Section 11: Precast and Prefabricated Substructure Alternatives
General
Allow precast and prefabricated alternatives to the as designed cast-in-place concrete or precast bridge substructures. If it is desired to allow post-letting precast and prefabricated bridge element alternates, include the “Precast Alternates” working drawing found online at:
. This working drawing must be modified on project-by-project basis, then signed and seal.
Develop alternates using the TxDOT Bridge Standards and working drawings for precast elements. For alternates not covered by the standards, develop these alternates based on the relevant concepts demonstrated within the standards and working drawings. Do not develop complex precast alternatives that will require additional research or investigation without prior approval from Bridge Division.
Do not develop entire bridge redesigns, unless specific plan sheets clearly state entire bridge redesign is permitted. In such cases, the contractor has the option to propose a new design, assuming the role as the new Engineer of Record, and the new plans must adhere to the design intent of the original plans. The new Engineer of Record must be precertified by TxDOT and provide signed and sealed plans and calculations for the redesign.
Bent Caps and Abutments
Provide equal or better corrosion resistance to the originally designed bent cap and cap to column connection as shown in the project plans.
Limit initial tension stress to 0, “no tension” during release, lifting, and hauling. Precast, prestressed bent caps designed to “no tension” using uncoated strand and reinforcement provides the equal corrosion resistance to uncoated, epoxy coated, and galvanized reinforcement.
If the precast bent cap alternate reduces the number of columns, design the alternate bent cap and columns to meet the requirements for vehicular collision presented in Chapter 2, Section 2, and Chapter 4, Section 7.
Do no use the following without prior approval from TxDOT Bridge Division:
- Hollow shells subsequently infilled
- Hollow voids
- Lightweight concrete
- Separate pieces joined together in the field
Precast Concrete Columns
Do not use precast concrete columns without prior approval from the TxDOT Bridge Division.
Prefabricated Steel Bent Caps
Design prefabricated steel bent caps for load path redundancy, system redundancy, or internal redundancy. Due to level of effort associated with pursuing acceptance of system redundancy or internal redundancy, obtain prior approval from the TxDOT Bridge Division before progressing with design.