L14: 2D Truss - Thermal Loads and Settlement ✔

2D truss shown below is subjected to various loads. In case 1, the truss is subjected to a uniform temperature rise of 70 degrees Fahrenheit. In case 2, concentrated forces of 10,000 lb. each are applied at the joints of the top chord of the truss. In addition to applied loads, the right support undergoes some settlement relative to the support. The vertical settlement is 0.01 ft down and the horizontal settlement is 0.01 ft towards right. In case 2, the temperature drops 40 degrees F.

Calculate the vertical deflection at the top hinge (at Joint 5).

The material properties for the truss bars are:

Modulus of Elasticity = 30,000,000 psi

Coefficient of Thermal Expansion = 0.0000065

The section property for the truss bars is:

Axx = 2.0 in2

The finite element model consists of 14 truss elements. Linear static analysis is performed with 2 primary load cases.

Tested Features

App

Object Link : https://openbrim.org/objidh7p24ppa4ebym46mrkbpgg.project

Library

Object Link : https://openbrim.org/objidw03yw72ctm4hzwi2a56ea.libobj

Sources

Timoshenko, S.P. and Young, D.H., "Theory of Structures,", 2nd ed., McGraw-Hill, New York, 1965, pp. 266-267.
LARSA 4D

Result Comparison

Translational disp in global direction at jt 5 (ft)

Timoshenko

LARSA

OpenBrIm

Percent Difference

LARSA vs. Timoshenko

Percent Difference

Openbrim vs. Timoshenko

Load Case 1

0.158

0.1576

0.25%

Load Case 2

-0.223

-0.2229

0.04%