Major types of loads on building structures

S.L. Khan, the renowned engineer, provides brief explanation on the various types of loads which operate on structures.

The loads are imposed on a completed or temporary structure throughout and as a result of the construction process

Loads are categorized as follow :-

1) Dead loads.
2) Live loads.
3) Environmental loads.

DEAD LOADS: Dead loads mean the loads which are constant in magnitude and set in location during the life span of the structure. Generally, the major part of the dead load is the self weight of the structural systems like walls, columns, beams, space frame, cladding material (interior & exterior), slabs, partition walls as well as weight of other permanent service equipment HVAC or plumbing).

These can be found with exact precision from the design configuration, structure dimensions and density of the material.

For buildings the weight of floor fills, finish floor and plaster ceilings are generally considered as dead loads. An allowance is provided for suspended loads like piping and lighting fixtures. For bridges dead loads may comprises of wearing surfaces, sidewalks and curbs, and an allowance is provided for piping and other suspended loads.

LIVE LOADS: Live loads are generally unsteady or just moving loads, or it can be said that live loads mainly comprising of occupancy loads in buildings and traffic loads on bridges.

They contain all the movable weights ranging from human, furniture and fixtures as well as other non structural components like rain, snow & ice. The wind pressure, water pressure or push of earth are also treated as live load. They are either fully or partially in place or not exist at all, may also vary location wise. Their magnitude and distribution at any stipulated time are unpredictable. Their maximum intensities during the Life time of the structure can’t be determined exactly.

The minimum live loads applicable to design the floors and roof of the building are mentioned in the building code that is controlled at the construction site. The illustrative values of minimum live loads should be applied in different types of buildings which are set up in minimum design loads for buildings and other structures.

The type of occupancy should be taken into consideration and the projected loads are measured as precisely as possible. Live loads for highway bridges are stated by the American association of state highway and transportation officials (AASHTO) in its LRFD bridge design specifications.

ENVIRONMENTAL LOADS: Environmental Loads are loads generated with natural forces like wind pressure, rain load, snow load, earthquake loads, soil pressure on subsurface structures as well as temperature difference. These loads are changed instantly or employed abruptly.

Environmental loads at any stipulated time are dubious in both distribution and magnitude.

To get more clear ideas with diagrams, go through the following video tutorial.

Video Source: SL Khan