Structural analysis is concerned with both static and dynamic loading as it is used to determine how physical structures behave when subjected to force. These forces can include anything from people to vehicles and furniture to wind, snow or other natural forces such as earthquakes.
The application of these forces determine whether they are dynamic or static, if applied quickly they count as dynamic and when applied slowly they are static. Dynamic analysis is used to determine dynamic loads and static analysis is used to determine static loads.
The equation of force (force = mass x acceleration) means that dynamic loads tend to have a greater impact on a structure than static loads. Sudden deceleration also causes an increase in force, such as when a wrecking ball strikes a building.
However, there are some instances where research on dynamic and static loading seem to show contradictory results, such as with buried pipes. Some studies have shown that the amount of displacement in buried pipes can actually be greater with static loads than with moving loads in the long term. It was also found that the ratio of pipe displacement between static and dynamic loading decreased as the pipe stiffness increased. Despite this, as a general rule, dynamic loads exert more force than static loads.
The equation of force is used in structural engineering to work out the force exerted by a dynamic load and create safety margins, such as with a roadside crash barrier used to prevent traffic from leaving a lane.
As dynamic loads tend to change over time, static loading measurements are often used to simplify structural engineering calculations, with standards ensuring that structures can withstand the additional dynamic forces too.
All materials have limits as to how much compression or tension stress they can withstand before they yield or permanently deform. The fundamental material properties can be tested to work out the maximum stress the material can handle. This stress is used as a measure of the force per unit area in a cross section of the material. Once this stress becomes too much for the material, microscopic fractures develop and grow as the stress continues to be applied until, eventually, the material breaks completely. This breaking point is known as the material’s ultimate tensile strength.
The differing material strengths and properties help determine which applications they can be used for.
Static loads, or dead loads, don’t change over time and include a wide range of different types of load.
For example, if people stand in a lift waiting for the doors to close, they exert a static load as they people and the lift are not moving relative to each other. As soon as the people move, the load becomes dynamic and the stresses exerted on the lift start to vary depending on where the people are and how they are moving (i.e. walking around compared to jumping up and down).
Other types of static load include filing cabinets or furniture that is placed on a floor or buildings on a bridge.
What is an Example of a Static Load?
Examples of static loads include the weight of a building bearing down on the ground or a car parked on a road. However, if the car begins to move, it becomes a dynamic load.
What is Static Loading in a Structure?
A static load in a structure refers to any load, whether the weight of furnishings or another stationary load, that exerts itself on the structure. For example, a crane placed on top of a building is a static load (until it moves!).
What is a Static Load Called?
Static loads are also known as dead loads or holding loads.
Static loading is any load that is applied slowly to an assembly, object or structure. Static loads are also those that remain consistent and do not move at all. They are used to work out the maximum load for a range of structures and objects as well as for determining the ultimate tensile strength of materials.
Dynamic loads, by contrast, are those that are applied quickly and can change, including cars moving across a bridge, people jumping up and down on a dancefloor or snow piling up on a roof.