1.A steel bridge spans a channel 2000 ft. wide. What change in length would cause by change in
temperature from 10oF to 130oF. αα = 6.5 xx 10−6 per oF.
2. What is the maximum horsepower of a solid steel shaft 2 inches in diameter can transmit at 300
rpm if maximum allowable shearing stress is 10,000 psi.
ANSWER:
𝟏𝟔𝑻
Tmax= 𝝅𝒅𝟑
𝟏𝟔𝑻
10,000= 𝝅(𝟐)𝟑
T = 15708 lb•in
T=
𝑷
𝟐𝝅𝒇
15708=
𝑷(𝟑𝟗𝟔 𝟎𝟎𝟎)
𝟐𝝅(𝟑𝟎𝟎)
P = 74.77 hp
3. Find the required diameter of a steel member if the tensile design load is 7,000 pounds. Assume a
safety factor of 5 based on an ultimate strength of 60,000 psi.
ANSWER:
GIVEN:
Ꝺ=60,000 psi
K=5
P = 7000 lbs
𝑲𝑷
A= Ꝺ
A=
𝟓(𝟕𝟎𝟎𝟎)
𝟔𝟎𝟎𝟎𝟎
A = 0.583 𝒊𝒏𝟐
𝝅
A = 𝟒 𝒅𝟐
𝝅
0.583 𝒊𝒏𝟐 = 𝟒 𝒅𝟐
D = 0.86 in.
4. What is the maximum normal stress in a solid circular shaft 8 cm. in diameter, that transmits a
torque of 1000 N-m?
ANSWER: