OCD59 UNIVERSITY OF BOLTON WESTERN INTERNATIONAL CENTRE FZE BEng (HONS) CIVIL ENGINEERING SEMESTER ONE EXAMINATION 2015/2016 ADVANCED STRUCTURAL ANALYSIS AND DESIGN MODULE NO: CIE6001 Date: Tuesday 12 January 2016 Time: 10.00am to 01.00pm INSTRUCTIONS TO CANDIDATES: There are FIVE questions on this paper. Answer ALL questions. All questions carry equal marks. Marks for parts of questions are shown in the brackets. This examination paper carries a total of 100 marks. All working must be shown. A numerical solution to a question obtained by programming an electronic calculator will not be accepted. Extracts from EC3 for use in Question 1 are attached on Pages 9-10 of this paper.
Page 2 of 11 Question 1 A multi-storey building requires an internal steel column which will carry an ultimate design axial compressive load of 1650 kn. The column has pinned boundary conditions at each end, and the inter-storey height is 5.5 m. Two alternatives are proposed: A hot finished 200x200x10 SHS in S355 steel and Class 2 section as shown in Figure Q1(a). Hot rolled UKC 254x254x89 Class 1 section as shown in Figure Q1(b). a). By using the EC3 method, assess the suitability of both alternatives to resist the ultimate design axial compressive load. (17 marks) b). What conclusion do you draw from the results in part (a)? Which section shape do you recommend and why? (3 marks) h= 200mm t= 10mm A= 74.9cm 2 I y =I z = 4470cm 4 Class 2 section Steel Grade S355 E= 210x10 3 N/mm 2 Figure Q1(a) 200x200x10 SHS h= 260.3mm b= 256.3mm t w = 10.3mm t f = 17.3mm A= 113cm 2 I y = 14300cm 4 I z = 4860cm 4 i y = 11.2cm i z = 6.55cm Class 1 section Steel Grade S275 E= 210x10 3 N/mm 2 Figure Q1(b) UKC254x254x89 Total 20 marks Please turn the page
Page 3 of 11 Question 2 The L shaped bracket shown in Figures Q2 (a) and Q2 (b) on Page 4 is connected to a steel column 400mm deep with 8No M20 grade 8.8 bolts. The shear capacity of one bolt is 91.9kN and the tensile capacity of one bolt is 110kN. The bracket is formed from UB409 x 178 x 74kg/m steel section with the following properties: Web thickness Flange thickness Depth of section Width of section 9.5mm 18mm 413mm 190mm A factored vertical load 100 kn is applied at Point A at the location shown in the plan view of the bracket. a) What is the out of plane moment in the bolt group? (2 marks) b) What is the in plane moment in the bolt group? (2 marks) c) What are the tension and the shear forces in the hardest working bolts? (16 marks) Total 20 marks Question 2 continued over the page
Page 4 of 11 Question 2 continued 410mm 805mm 80mm 660mm Figure Q2 (a) PLAN VIEW ON BRACKET 60mm 95mm 95mm 95mm 68mm 80mm Figure Q2 (b) SECTIONAL ELEVATION A-A ON BOLTED ENDPLATE SHOWING SETTING OUT OF BOLTS Please turn the page
Page 5 of 11 Question 3 1500mm Concrete slab 1500mm x 120mm E = 13.3 kn/mm 2 f cd = 16.7N/mm 2 120mm 310mm y y Steel beam 305x127x48 kg/m UB Grade S275 I yy = 9500cm 4 Area = 60.8 cm 2 E = 205 kn/mm 2 Figure Q3 Figure Q3 shows the section of a composite steel/concrete beam. The E value of the steel is 205 kn/mm 2 and the E value of the concrete is 13.3 kn/mm 2. The beam is simple supported over a span of 6.0m and carries the following factored uniformly distributed loads: During construction (steel section alone carries loads): 10kN/m Dead Load + 15kN/m Imposed Load In service (Loads are carried by the composite action): 15kN/m Dead Load + 18kN/m Imposed Load a). Find the maximum working stress and maximum deflection of the beam during construction. (3 marks) b). Transform the composite section to an equivalent steel beam. Find the position of the neutral axis, the value of the moment of inertia, I y,comp, and the values of elastic section modulus, W el,y,comp, for the transformed beam. (10 marks) Question 3 continued over the page
Page 6 of 11 Question 3 continued c). d). DATA For the in-service condition, find the maximum stress in the steel, the maximum stress in the concrete and the maximum deflection of the composite beam (5 marks) Check whether the stresses in steel and concrete are within the allowable limits. (2 marks) The central deflection of a simply supported beam carrying a uniformly distributed load w per unit length is given by: 4 5wL 384EI Total 20 marks Question 4 Figure Q4 Question 4 continued over the page
Page 7 of 11 Question 4 continued Figure Q4 on Page 6 shows a rigid-jointed frame ABCDE fixed to a support at A and pinned to a support at E. The plastic moment of resistance of the columns AB and DE is M p each and the plastic moment of resistance of the beam BCD is 2M p. The frame carries a vertical point load of 24kN at C and a horizontal point load of 12kN at D. a). Find the values of M P which correspond to the following collapse mechanisms: i. Plastic hinges at B, C and D. ii. Plastic hinges at A, B and D. iii. Plastic hinges at A, B and C. (13 marks) b). Draw the bending moment diagram for the critical collapse mechanism showing values at A, B, C, D and E (7 marks) Total 20 marks Please turn the page
Page 8 of 11 Question 5 1300mm 100mm 368mm 400mm 100mm 400mm Figure Q5 Figure Q5 shows the cross-section of a pre-stressed concrete beam. The beam contains seven pre- stressing strands (13.5 mm diameter, 7 wire super strands) at a height of 100mm from the bottom of the beam. The beam supports dwellings and so the proportion of the variable load to be considered in the quasi permanent loading condition is 0.3. In service, the beam is simply supported over a span of 7.0m and carries the following loads: Permanent load (including beam self-weight) 50 kn/m Variable load 35 kn/m Characteristic breaking load of one strand = 186KN Initial pre-stress = 70% of UTS Pre-stress losses = 25% of initial pre-stress I NA = 1.136X10 10 mm 4 Concrete strength at transfer f ck = 35 N/mm 2 Concrete strength in service f ck = 45 N/mm 2 Limiting stresses in concrete: At transfer 0.6 fck in compression; 1 N/mm 2 in tension In service 0.45 fck in compression; 3.8 N/mm 2 in tension Question 5 continued over the page
Page 9 of 11 Question 5 continued a). Calculate the stresses in the concrete at the top and bottom of the beam: (i) at transfer; (ii) in service under quasi-permanent loads (13 marks) b). Draw the distribution of stress over the height of the beam in transfer and in service under quasi-permanent loads (4 marks) c). Compare the calculated values of stress in the concrete with the limiting values of stress in the concrete: (i) at transfer; (ii) in service under quasi-permanent loads. Comment on the adequacy of the beam (3 marks) Total 20 marks END OF QUESTIONS Please turn the page for supplementary information
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