What Is Dead Load In Construction?
What Is Dead Load In Construction?
Dead loads are the weight of a building or structure’s fixed components, such as its beams, walls, and roof. They are also known as permanent or static loads, as they remain relatively constant over time.
Dead loads may include non-structural elements like built-in cabinets and immovable fixtures. Calculating dead loads is an important part of an engineer’s structural calculations, which are used to ensure the safe design of buildings, bridges, dams, and other structures.
Dead loads can be calculated based on the weight and volume of materials specified in drawings. However, engineers may overestimate dead loads to allow for a margin of error and to account for changes over time. The weight of structural members, like walls and beams, is an important part of determining the overall dead load of a structure.
This process may involve adjusting the size and weight of these members’ multiple times until a final size is reached that can support both the member’s weight and any additional loads placed on the structure.
What Is Structural Load In Construction?
Structural loads are forces, deformations, or accelerations that are applied to the elements of a structure, causing stress, deformation, and displacement. Structural analysis, a field in engineering, studies the effects of these loads on structures and their components. It is important to consider and control excess loads, as they can cause structural failure.
Certain types of structures, such as aircraft, satellites, and ships, are subject to specific structural loads and actions. Engineers often evaluate these loads based on published regulations, contracts, and specifications, and use accepted technical standards for acceptance testing and inspection.
Types Of Structural Loads
There are two main types of structural loads: dead loads and live loads. Dead loads are static forces that remain constant over a long period of time and can be either in tension or compression. Examples of dead loads include the weight of a structure’s own elements, such as walls and beams, and permanent fixtures like built-in cabinets.
Live loads are variable or moving forces that may have a significant dynamic component and may involve factors such as impact, momentum, vibration, and the sloshing of fluids. Impact loads are those that are applied to a material for a period of time that is less than one-third of the material’s natural period of vibration.
Cyclic loads, which can be repeated loadings or caused by vibration, can lead to fatigue damage, cumulative damage, or failure in a structure.
In the design of buildings and other structures, it is important to consider the various types of loads that the structure may be subjected to during its service life and ensure that it is strong enough to resist these loads while remaining fit for use. Building codes specify minimum loads or actions for different types of structures, locations, materials, and uses.
These loads are often increased by load factors, which are ratios of the structure’s theoretical design strength to the maximum load expected in service. Load factors are based on probabilistic studies that take into account the load’s origin, frequency, distribution, and static or dynamic nature.
Dead loads, also known as permanent or static loads, include the weight of the structure itself and any permanent fixtures, while live loads are usually variable or moving forces. Building materials are not considered dead loads until they are permanently installed in a structure.
Live loads are forces that are temporary, short-lived, or moving, and can include impact, momentum, vibration, and the sloshing of fluids. These loads can be referred to as probabilistic loads, as they are variable within the normal operation of a structure and exclude construction or environmental loads.
Live loads can be produced by maintenance workers, equipment, and materials, as well as by movable objects like planters or people in a building. In the case of a bridge, live loads are created by vehicles traveling over the deck.
Environmental loads are structural loads caused by natural forces such as wind, rain, snow, earthquake, or temperature changes, and can include wind loads, snow and ice loads, seismic loads, and thermal loads caused by expansion and contraction due to temperature fluctuations.
Other examples of environmental loads include hydrostatic loads, frost heaving, lateral pressure from soil or bulk materials, and loads from fluids or floods.
How Dead Load Is Calculated?
The dead load on a structure refers to the weight of the permanent components, such as beams, floor slabs, columns, and walls. These components contribute a constant weight, or dead load, to the structure throughout its lifespan.
Dead loads act in the vertical plane and can be calculated by determining the volume of each member and multiplying it by the unit weight of the materials it is made of. The dead load for each component can then be calculated and added together to determine the total dead load for the structure.
