Problem 3

A rigid beam is subjected to a linearly distributed load and is supported by three bars, as shown in

Figure 3. Bars AB and EF are made of steel and bar CD is made of aluminum. The cross-sectional

areas are 1000 mm² for the steel bars and 450 mm² for the aluminum bar.

Assuming that all the bars remain elastic,

a) Find the value of the distributed load q so that the elongation of the aluminum bar is 5 mm.

b) Find the value of the distributed load q so that the minimum elongation of the steel bars is

at least 2 mm.

The moduli of elasticity are given as: Ea-200 GPa, Ea-70 GPa

2.0 m

st

E

TI

2.0 m

al

с

D

st

B

Figure 3: Rigid beam supported by three bars.

3.0 m