Numerical and Experimental Investigations of the Effect of Cable Profile on Prestressed Concrete Beams

Abstract

Prestressed concrete is a typical set up of cable and concrete which makes a newlineprestressed concrete section considerably stiffer than reinforced concrete section. In newlineprestressed concrete, cable layout plays an important role in reducing tension from newlinethe concrete. Due to curvature, cable exerts forces on the concrete to newlinecounterbalance the forces causing tension. In curved tendons, upward force is newlineimposed on the concrete which may reduce or eliminate the downward deflection as newlinewell; which is almost always the governing factor in structural design. Cables are laid newlineas a continuous Curve, but for analysis purpose they are modeled by Some newlinemathematical curve. The modeling of the prestressing cable in the finite element newlineanalysis is difficult and time consuming as concrete cable interaction involves newlinevarious phenomena. The cable exerts longitudinal and transverse forces on the newlineconcrete due to friction and curvature. Also cable stiffness should be considered in newlineFEA. In continuous structures the cable has been considered to consist of several newlineparabolas. The reason is, for parabolic profile, curvature becomes constant and newlinecable force can be represented as an equivalent uniformly distributed load acting in newlinethe opposite direction to the working loads. Although, parabolic assumption simplifies newlineanalysis, the cable profile becomes discontinuous at intermediate supports i.e. at the newlinejuncture of two parabolas. Due to this, there appears discontinuity at the juncture of newlinetwo parabolas. Actual cable profile is a smooth curve passing through all the spans. newlineFor realistic modeling of the cable in this study, the cable profiles were newlinemodeled by smooth curve like B-spline, which avoided most of the drawbacks of the newlineparabolic modeling. Effect of cable force on concrete, cable stiffness, friction loss newlineetc., has been considered by a realistic formulation. An in-house developed FEA newlinesoftware considering these features has been used in this study. newlineI newlineUsing the results of finite element analysis, cable profile has been designed. newline