FDOT Standard Plans Index 450-120: AASHTO Type II Beams

Design Criteria

Design Criteria AASHTO LRFD Bridge Design Specifications ; Structures Detailing Manual ( SDM ) ; Structures Design Guidelines ( SDG )

Design Assumptions and Limitations

Design Assumptions and Limitations Index 450 - 120 is the standard for the AASHTO Type II Beam. Use this standard with Indexes 450 - 199, 400 - 510, and 45 0 - 511 or 45 0 - 512. This standard must be supplemented with project specific information including a Table of Beam Variables, Strand Pattern Details and a Strand Debonding Legend which must be completed and included in the Structures Plans.

This standard and the supplemental project specific information that is included in the plans provides sufficient information to permit beam fabrication without the submittal of shop drawings. Data tables for associated Indexes 45 0 - 199, 40 0 - 510 and 45 0 - 511 or 45 0 - 512 must also be completed and included in the plans. A Framing Plan is required for bridges meeting the criteria stated in the SDM .

The use of End Diaphragms is not preferred on simple span, pretensioned, I - Beam structures. In lieu of End Diaphragms, the preferred detail is a Thickened Slab End at all locations of slab discontinuity. Where End Diaphragms are required by design or for w idening projects, partial depth diaphragms are preferred.

See SDM Chapter 15 for suggested details. Except for widening projects where special details may be required, squared beam ends are preferred on all pretensioned I - Beam structures. The prestressed beams in these Standard s are generally assumed to act as simple spans under both Dead Load and Live Load even where the deck is detailed to be continuous across the intermediate supports or back - to - back diaphragms are present.

For detailing purposes, Prestressed I - Beams are assum ed to be erected plumb. When the total initial tensioning force of the fully bonded strands required by design exceeds the value shown below, shield additional strands at the end of the beam when possible. The end reinforcement may only be redesigned to accommodate an increased v ertical splitting force when approved by the State Structures Design Office.

If approval is granted, Index 45 0 - 120 must then be modified for inclusion in the contract documents and signed and sealed by the EOR. To limit vertical splitting forces in the webs of beams, the maximum prestress force at the beam ends from fully bonded strands must be limited to the following: Index No. Beam Type Max.

Bonded Prestress Force Last Revision Date 45 0 - 120 AASHTO Type II 755 Kips 07/01/05 or later Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 120 AASHTO Type II Beams Do not apply losses and use the jacking force of all the strands located in the bottom half of the beam when calculating the Bonded Prestress Force. If the beam grade exceeds 2%, provide Embedded Bearing Plates and Beveled Bearing Plates at each end of the beam as shown on Index 45 0 - 511 or 45 0 - 512.

See additional instructions in the SDG .

Payment

Payment Item number Item Description Unit Measure 450 - 1 - 1 Prestressed Beams: AASHTO Type II LF

Design Aids

Design Aids Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 120 AASHTO Type II Beams Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 120 AASHTO Type II Beams Section Properties * Beam Area (in.

2 ) Ixx (in. 4 ) Iyy (in. 4 ) y t (in.) y b (in.) AASHTO Type II 369 50,979 5,333 20.17 15.83 * These section properties are based on gross section properties and neglect the 3/4" chamfers on the bottom flanges.

What your plans must show

Plan Content Requirements for this index — the SPI's checklist for designers.

• - 120 and include it in the plans as follows:
• • Modify the Standard Plan s in accordance with Method 1, Method 2 or Method 3 as defined in the Terms Of Use for the Borderless DGNs provided in the Standard Plan s eBooklet.
• - outs and details regarding cutting the strands and coating the ends of the beams with epoxy.
• Standard Plan s Instructions Topic No. 625
• - 120 AASHTO Type II Beams
• - outs and details to ensure proper placement of Bars 4L as shown in the 2010 Design Standards Index 20120 . Detail the number of bars, bar locations and bar bending diagrams .
• Standard Plan s Instructions Topic No. 625
• - 120 AASHTO Type II Beams Standard Plan s Instructions Topic No. 625
• - 120 AASHTO Type II Beams