10.5 : Effects of Creep

Creep in concrete, the gradual deformation under prolonged stress, significantly impacts the integrity of structures. For reinforced concrete beams, it can be a vital design consideration, as it increases deflection, sometimes necessitating additional design measures. In columns, especially slender ones under eccentric loads, creep can cause buckling, compromising their stability. However, creep can be beneficial in indeterminate structures by mitigating stresses that arise from shrinkage, temperature fluctuations, or support movements, thus reducing potential cracking.

In massive concrete structures like dams, creep can result in cracking due to constraints during temperature cycles from hydration heat and subsequent cooling. High-rise buildings may experience differential creep, leading to partition movements and cracks. Additionally, exterior cladding fixed to columns that undergo creep can also develop cracks. For longevity and safety, provisions for accommodating potential movement and stress changes due to creep are essential in concrete structure design and maintenance.

Prestressed concrete elements, crucial in bridges, suffer from prestress loss over time due to creep, a problem once so significant it prompted the introduction of high-tensile steel to counter it.