Haunch Girder

Dallas, Texas

HAUNCH AND TYPICAL GIRDER FORMS

"On a complex design/build project of this magnitude, the forming system plays a critical role in the project's success. Hamilton Form has expertise and experience in designing and fabricating complex forms for these types of major infrastructure projects."

Jorge Hinojosa P.E., M.S.
Bexar Concrete Products I, Ltd.
San Antonio, TX

The Dallas Area Rapid Transit Authority (DART) launched a major expansion to its 45–mile light rail system in and around the Dallas area. One section of the rail system will travel over a 550–foot precast/prestressed concrete bridge that spans the Trinity River levy northwest of downtown Dallas. The main span of the bridge consists of a 260–foot clear span made up of two 97–foot by 10–foot 10–inch haunch girders at the piers and a 160–foot middle "drop–in" beam section. The end and center spans utilize typical TX82 girders.

For the haunch girders, Hamilton Form designed a variable height soffit configured to the profile of the bottom of the beam. The configured soffit allowed the 11–foot 2–inch tall sideforms to be built as a rectangular profile, providing better stability and ease of handling.

Sealing of the form against the soffit was accomplished with a thru–tie system just below the bottom casting surface. The haunch girder was post–tensioned rather than prestressed so the form required end blocks. Two pour openings were provided to prevent the concrete from dropping the full height of the form during the pour.

Also fabricated were 82–inch sideforms for the typical girders with Vibrotrack&trade installed low on one side and high on the other for uniform concrete consolidation. To improve productivity, Bexar was supplied with enough bed feet of soffit to allow three beams to be set–up at once and so that the sideforms could leap–frog down the soffit.

The soffit for the beams was an atypical bottom width of 33 inches. Hamilton Form designed the understructure of the soffit so it could later be modified to a more common 32 inch width.

Haunch Girder

Haunch girder with sloping soffit and header.

Haunch Girder Haunch Girder Haunch Girder Haunch Girder