Creep of concrete

Creep of concrete

Main aspects of deformation/creep in concrete

The deformation of concrete depends on various aspects as follows:-

· Concrete strength

· Strength of concrete at the time of transfer of the load

· Applied stress level

· Humidity and atmospheric condition

· Time at which creep deformation is measured

Loss of pre-stress due to creep of concrete

The loss of pre-stress due to creep of concrete under load shall be determined for all the permanently applied loads including the pre-stress. The creep loss due to live load stress, erection may b ignored. The loss of pre-stress due to creep of concrete is obtained as a product of modulus of elasticity of the pre-stressing steel and ultimate creep strain of the concrete fiber integrated along the line of center of gravity of pre-stressing over its entire length.

The total creep stain during any specific period shall be assumed for all practical purpose, to be creep stain due to sustained stress equal to the average of stresses at the beginning and end of the period.

National building codes adopt different formula for calculating the creep stain which involves not only the age of concrete at which the stress is transferred but also the cube strength, relative humidity etc as detailed below:-