V. Moving Load Generator
To validate the effect of wheel load assembly on bridge girders simulated by a series of equivalent concentrated loads for a particular wheel position, generated by Moving Load generation option.
Details
A bridge decking system of 10m span is simulated by three longitudinal girder of size 0.3m×0.6m (Concrete) at a spacing of 2m and six transverse girders of size 0.3m×0.45m (Concrete) at a spacing of 2m. Longitudinal girders are pinned support at both the ends.
Vehicle definition – 10 kN and 16 kN per wheel in the Front and Rear Axle respectively. The vehicle width is 1.2m and the axle distance is 1.5m. Starting position is from the end of the deck, aligning the rear axle along the last transverse girder. The direction of movement along the longitudinal girder with an incremental distance of 0.5m.
Validation
Among the generated wheel loads, for the 9th position of the wheel assembly, the structure is analyzed for that generated load. The structure is again analyzed with the static load system equivalent to the generated wheel load and observed the difference in results if any.
The model uses the moving load generator facility and a static load equivalent to the generated Load Case 9 (i.e., 9th position of the wheel assembly). Both support reactions and joint displacements are compared.
STAAD Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2023\Samples \Verification Models\06 Loading\Moving Load\Moving Load Generator.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 23-Apr-19
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 10 0 0; 3 2 0 0; 4 4 0 0; 5 6 0 0; 6 8 0 0; 7 0 0 2; 8 10 0 2;
9 2 0 2; 10 4 0 2; 11 6 0 2; 12 8 0 2; 13 0 0 4; 14 10 0 4; 15 2 0 4; 16 4 0 4;
17 6 0 4; 18 8 0 4;
MEMBER INCIDENCES
1 1 3; 2 3 4; 3 4 5; 4 5 6; 5 6 2; 6 1 7; 7 2 8; 8 3 9; 9 4 10; 10 5 11;
11 6 12; 12 7 9; 13 9 10; 14 10 11; 15 11 12; 16 12 8; 17 7 13; 18 8 14;
19 9 15; 20 10 16; 21 11 17; 22 12 18; 23 13 15; 24 15 16; 25 16 17; 26 17 18;
27 18 14;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 2.17185e+07
POISSON 0.17
DENSITY 23.5616
ALPHA 1e-05
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 27579
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 5 12 TO 16 23 TO 27 PRIS YD 0.6 ZD 0.3
6 TO 11 17 TO 22 PRIS YD 0.45 ZD 0.3
CONSTANTS
MATERIAL CONCRETE ALL
SUPPORTS
1 2 7 8 13 14 PINNED
DEFINE MOVING LOAD
TYPE 1 LOAD 16 10
DIST 1.5 WID 1.2
LOAD GENERATION 18
TYPE 1 0 0 2.6 XINC 0.5
LOAD 19 LOADTYPE Live TITLE STATIC POS9
MEMBER LOAD
9 CON GY -16 1.4
20 CON GY -16 0.6
14 CON GY -14 1.5
3 25 CON GY -3 1.5
PERFORM ANALYSIS PRINT LOAD DATA
LOAD LIST 9 19
PRINT SUPPORT REACTION ALL
PRINT JOINT DISPLACEMENTS ALL
FINISH