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# Types of Loads on Structure

## Types of Loads on Structure

The structure should be designed to safely bear the different types of applied loads & that structure should not face any kind of failure. For estimating the total load acting on the structure must be calculated before designing. There are different codes for calculating the total load.

• Indian standard code is: 875-1987.
• American standard code ASCE7: minimum design loads for building and other structures.

Loads have a tendency to cause stress, displacement, deformation in a structure which leads to failure in the structure or can cause structural problems.

Structural analysis means analysis of loads or to find/calculate the loads on the structure. It is a very important and major part of the designing of structure. A structure may be building, road, dam, spillway, bridge, culvert, retaining wall, etc. There are a lot of different types of loads that are applied on a structure. Some loads are permanent and some loads are temporary. Generally, the load is measured in “Newton”. Newton is represented by “N”.

### Types of Loads on structure:

The type of load that is applied on a structure in a vertical direction is called a vertical load. The vertical load is further classified into the following types:

The load that is constant in magnitude and fixed in location throughout the lifetime of the structure is called Dead Load. It is a permanent load and cannot be moved from the applied surface because it is a part of the structure itself.

It can be calculated with good accuracy from the design configuration, density of the material, and dimension of structure members. For example in a house or building, slabs, beams, floor & ceiling are included as dead loads. To find the total load, the “1.2” coefficient should be multiplying with the dead load. The equation for the total load is;

W = 1.2 (D.L) + 1.6 (L.L)

• L indicates the live load

For culverts and bridges, the dead loads are sidewalks, girder, curbs, wearing surface, and other suspended loads. Here is the list of materials with their density.

 S.No Material Density(Kg/m3) S.No Material Density(Kg/m3) 1 Water 1000 9 P.C.C concrete 2400 2 Steel 7850 10 R.C.C concrete 2500 3 Silt 2100 11 Ash white 670 4 Cement 1440 12 Ash black 540 5 Bamboo 300-400 13 Asphalt 721 6 Clay soil 1900 14 Cement mortar 2080 7 Sandstone 2000 15 Lime 640 8 Shale 2500

Let’s look into an example of how to find the dead load. For example, there is a beam of R.C.C & the density of R.C.C is 25 KN/m3 and the volume or dimension of the beam is 10 m3.

• V indicates the volume of the structure
• d indicates the density of the material

Live load is another type of vertical load. It can be defined as the load that is applied on a structure that is not fixed or permanent. It is a movable or moving load without any acceleration or impact. The live load cannot be calculated from the specific formula. Generally, it is assumed for a design. The minimum values of live loads to be assumed are given in IS 875 (part2) – 1987. It depends on the use of the structure.

The following table shows the values of live loads for the following occupancy classification:

• Apartment
• Assembly area
• Resident
• Libraries
• Hospitals
• Recreational area
• Balconies
• Corridors
• Manufacturing
• Office buildings
• Roofs
• Storage area above the ceiling
• Schools
• Stores
 S.No Occupancy Live Load (KN/m3) S.No Occupancy Live Load (KN/m3) 1 Apartments 7 School Office use 2.4 Classroom 1.9 Computer use 4.8 Corridor above First Floor 3.8 Armories and Drill Rooms 7.2 First Floor Corridor 4.8 2 Assembly Area Sidewalks, Vehicular Driveways, and Yards 12 Lobbies 4.8 8 Stores Movable Seats 4.8 First Floor 4.8 Platforms (Assembly) 4.8 Upper Floor 3.6 Stage Floors 7.2 Whole Sale, All Floors 6 Balconies 4.8 Yards and Terrace, Pedestrians 4.8 3 Corridor 9 Residential First Floor 4.8 One or Two Family 4 Hospitals Uninhabitable Attics without Storage 0.5 Operating Rooms, Laboratories 2.9 Uninhabitable Attics with Storage 1 Patient Room 1.9 Habitable Attics and Sleeping Area 1.4 Corridor above First Floor 3.8 Hotel and Multi Families Houses 5 Libraries Private Rooms and Corridors Serving them 1.9 Reading Room 2.9 Public Rooms and Corridors Serving them 4.8 Stake Room 7.2 Corridor above First Floor 3.8 6 Manufacturing Light 6 Heavy 12 Marquise and Canopies 3.6
• Garages having trucks and buses should be designed in accordance with an approved method that contains a provision for truck and bus loading.
• In buildings, the room’s height should not be exceeding than 2.3 meters. The nominal shelf depth should not be exceeding than 0.3 meters for each face.
• Live load for railway bridges specified by American Railway Engineering and Maintenance of Association (AREMA) has shown the manual of railway engineering.
• While for highway bridges the live loads are specified by the American Association of state highway and transportation official (AASHTO) in its LRFD bridge design specification.

In multistoried bridges, the live load is directly proportional. The code makes for the reduction of live load in designing structural members like a beam, column, shear wall, slabs, etc. The table shows the reduction of live load In percentage per floor.

 No of floors Reduction in live load in (%) 1 0 2 10 3 20 4 30 5_10 40 over 10 50

It is a type of vertical load in which the load may act on a structure as a result of topographic or weather conditions. Weather condition means temperature rise at a high level or low. The sudden rise and fall of temperature can also damage the structure.

It is the type of vertical load. The snow which is accumulated on structural member has a tendency to fail the structure or can cause the cracks. Snow loads are present only in snowfall places where snowfall occurs. For example, in hilly areas such as in China, Russia, Europe, Asia, India, and in Pakistan. The IS 875 (part 4) – 1987 deals with snow loads on roofs of the building.

The load applied on structure suddenly is known as impact load. Impact load is dangerous than a uniformly distributed load because the intensity of the impact load is more than a uniformly distributed load. If the value of the impact load is very high, it will directly fail & it won’t even give a chance for the structure to crack.

The load applied on structure in a horizontal direction. Horizontal loads are on the x-axis. This load is very effectual because most of the structure is design for vertical force. In this situation, if the horizontal load is applied on structure. The structure will directly fail. The types of horizontal load are given below:

The wind load is applied in the horizontal direction on the structure & it is caused by air. Wind load is not effectual for low story building or high rise building maximum up to five stories. These low rise buildings will not get damaged by wind load.

For the designer, the wind load should be kept in mind while designing the building because, for high rise buildings, the wind load is dangerous. It can damage the structure and also can fail the structure.

For calculating the wind load the details of codes are given in IS – 875 (part3) 1987. For designing the wind velocity v2 this equation must be used:

V2 = k1. k2. k3. Vb

Where

k1 = risk coefficient

k2 = coefficient based on height and structure size

k3 = Topography factor

Above the 30m height, Wind pressure is increased. To calculating the wind load two components should be kept in mind.

• Velocity of wind
• Size or height of the building