Concept

Arching or compressive membrane action in reinforced concrete slabs

Résumé

Arching or compressive membrane action (CMA) in reinforced concrete slabs occurs as a result of the great difference between the tensile and compressive strength of concrete. Cracking of the concrete causes a migration of the neutral axis which is accompanied by in-plane expansion of the slab at its boundaries. If this natural tendency to expand is restrained, the development of arching action enhances the strength of the slab. The term arching action is normally used to describe the arching phenomenon in one-way spanning slabs and compressive membrane action is normally used to describe the arching phenomenon in two-way spanning slabs. The strength enhancing effects of arching action in reinforced concrete floors were first recognised near the beginning of last century. However, it was not until the full scale destructive load tests by Ockleston on the Old Dental Hospital in Johannesburg that the extent of strength enhancement caused by arching action was really appreciated. In these tests, collapse loads of between 3 and 4 times those predicted by yield-line theory were obtained. Since the 1950s there have been several attempts to develop theories for arching action in both one and two-way slabs. One of the principal approaches to membrane action was that due to Park which has been used as a basis for many studies into arching action in slabs. Park's approach was based on rigid plastic slab strip theory, and required the assumption of a critical deflection of one half of the slab depth at failure. Park's approach was later extended by Park and Gamble in their method for predicting the plastic load-deformation response of laterally restrained slabs. In 1971, the American Concrete Institute produced a special publication which presented the most recent research, to that time, on arching and compressive membrane action in reinforced concrete slabs. A comprehensive review of the literature and studies of both rigid-plastic and elastic-plastic approaches to arching have been compiled by Braestrup and Braestrup and Morley.

Source officielle

https://en.wikipedia.org/wiki/Arching_or_compressive_membrane_action_in_reinforced_concrete_slabs

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