Strength of shear keys used in pre-cast prestressed composite beams

摘要

This work investigates the shear strength of shear keys used in slab-web connections in pre-cast bridge systems. In pre-cast systems where the slab is also a pre-cast element, the slab-web connection is discontinuous and usually made by casting concrete plugs (shear keys) through holes left over on the line of connection with the web at prescribed spacing. The contribution of the slab to the flexural strength of the composite beam is highly dependent on the individual shear strength of the keys and the spacing between them. In this work a test program was developed to estimate the shear strength of full scale shear keys used in practice to combine pre-cast reinforced concrete slab bridge deck to pre-cast prestressed pretentioned concrete girders, as a function of the amount and type of connection steel. On the basis of test results and the shear-friction model, an equation for the estimation of the shear strength of the shear keys is here proposed.