FDOT Standard Plans Index 450-210: Series Florida - U 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 45 0 - 210 is the lead standard for the Florida - U Beam standard series which includes Indexes 45 0 - 210 through 45 0 - 272. Use this standard with Indexes 45 0 - 248, 45 0 - 254, 45 0 - 263, 45 0 - 272, 45 0 - 299 and 450 - 502. The standard Florida - U Beams are applicable for spans with skewed end conditions less than or equal to 15 degrees.

For beams with skewed end conditions greater than 15 degrees the EOR shall develop a custom design and details using the standards as a basis . These standards 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. These standards and the supplemen tal project specific information that is included in the plans provide sufficient information to permit beam fabrication without the submittal of shop drawings.

Data tables for associated Indexes 45 0 - 299 and 450 - 502 must also be completed and included in the plans. Florida - U Beams are typically placed parallel to the cross slope of the bridge deck. The prestressed beams in these Standard Drawings 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.

When the total initial tensioning force of the fully bonded strands required by design exceeds the values shown below, shield additional strands at the end of the beam when possible. The end reinforcement may only be redesigned to accommodate an increased vertical splitting force when approved by the State Structures Design Office. If approval is granted, Index 45 0 - 210 and the appropriate Standard Plans Detail Drawings must then be modified for inclusion in the contract documents and signed and sealed by th e 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 - 248 Florida - U 48 2790 Kips 07/01/05 45 0 - 254 Florida - U 54 2790 Kips 07/01/05 45 0 - 263 Florida - U 63 3070 Kips 07/01/05 45 0 - 272 Florida - U 72 3070 Kips 07/01/05 Standard Plan s Instructions Topic No.

625 - 010 - 003 Index 450 - 210 Series Florida - U 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. Stay - In - Place Metal Forms are required to be used to form the deck within the individual Florida - U Beams. Due to the absence of external end diaphragms between individual Florida - U Beams, a thickened deck edge beam at deck expansion joints is required to support wheel loads.

Generally, the depth of the Edge Beam shall extend from the top of the deck to the bot tom face of the top flanges of the Florida - U Beams.

Payment

Payment Item number Item Description Unit Measure 450 - 4 - AAA Prestressed Beam - FL U - Beam LF Example Problem The following example shows the data required for completion of a Florida - U Beam Table of Beam Variables. The example assumes a two span bridge with Florida - U 72 Bea ms designed for the following conditions: Live Load: HL - 93 Future Wearing Surface: Design includes allowance for 15 PSF. Stay - in - Place Metal Forms: Design includes allowance for 20 PSF non - composite dead load over the projected plan area of the forms for the unit weight of metal forms and concrete required to fill the form flutes.

Environment (Superstructure): Moderately Aggressive Bridge Characteristics: Length: 249' - 4" Width: 59' - 1" (out - to - out) Clear Roadway: 56' - 0" Superstructure: Two simple spans of prestressed concrete beams with 8 - inch composite deck slab S pan: 124' - 8", 124' - 8" Sidewalk: None Horizontal Alignment: Straight Vertical Alignment: 0.00% Grade Skew Angle: 0 degrees Beam Design: Beam: Florida - U 72 Beam Spacing: 21' - 0" Desig n Span Length: 122' - 4" Composite Dead Load (per girder): 603 PLF Non - Composite Dead Load: 124' - 8" Span: 4163 PLF Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 210 Series Florida - U Beams Diaphragm Dead Load: End: 8.6 kips each Intermediate: 4.3 kips each Bonded Strand Development Multiplier = 1.60 Tension Stress Limits at Release as per SDG Live Load Distribution Factors (interior beam): Shear: 1.50 Moment: 1.5 0 Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 210 Series Florida - U Beams Standard Plan s Instructions Topic No.

625 - 010 - 003 Index 450 - 210 Series Florida - U Beams

Design Aids

Design Aids Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 210 Series Florida - U Beams Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 210 Series Florida - U Beams Section Properties Beam Size Area (in.

2 ) Ixx (in. 4 ) Iyy (in. 4 ) y t (in.) y b (in.) F U B - 4 8 1,206 321,222 905,815 28.53 19.47 F U B - 54 1,275 439,370 1.026 x 10 6 31.99 22.01 F U B - 63 1,377 659,103 1.222 x 10 6 37.08 25.92 F U B - 72 1,479 933,707 1.438 x 10 6 42.09 29.91

What your plans must show

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

• In the Structures Plans: Complete the following "FLORIDA
• - TABLE OF BEAM VARIABLES" and include it in the plans. Use additional sheets when the actual number of beams or strand patterns exceeds the capacity of a single plan sheet using the standard table. Supplemental detai ls and modifications are permitted if special conditions require dimensions, details or notes. However, the "FLORIDA
• Standard Plan s Instructions Topic No. 625
• - U Beams Prepare a Framing Plan for bridges meeting the criteria stated in the SDM. Show Stay
• - Place Metal Form details for the forms within the individual Florida
• - U Beams. Design and detail a thickened deck edge beam at deck expansion joints between individual Florida
• Standard Plan s Instructions Topic No. 625
• - U Beams Standard Plan s Instructions Topic No. 625