions constructed in future under this provision does not exceed the allowance made.
Table 1.2 ,
So the weights of some of the common materials used in the construction of a building.It should be noted that these weights are for solid materials and suitable allowance should be made for broken materials depending upon the percentage of voids.The weight of green timber is about 20 % to 50% more than the weight of the dry timer.
Weights of various materials
|11||Dry River Sand||26.19|
|19||Plaster , Cement||20.40|
|20||Plaster , Lime||18.84|
|25||Teak Wood||6.57 to 8.14|
|2||Plain Concrete||18.84 to 23.54|
|1||Asbestos cement Sheet||0.17|
|2||Corrugated galvanised Iron Sheet||0.98|
|3||Doors with Frames||0.38|
|4||Double Country tiles with battens||1.15|
|5||Floor Finish||0.57 to 0.86|
|6||Jack arch roofs||7.18|
|7||Manglore tiles with battens||0.67|
|8||Window with Frame||0.28|
So, these are the weight of various materials which impact on Types of Loads on Foundations – Building and Other Structure
2). Live Load :-
Live load is the 2nd Loads on Foundation . This is the movable load on the floor and hence it is variable. It is also sometimes known as Super-Imposed load.It includes the load of persons standing on a floor,articles of furniture,Weight of materials temporarily stored on a floor, weight of snow on a Roof,etc.
For the purpose of design ,the live load is converted into equivalent dead load.
table 1.3 gives the values of equivalent dead load for floors of different types of buildings.Further,A percentage reduction is applied in the design of piers,Columns,walls,and foundations of a multi story building as shown in table 1.4.
This reduction is not applied for factories ,ware houses,garage,stores etc which are designed for a live load less than 5 KN per m 2.
|No.||Type Of Building||
Minimum equivalent dead load on the floor
|Kg/m 2||k N/m 2|
|1||Residential buildings, hospital rooms and wards and hotel bedrooms.||250||2.50|
|2||Office buildings, churches, school buildings, art galleries, stairs in residential buildings, retail shops and light garages.||400||4.00|
|3||Public buildings, assembly halls, dance halls,theaters, cinemas,restaurants, gymnasiums, stairs in public buildings cafes and light workshops.||500||5.00|
Heavy workshops, printing presses and factories.
|5||Warehouses, books stores, stationery stores and heavy garages.||1000||10.00|
REDUCTION OF SUPER IMPOSED LOADS
Position of Floor
|1||Topmost Story||No reduction|
|2||Next Story from Topmost Story||10|
|3||Next Story below 2||20|
|4||Next Story below 3||30|
|5||Next Story below 4||40|
|6||All Subsequent Story||50|
The Roofs are also subjected to the live loads.The flat roofs of buildings likely to be used for incidental assembly
should be designed for a minimum load of 400 kg/m 2 or 4 k N/m 2 or heavier , if required.
The sloping and curved roofs should be designed for snow loads and rainwater loads.The actual loads due to snow will depend upon the shape of roofs and its capacity to retain the snow.
The rainwater load will depend on the shape of roof,drainage system provided,Chances of water to accumulate,etc.
3). Wind Load :-
In Case of tall Buildings, the effect due to wind should be considered.The exposed sides and roofs of such buildings are subjected to wind pressure and its effect is to reduce the pressure on foundation on the windward side and to increase the pressure on the foundation on the leeward side.The slopes of the roofs on the windward direction is known as the windward slope while the slope of the other side of wind direction is known as leeward slope.
Following points should be noted in the construction……..
(i). The wind pressure will depend on the velocity of the wind,location of structure and various other local meteorological data.In absence of any other data,the following relationship may be adopted:-
P = kV2
Where P = Wind pressure in kg/m 2
V = Velocity of wind in km p.h.
K = Coefficient whose value depends on various factors such as wind
speed, temperature of air,shape of structure,etc.
The value of coefficient k has been taken as 0.006 by the NBC for the preparation of wind pressure maps.The reference to these maps should be made for detailed study of wind load.It may be noted that these maps and the associate charts give the variation in wind pressure and height.
(ii). If the height of building is less than twice its effective width and further, if a building is sufficiently stiffened in addition by cross walls, floor slabs,etc.the wind pressure may be neglected.
(iii). If the amount of bearing pressure due to wind only is less than 25 % of that due to dead loads and live loads,the wind pressure may be neglected in the design.
In case where the ration exceed 25%,the design of foundation made in such a way that the bearing pressure due to combined effects of live loads,dead and wind loads does not exceed the allowable bearing pressure by more than 25 per cent.
(iv). The effect of wind pressure on a pitched roof depend on the angle of inclination and its value are worked out by referring to the relevant code of BIS.
(v). The provision for the wind pressure should be made according to the prevailing by – laws in the locality where the building to be constructed. Usually all such by-laws mentioned a wind pressure of 1 KN/m 2 in any horizontal direction for the design purposes.
For roofs inclined at an angle greater than 20 degrees with the horizontal,the wind pressure is taken as 1 k N/m 2 acting inwards in a normal direction on the wind wards side and as 0.5 KN/m 2 acting outwards in a normal direction on the leewards side.The stress due to wind pressure in case of inclined roofs are worked out separately with or without suction.
(vi). The term winds denote almost exclusively the horizontal wind and hence the wind pressure acts horizontally on the exposed vertical surfaces of the walls,Columns,etc.and inclined roof of the structure.
For Structures of various plan shapes other than rectangular plan shape, it becomes necessary to apply the shape factor to the value of wind pressure (P) . Table 1.5 gives the shape factor to be adopted for different plans shapes of the structures.
PLAN SHAPE FACTOR
|No||Plan Shape of Structure||Shape Factor with respect to ratio of height to the base width|
|0 – 4||4 – 8||Over 8|
|3||Square ( wind perpendicular to diagonal )||0.8||0.9||1.0|
|4||Square ( wind perpendicular to face)||1.0||1.15||1.3|
So,Basically these are the 3 important Types of Loads on Foundations – Building and Other Structure.
Thanks for your Great Attention
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Happy Learning 😆
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