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UNIVERSITY OF BOLTON SCHOOL OF ENGINEERING BEng …...BEng (Hons) Degree in Civil Engineering...

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UNIVERSITY OF BOLTON

SCHOOL OF ENGINEERING

BEng (Hons) CIVIL ENGINEERING

SEMESTER 2 EXAMINATION 2015/2016

ADVANCED STRUCTURAL ANALYSIS & DESIGN

MODULE NO. CIE6001

Date: Thursday 19th May 2016

Time: 10.00 – 1.00

INSTRUCTIONS TO CANDIDATES:

There are FOUR questions Answer ALL questions All questions carry equal marks Total 100 marks for the paper. Extracts from EC3 to be used with Question 2 are included with this paper.

Page 2 of 13

School of Engineering BEng (Hons) Degree in Civil Engineering Semester 2 Examination 2015/2016 Advanced Structural Analysis & Design Module CIE6001

Question 1

32 kN

D B

5m

3m 2m

F

1.5Mp C

2m

2m A

3m E

Mp

Mp 64 kN

Figure Q1

Figure Q1 shows a rigid-jointed frame ABCDEF fixed to supports at A and at F. The plastic moment of resistance of the columns AB and DEF is Mp, the plastic moment of resistance of the beam BCD is 1.5Mp

The frame carries a vertical point load of 32 kN at C and a horizontal point load of 64 kN at E. (a) Find the values of MP which correspond to the following collapse mechanisms:

i) Plastic hinges at B, C and D. ii) Plastic hinges at D, E and F iii) Plastic hinges at A, B, D and F. iv) Plastic hinges at A, B, E and F (15 marks)

(b) Draw the bending moment diagram for the critical collapse mechanism showing values at the joints and the point load positions. (10 marks)

(Total 25 marks) Please turn the page

Page 3 of 13

School of Engineering BEng (Hons) Degree in Civil Engineering Semester 2 Examination 2015/2016 Advanced Structural Analysis & Design Module CIE6001

Question 2

(a) What is the difference in structural behaviour between a short and slender column? (2 marks)

(b) List three examples of imperfections that affect the buckling behaviour of real slender columns. (3 marks)

(c) A multi-storey building requires an internal steel column which will carry an

ultimate design axial compressive load of 1700 kN. The column has pinned boundary conditions at each end, and the inter-storey height is 6 m.

Two alternatives are proposed:

i) A hot formed circular hollow section with a diameter 200 mm and wall thickness of 10 mm with Class 2 section, as shown in Figure Q2(a).

ii) Hot rolled UKC 203x203x60 section in steel grade S355 and Class 1 section, as shown in Figure Q2(b).

(1) Assess the suitability of both alternatives to resist the ultimate design axial

compressive load. (17 marks) (2) What conclusion do you draw from the results in part (1)?

Which section shape do you recommend and why? (3 marks)

(Total 25 marks)

d = 200 mm

t = 10.0 mm A = 74.9 cm2 Iy=Iz = 4470 cm4

S355

fy = 355 N/mm2

Figure Q2 Additional information:

Euler critical load 𝑁𝑐𝑟 =𝜋2𝐸𝐼

𝑙𝑐𝑟2

Modulus of Elasticity E = 210 kN/mm2

Extracts from EC3 to be used with Question 2 are included in Appendix A.

Please turn the page

(a) (b)

h = 209.6 mm b = 205.8 mm tw = 9.4 mm tf = 14.2 mm A = 76.4 cm2 Iy = 6120 cm4 Iz = 2060 cm4

iy = 8.96 cm iz = 5.2 cm S355 fy = 355 N/mm2

t

d

y h

b z

y

z

Page 4 of 13

School of Engineering BEng (Hons) Degree in Civil Engineering Semester 2 Examination 2015/2016 Advanced Structural Analysis & Design Module CIE6001

Question 3

650mm

375mm

1200mm

N A

175mm

125mm

600mm

Figure Q3 Figure Q3 shows a pre-stressed concrete beam. The beam contains twelve 12.9mm diameter (7wire Super Strand) pre-stressing strands, each with a characteristic breaking load of 186kN, at a height of 125mm from the bottom of the beam. The beam supports offices 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 10.0m and carries the following loads: Permanent load (including beam self-weight) 25 kN/m Variable load 15 kN/m Characteristic strength of one pre-stressing strand = 186 kN Initial pre-stress = 75% of UTS Pre-stress losses = 30% of initial pre-stress Concrete strength at transfer fck = 35 N/mm2 Concrete strength in service fck = 45 N/mm2 For the whole concrete section: Area = 495 x 103 mm2

INA = 18.7 x 109 mm4 Limiting stresses in concrete: At transfer 0.6 fck in compression; 1 N/mm2 in tension In service 0.45 fck in compression; 3.8 N/mm2 in tension (a) Evaluate the advantages and disadvantages of bonded and unbonded construction and recommend one preferred method of construction for an office building, considering the whole life of the structure. (4 marks) (b) Calculate the stresses in the concrete at the top and bottom of the beam: (i) at transfer; (ii) in service under quasi-permanent loads (12 marks)

Question 3 continued on next page…..

Page 5 of 13

Question 3 (continued) (c) Draw the distribution of stress over the height of the beam: (i) at transfer; (ii) in service under quasi-permanent loads (4 marks) (d) 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 (3 marks) (e) Comment on the adequacy of the beam. Suggest two ways to improve the capacity of the beam (2 marks)

(Total 25 marks)

Please turn the page

Page 6 of 13

Question 4 PART A Eccentric bolted connection Refer to Figures Q4-1, Q4-2, Q4-3 and Q4-4 which show the structure of a motorway signboard.

Figure Q4-1 3-D Sketch showing motorway signboard structure

Figure Q4-2 Elevation on motorway signboard

Figure Q4-3 Plan view of motorway signboard

Question 4 continued on next page….. Please turn the page

Page 7 of 13

Question 4 (continued) PART A Eccentric bolted connection

Figure Q4-4 Detailed plan of baseplate, showing holding down bolts The motorway signboard structure shown in the figures above has a CHS post with a circular baseplate with eight holding down bolts. The signboard has a self-weight of 15 kN acting at its centre. The CHS post has the following properties: Outside diameter 244.5mm Wall thickness 12.5mm Mass per metre 71.5 kg/m There is a wind load of 8 kN acting at the centre of the signboard. All loads given are unfactored and in the following calculations use unfactored loads. (a) Calculate the in plane and out of plane moments acting on the holding down bolts of the bolt group. Also state the direct shear acting on the bolt group.

(4 marks) (b) Clearly show which of the eight holding down bolts is subject to the largest shear force (if the answer includes more than one bolt, then show all that are required).

(2 marks) (c) State the size of the maximum shear force in the bolt that is subject to the largest shear force. (6 marks)

Question 4 continued on next page….. Please turn the page

Page 8 of 13

Question 4 (continued) PART B Understanding structural behaviour In answering Question 4 PART B please tear out and use the multiple choice marking sheet in Appendix B

Q4B - 1 Choose the bending moment diagram (BMD) that matches the structure shown (2 marks)

A

B

C

D

Question 4 continued on next page….. Please turn the page

Page 9 of 13

Question 4 (continued) PART B Understanding structural behaviour

Q4B - 2 Choose the summary diagram showing the nature of the member forces that matches the structure shown [C is compression, T is tension and 0 is zero force]. All horizontal and vertical members in the structure are of equal length (2 marks)

A

B

C

D

Q4B - 3 Choose the answer in the table that matches the structure shown. Consider both the value and the nature of the forces in Members 1 and 2 . (4 marks)

Member 1 Member 2

A 80 kN compression 100 kN compression

B 80 kN tension 84.8 kN compression

C 80 kN compression 100 kN tension

D 60 kN compression 84.8 kN tension

Question 4 continued on next page….. Please turn the page

Page 10 of 13

Question 4 (continued) PART B Understanding structural behaviour

Q4B - 4 Choose the bending moment diagram (BMD) that matches the structure shown (2 marks)

A

B

C

D

Q4B - 5 Choose the bending moment diagram (BMD) that matches the structure shown. Consider the values of the bending moments given in the answer choices (3 marks)

A

B

C

D

(Total 25 marks)

End of Questions Please turn the page

Page 11 of 13

APPENDIX A – Extract from EC3 to be used with Question 2

Please turn the page

Page 12 of 13

APPENDIX A – Extract from EC3 to be used with Question 2

Please turn the page

Page 13 of 13

APPENDIX B Multiple choice answer sheet to be used with Question 4 PART B

Please tear out of the exam paper and enclose with your exam script

Student number:

Student name:

Questions Circle the correct answers

Marks (please

leave this column blank)

Q4B - 1 A B C D

Q4B - 2 A B C D

Q4B - 3 A B C D

Q4B - 4 A B C D

Q4B - 5 A B C D

TOTAL

It is essential that your answers are clear, as ambiguous answers and crossing out may make it impossible to award marks for parts of this question.

END OF PAPER

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