Static - Beam Element > A-09 (2D Truss with Tension Only Member)

Objective

To verify the behavior of the tension only element

Problem Description

A member connecting node 2 and node 4 is tension only in the 2D truss shown below.

Lengths: shown in parentheses in meters

Material properties: E = 205 kN/mm2, ν = 0.3

All Sections: Az = 1500 mm2

Loads: as shown

A-09 (2D Truss with Tension Only Member)1

Finite Element Model

8 beam elements, with one member connecting N2-N4 being tension only

Model type: 2D Truss

Results

The displacements and internal forces given by ENERCALC 3D are compared with the reference [Ref 1].

	ENERCALC 3D	Ref 1
Displacement Dx @ N3 (mm)	3.469	3.46
Displacement Dy @ N3 (mm)	19.12	19.13
Axial Force in Member connecting N1-N5 (KN)	181.67	181.7

Comments

The results given by ENERCALC 3D are very close to the referenced values. Since the member connecting N2-N4 is tension only but subjected to compression force, its stiffness is ignored in the 2nd iteration during the solution of this nonlinear model. We can also set the member to be inactive to achieve the same effect. The difference between using tension/compression only members and inactive members is that the former requires non-linear solution while the latter does not (unless other nonlinearities such as non-linear springs or P-Delta analysis exist).

Reference

[1]. William M.C. McKenzie, “Examples in Structural Analysis”, pp 125, Taylor & Francis, 2006.