BRASS-GIRDER ™ : Version 7.1 October 2013
This program is current with the AASHTO Standard Specifications for Highway Bridges, 17th Edition, 2002 and the AASHTO LRFD Bridge Design Specifications, Sixth Edition, 2012, with 2013 Interim Revisions. Load Factor analysis is supported for steel, reinforced concrete, and prestressed concrete structures. Allowable Stress analysis is supported for timber. Load and Resistance Factor analysis is supported for steel, reinforced concrete, prestressed concrete, and timber structures. The corresponding rating modules are current with the AASHTO Manual for Bridge Evaluation, Second Edition, 2010, with 2011 and 2013 Interim Revisions.
BRASS-GIRDER™ is a comprehensive system for the analysis and rating of highway bridge girders. The program utilizes finite element theory of analysis and current AASHTO Load Resistance Factor Design (LRFD) specifications. Input and output may be created using English Units. The program computes moments, shears, axial forces, deflections and rotations caused by dead loads, live loads, settlements and temperature changes. These actions are utilized by various subroutines to analyze user-specified sections of the girder.
Girder types may be simple span, continuous, hinged or cantilevered - with or without integral leg frame configuration. Girders may be constructed of steel, reinforced concrete, prestressed concrete (pre- and post-tensioned), and timber. Composite steel and composite prestressed concrete girders may be included.
BRASS can analyze variable depth girders, such as tapered or parabolic. The bridge configuration may be specified by limits of typical cross-sectional elements such as flanges, webs, cover plates, angles, etc. and by the bridge deck cross section. The web depth variation may be linear, parabolic, elliptic, or in steps. The cross section at any point along a span is a combination of the properties of the section and the web depth at that location.
The user may specify (by name) predefined cross sections that are stored in the cross section library. The library contains nearly all AISC rolled wide flange shapes and most AASHTO standard shapes for prestressed concrete I-beams. Using the Library Utility program, the user may modify the geometry of the existing sections, add new sections, or delete existing sections.
Staged construction may be modeled by respective cycles of the system for girder configuration and load application. Cycles are automatic if desired.
The dead load of structure members is automatically calculated if desired. Additional distributed loads and point loads may be applied in groups and each group assigned to a specific construction stage. Distributed loads may be uniform or tapered and divided into sections to model sequential slab pours. Loads due to prestressing are calculated and applied internally.
Live loads may be moving trucks or uniform lanes loads, which include the HL-93 vehicles described in the AASHTO LRFD specifications. A truck may have up to 24 axles. Up to 80 axles per truck may be input when using the Special Vehicles tab in the user interface. Up to 100 vehicles may be analyzed in one run. Dynamic load allowance (impact) may be user-defined, as specified by AASHTO, or the user may reduce impact to model reduced speed limits.
Prestressed girder features:
- Simple span for dead load, continuous span for live load.
- Straight, harped or parabolic tendon paths.
- Secondary moments due to creep and shrinkage.
- Stress relaxation of steel strand is accounted for as a function of time.
- Effects of temperature change can be analyzed at any stage.
- Support conditions can change from stage to stage.
- Results of individual loads may be obtained.
- Composite girders may be analyzed.
Operating System Microsoft Windows™ XP (SP2 or SP3), Vista, 7, or 8.
Microprocessor Pentium IV or higher
Microsoft .NET Framework 4.0
Memory 16 MB required, more is better
Hard Disk Space Approximately 143 MB
Disk Drive DVD drive