Extended span precast girders
Bridge design, construction, maintenance, inspection, and management
TxDOT is adopting and implementing the following standards cross-sections for extended span lengths, including a deeper pretensioned girder section and a series of I- and U-sections targeted for spliced girder applications.
To minimize costs, these sections should be used whenever possible.
The Tx84 section is a pretensioned girder for use in simple span units. The span of the Tx84 can be up to 170 feet, which is generally limited by hauling constraints.
The STx and HSTx girders are for use in multi-span continuous units or simple span units, with a main span range of 170 feet to 325 feet. At shorter spans, the constant depth STx girders can be spliced together to form a single span or continuous unit. At longer span ranges in continuous units, the STx girders act as drop-in sections spliced to the haunched HSTx girders. The HSTx girders are placed at piers, connected to the constant depth girders by a height transition.
The STx and HSTx girders are pretensioned, post-tensioned, or both for self-weight during handling and transport. Post-tensioning tendons splice the girder segments together and carry superimposed dead load and live load. Provision is made for up to four 19-0.6 inch strand tendons.
Three constant depth U-girder sections are provided for use in straight or curved, spliced, multi-span continuous units. These girders do not utilize haunched sections. The 9-inch-minimum web and bottom flange thicknesses may be increased internally to satisfy structural demand and accept a larger duct size.
U-girders are pretensioned, post-tensioned or both for self-weight during handling and transport. Pretensioning is not feasible in curved girder cases. Post-tensioning tendons splice the girder segments together and carry super-imposed dead load and live load. Provision is made for up to four 19-0.6 inch strand tendons in each web.