FDOT Modifications to LRFR 
Jan 2009 


6.1.7.1 Design Load RatingReplace the 3rd sentence of the 1st paragraph with the following: Under this check, bridges are screened for both the strength and service limit states. Delete the 4th and 5th sentences of the 1st paragraph. Replace the 2nd sentence of the second paragraph with the following: Bridges that have a design load rating factor equal to or greater than 1.0 at the operating level will have satisfactory load rating for all three Florida legal loads. 

6.1.7.2 Legal Load RatingReplace the 3rd sentence of the 1st paragraph with the following: Using this check, bridges are screened for both the strength and service limit states as noted in Table 61. Delete the 4th and 5th sentences of the 1st paragraph. 

6.1.8 ComponentSpecific EvaluationAdd the following: Bridges may contain local details that must be appropriately designed to carry local loads or distribute forces to the main bridge components (beams). Although forces in these details can vary as a function of the applied live loads (with the exception of inspan beam splices), it is recommended that they not be included in the load rating. Rather, the capacities of such details should be check only for critical loads or ratings and then only if there is evidence of distress (e.g. cracks). 
C6.1.8 Add the following: Important local details in concrete bridges include diaphragms and details, such as corbels, that support expansion joint devices and anchorages for posttensioning tendons. The behavior of these details and the forces to which they are subjected may be determined by appropriate models or hand calculations. Analysis methods and design procedures are available in LRFD (e.g. strut and tie analysis). 
6.1.8.3 DiaphragmsThe main purpose of transverse diaphragms is to provide lateral stability to girders during construction and wind loading. Transverse diaphragms themselves need not be analyzed as part of a routine load rating. Only if there is evidence of distress (e.g. efflorescence, rust stains or buckling), or at the discretion of the engineer, should it be necessary to more closely consider the forces and stresses in a diaphragm. The stiffness of any transverse diaphragms should be included, if significant and appropriate, in any finite element analysis program used to establish Live Load Distribution Factors. 

6.1.8.4 Support for Expansion Joint DevicesExpansion joint devices are usually contained in a recess formed in the top of the end of the top slab and transverse diaphragm. Occasionally, depending upon the need to accommodate other details, such as drainage systems, this may involve a corbel  usually as a contiguous part of the expansion joint diaphragm. It is not necessary to analyze such a detail for routine load rating. Only if there is evidence of distress (e.g. cracks, efflorescence or rust stains), or at the discretion of the engineer, should it be necessary to more closely consider the forces and stresses in such a detail. 

6.1.8.5 Anchorages for PostTensioning TendonsAnchorages are normally contained in a widened portion of the web at the ends of a beam. It is not necessary to analyze anchorage details for routine load rating. Only if there is evidence of distress (e.g. cracks, efflorescence or rust stains) should it be necessary to more closely consider the forces and stresses in such a detail itself. Changes in the gross section properties at anchor block zones should be properly accounted for in any finite element analysis program used to establish principal tension/bursting. 

6.1.8.6 Post Tensioned Concrete Beam Splices within a SpanBeam splices within a span are frequently used to connect portions of continuous girders. Such splices usually require reinforcing bars projecting from the ends of the precast beams and into a reinforced, castinplace transverse diaphragm. Longitudinal posttensioning ducts are connected and tendons pass through the splice. Beam splices are typically near inflection points; consequently, live load effects may induce longitudinal tensile stress in the top or bottom. Therefore, the longitudinal tendons are approximately concentric, i.e. at middepth of the composite section. It is necessary to check longitudinal flexure and shear effects at inspan beam splices. 

6.1.8.7 Post Tensioned Concrete Beam Dapped Hinges within a SpanDapped hinges are rarely used in beam bridges in Florida. Forces acting through dapped hinges within a span should be calculated for statically determinate structures or be determined as a part of the timedependent construction analysis for indeterminate structures. Maximum live load reactions should also be calculated. Once all reaction forces are known, local analyses should be performed to develop the hinge forces into the main beam components using suitable strutandtie techniques. An alternate approach would be to develop threedimensional finite element models to analyze the flow of forces. 

6.1.8.8 Bascule BridgesWhen evaluating Bascule Bridges, assume the main girders act as a cantilever without any benefit from the span locking device. 

6.1.8.9 Gusset Plates on Truss BridgesWhen evaluating new and existing truss bridges with gusset plates, follow FHWA Technical Advisory T 5140.29 "Loadcarrying Capacity Considerations of Gusset Plates in NonLoadpathredundant Steel Truss Bridges." 

6.2 LOADS FOR EVALUATION 

6.2.3 Transient Loads6.2.3.1 Vehicular Live Loads (Gravity Loads): LLReplace the vehicles given after Legal Loads: with the following: Florida Legal Loads (SU4, C5, and ST5, see 6.4.4.2.1 for vehicle configurations). Replace the vehicle given after Permit Loads: with the following: Florida Permit Load (FL120, see 6.4.5.4.2.1 for vehicle configurations). For new bridges the minimum rating factor for the FL120 is 1.0. 
C6.2.3.1 Add the following: For simple span bridges, see figure C64 for a comparison of legal loads and HL93.

6.3 STRUCTURAL ANALYSIS 

Add the following: Transverse and longitudinal ratings shall be reported for posttensioned concrete segmental bridges. All bridge decks designed with transverse prestressing require transverse ratings. For all other bridges, only longitudinal ratings are typically required. 

6.3.2 Approximate Methods of Structural AnalysisAdd the following: Approximate methods include onedimensional linegirder analysis using LRFD distribution factors. For bridge superstructures meeting the requirements of LRFD 4.6.2.2, use the approximate live load distribution factors in the initial load rating. For bridges constructed with composite prestressed deck panels, the live load distribution factors will be increased by a factor of 1.1 thus increasing the load and reducing the capacity. 
C6.3.2 Add the following: Deck superstructures, utilizing composite prestressed deck panels have performed poorly. The deck cracked around the perimeter of the panel and the deck stiffness is softened therefore, a reduction in stiffness occurs. If conditions are severe, the live load distribution can be calculated as if the deck panels are simple supported on the girders. 
6.3.3 Refined Methods of AnalysisAdd the following: Refined methods of analysis include two or three dimensional models using grid or finiteelement analysis. All analyses will be performed assuming no benefit from the stiffening effects of any traffic railing barrier or other appurtenances. When a refined method of analysis is used, indicate the name, version, and date of the software used on the FDOT Load Rating Summary Tables. 
C6.3.3 Delete the second paragraph of the commentary in its entirety 
6.4 LOAD RATING PROCEDURES 

6.4.2 General Load Rating Equation (07/07)Add the following: When calculating the Service Limit State capacity for prestressed concrete flat slabs and girders with bonded tendons/strands, use transformed section properties when calculating stresses before losses (at transfer) and after losses (including loss of prestress.) 
C6.4.2 Add the following: For a detailed explanation of stress calculations in prestressed concrete girders, see NCHRP 496. The correct use of transformed section properties for calculation of prestress losses is essential for the precise calculation of stresses at service limit state. 
6.4.2.2 Limit StatesReplace Table 61 with FDOT Table 61 

6.4.2.3 Condition FactorDelete the first sentence. Add the following after Table 62: The Florida DOT prefers load ratings be performed taking account of field measured deterioration. However, in the absence of measurements, global condition factors shall be used. 

6.4.2.4 System FactorDelete the third paragraph. Replace Table 63 with FDOT Tables 63A, B, C and D. Replace the second paragraph with the following: The system factors of FDOT Tables 63A, 63B, 63C, and 63D shall apply for flexural and axial effects at the Strength limit states. Higher values than those tabulated may be considered on a casebycase basis with the approval of the Department. System factors need not be less than 0.85. In no case shall the system factor exceed 1.3. 

6.4.4 Legal Load Ratings6.4.4.1 PurposeReplace the 1st sentence of the 1st paragraph with the following: Bridges that do not have sufficient capacity under the designload rating operating level (i.e. RF 1.0 or less) shall be load rated for the SU4, C5, and ST5 legal loads to establish the potential need for load posting or strengthening. 

6.4.4.2.1 Live Loads (01/09)Replace this article with the following: For all span lengths, the critical load effects shall be created by:
In addition, for span lengths greater than 200 ft., critical load effects shall be created by:
Dynamic load allowance shall be applied to the legal vehicles and not the lane loads. 

6.4.4.2.3 Generalized Live Load FactorsRevise Table 65 as follows: For all Traffic Volumes, revise all Load Factors to 1.35. 
C6.4.4.2.3 Add the following: The LRFD HL93 liveload model envelopes FDOT legal loads. As such, if the live load factor of 1.35 for the designload operating rating yields a reliability index consistent with traditional operating ratings, this live load factor can be used for legalload rating of the FDOT legal loads. Live load factors for FDOT legal loads are not specified as a function of ADTT. 
Figure 63 

Bridge Type 
Direction 
Limit State 
Load Factors 

Permanent Load 
Transient Load 
Design Load 
Legal Load 
Permit Load  
DC 
DW 
EL 
FR 
TU(2) CR SH 
TG(2) 
Inventory 
Operating 

LL 
LL 
LL 
LL  
Steel 
Longitudinal 
Strength I 
1.25 
1.50 
n/a 
n/a 
n/a 
n/a 
1.75 
1.35 
1.35 
n/a 
Strength II 
1.25 
1.50 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
1.35  
Service II (3) 
1.00 
1.00 
n/a 
n/a 
n/a 
n/a 
1.30 
1.00 
1.30 
0.90  
Reinforced Concrete 
Longitudinal 
Strength I 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
1.75 
1.35 
1.35 
n/a 
Strength II 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
1.35  
Prestressed Concrete (Flat Slab and Deck/Girder) 
Longitudinal 
Strength I 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
1.75 
1.35 
1.35 
n/a 
Strength II 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
1.35  
Service III (1) 
1.00 
1.00 
n/a 
n/a 
n/a 
n/a 
0.80 
0.80 
0.80 
0.70  
Wood 
Longitudinal 
Strength I 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
1.75 
1.35 
1.35 
n/a 
Strength II 
1.25 
1.5 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
1.35  
Posttensioned Concrete 
Longitudinal 
Strength I 
1.25 
1.5 
1.00 
1.00 
0.50 
n/a 
1.75 
1.35 
1.35 
n/a 
Strength II 
1.25 
1.5 
1.00 
1.00 
0.50 
n/a 
n/a 
n/a 
n/a 
1.35  
Service III (1) 
1.00 
1.00 
1.00 
1.00 
1.00 
0.50 
0.80 
0.80 or 1.0 SL (4) 
0.80 or 1.0 SL (4) 
0.70 or 0.90 SL (4)  
Transverse 
Strength I 
1.25 
1.50 
1.00 
n/a 
n/a 
n/a 
1.75 
1.35 
1.35 
n/a  
Strength II 
1.25 
1.50 
1.00 
n/a 
n/a 
n/a 
n/a 
n/a 
n/a 
1.35  
Service I 
1.00 
1.00 
1.00 
n/a 
n/a 
n/a 
1.00 
1.00 
1.00 
1.00  
(1) For Service III tensile stress limits, see FDOT Table 69B. 

(2) TU and TG is considered for Service I and Service III Design Inventory only. 

(3) The Service II limit state need only be checked for compact steel girders. For all other steel girders, the Strength limit states will govern. 

(4) For Igirders use a load factor of 0.8 (inventory, operating, legal) or 0.7 (permit); for segmental box girders use 0.8 (inventory) or 1.0 and striped lanes (SL) (operating and legal) or 0.9 and striped lanes (SL) (permit). 
FDOT Table 63A General System Factors (φs) (01/09) 

Superstructure Type 
System Factors (φs) 
Rolled/Welded Members in Two Truss/Arch Bridges* 
0.85 
Riveted Members in Two Truss/Arch Bridges* 
0.90 
Multiple Eye bar Members in Truss Bridges 
0.90 
Floor beams with Spacing > 12 feet and Noncontinuous Stringers and Deck 
0.85 
Floor beams with Spacing > 12 feet and Noncontinuous Stringers but with continuous deck 
0.90 
Redundant Stringer subsystems between Floor beams 
1.00 
All beams in nonspliced concrete girder bridges 
1.00 
Steel Straddle Bents 
0.85 
* Pertains to type of builtup or rolled members not type of connection. 
FDOT Table 63B System Factors (φs) for PostTensioned Concrete Beams 

Number of Girders in Cross Section 
Span Type 
Number of Hinges Required for Mechanism 
System Factors (φs) 

Number of Tendons per Web 

1 
2 
3 
4  
2 
Interior 
3 
0.85 
0.90 
0.95 
1.00 
End 
2 
0.85 
0.85 
0.90 
0.95  
Simple 
1 
0.85 
0.85 
0.85 
0.90  
3 or 4 
Interior 
3 
1.00 
1.05 
1.10 
1.15 
End 
2 
0.95 
1.00 
1.05 
1.10  
Simple 
1 
0.90 
0.95 
1.00 
1.05  
5 or more 
Interior 
3 
1.05 
1.10 
1.15 
1.20 
End 
2 
1.00 
1.05 
1.10 
1.15  
Simple 
1 
0.95 
1.00 
1.05 
1.10  
The tabularized values above may be increased by 0.05 for spans containing more than three intermediate, evenly spaced, diaphragms in addition to the diaphragms at the end of each span. 
FDOT Table 63C System Factors (φs) for Steel Girder Bridges 

Number of Girders in Cross Section 
Span Type 
# of Hinges required for Mechanism 
System Factors (φs) 
2 
Interior 
3 
0.85 
End 
2 
0.85  
Simple 
1 
0.85  
3 or 4 
Interior 
3 
1.00 
End 
2 
0.95  
Simple 
1 
0.90  
5 or more 
Interior 
3 
1.05 
End 
2 
1.00  
Simple 
1 
0.95  
The tabularized values above may be increased by 0.10 for spans containing more than three evenly spaced intermediate diaphragms in addition to the diaphragms at the end of each span. The above tabularized values may be increased by 0.05 for riveted members 
FDOT Table 63D System Factors (φs) for Concrete Box Girder Bridges 

Bridge Type 
Span Type 
# of Hinges to Failure 
System Factors (φs) 

No. of Tendons per Web 

1/web 
2/web 
3/web 
4/web  
Precast Balanced Cantilever Type A Joints 
Interior Span End or Hinge Span Statically Determinate 
3 
0.90 
1.05 
1.15 
1.20 
2 
0.85 
1.00 
1.10 
1.15  
1 
n/a 
0.90 
1.00 
1.10  
Precast SpanbySpan Type A Joints 
Interior Span End or Hinge Span Statically Determinate 
3 
n/a 
1.00 
1.10 
1.20 
2 
n/a 
0.95 
1.05 
1.15  
1 
n/a 
n/a 
1.00 
1.10  
Precast SpanbySpan Type B Joints 
Interior Span End or Hinge Span Statically Determinate 
3 
n/a 
1.00 
1.10 
1.20 
2 
n/a 
0.95 
1.05 
1.15  
1 
n/a 
n/a 
1.00 
1.10  
CastinPlace Balanced Cantilever 
Interior Span End or Hinge Span Statically Determinate 
3 
0.90 
1.05 
1.15 
1.20 
2 
0.85 
1.00 
1.10 
1.15  
1 
n/a 
0.90 
1.00 
1.10  
For box girders with 3 or more webs, table values may be increased by 0.10. 
6.4.5 Permit Load Ratings6.4.5.1 BackgroundAdd the following: Calculate the capacity for permit trucks using one lane distribution factor for single trip permits and two or more lanes distribution factor for routine or annual permits as shown in Table 66. The two or more lanes distribution factor assumes the permit vehicle is present in all loaded lanes and LRFD live load distribution equations are used. Do not use LRFD formula 4.6.2.2.41 since mixed traffic calculations are not performed.

C6.4.5.1 Add the following: Florida has chosen to apply a service limit state rating for permitting overload vehicles using load factors that include a reduced reliability factor. The live load factor is applied to a capacity calculated with the rating vehicle placed in all lanes. The load factor was developed to simulate a rating vehicle in the rating lane with adjoining lanes filled with legal vehicles (tractor trailers). The combined effect of these loads is multiplied by the multiple presence factor of 0.9 (Ontario Bridge Code). 
6.4.5.2 PurposeAdd the following: Bridges designed after January 1, 2005 are required to have rating factors for the FL120 permit truck. Rate the FL120 for both Strength and Service Limit State. 

6.4.5.4.2 Load Factors 
C6.4.5.4.2 Add the following: Since routine permits are evaluated using the FL120 permit truck and values of ADTT are not well known, a single load factor is specified for routine permit load rating. Similarly, a single load factor is specified for singletrip permits. 
6.4.5.4.2.1 Routine (Annual) PermitsRevise Table 66 as follows: For all Permit Types, revise all the Load Factors by Permit Type to 1.35 except the escorted single trip load factor will remain 1.15. Add the following: The FL120 permit truck shall be considered as routine annual permit vehicle to be used to verify overload capacity of Florida bridges. The FL120 shall be checked at Strength Limit State and Service Limit State as noted in FDOT Table 61 and the minimum rating factor for new bridges is 1.0. For spans over 200 feet assume the FL120 permit truck with coincident 0.20 kips per foot lane load. Assume the permit trucks are in each lane; do not mix trucks. The FL120 permit truck configuration is shown in the figure below:

C6.4.5.4.2.1 Add the following: The FL120 permit truck is conceived to be a benchmark to past load factor design (LFD) practice in which the HS20 truck was rated at the operating level with a load factor of 1.3. A LRFR Permit Load rating for the FL120 permit truck equal to 1.0 is equivalent to an LFD operating rating for the HS20 truck equal to 1.67. The axle spacing of the FL120 is not changed to emulate a truck crane. It is reasonable to use the multiplelane distribution factor for the permit load rating since the force effects of the permit trucks are similar to the HL93 notional load have been shown to be very similar. Thus, this application is close to the intent of the AASHTO LRFR methodology where the HL93 is placed in remote lanes. The FL120 is intended to replicate the traditional HS20 operating rating where all lanes were occupied by the same truck. Thus, the use of multiplelane distribution factors is equally appropriate for the FL120 permit load rating.

6.4.5.5 Dynamic Load AllowanceEnd the first sentence after legal loads. Add the following: For exclusiveuse vehicles with escort and speeds less than or equal to 5 mph, IM may be decreased to 0%. 

6.4.5.8 Adjoining Lane LoadingWhen performing refined analysis for permit vehicles, combine the permit vehicle with the same permit vehicle in the adjoining lanes. For spans over 200 feet, add a 0.20 kip per foot lane load to all vehicle loadings. 

6.4.5.9 Multiple Presence FactorsFor Permit load ratings, the LRFD multiple presence factors shall be equal to or less than 1.0. 

6.5 CONCRETE STRUCTURES 

6.5.2 MaterialAdd the following: For concrete made with Florida aggregate calculate the modulus of elasticity by applying a 0.9 factor times the value found in the specifications. 

6.5.4 Limit States6.5.4.1 DesignLoad Rating (01/07)Add the following: For prestressed concrete bridges, perform PermitLoad ratings for: 1. Service I transverse compressive and tensile stress checks in the deck of transversely prestressed bridges. 2. Service III tensile stress checks in the longitudinal direction of all prestressed concrete bridges.
The stress limits given in FDOT Table 69B shall be satisfied by all prestressed concrete bridges.
Prestressed deck/girder bridges with a continuous deck but without continuous girders shall be load rated as simple spans. 
C6.5.4.1 Delete the first sentence of the commentary. 
6.5.4.2 Legal Load Rating and Permit Load Rating6.5.4.2.2.1 Legal load RatingDelete both sentences and replace with the following: Legal load rating of prestressed concrete bridges is based on satisfying strength and service limit states (see FDOT Table 61) 
C6.5.4.2.2.1 Delete the entire commentary.



FDOT Table 69B Stress Limits for Prestressed Concrete Bridges 

Condition 
Design Inventory 
Design Operating, Legal, and Permit 
Compressive Stress  All Bridges (Longitudinal or Transverse) 

Compressive stress under effective prestress, permanent loads, and transient loads (Allowable compressive stress shall be reduced according to LRFD 5.9.4.2.1 when slenderness of flange or web is greater than 15) 
0.60f'c 
0.60f'c 
Longitudinal Tensile Stress in Precompressed Tensile Zone  Nonsegmental Bridges (including PostTensioned IGirders) 

For components with bonded prestressing tendons or reinforcement that are subject to not worse than: 


(a) an extremely aggressive corrosion environment. 
3√f'c psi 
7.5√f'c psi 
(b) slightly or moderately aggressive corrosion environments. 
6√f'c psi 
7.5√f'c psi 
Longitudinal Tensile Stress in Precompressed Tensile Zone  Segmental Box Girder Bridges 

For components with bonded prestressing tendons or reinforcement that are subject to not worse than: 


(a) an extremely aggressive corrosion environment. 
3√f'c psi 
3√f'c psi 
(b) slightly or moderately aggressive corrosion environments. 
6√f'c psi 
6√f'c psi 
For components with unbonded prestressing tendons 
No Tension 
No Tension 
For components with Type B joints (dry joints, no epoxy) 
100 psi comp 
No Tension 
Tensile Stress in Other Areas  Segmental Box Girder Bridges: 

Areas without bonded reinforcement 
No tension 
No tension 
Areas with bonded reinforcement sufficient to carry the tensile force in the concrete calculated on the assumption of an uncracked section is provided at a stress of 0.5fy (<30 ksi) 
6√f'c psi tension 
6√f'c psi tension 
Transverse Tension, Bonded PT  Segmental Box Girder Bridges: 

Tension in the transverse direction in the precompressed tensile zone calculated on the basis of an uncracked section (i.e. top prestressed slab) for: 


(a) an extremely aggressive corrosion environment 
3√f'c psi 
6√f'c psi 
(b) slightly or moderately aggressive corrosion environments 
6√f'c psi 
6√f'c psi 
Principal Tensile Stress at Neutral Axis in Webs  Segmental Box Girder Bridges: 

All types of segmental construction with internal and/or external tendons. 
3.5√f'c psi tension 
3.5√f'c psi tension 
6.5.4.2.2.2 Permit load RatingDelete the first sentence and replace with the following: Permit load rating of prestressed concrete bridges is based on satisfying Strength and Service limit states (see FDOT Table 61). Delete the second paragraph. 
C6.5.4.2.2.2 Delete the first and second paragraphs. Florida has elected to use a service limit state for permit analysis and has removed the check for stress in the reinforcing at the strength limit state. 
6.5.7 Minimum Reinforcement (07/07)Delete equation 64 and use LRFD Equation 5.7.3.3.21. Add the following: See SDG 4.1.5 for clarification of the appropriate application of minimum reinforcing at the ends of simply supported bridge girders. 

6.5.9 Evaluation for Shear (01/09)Delete the second sentence and replace with the following: Design and legal loads shall be checked for shear. Add the following: For shear load rating using the Strength Load Combinations I & II, use the area of stirrup reinforcement intersecting the plane created by the theta (q ) angle. The plane will extend a distance of 0.5 dv cot ( q ) either side of the design section under review but not past the centerline of the bearing. This concept is shown in LRFD [Figure C5.8.3.22]. 

6.5.12 Temperature, Creep and Shrinkage EffectsDelete the sentence and replace with the following: At the service limit state, all prestressed concrete bridges shall include the effect of uniform temperature (TU), when appropriate), creep (CR), and shrinkage (SH). In addition, temperature gradient (TG) shall be included for posttensioned beam and box girder structures. See FDOT Table 61 for clarification. 



6.6 STEEL STRUCTURES 

6.6.1 Limit States (07/07) 

6.6.4 Limit States6.6.4.1 DesignLoad RatingDelete both paragraphs and replace with the following: Bridges shall not be rated for fatigue. If the fatigue crack growth is anticipated, Section 7 of the Guide Manual for Condition Evaluation and Load and Resistance Factor Rating of Highway Bridges can be used to estimate the remaining fatigue life. 
C6.6.4.1 Add the Following: The estimate of the remaining fatigue life of Section 7 of the Guide Manual requires a historical record of past truck traffic in terms of average daily truck traffic (ADTT) and projected future traffic. Many times, conservative recreation and projection of traffic volumes produces a worst case scenario which results in low remaining fatigue lives or totally exhausted fatigue lives. As fatigue life estimates are based upon statistical evaluation of laboratory tests, different levels of confidence are presented in Section 7. The minimum expected fatigue life, the evaluation fatigue life and the mean fatigue life are based upon approximately 98%, 85% and 50% probabilities of cracking, respectively. Judgment must be used in evaluating the results of the fatiguelife estimates. 
6.6.13 FractureCritical Members (FCMs)As with all other steel members, the appropriate system factors of FDOT Tables 63A or 63C shall be applied in the ratings of FCMs. Steel members which are traditionally classified as FCMs may be declassified through analysis if the material satisfies the FCM fracturetoughness of LRFD Table 6.6.22. After the approval of an exception based upon an approved refined analysis demonstrating that the bridge with the fractured member can continue to carry a significant portion of the design load, the member may be declassified and treated as a redundant member. See LRFD Article C6.6.2. After declassification, the member may be rated using a system factor of 1.0. 
C6.6.13 (new) Only FCMs which are fabricated from material meeting the FCM fracturetoughness requirements are candidates for declassification. Newer bridges designed, fabricated and constructed since the concept of FCMs was introduced should meet this material requirement. The demonstration of nonfracture criticality must include an analysis of the damaged bridge with the member in question fractured and a corresponding dynamic load representing the energy release of the fracture. Acceptable remaining load carrying capacity may be considered equal to the full factored load of the strength I load combination associated with the number of striped lanes. 
6.6.14 DoubleLeaf Bascule with Span LocksEvaluate all appropriate load combinations at Strength Limit State II. Apply the full load to the cantilever leaf of the bascule bridge assuming the span locks are not engaged to transmit live load to the opposite leaf. 

6.8 POSTING OF BRIDGES 

Add the following: Posting avoidance is the application of engineering judgment to a load rating by modifying the specification defined procedures through use of variances and exceptions. 

6.8.3 Posting Analysis (01/07)Add the following before the existing text: Before weight limit posting is recommended, posting avoidance strategies should be discussed and approved by the FDOT and may require additional analysis. 

A.6.1 LOAD AND RESISTANCE FACTOR RATING FLOW CHARTReplace the flowchart with FDOT Figure 61. 

A.6.2 LIMIT STATES AND LOAD FACTORS FOR LOAD RATINGDelete all three tables and use FDOT Table 61. 

B.6.2 AASHTO LEGAL LOADSDelete section a) and use the Florida legal trucks defined in article 6.4.4.2.1. 

D.6  ALTERNATE LOAD RATING 

D.6.1 GENERALAdd the following paragraph: Use the 17th Edition of the AASHTO Standard Specification with the allowable stresses shown in FDOT Table 69B. 

D.6.1.4 Application of Standard Design Specifications (01/07)Add the following before the existing text: When using the AASHTO Standard Specifications for Highway Bridges, follow explicitly the guidance in the Specifications. All deviations from the Specifications require approval by the FDOT. 

D.6.6 NOMINAL CAPACITYD.6.6.3 Load Factor MethodD.6.6.3.3 Prestressed Concrete (07/07)After the 5th RF equation, add the following heading: Operating Rating After the last paragraph, add the following: See SDG 4.1.5 for clarification of the appropriate application of minimum reinforcing at the ends for simply supported bridge girders.


D.6.7 LOADINGS 

D.6.7.2 Evaluation for ShearDelete the last sentence. 

E.6 RATING OF SEGMENTAL CONCRETE BRIDGES 

E.6.2 GENERAL RATING REQUIREMENTSAdd the following: Six features of concrete segmental bridges are to be load rated at the Design Load (Inventory and Operating) Levels. Three of these criteria are at the Service Limit State and three at the Strength Limit State, as follows: At the Service Limit State: " Longitudinal Box Girder Flexure " Transverse Top Slab Flexure " Principle Web Tension At the Strength Limit State: " Longitudinal Box Girder Flexure " Transverse Top Slab Flexure " Web Shear In accordance with AASHTO LRFR Equation 61, the general Load Rating Factor, RF, shall be determined according to the formula: 

Where: For Strength Limit States: C = Capacity = (φc x φs x φ ) Rn. φc = Condition Factor per Article 6.4.2.3. φs = System Factor per Article E.6.4.2.4. φ = Strength Reduction Factor per LRFD. Rn = Nominal member resistance as inspected, measured and calculated according to formulae in LRFD with the exception of shear, for which, capacity is calculated according to the AASHTO Guide Specification for Segmental Bridges. For Service Limit States: C = fR = Allowable stress at the Service Limit State (FDOT Table 69B). 

E.6.8 APPENDIX E6 STEPBYSTEP SUPPLEMENT 

F.6 POSTING AVOIDANCE 

G.6 LOAD RATING SUMMARY and DETAIL SHEETS (01/09) 

See Section G.6 for the Load Rating Summary detail sheets. 


