Strand Prediction in Selected Precast Flexural Members

Abstract

T his article presents general empirical equations for predicting strand requirements in precast prestressed double tees and bridge girders for a given situation. It is assumed that the number of strands for a different span, loading and/or girder spacing is already known. The superimposed loads are assumed uniform for the case of double tees and according to AASHTO Specifications for the bridge girders. It is also assumed that service load stresses govern. The case of rectangular or Lbeams with straight strands is not discussed because the solution is straightforward, as shown in Appendix A. The given equations may be used directly in preliminary estimates or in computer program algorithms to accelerate convergence toward the exact solution. Another possible use for the formulas is in the feasibility studies for a new section where span and load ranges are sought.