FDOT Standard Plans Index 450-010: Series Prestressed Florida - I 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 - 010 is the lead standard for the Prestressed Florida - I Beam standard series which includes Indexes 450 - 010 through 450 - 0 96. Use this standard with Indexes 450 - 0 36, 450 - 0 45, 450 - 0 54, 450 - 0 63, 450 - 072 , 450 - 078 , 450 - 0 84, 450 - 0 96, 450 - 199, 400 - 510 , and 450 - 511 or 450 - 512. These Indexes 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 Indexes and the supplemental 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 450 - 199 , 400 - 510 , and 450 - 511 or 450 - 512 must also be completed and included in the plans. The use of End Diaphragms is not preferred on simple span, pretensioned, Florida - 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 widening 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 Florida - I Beam structures. 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 or back - to - back diaphragms are present. For d etailing purposes, Prestressed Florida - I Beams are assumed to be erected plumb.

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 450 - 010 and the appropriate Standard Detail Drawings 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: Design Standard Instructions Topic No. 625 - 010 - 003 Index 450 - 010 Series Prestressed Florida - I Beams Index No. Beam Type Max.

Bonded Prestress Force Last Revision Date 45 0 - 036 Florida - I 36 1450 Kips 07/01/09 45 0 - 045 Florida - I 45 1670 Kips 07/01/09 45 0 - 054 Florida - I 54 1740 Kips 07/01/09 45 0 - 063 Florida - I 63 1740 Kips 07/01/09 45 0 - 072 Florida - I 72 1980 Kips 07/01/09 45 0 - 078 Florida - I 78 2230 Kips 07/01/09 45 0 - 084 Florida - I 84 2375 Kips 07/01/10 45 0 - 096 Florida - I 96 2375 Kips 07/01/10 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. Embedded Bearing Plates are required for all beams. If the beam grade exceeds 2%, provide Beveled Bearing Plates at each end of the beam as shown in Index 450 - 511 or Index 450 - 512 .

Prestressed Beam Suppliers typically utilize side forms for casting which are not easily or economically modified. If modifications to beam cross - sections are required for any reason other than haunched sections, maintain profile dimensions of the form. Fo r example: To thicken the web, increase the spacing between side forms.

To increase the beam height, increase the thickness of the top flange. In any case, do not reduce the standard thickness of either the top or bottom flange. See additional instructions in the SDG .

Payment

Payment Item number Item Description Unit Measure 450 - 2 - AAA Prestressed Beams: Florida - I Beam LF Example Problem The following example shows the data required for completion of a Florida - I Beam Table of Beam Variables. The example assumes a three span bridge with Florida - I 45 Beams designed for the following conditions: Live Load: HL - 93 No intermediate Diaphragms Stay - in - Place Metal Forms: Allowance of 20 PSF non - composite dead load over the projected plan area of the forms (this includes the unit weight of metal forms and the concrete required to fill the form flutes). Environment (Superstructure): Moderately Aggressive Bridge Characteristics: Length: 276 ft.

Width: 51' - 1" (out - to - out) Clear Roadway: 48 ft. Superstructure: Three simple spans of prestressed concrete beams with 8 - inch composite deck slab (plus ½" sacrificial deck thickness) Span: 87' - 0", 102' - 0", 87' - 0" Sidewalk: None Horizontal Alignment: Straight Vertical Alignment: 0.00% Grade Skew Angle: 15 degrees (Right) Beam Design: Beam: Florida - I 45 Beam Spacing: 11' - 3", 87' Span (5 Beams) 9' - 0", 102' Span (6 Beams) Design Span Length: 84' - 6" (Spans 1 & 3) 99' - 8" (Span 2) Standard Plan s Instructions Topic No. 625 - 010 - 003 Index 450 - 010 Series Prestressed Florida - I Beams Standard Plan s Instructions Topic No.

625 - 010 - 003 Index 450 - 010 Series Prestressed Florida - I Beams

Design Aids

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

2 ) Perimeter (in.) Ixx (in. 4 ) Iyy (in. 4 ) y t (in.) y b (in.) FIB - 36 806.58 206.57 127,545 81,070 19.51 16.49 FIB - 45 869.58 224.57 226,581 81,327 24.79 20.21 FIB - 54 932.58 242.57 359,929 81,584 29.96 24.04 FIB - 63 995.58 260.57 530,313 81,842 35.04 27.96 FIB - 72 1,058.58 278.57 740,416 82,099 40.06 31.94 FIB - 78 1,100.58 290.57 903,861 82,270 43.37 34.63 FIB - 84 1,142.58 302.57 1.087 x 10 6 82,442 46.66 37.34 FIB - 96 1,226.58 326.57 1.515 x 10 6 82,785 53.18 42.82

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
• - TABLE OF BEAM VARIABLES" itself should not be modified. See FDM 115 for more information regarding use of Data Tables. Report elastic and time dependent shortening effects (DIM R) at mid
• - height of the beam @ 120 days. The average of the calculated values for the top and bottom of the beam may be used. Report DIM P for beams placed on grade if the calculated value is equal or greater than 1" using ⅛" increments. Also consider the effect of beam end rotations for Florida
• - I 84 and 96 beams, if significant. Different “P” dimensions at each end may be necess ary for accommodating these effects, which will require modifying the "FLORIDA
• - TABLE OF BEAM VARIABLES" using suggested DIM P1 and DIM P2.
• Design Standard Instructions Topic No. 625
• - 010 Series Prestressed Florida
• - 010 and the appropriate Index associated with the specific beam height and include them 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.
• - outs and details to ensure proper placement of Bars 4L as shown in the 2010 Design Standards Index 20010 Series Interim s Dated 01/01/10 (Effective Date: July 1, 2010). Detail the number of bars, bar locations and bar bending diagrams .
• Standard Plan s Instructions Topic No. 625
• - 010 Series Prestressed Florida
• - I Beams Standard Plan Instructions Topic No. 625
• - 010 Series Prestressed Florida