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TRAP
Truss Rating and Analysis Program
| The computer program TRAP will perform an analysis
or rating group loading of a simply supported or continuous span truss
having up to six spans, in accordance with the latest AASHTO specifications.
Also, the program is capable of performing the analysis and rating of a
prestressed truss. Live load, using State of Maryland or AASHTO, is
performed automatically. In addition, a general truck configuration or rail
road loading (Cooper E60, E70, and E80) having up to 40 axles may be input
for a special posting rating analysis.
The program uses the direct stiffness
method to generate influence lines for truss member forces, cable forces,
reactions, and panel point deflections. These influence lines then are used
to determine the maximum compressive and tensile forces in each member under
the indicated live loading. Capabilities include the automatic computation
of Inventory, Operating, and Postings Ratings per AASHTO recommendations.
Output contains a verification of truss
geometry and loading input, and includes member, cable and panel point data,
truss heights, and geometric data for all members. Also included in the
output are panel point dead loads, deflections, reactions, and a force
summary due to DL + LL + I for all members. Finally, a summary of the truss
rating analysis output is given. Output of a group loading analysis and the
governing case can be obtained by inputting the appropriate program option.
Rating is allowed to use either Load
Factor (LFD) or Load and Resistance Factor (LRFD) methods, which are based
on the following criteria:
- Load and Resistance Design (LRFD)
Rating, based on the AASHTO "Guide Specifications for Strength
Evaluation of Existing Steel and Concrete Bridges," 1989 and updated
Interims;
- National Bridge Inventory (NBI) Rating,
based on the AASHTO "Manual for Condition Evaluation of Bridges,"
1994 amd updated Interims;
- Load Factor (LFD) Rating, based on the
AASHTO "Guide Specifications for Strength Design of Truss Bridges (Load
Factor Design)," 1985 and updated Interims.
- New Load and Resistance Factor Design
(LRFD) based on the AASHTO LRFD Bridge Design Specifications, 1998 - 2000
Interim Revisions.
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- Conforms to the latest AASHTO Specifications for design and Guide
Specifications for rating, Working Stress Design (WSD), Load Factor Design
(LFD), and Load and Resistance Factor Deaign (LRFD);
- Automated DL for all construction conditions including ties;
- Automated LL for AASHTO, Interstate, AREA, state specified and special
trucks, simultaneously or separately;
- All impact factors are calculated automatically, either on the basis
of the actual span length or loaded lengths (where appropriate)
- Bridge may be determinate or indeterminate and of any configuration
(e.g., deck truss, through truss, etc.);
- Maximum positive and negative effects are given for all members and
cables, reactions, and deformations;
- User-specified truck loadings;
- User can specify different levels of output;
- Influence line option;
- Combination of loads;
- Complete analysis of prestressed cable truss system;
- Complete rating for all members and all input trucks.
- Both English and S.I. Units allowed
- WINDOWS based program including Input, Run, Graphic, Print and Help
utilities.
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