There are various types of loads for engineering concern. In civil engineering, the various types of loads are of vital importance as they are responsible for the forces or stresses acting on a structural member. Hence, loads and their effects on structures are often analyzed and structural members are designed so as to withstand the impact of the loads acting on them.

Common types of loads in civil engineering include dead loads, live loads, wind loads, working loads, factored loads, earthquake/seismic loads), etc.

Now let us take a look at the various types of loads for engineering applications.

Working Loads: Working loads are the actual loads a structure is designed to carry. This type of load may also be referred to as characteristic, specified or nominal load. This is the maximum load which must not be exceeded, or thought of not being exceeded during the life span of the structure. Working or characteristic loads have a 95% chance of not being exceeded.

Three main types of loads on buildings are:

Dead loads: These loads are due to the self weight of the structural members. They are expected to remain constant throughout the life span of the structure. Because they do not change, they could also be referred to as static loads or permanent loads. Examples include weights of floor slabs weight of plaster, etc. BS 6399: part 1 gives dead loads of various materials.

Imposed Loads: These loads are due to the weights of objects or people that inhabit the building or structure. They are also called live loads or variable loads. These loads are not constant and may change from time to time. Live loads are estimated based on the intended use of the building or structure. Examples of live loads include weights of people, furniture, vehicles, equipment, etc.

Wind Loads: Wind loads are due to the effect of wind on buildings or structural members. These loads are more horizontally pronounced on buildings. Wind load effects on a building depends upon the location and size of the building. CP3 chapter V: part 2 provides information on wind loads.

Other types of loads considered in civil engineering are:

Dynamic Loads: Dynamic loads are loads that change with time. These loads have a magnitude which is greater than their static equivalent. A person jumping up and down on a floor slab for example, would exert a dynamic load on the floor. Examples of dynamic loads on structures include the effects of cranes, moving people, waves, ice, vibrations on floors or structural members due to earthquake, etc. As opposed to static load which changes very slowly if at all, dynamic loads have a rapid rate of change. For more on dynamic loads, see BS 6399: part 1.

Factored Loads: These are loads that, a suitable factor of safety has been applied to. There are various factors of safeties used for factoring loads based on the design code used. Factored loads are used in design calculations for strength and safety.

Mathematically, Factored load = Working load * Overall Factor of Safety (F.O.S).

Table 2, BS 5950: part 1 gives the overall factor of safety for various types of loads. Below is an except:

Table 2.1 – Overall Load Factors (Yt)