What is live load?
Live load is what is produced during the use of the structure. It is also called imposed load or probabilistic load since its calculation is based on projections and not real data. This term encompasses people (or other living beings), furniture, vehicle traffic, various equipment, temporary structures, etc. that must be considered. At the time of the structural analysis and design of structures, a number of structural loads must be taken into account. Live load is one of them.
Also included within the live load calculation are the weight of the partitions and loads generated by the operation of construction and maintenance (workers, machinery, etc.).
What is the difference between live load and dead load?
Dead load refers to the weight (which generates a vertical load) of all the elements of the structure itself. These elements can be structural or non-structural, but they are a permanent part of the structure; unlike the live load, they are not due to the occupation and use of the structure.
Some elements of dead load may include siding, stairs, ceilings, floors, etc.
There really is no factual difference between live load and dead load; both are part of the actual load that supports a structure. However, this differentiation has pragmatic purposes: it is simpler to perform different calculations. This way, errors are reduced (especially those of omission), and the calculation is more accurate and, thus, safer.
How is live load calculated?
In structural analysis, it is necessary to calculate the maximum live load that is expected for the building. This will be very different depending on each situation, and it may vary greatly between, for example, a single-family home, a school, and a stadium. Regardless of the calculation made, there are regulated tables for minimum live loads that every structure must comply with.
Live loads are determined with a set base related to daily use and a variable part. To simplify the calculation, live loads are calculated as uniform loads applied over the area of the structure.
What elements should be taken into account in calculating live load?
Much of the live load is not static. The movements performed involve forces applied on the structure that must also be considered in load calculations. Some of these factors are:
- Amount of movement.
- Material wear.
- Fluid dynamics.