1. The relationship between its value and time is different
Permanent load (dead load), its value does not change with time; or its change cannot be ignored compared with the average value. For example, structure self-weight, earth pressure, prestress, foundation settlement, concrete shrinkage, welding deformation, etc. Dead load, also known as permanent load, is a load that is constant (or the change is negligible compared with the average value) applied to the engineering structure.
Such as the self-weight of the structure, plus the weight of permanent load-bearing, non-load-bearing structural components and building decoration components, earth pressure, etc. Because dead loads are continuously exerted on a structure throughout its service life, its long-term effects must be considered when designing the structure. The self-weight of the structure is generally determined based on the geometric dimensions of the structure and the standard value (also called the nominal value) of the material bulk density
Variable load (live load), whose value changes with time during the design basis period, and It is a load whose variation value cannot be ignored compared with the average value. For example, floor live load, roof live load and dust load, crane load, wind load, snow load, etc.
Live load, also called variable load, is the use or occupancy load and naturally occurring natural load imposed on the structure caused by people, materials and vehicles. Such as industrial building floor live load, civil building floor live load, roof live load, roof dust load, vehicle load, crane load, wind load, snow load, ice load, wave load, etc.
2. Effects are divided into direct effects and indirect effects
Direct effects refer to the set of forces (including concentrated forces and distributed forces) acting on the structure, which are customarily collectively referred to as loads; indirect effects Actions refer to those actions that do not appear directly in the form of force sets, such as those caused by foundation deformation, concrete shrinkage and creep, temperature changes, earthquakes, etc., which are commonly referred to as dead loads.
3. Different determination methods
The dead load of the floor includes the self-weight of the structure and the decorative surface, ceiling, etc. It is determined by the construction and structural practices; the floor live load includes the load of people, equipment, furniture, etc. Determined by building functional use. In other words, the dead load is generated by the building itself, and the live load is generated by the users. ?
Extended information:
Classification of loads:
1. Classification according to variation over time
(1) Permanent action ( Permanent load or dead load)
For example: the self-weight of fixed partition walls, constant water pressure, prestress, foundation deformation, concrete shrinkage, steel welding deformation, various external deformations or constrained deformations of the structure. construction factors.
(2) Variable effects (variable load or live load)
Such as: floor live load, roof live load and dust load, movable partition wall self-weight, installation load , vehicle load, crane load, wind load, snow load, water pressure and temperature changes due to water level changes.
(3) Accidental effects (accidental loads, special loads)
Such as: impact, explosion, earthquake effect, tornado, fire.
2. Classification according to structural response
(1) Static action (static action)
For example: fixed partition wall dead weight, residential and office buildings Floor live load, snow load.
(2) Dynamic effects (dynamic effects)
For example: earthquake effects, crane equipment vibration. Classified according to the size of the load action surface:
a. Uniform surface load
For example: laid wooden floor, floor tile, granite or marble surface
b. Line load
Various surface loads on the original floor or roof of the building are transmitted to the beams or strip foundation.
c. Concentrated load
Place or hang heavy objects (washing machines, refrigerators, air conditioners, chandeliers) on the original floors or roofs of the building.
3. Classification according to the direction of load action
1. Vertical load
For example: structure self-weight, snow load.
2. Horizontal load
Such as: wind load, horizontal earthquake action.
Baidu Encyclopedia-Load