AASHTO LOAD AND RESISTANCE FACTOR “LRFD” BRIDGE DESIGN SPECIFICATIONS
LRFD IMPLEMENTATION BY OHIO DEPARTMENT OF TRANSPORTATION
1. All new bridges on which States initiate preliminary engineering after October 1, 2007, shall be designed by the LRFD Specifications. http://www.fhwa.dot.gov/bridge/lrfd/index.htm
2. All new culverts, retaining walls, and other standard structures on which States initiate preliminary engineering after October 1, 2010, shall be designed by LRFD Specifications, with the assumption that the specifications and software for these structures are "mature" at this time. http://www.fhwa.dot.gov/bridge/lrfd/index.htm
3. States unable to meet these dates will provide justification and a schedule for completing the transition to LRFD. http://www.fhwa.dot.gov/bridge/lrfd/index.htm
4. For modifications to existing structures, States would have the option of using LRFD Specifications or the specifications which were used for the original design. http://www.fhwa.dot.gov/bridge/lrfd/index.htm
http://www.dot.state.oh.us/se/
1. Major Projects as defined by the PDP – Projects starting Step 6 after July 20, 2007 shall have the structures designed using the LRFD Bridge Specifications.
2. Minor Projects as defined by the PDP – Projects starting Step 3 after July 20, 2007 shall have the structures designed using the LRFD Bridge Specifications.
3. Minimal Projects as defined by the PDP – Projects starting Step 1 after July 20, 2007 shall have the structures designed using the LRFD Bridge Specifications.
Local projects using the Federal Aid and the ODOT PDP process shall have the structures designed using the LRFD Bridge Specifications after October 1, 2007 .
This commitment does not apply to the rehabilitation of existing structures. Until further notice, the design for rehabilitation of existing structures should be in accordance with the AASHTO Standard Specifications for Highway Bridges, 17th Edition, and the ODOT Bridge Design Manual.
This commitment does not apply to the rehabilitation of existing structures. Until further notice, the design for rehabilitation of existing structures should be in accordance with the AASHTO Standard Specifications for Highway Bridges, 17th Edition, and the ODOT Bridge Design Manual.
The Department’s Consultants Committee has decided that completion of specific training courses will not be a prequalification requirement. However, beginning immediately all website This commitment does not apply to the postings for new consultant contracts that include rehabilitation of existing structures. Until bridge design will include a requirement to address the training and experience (in LRFD) of further notice, the design for rehabilitation the proposed staff. of existing structures should be in accordance with the AASHTO Standard Additionally, firms with current contracts that will Specifications for Highway Bridges, 17th require LRFD as a result of the project Edition, and the ODOT Bridge Design development schedule will be required to Manual. demonstrate an adequate combination of training and experience in the new design methods.
ODOT LOAD AND RESISTANCE FACTOR DESIGN TRAINING COURSES
LRFD Loads & General Overview
Reinforced Concrete Design Prestressed Concrete Design Steel Design
Foundation Design
ONLINE REGISTRATION
LRFD BRIDGE DESIGN SPECIFICATIONS AND THE 2007 ODOT BRIDGE DESIGN MANUAL
BDM SECTION 1000: LISTS AND ADDRESSES THE EXCEPTIONS TAKEN BY THE OhioDOT TO THE LRFD BRIDGE DESIGN SPECIFICATIONS
LOADS, LOAD COMBINATIONS AND LIMIT STATES
Load Definitions Permanent Loads • DD - Downdrag • EH - Horizontal Earth Pressure • DC - Structural Components and Attachments • EL - Locked-In Force Effects Including Pretension • DW - Wearing Surfaces and Utilities • ES - Earth Surcharge Load • EV - Vertical Pressure of Earth Fill
Load Definitions Transient Loads • BR - Veh. Braking Force • LS - Live Load Surcharge • PL - Pedestrian Live Load • CE - Veh. Centrifugal Force • SE - Settlement • CR - Creep • SH - Shrinkage • CT - Veh. Collision Force • TG - Temperature Gradient • CV - Vessel Collision Force • TU - Uniform Temperature • EQ - Earthquake • WA - Water Load • FR - Friction • WL - Wind on Live Load • IC - Ice Load • WS - Wind Load on Structure • LL - Veh. Live Load • IM - Dynamic Load Allowance
STANDARD SPECIFICATIONS LIVE LOAD MODEL
LRFD LIVE LOAD MODEL
Load Combinations and Load Factors DC Use One of These at a Time DD LL DW IM EH CE EV BR TU Load ES PL CR EQ IC CT CV Combination EL LS WA WS WL FR SH TG SE γ p γ tg γ se Strength I 1.75 1.00 --- --- 1.00 0.50/1.20 --- --- --- --- γ p γ tg γ se Strength II 1.35 1.00 --- --- 1.00 0.50/1.20 --- --- --- --- γ p γ tg γ se Strength III --- 1.00 1.40 --- 1.00 0.50/1.20 --- --- --- --- γ p Strength IV --- 1.00 --- --- 1.00 0.50/1.20 --- --- --- --- --- --- γ p γ tg γ se Strength V 1.35 1.00 0.40 1.00 1.00 0.50/1.20 --- --- --- --- γ p γ eq Ext Event I 1.00 --- --- 1.00 --- --- --- 1.00 --- --- --- γ p Ext Event II 0.50 1.00 --- --- 1.00 --- --- --- --- 1.00 1.00 1.00 γ tg γ se Service I 1.00 1.00 1.00 0.30 1.00 1.00 1.00/1.20 --- --- --- --- Service II 1.00 1.30 1.00 --- --- 1.00 1.00/1.20 --- --- --- --- --- --- γ tg γ se Service III 1.00 0.80 1.00 --- --- 1.00 1.00/1.20 --- --- --- --- Service IV 1.00 --- 1.00 0.70 --- 1.00 1.00/1.20 --- 1.00 --- --- --- --- Fatigue --- 0.75 --- --- --- --- --- --- --- --- --- --- ---
Load Combination Descriptions • Strength I: Basic load combination relating to the normal vehicular use of the bridge without wind. • Strength II: Load combination relating to the use of the bridge by Owner-specified special design vehicles, evaluation permit vehicles, or both, without wind. • Strength III: Load combination relating to the bridge exposed to wind in excess of 55 mph. • Strength IV: Load combination relating to very high dead load to live load force effect ratios. • Strength V: Load combination relating to normal vehicular use with a wind of 55 mph.
Load Combination Descriptions • Extreme Event I: Load combination including earthquakes. • Extreme Event II: Load combination relating to ice load, collision by vessels and vehicles, and certain hydraulic events with a reduced live load.
Load Combination Descriptions • Service I: Load combination relating to normal operational use of the bridge with a 55 mph wind and all loads at nominal values. • Service II: Load combination intended to control yielding of steel structures and slip of slip-critical connections due to vehicular load. • Service III: Load combination relating only to tension in prestressed concrete superstructures with the objective of crack control. • Service IV: Load combination relating only to tension in prestressed concrete columns with the objective of crack control.
Load Combination Descriptions • Fatigue: Fatigue and fracture load combination relating to repetitive gravitational vehicular live load and dynamic responses under a single design truck.
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