AASHTO Asset Management Task Force
NCHRP 20-7
Proposed Research Needs Statement
AASHTO Subcommittee on Bridges and Structures
Chair, Gregg Fredrick, Wyoming Department of Transportation
June 2014
TITLE
Guidelines for Design and Construction of Temporary Bridges
BACKGROUND / NEEDS STATEMENT
Temporary bridges are often desired to maintain traffic during bridge reconstruction projects and are also utilized on an emergency basis to accommodate structures that are taken out of service by unforeseen circumstances such as nature or vehicular collisions. From a national perspective, the design and construction criteria for temporary bridges is an inconsistent practice among agencies. Some agencies have special provisions covering this work, while other agencies have no such provisions. Design of temporary bridges in accordance with the current AASHTO LRFD Bridge Design Specification or alternative specifications may result in potential over/under design for the following areas:
• Satisfying the Fatigue Limit State, and specifying details with infinite fatigue life, or a specified number of cycles;
• Satisfying the Extreme Event Limit State for seismic, wind, stream, and vessel impacts, where the bridge is not anticipated to be in service for a particular event recurrence interval;
• Satisfying exterior beam, deck overhang, and parapet loading criteria;
• Satisfying bridge width, striping, and end treatment criteria;
• Long term creep or prestressing losses in concrete elements;
• Design of foundations for contraction scour, local scour and long term scour, and required hydraulic opening for a given design flood event;
• Live Load requirements, including special and routinely permitted vehicle classes;
• Inspection frequency and coding requirements subject to NBI compliance;
• Load rating requirements;
• Limited traffic for temporary bridges where certain vehicles are restricted from use
It is also desirable to provide definitions and requirements to address the anticipated service durations for “temporary” and “interim” bridges - given that these durations may vary considerably, and may require the need for different structural and safety performance. The need to define requirements regarding single-use temporary bridges/components versus multiple deployment temporary bridges/components also exists.
Obtaining a national perspective of the current design and construction requirements used by agencies for the procurement of temporary bridges may lead to the development of a more consistent and unified set of performance based criteria. To achieve this goal, focused analytical studies of existing temporary bridge specifications along with comparisons to AASHTO LRFD Bridge Design Specifications, 17th Edition Standard Specifications, and the AASHTO Guide Design Specifications for Bridge Temporary Works will need to be performed.
RESEARCH OBJECTIVE
The objective of this research is to synthesize the design and construction criteria that are used to procure temporary structures to develop an AASHTO based document for temporary bridge structures. This guideline will provide more consistency in the reliability and performance of temporary bridges, and offer agencies with economically feasible options that will eliminate the concerns of under/over designed temporary structures.
WORK TASKS
Tasks anticipated in this project include the following:
• Solicit individual agencies or manufacturers and compile temporary bridge design and construction specifications.
• Investigate the applicability of various AASHTO bridge design specifications for temporary bridges such as:
o AASHTO LRFD Bridge Design Specification
o AASHTO 17th Edition Standard Specifications for Bridge Design
o AASHTO Guide Design Specifications for Bridge Temporary Works
• Develop design and construction requirements, identify materials and create definitions for the classes of temporary bridges based on anticipated service duration.
• Recommend future guidelines for the selection, design and construction of temporary bridges.
URGENCY
Owners, Designers, Contractors and Suppliers will have the information they need to make better informed decisions regarding the design, construction, and specifications for temporary bridges that are economically feasible and perform as intended. Focused analytical studies are needed to develop these required guidelines.
FUNDING REQUESTED AND TIME REQUIRED
It is estimated that this research will take 12 months to complete and will require $100,000.
CONTACT PERSON
Carmen Swanwick, P.E.
Chair, T-4 Technical Committee for Bridge Construction
Chief Structural Engineer
Utah Department of Transportation
4501 South 2700 West
P.O. Box 148470
Salt Lake City, Utah 84114-8470
Phone: 801-965-4981
E-mail: cswanwick@
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.