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Permanent and variable loads

A building must carry its own weight and everything that comes on top. Self-weight is permanent and known quite accurately. Imposed load, snow and wind are variable loads that come and go, and they are more uncertain.

G = \gamma_{mat}\cdot V

self-weight from the unit weight of the material

q = q_k\cdot A

imposed load on an area

Symbols

$G$	self-weight	kN
$\gamma_{mat}$	unit weight (concrete about 25)	kN/m³
$q_k$	characteristic imposed load	kN/m²
$A$	area	m²

Example

A concrete slab 5 × 4 × 0.2 m:

$G = 25\cdot 4 = 100$ kN.

Self-weight always acts. Variable loads act only sometimes and are therefore combined with their own factors.

Practise loads and load combinations for free →

Load factors →

Part of Building and Structures: Loads and load combinations.