Fundamental Study on Reinforcement of Notched Anchorage Zone in Prestressed Concrete Member

Abstract

The reinforcement of “a notched-anchorage”, which is an intermediate anchorage with a suitable pocket for accomodating the anchor plate and the prestressing jack, should be designed to resist particularly the following tensile forces : (a) the tensile force (Z') in the bursting zone and (b) the tensile force (Z) around the corner of the notch.
In this paper, the effects of several influencing factors on the magnitude of the tensile forces are investigated in detail by using the finite element method. From this investigation, the following conclusions are obtained :
(1) The tension Z' increases with decreasing the angle θ of inclination of the prestressing force (P₁) with respect to the axis of the member. But its magnitude is comparatively small, and Z'/P₁ is about 0.05 in case of θ=0°.
(2) The direction of the maximum tensile stress at the corner of the notch inclines by about 40° to the plane on which the prestressing force is applied.
(3) The total tensile force Z depends mainly on the angle θ, and the maximum value of Z/P₁ is about 0.20 in case of θ=0°.
In addition, it is pointed out that the corner zone of the notch can be designed by full prestressing, and a new design method is presented here.