entrance sign pratt 01

A truss structure is used to hang signs at an entrance to a stadium. The locations of the centers of gravity of the signs are given by dimensions c and d. Find the forces and stresses carried in the members indicated in the table below, as well as the changes in length of those members. Dimensions, weights, and cross-sectional areas are given below. The members of the truss are composed of 2014-T4 aluminum. Neglect self-weight of the truss.

a	b	c	d	Left Sign Weight	Right Sign Weight
11 in	27 in	5.13 ft	5.625 ft	78 lb	110 lb

Reactions:

$R_A$
$R_L$

Members:
(Denote tension forces, tensile stresses, and elongations with positive values; compressive forces, compressive stresses and compactions with negative values.)

Member	Cross-   Sectional   Area $(in^2)$	Force	Stress	Change in Length
$EG$	0.75
$EQ$	0.125
$QR$	0.125
$GQ$	0.75
$GH$	0.75
$HQ$	0.125
$PQ$	0.125

be sure to include units with your answers