TEST CASE 9.1 BAR STRUCTURE LOADED BY CONCENTRATED FORCES IN THE AXIAL DIRECTION
Reference:
Perelmuter A.V., Kabantsev O.V. Analysis of structures with a changing design scheme, M.: Publishing House of SKADSOFT, 2015, p. 44.
Problem description:
The rack, rigidly restrained on both sides, consists of 4 sections, which are mounted in turn and loaded with concentrated longitudinal forces F. Determine the internal longitudinal forces N in the sections of the rack at each stage of assemblage.
Problem sketch:
Type of created problem:
Flat frame (X, Z, UY).
Geometric characteristics:
L = 1 m.
Material properties:
Bending stiffness: EI = 313.32 N·m^{2};
Axial stiffness: EA = 1000 N.
Boundary conditions:
Node 1 and 5: X = Z = UY = 0.
Loads:
F = 50 N.
Model description:
The system is modeled by 4 general finite elements of spatial bar (FE type is 10). Task is solved using two different approaches. The fist problem (option a) is done via classical staging. The second problem (option b) is modeled in the "Assemblage" system.
Calculation results:
Target value 
Classical staging (option a) 
Accounting for the assemblage stages (option b) 

1 
2 
3 
4 

N_{12}, N 
75 
50 
100 
150 
150 
N_{23}, N 
25 
– 
50 
100 
100 
N_{34}, N 
25 
– 
– 
50 
50 
N_{45}, N 
75 
– 
– 
– 
0 
Internal forces N (option a), N

Internal forces N at the 4th stage of assemblage (option b), N 