Creep

Creep is the long-term deformation of concrete under sustained loads (Fig. 3.12). The extent of creep is largely dependent upon the modulus of elasticity of the aggregate. Thus an aggregate with a high modulus of elasticity offers a high restraint to creep. The extent of creep may be several times that of the initial elastic deformation of the concrete under the same applied load. Where rigid cladding is applied to a concrete-frame building, compression joints at each storey must be sufficiently wide to take up any deformation due to creep, in addition to normal cyclical movements.

L__

Creep strain

Instantaneous recovery

Instantaneous strain

s--

_ Creep recovery

Residual strain 1

Time —► 1

Load Load applied removed

Load Load applied removed

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