Types of Loads on Structures

By Aina Parasher|Updated : October 4th, 2022

Various types of loads on a structure can cause stress or deformation in the structure. This causes structural issues and even structural failure. Determining the overall load on structures is a crucial and complicated process in structural design.

To determine the total load on structures, different types of loads acting on the structure and their combination is one of the important parameters that need to be understood. In this article, we will discuss various types of loads in Civil Engineering and their design considerations.

Table of Content

Different Types of Loads in Civil Engineering

Any structure must be created to be sufficiently strong to support any type of load at any moment during its expected lifetime. IS: 875–1987 is the Indian Standard Code that gives design considerations for various types of loads acting on a structure. These different types of loads have been listed below:

  1. Dead Loads
  2. Imposed Loads
  3. Wind Loads
  4. Snow Loads
  5. Earthquake Loads
  6. Other Loads

Types of Loads- Dead Loads (DL)

Dead loads are those types of loads that are permanent or immobile and are applied to a structure over its entire lifetime. Dead load is generally caused by the own weight of structural elements such as walls, roofs, beams, columns, etc., stationary equipment, and the weight of various materials.

The volume of each element is multiplied by the unit weight of the material used for that element to determine the dead loads for each structure. Unit weight of some of the materials commonly used in construction has been listed below:

Materials

Unit Weight

Brickwork

19 kN/m3

Timber

6 - 8 kN/m3

Plain cement concrete (PCC)

24 kN/m3

Reinforced cement concrete

25 kN/m3

Steel

78.5 kN/m3

Types of Loads- Imposed Loads (IL) or Live Loads (LL)

Imposed or live loads are those types of loads that change with time. Live loads consist of moving loads or movable loads such as the weight of the furniture, people occupying the floor etc. The designer appropriately assumes these types of loads. The minimum value of live loads for some of the important types of occupancy as per IS: 875–1987 has been mentioned in the table below:

Occupancy

U.D.L

Concentrated Load

Residential Buildings- Dwelling houses

All rooms and kitchens

2.0

1.8

Toilet and bathrooms

2.0

-

Corridors, passages, staircases

3.0

4.5

Balconies

3.0

1.5/m run concentrated at the outer edge

Residential Buildings- Hotels, hostels, lodging houses, dorms, residential clubs

Living rooms, bedrooms, and dormitories

2.0

1.8

Kitchens and laundries

3.0

4.5

Dining rooms, cafeterias, and restaurants

4.0

2.7

Baths and toilets

2.0

-

Educational Buildings

Classrooms and lecture rooms Dining rooms, cafeterias, and restaurants

3.0

2.7

Offices, lounges, and staff rooms

2.5

2.7

Toilets and bathrooms

2.0

-

Institutional Buildings

Bedrooms, wards, dormitories, and lounges

2.0

1.8

Kitchens, laundries, and laboratories

3.0

4.5

Dining rooms, cafeterias, and restaurants

3.0

2.7

Toilets and bathrooms

2.0

-

Types of Loads- Wind Loads

Wind loads are generally horizontal loads caused due to the movement of air relative to the earth surface. These types of loads are not considered for the design of small and low-rise buildings but are assumed for high-rise buildings. As per IS: 875 (Part 3), the design wind load depends upon wind speed, topography, location and shape of the structure, etc. The design speed of wind Vz at any height z can be calculated as

VZ=k1k2k3Vb

where k1 = risk coefficient

k2 = Coefficient based on terrain, height, and size of the structure

k3 = topography factor

Vb = basic wind speed (m/sec)

The design wind pressure (pz) at a height z is given as

pz=0.6VZ2

where VZ is in m/s

pz is in N/m2

Types of Loads- Snow Loads

The snow loads are to be considered for the buildings located in the regions where snow is likely to fall. These types of loads act vertically downward. A roof's shape plays a significant role in the value of snow load. The design snow load on the plan area of the roof or any other area above ground can be calculated as-

S=μS0

where S = design snow load

μ = shape coefficient

S0 = ground snow load

Types of Loads- Earthquake Loads

Shocks due to earthquakes can cause movement of the foundation of structures. Due to these movements, additional inertial forces develop in the superstructure. Total vibration caused by an earthquake may be resolved in three mutually perpendicular directions. (one vertical and two horizontal directions). The movement in the vertical direction does not cause significant forces in the superstructure, but movements in horizontal directions need special consideration.

The type of soil, the size, and method of construction, as well as the duration and severity of ground motion, all affect how the building responds to ground vibration. The details of such estimates for structures standing on soils that will not noticeably settle or slide due to an earthquake are provided in IS 1893-2014.

Some Other Types of Loads

In addition to the types of loads already mentioned, some special types of loads and effects can affect the structure. Some of these loads have been listed below:

  • Earth and Hydrostatic pressure: In the design of a structure, partially or fully below ground level, the pressure exerted by soil, water, or both must be considered.
  • Erection loads: Special types of loads are generated during the erection of materials and equipment due to the impact of hoisting equipment.
  • Accidental loads: These types of loads are a result of human action, including impact, collision, explosions, and fire.
  • Settlement loads: These types of loads occur due to differential settlement of the foundations.

Important GATE Topics

Work Done By A ForceMotion Under Gravity
Dynamic ResistanceStatic Resistance
Ideal DiodeBettis Theorem
Work Done By A Constant ForceApplication Layer Protocols
Castigliano's TheoremPortal Frames

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FAQs on Types of Loads

  • The different types of loads are given below.

    • Dead Loads
    • Imposed Loads
    • Wind Loads
    • Snow Loads
    • Earthquake Loads
    • Other Loads
  • The three major types of loads considered in designing a structure or a building are given below.

    • Dead loads: the permanent loads acting on a structure throughout its lifetime. 
    • Live loads: the types of loads that vary with time. 
    • Wind loads: the horizontal loads acting on a structure due to the action of the wind.
  • Dead loads are the types of loads that are static or permanent loads acting on a structure over its full lifetime. Dead loads are generated caused by the self-weight of the structural components, the weight of fixed and permanent equipment, and the self-weight of the materials.

  • Live loads, also known as temporary loads are the types of loads that vary with time. The magnitude of the load is either variable, or the load is movable.

  • The different types of loads and their respective IS code have been mentioned in the table given below:

    • Dead Load- IS 875 (part-I):1987
    • Live Load- IS 875 (part-II):1987
    • Wind Load- IS 875 (part-III):1987
    • Snow Load- IS 875 (part-IV):1987
    • Earthquake Load- IS 1893:2014
  • Live loads are the types of loads that either changes their magnitude or location with time. Some of the common examples of live loads are people occupying the structure, furniture, vehicles, etc.

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