Three element space truss supports 50 lb load. The bars are attached to the ceiling. The truss elements are steel (E = 30x10^6 psi) and the cross-sectional area of each element is 1 in^2. Determine the axial force in each bar.

The model consists of 4 joints and 3 truss elements. The rotational degrees of freedom are deleted from the 3D model. The joints 1, 2 and 3 are pin supports.

The material property data is given as:

Modulus of Elasticity = 30,000,000 lb/in^2

The sectional property data for the truss bar is:

Area of each truss bar = 1 in^2

The load of 50 lb is applied in the vertical Global Z-direction. The applied load is:

Load P @ Joint 4 in Z = -50 lb

Linear static analysis with one (1) load case is performed.

All truss elements are in tension.

Tested Features

App

Object Link: https://openbrim.org/objidlhmn9ovakfckbgfyo137xi.project

Library

Object Link: https://openbrim.org/objidfcp3gro45cp3reoyqjpzxg.libobj

Sources

Beer, F.P., and Johnston, Jr., E.R., "Vector Mechanics for Engineers, Statics and Dynamics," McGraw-Hill Book Co., Inc. New York, 1962, p. 47.
LARSA 4D

Result Comparison

	Independent (Beer)	Larsa	OpenBrIM	Percent Difference (Larsa vs Independent)	Percent Difference (OpenBrIM vs Independent)
Truss force F1 (lb)	0.0104	0.0104	0.0104	0%	0%
Truss force F2 (lb)	0.0312	0.0312	0.0312	0%	0%
Truss force F3 (lb)	0.0229	0.0229	0.0229	0%	0%

Independent

(Beer)

Larsa

OpenBrIM

Percent Difference

(Larsa vs Independent)

Percent Difference

(OpenBrIM vs Independent)

Truss force F1 (lb)

0.0104

Truss force F2 (lb)

0.0312

Truss force F3 (lb)

0.0229

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