assigment

1. ASSIGNMENT 1 – CIE 252 (DUE DATE: FRIDAY, 03RD
MRCH 2018 AT 13:00 HRS, OBSERVE TIME)
1. A 3 m long tie in a steel frame is made of circular hollow section steel with an outer diameter of 80 mm and
a wall thickness of 4 mm. The properties of the steel are as follows: Young’s modulus: 210 GPa
Yield stress: 350 MPa
Poisson’s ratio: 0.2
a. What is young’s modulus, yield stress, ultimate stress and Poisson’s ratio?
b. What is the relationship between stress and strength?
c. How do you determine the strength of a given engineering material?
d. What is strain?
e. What is the difference between normal and shear strain?
f. What is difference between elastic and plastic strain?
g. What is creep?
h. What is fatigue strength?
i. List four types of loading conditions.
j. Sketch the problem of the steel frame loaded with 200 kN in diagram form and later draw the free
body diagram.
k. What is the elongation of the tie when the tensile load in it is 200 kN?
l. What is the shortening in wall thickness when this load of 200 kN is applied?
2. A water tank is supported by four identical timber posts that all carry an equal load. Each post measures 80
mm by 100 mm in cross-section, and is 2.0 m long. When 0.8 m3
of water is pumped into the tank, the posts
get 0.1 mm shorter. Include the sketches of each problem and later draw the free body diagrams.
a. What is the Young’s modulus of the timber in the direction of loading?
b. If the cross-sections measure 100.002 mm by 80.00015 mm, after loading, what are the relevant
Poisson’s ratios?
c. If 200 L of water are now pumped out of the tank, what are the new dimensions of the post?
(Assume that the strain remains elastic.)
3. The below figure shows observations that were made when a 100 mm length of 16 mm diameter steel bar
was loaded in tension. The equation given is for a trendline that has been fitted to the straight portion of the
graph.
Calculate the following:
a. The Young’s modulus,
b. The estimated yield stress,
c. The ultimate stress.

2. 4. A 100 mm diameter concrete cylinder 250 mm long is loaded on the end with 8 tonnes, including the
sketches of each problem and later draw the free body diagrams.
a. What is the stress in it?
b. The Young’s modulus of the cylinder is 25 GPa. What is its height after loading?
c. The Poisson’s ratio of the cylinder is 0.17. What is its diameter after loading?
d. A column 2 m high, measuring 350 mm by 600 mm on plan, is made with the same concrete as in the
cylinder and supports a bridge. In order to prevent damage to the deck, the maximum permitted
compression of the column is 0.2 mm. Assuming that the column is not reinforced, calculate the
compression of the column when it is supporting the full weight of a 40-tonne lorry, and state
whether the deck will fail.
5. Solve the following problems including the sketches of each problem and later draw the free body diagrams.
a. A 250 mm diameter concrete cylinder 1000 mm long is loaded on the end with 50 kN. What is the
stress in it?
b. The Young’s modulus of the cylinder is 25 GPa. What is its height after loading?
c. The Poisson’s ratio of the cylinder is 0.15. What is its diameter after loading?
d. A column 1000 mm high, measuring 300 mm by 200 mm on plan, is made with the same concrete as
in the cylinder and supports a bridge. In order to prevent damage to the deck, the maximum
permitted compression of the column is 0.03 mm. Assuming that the column is not reinforced,
calculate the compression of the column when it is supporting the full weight of 500 kN truck and
state whether the deck will fail.