PROCEDURE FOR CASTING DIFFERENT LENGTH PRECAST/PRESTRESS

CONCRETE BRIDGE UNITS (Combined Beam Pours)

SCOPE:

To establish procedures for the fabrication of beams with different lengths on one casting bed set-up. Any deviation from the beam design standard or the Combination Pour Charts is not allowed.

This procedure allows the casting of two different length beams together in the same line in accordance with Combination Pour Charts. For example, a D95 beam may be cast with a D100 beam with the following modifications made to the D95 beam:  deflection strands are raised by 4 in. and compressive strength at release and at 28 days are increased to 6000 psi and 7500 psi respectively.

Use of the next longer beam strand pattern may result in camber increase in the modified beams. For example, the calculated camber at the time of erection for a D90 beam (with D95 strand pattern) will increase by approximately 0.25 inch. Whenever such beam modifications are used, the fabricator shall notify the District Materials Engineer prior to fabrication.  No additional acknowledgements will be required as the fabricator will comply with the combination pour charts.