Written by Anton Valdivia Updated by Csaba Benedek
While calulations based on the Method of Joints can only solve
statically determinate problems, the FEM based calculations of this page calculate support forces, truss
forces and node displacements for 2D-truss structures that can also be
statically indeterminate.
Steps to set up a new model:
define the node points of the structure by their 2 coordinates (or
double click in the pane)
define each truss element by its 2 nodes (or drag the mouse bewteen 2
nodes) and its material number
define the material data (cross-section A and Young's modulus E)
define the loads
define which node is supported in which direction
If all bars have the same cross-section A and the same Young's modulus E and
you are not interested in displacements, you can simply enter 1 for A and
E.
A and E have no influence on the bar forces in this situation.
When visualizing bar forces, the colors are different:
Trusses under compression in blue, trusses under
tension in red and zero force members in white.
Points
i
xi
yi
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
When entering data, there are no units. The user is responsible for
providing data regarding consistent units
e.g.
point coordinates in m, loads in N, cross sections in
m² and the modulus of elasticity in N/m²,
displacements then will be in m, bar forces in N, normal
stress in N/m².
or
point coordinates in mm, loads in N, cross sections in
mm² and the modulus of elasticity in N/mm²,
displacements then will be in mm, bar forces in N, normal
stress in N/mm².
or
point coordinates in in, loads in lbf, cross sections in
in² and the modulus of elasticity in psi,
displacements then will be in in, bar forces in lbf, normal
stress in psi.
Additionally to the table of results the bars may be clicked to display the
according force, the nodes may be clicked to show the according
displacement.