A study on the enhancement of the shear capacity of reinforced concrete half-joints through the introduction of steel sections

Abstract

Half-joints are a particular type of connection, mostly associated with precast construction. They are widely used in buildings and bridges. The abrupt change in the cross section of the beam causes the beam to behave differently. For this reason, alternative methods of analysis to simple bending theory have been developed, namely the strut-and-tie method. In this research study, a variation of the typical reinforcement layout in the nib area was examined. This included the introduction of a steel beam section in the nib area. The effects of this type of reinforcement on the strength of the nibs were studied by means of physical testing and a non-linear finite element analysis. A comparative study was conducted to quantify the increase in strength capacity generated by the steel beam section and to numerically model the results obtained by using the finite element method of analysis. From the finite element model, a parametric study was possible. The effects of changing the stirrup diameter, the size and position in the nib of the steel beam, the middle reinforcement diameter and the bottom reinforcement diameter were analysed. The introduction of the steel beam section generated 13% increase in capacity in the physical test while a 20% increase was observed from the finite element model. This enhancement in capacity was compared to results obtained from previous work to be able to evaluate the efficiency of this strengthening technique.