Three Categories of Loads on Structures
In this article, we will discover and learn about the loads that act on typical civil and structural engineering structures. These loads can be categorized into 3 categories, namely:
- Dead loads are gravity loads due to self weight of structural elements and other material that are permanently attached to it.
- Live loads are loads due to moving loads, or movable objects present on the structure due to the use of the structure. When live loads are applied rapidly to a structure, they cause dynamic effect that causes increase in stress in the structure referred to as impact load.
- Environmental loads are loads on the structure that are caused by environmental effect such as snow, wind, earthquake, hydrostatic, soil pressures, thermal and other effects.
In designing a structure, a structural engineer shall clearly specify all the loads which can be expected to act on a structure on its entire lifespan. The purpose of an engineer is to design a structure that will be able to resist all the specified loads while serving its intended purpose throughout its lifespan. In estimating the design loads, an engineer shall also consider the possibility that some of these loads will act simultaneously on the structure. The structure shall be designed so that it can withstand the maximum load combination that is likely to act on the structure throughout its lifespan.
Different building codes requires load combinations for which the structure shall be designed. The loads described on the codes are minimum requirements based on the past occurrences and study. Therefore, an engineer must decide if the structure will be subjected to any additional load in addition to what are specified on the codes. The engineer is responsible for the safe design of any structure.