Maximum effective transference length in column strengthening by reinforced concrete

Abstract

Load transference in column strengthening by reinforced concrete collaring occurs by shear stresses in the contact surface between the column and its collar. Actually the contact surface doesn?t usually have any sewing steel reinforcement, so the kind of failure to be expected is fragile and with little redistribution capacity. Therefore there is just a limited length of load transference, and it is on this limited zone where the maximum values of shear stresses are reached, without significant redistribution. This article compares the results of a specific series of test with the theoretical phenomenon. The basis of the theoretical formulation is that the compression stresses that keep the friction on the contact surface are due to the superficial thrusting between the column and its collar. In fact, as a result of this thrusting steel reinforcement bars are strained and consequently stresses, so compression stresses appear on the contact surface.