BRASS-GIRDER(STD)

BRASS-GIRDER(STD)

Girder types may be simple span, continuous, hinged or cantilevered - with or without integral leg frame configuration. Girders may be constructed of steel, timber, reinforced concrete or prestressed concrete (pre- and post-tensioned). 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 web-depth variations, girder cross sections and bridge deck cross section. One important aspect of defining cross sections is the web depth, which is defined with a span profile rather than with the cross section. This is done because the web depth of the section may vary along the length of the span and independently of cross section. This 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 a library utility program, the user may modify the geometry of the existing sections, add new sections or delete existing sections.
 
Stage 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 including AASHTO HS type trucks or AASHTO lane type loadings. A truck may have up to 24 axles. Up to 10 trucks may be analyzed in one run. Impact may be user defined, as specified by AASHTO, or the user may reduce impact to model reduced speed limits. Concurrent actions and interactions are produced.
 
Design functions are included for (1) reinforcing steel in concrete decks or girders using either working stress analysis or ultimate strength analysis. Results include bar cutoff lengths, stirrup size and spacing, (2) stiffener design on steel girders, (3) splice plate and fastener details, and (4) prestressed concrete girders.
Ratings of the maximum load carrying capacity may be determined in one run for four different stress levels: inventory, operating, posting and safe load capacity.
 
Prestressed girder features:
* Simple span for dead load, continuous span for live load.
* Straight, harped or parabolic cable 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.
 
The BRASS input language allows the bridge engineer to communicate with the problem-solving capabilities of BRASS using terminology common to the bridge engineering profession. System input is free format consisting of commands grouped logically to define the bridge structure, loads to be applied and the output desired.
 
Shown below is a typical set of commands needed to describe a bridge:

COMMAND
COMMAND ABBR NUMBER USAGE
TITLE TLE 10 Required
COMMENT COM 20 Optional
DECK-CON DCN 60 Required
DECK-MAT DMT 90 Optional
DECKC-STR1 DS1 100 Optional
DECKC-STR2 DS2 110 Optional
DECKC-DIM1 DD1 120 Required
DECKC-DIM2 DD2 130 Required
DECKC-DIM3 DD3 140 Required
DECKC-BARA DBA 180 Required
DECKC-LODG DLG 190 Optional
DECKC-LODC DLC 200 Optional
DECK-TRK1 DT1 290 Required
DECK-TRK2 DT2 300 Optional
ANALYSIS ANL 310 Required
XSECT-STD XST 340 Required
SPAN-A SPA 460 Required
SPAN-C SPC 480 Required
FIXITY FIX 500 Optional
PROPERTIES-ST1 PS1 530 Optional
DEAD-LOAD DLD 830 Required
LIVE-LOAD LLD 880 Required
TRUCK-WFR TRW 900 Optional
TRUCK-IMP TRI 910 Optional
TRUCK-CODE1 TR1 920 One or more
TRUCK-CODE2 TR2 930 of these
SPECIAL-TRUCK STR 940 are required
SPECIAL-LANE SPN 950
LANE-OUT1 LA1 960 Optional
LANE-OUT2 LA2 970 Optional
DESIGN DES 980 Required
INVENTORY INV 990 Required
STEEL-1 SL1 1030 Required
STEEL-2 SL2 1040 Required for Optional
STEEL-3 SL3 1050 each analysis Optional
STEEL-4 SL4 1060 point desired Required

The output is logically arranged and self-explanatory. The amount of detail is controlled by the user.

BEAM PROPERTIES STANDARD SECTION INPUT

SPAN NO. 1 SPAN LENGTH = 23.500 SPAN RATIO =1.000 CONSTRUCTION STAGE 1 E = 29000.KSI
WEB XSECT MOMENT OF DIST OF WIDTH OF WIDTH OF FLNG THICK FLANGE WIDTH
POINT DIST DEPTH AREA INERTIA CET (X) WEB TOP WEB BOT TOP BOT TOP BOT
1.000 0.00 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.100 2.34 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.200 4.69 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.300 7.04 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.400 9.39 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.500 11.74 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.600 14.09 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.700 16.44 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.800 18.79 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
1.900 21.14 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
2.000 23.50 19.76 14.7 984. 10.4 0.380 0.380 0.535 0.535 6.53 6.53
** GIRDER ACTIONS DUE TO APPLIED LIVE LOADS **
** CONSTRUCTION STAGE 1 **
LENGTH OF SPAN NO.1 = 23.50 FEET MAX ACTIONS AND DISPLACEMENTS FOR TRUCK NO. 1
AASHTO HS20-44 (MS 18) TRUCK
WHEEL DISTRIBUTION FACTOR = 0.876
POINT POS NEG POS NEG POS NEG POS NEG POS NEG POS NEG POS NEG
MOMENT MOMENT AXIAL AXIAL SHEAR SHEAR REACT. REACT. X X Y Y REACT. REACT.
DEF. DEF. DEF. DEF. IMPACT IMPACT
X-FT X-FT KIPS KIPS KIPS KIPS KIPS KIPS FEET FEET FEET FEET % %
1.00R 0.0 0.0 0.0 0.0 25.5 0.0 25.5 0.0 0.0000 0.0000 0.0000 0.0000 30.0000 0.0000
1.10 51.8 0.0 0.0 0.0 22.0 -1.8 0.0000 0.0000 0.0095 0.0000
1.20 86.5 0.0 0.0 0.0 18.4 -3.6 0.0000 0.0000 0.0179 0.0000
1.30 104.0 0.0 0.0 0.0 14.8 -5.5 0.0000 0.0000 0.0241 0.0000
1.40 104.4 0.0 0.0 0.0 11.1 -7.3 0.0000 0.0000 0.0277 0.0000
1.50 107.0 0.0 0.0 0.0 9.1 -9.1 0.0000 0.0000 0.0288 0.0000
1.60 104.4 0.0 0.0 0.0 7.3 -11.1 0.0000 0.0000 0.0277 0.0000
1.70 104.0 0.0 0.0 0.0 5.5 -14.8 0.0000 0.0000 0.0241 0.0000
1.80 86.5 0.0 0.0 0.0 3.6 -18.4 0.0000 0.0000 0.0179 0.0000
1.90 51.8 0.0 0.0 0.0 1.8 -22.0 0.0000 0.0000 0.0095 0.0000
1.10L 0.0 0.0 0.0 0.0 0.0 -25.5 25.5 0.0 0.0000 0.0000 0.0000 0.0000 30.0000 0.0000 

 


BRASS-GIRDER (STD) Files