Crack Width Prediction for Ledges in Inverted ‘T’ Bent Caps

Abstract

Inverted "T" bent caps are used frequently on Texas bridges because they are aesthetically pleasing and offer a practical means to increase vertical clearance. Since the current design guidelines do not address the existing problem of crack control at service load adequately, explicit design provisions for cracking need to be developed. This research seeks to develop a serviceablity design method for controlling crack widths at the re-entrant corners of inverted "T" bent caps. The design method is based on a rational physical model and is collaborated by an extensive experimental program. The three types of specimens tested were: the 2-D specimens, 3-D specimens and whole-bent-cap specimens. Three equations are proposed to control the diagonal crack widths at the re-entrant corners of the inverted "T" bent caps. The equations are: one for crack widths at the vicinity of interior applied loads, and the other two for crack widths at the end faces of exterior spans; the equations are applicable to full size highway bridges and are suitable for incorporatiion into the AASHTO Specifications.