THE UNIVERSITY OFNEW SOUTH WALES

SCHOOL OF ClVIL AND ENVIRONMENTAL E GINEERING

CVEN 2302 MATERIALS AND STRUCTURES

FINAL EXAMINATION

NOVEMBER 2010

Time Allowed - 3 Hours

All Questions to be answered

ANSWER QUESTION 1 IN ONE BOOKLETANSWER QUESTIO S 2-4 IN A SEPARATE BOOKLET

Questions are NOT of equal value

Closed Book Examination

This paper may be retained by the candidate

Electronic calculators anddrawing instruments may be used

All answers to be legibly written in ink

Pencil may be used for drawings, sketches and graphs.

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SECTION A MATERIALS

Answer this Section in a separate booklet

QUESTION 1 (34 Marks)

(a) Discuss the contribution of C3S and C3A (of General Purpose Portland cement) on heat ofhydration. (3 marks)

(b) Describe Slump Test and Compacting Factor method for the measurement of workability ofconcrete. (8 marks)

(c) What are the advantages of testing cylinders to obtain the compressive strength of concretewhen compared with cubes? (3 marks)

(d) Determine the modulus of rupture of the prism having a cross-section of 102 x 102 mm, span of300 mm and a failure load of 20 kN. (3 marks)

(e) Describe the causes of corrosion of steel reinforcement. What remedial actions can be taken tominimise corrosion of reinforcement. (8 marks)

(f) What is alkali-silica reaction? What are the possible preventive measures? (9 marks)

SECTIONB STRUCTURES

Answer this Section in a separate booklet

QUESTION 2 (18 Marks)

A splice is made in an I-section tension member by bolting it to 2 - 400 x 20 mm plates of Grade 300

steel, one to each flange. The 18 mm bolts in 20 mm holes are arranged as shown with a gauge of 60

mm and a staggered pitch of 50 mm. (Grade 300 steel: h = 320 MPa,fu = 440 MPa)

(I) Calculate the gross and net cross-sectional area without stagger (Ag and A,,) for plates.

(2) Calculate the net cross-sectional area with stagger (A,,) for plates. (Hint: s~ Xg )(3) Determine the maximum design force N* that can be transmitted through the plates.

, , , , ,sp , -' '- '- ,, -, - ,- ,- ,-=

, , , , ,,50: 50 :50 :50 :50,

50 : : , ,

~5g=60--- -----o--~--o--~-_o-+-O-

- - - - - - - - +- - -(4)- -}- - -cD - -:- - Q - -i --

60_1_ ·····················+·········t··········f···········~···········l···········!··········+······· .

................. ,....•..........., -..,. ,. , , ..

- --- - ~ - -0- -:--0 -~--6-- ~------{!--~-~--~-\>-~--CF-i ....................-.-..........-.

(a) Plate Cb) I-section tension member

Figure 2

QUESTION 3 (24 Marks)

The floor shown in the figure below with an overall depth of 250 mm (reinforced concrete slab) is to be

designed to carry an imposed load of 4 kPa. Assume that the beam weight is 50 kN/m. The unit weight

of reinforced concrete is 20 kN/m] (Note: Generally strength limit state is used to calculate design

actions and beams are on the same level unless otherwise specified)

(1) Draw the tributary areas and calculate the design loads acting on beams BI-B3, Cl-C2 and CI-Dl.

(2) Determine the design shear force and bending moment for the strength limit state for beams B I-B3.

-03m

-03m

IB------a-----e---~-0I<::(:-_--'4--'.m"----_---7)I<::(__----"4:-<m'-'---_----;:»I"'(__4"--'.!m-'----__-3»I

(;) 0 (0 CVFigure 3

QUSTIO 4 (24 Marks)

The pin-joined truss with design loads are shown in Figure 4.

(1) Calculate the force in member DE.

(2) Check if a 125 x 75 x 5.0 RHS (Rectangular Hollow Section) is sufficient for member DE. Use

Grade 300 steel.

80kN !160kN 1c

1_4B_3_m__~1_4_3_m_-+l~1

3m

Figure 4

Notes:

I. All joints are laterally braced. Ignore the members' self-weight. Grade 300 steel: h = 320 MPa,fu =

440MPa.

2. Yield slenderness limit for all plates of RHS: 2,y = 45. Rectangular Hollow Sections:

125 mm

15

3. 2 =!:~ i y 1= bh 3

r = TT 2 = fk(L)~ i y

, t 250' 12' fA" v"" f r 250 .

a - {1-~I-(90J'1 _(2/90)'+1+17 2-2 +a.a a _ 2100(2.-13.5)4. c -~ ~2''; - 2(2/90)' , -. ba, a - 2~ -15.32. +2050 '

ab =-1.0, 17=0.00326(2-13.5»0.