THE UNIVERSITY OF NEW SOUTH WALES

SCHOOL OF CIVIL AND ENVmONMENTAL ENGINEERING

FINAL EXAMINATION - NOVEMBER 2009

CVEN3302

STRUCTURAL BEHAVIOUR AND DESIGN

Time allowed - 3 hours

Total number of questions - 4

Questions are of equal value

Open Book examinationAny electronic calculators and hand held computers are pennitted

This paper may be retained by the candidate

All answers mustbe legibly written in ink. Pencils may onlybe used for drawings, sketches and graphs

Show all relevant working and state any assumptions made

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QUESTION 1wi = 80kN/m

.15500I.

Im 1I [

7fT m

wt=30kN

Take f: = 25 MPa, f,y = 500 MPa, 'If, ~ 0.7 and 'lfz = 0.4.

For part c), the deflection at midspan may be approximated by (in the units of N and mm)

where L is the span, MM is the midspan moment and ML and MR are the moments at the leftand right ends of the member, respectively. You may approximate the midspan moment asbeing equal to the maximum moment.

QUESTION 2

~LT

1000

. 4'llb

X x-

-

()

'"410:1,2 -.i1

25"'0 500 ;2.51)

Figure 2 (dimensions in mm)

Sketch the M-N interaction diagram for the section given in Figure 2 for bending about thex-x axis. In your solution calculate the depth of the plastic centroid as measured from the topof the section and then calculate the following 4 points:

(i) Pure bending point(ii) Balanced point(Hi) Decompression point located where kud = D(iv) Squash load

Take f: ~ 40 MPa and fry ~ 500 MPa .

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700WB150

QUESTION 3

W* W*

~t.....--Im~~-"------i&l~""'--.....:~ I1.-'_--'s"'ID"'----_....I..I.-._---'su:ID"---o.1

Grade 300

Figure 3

The beam shown in Figure 3 is a 700WB 150 in Grade 300 steel. The member is subjected totwo point loads, W* as shown, acting on the top flange of the beam. You may ignore the self-weight of the beam.

For the beam you are to:

a) Draw the bending moment and shear force diagrams.b) Calculate the maximum value of W* for each of the following cases:

1. The beam has full lateral restraint along its entire length,

11. There is full restraint at both supports and both load points, and

Ill. There is full restraint at both supports only.

c) Check the adequacy of the beam in shear at the lowest design value of w* calculatedin part b) and, if required for strength, design intermediate web stiffeners.

d) If the stiff bearing plate length at each support is 300 mm, determine if load-bearingstiffeners are needed at the supports for the strength (ultimate) limit state.

For each case of part b), clearly indicate the values of Ms, Le' am, as and Mh, where relevant.

For all parts, fully justify your decisions through calculations.

4

4.5 m

QUESTION 4

40kN u=Ou=O u=O ~=O~=Z ~=~I J 200kN

"...- .....;.::+:..- .....: 4~~~ :L..-~lit

4.5m _I

Figure 4

I250UB37

Grade 300

The 9 metre long simply supported beam column shown in Figure 4 has the following design(factared) loads:

an axial compression force of 200 kN, and

a concentrated load of 40 kN located at the mid-span that gives bending about themajor principal axis.

The loads include an allowance for the self-weight of the member.

The engineer has decided to try a 250UB37 of Grade 300 steel. Does the beam-columnmember have an adequate factor of safety if the lateral deflection, u, and twist rotation, t/J, areprevented at each end and at the mid-span?

Fully justify your answer through appropriate calculations.

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