the university of bolton school of engineering beng … · 305x165x40kg/m steel section with the...

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THE UNIVERSITY OF BOLTON

SCHOOL OF ENGINEERING

BEng (Hons) CIVIL ENGINEERING

SEMESTER 2 EXAMINATION 2016/2017

ADVANCED STRUCTURAL ANALYSIS & DESIGN

MODULE NO. CIE6001

Date: Thursday 18 May 2017

Time: 10.00 – 1.00

INSTRUCTIONS TO CANDIDATES:

There are FOUR questions For Question 3, tear out and write on the page from the exam and include it in your answer booklet Total 100 marks for the paper. Extracts from EC3 to be used with Question 2 are included with this paper. PAST E

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of 13 School of Engineering BEng (Hons) Degree in Civil Engineering Semester 2 Examination 2016/2017 Advanced Structural Analysis & Design Module CIE6001

Question 1.

P

E

A

C

Figure Q1

6m

2m 4m

2m

2m

4m P

F

Mp = 120 kNm

Mp = 360 kNm

Mp = 360 kNm

B

D

Figure Q1 shows a rigid-jointed frame ABCDEF fixed to a support at A and pinned to a support at F. Member ABC has Mp = 120 kNm, members CDE and EF both have Mp = 360 kNm. There is a horizontal point load P at B and an equal vertical point load P at D

a. Find the values of P which correspond to the following collapse mechanisms: i) Plastic hinges at A, B and C ii) Plastic hinges at C, D and E iii) Plastic hinges at A, C and E iv) Plastic hinges at A, B and E (15 marks)

b. Draw the bending moment diagram for the critical collapse mechanism

showing the important values, and state the value of P that will cause the frame to collapse. (10 marks)

(Total 25 marks)

Please turn the page

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Question 2 a) Explain the difference in the mode of failure between a stocky and slender

column. What is the limiting value of the non-dimensional slenderness ratio for a slender column when using the EC3 method? (5 marks)

b) A column is laterally restrained every 3.5 m against buckling about the minor axis but has no intermediate restraints against buckling about the major axis as shown in Figure Q2. The column is considered to be pinned in both directions. The column is subjected to a design load NEd = 1000 kN. The size of the column is UKC 203x203x71 with a steel grade S275. Determine the buckling resistance of the column about both axes using EC3 method. Comment on the results. (20 marks)

UKC 203x203x71: A= 90.4 cm2

Iy = 7618 cm4 Iz = 2537 cm4 h = 215.8 mm b = 206.4 mm tw = 10.0 mm tf = 17.3 mm E = 210 kN/mm2 fy = 275 N/mm2

Partial safety factor 1 Cross-section is Class 2

2

2

cr

cr

EIN

Total 25 Marks

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


y h

b

z

y

z

tf

tw

m

mm

m

Figure Q2

= 1000 kN

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Question 3

740mm

442mm

1250mm

N A

180mm

150mm

550mm

Figure Q3-1

Figure Q3-1 shows a pre-stressed concrete beam. The beam contains seven pre-stressing strands (12.9mm diameter, 7 wire super strand) at a height of 150mm 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 9m and carries the following loads: Permanent load (including beam self-weight) 30 kN/m Variable load 25 kN/m Characteristic breaking load of one strand = 186 kN Initial pre-stress = 70% of UTS Pre-stress losses = 25% 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 = 533 x 103 mm2 Second moment of area of concrete section INA = 26.5 x 109 mm4 (a) Evaluate unbonded post-tensioned construction for an office building with respect to safety and sustainability considering the whole life of the structure (3 marks) (b) Calculate the stresses in the concrete at the top and bottom of the beam at transfer only (6 marks) (c) Draw the distribution of stress over the height of the beam at transfer and comment on the adequacy of the beam at transfer (4 marks) (d) Without doing any further calculations, estimate and sketch the distribution of stress over the height of the beam in service under quasi-permanent loads

(3 marks)

Question 3 continued over the page

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Question 3 (continued) The in-service stress distribution of a 285mm deep pre-stressed concrete slab with strands set at height h = 65mm above the bottom of the slab is shown in Figures Q3-2A and Q3-2B (the same diagram is repeated). Tear out this page and include it in your answer booklet. Add your student number at the bottom of the page. (e) On Figure Q3-2A annotate and sketch the stress distribution in service after increasing the height of the strands above the bottom of the slab (3 marks) (f) On Figure Q3-2B annotate and sketch the stress distribution in service after additional strands have been added to increase the tensile forces (with h = 65mm) (3 marks)

Figure Q3-2A

Figure Q3-2B (Total 22 marks)

Student number ……………………………………….. Please turn the page

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Question 4 PART A - ECCENTRIC BOLTED CONNECTION The L shaped bracket shown in Figures Q4A-1 and Q4A-2 is connected to a steel column 303.4mm deep with 6 NoM20 (8.8) bolts. The bracket is formed from a UB 305x165x40kg/m steel section with the following properties: Web thickness 6mm Flange thickness 10.2mm Depth of section 303.4mm Width of section 165mm A factored vertical force of 70kN is applied at the location shown in the plan view of the bracket. (i) What are the in and out of plane moments in the bolt group? (3 marks) (ii) Define the bolt carrying the greatest combined shear and tensile forces; give a brief explanation for your choice. (3 marks) (iii) State the maximum shear force in the left hand bolt of bolt row b3 (i.e. b3 L). (5 marks)

Question 4 continued on next page…..


Vertical load applied to L shaped bracket at location shown

600mm

420mm

AA

90mm

centre line of column

303.4mm

Figure Q4A-1 PLAN VIEW ON BRACKET

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Question 4 (PART A continued)

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

90mm

Figure Q4A-2 SECTIONAL ELEVATION A-A ON BOLTED ENDPLATE SHOWING SETTING OUT OF BOLTS

90mm

73.4mm

70mm

70mm

b3

b2

b1

L R

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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


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Question 4 (continued) PART B Understanding structural behaviour

Q4B - 2 A pre-stress load is applied to three rectangular reinforced concrete beams with tendons positioned in different ways. Match the tendon profiles (1, 2 and 3) with the corresponding deformed shapes of the beam (A, B and C). Ignore the self-weight of the beam (Hint – different tendon profiles may create similar deformed shapes). (3 marks)

Diagrams showing tendon profiles 1

2

3

Diagrams showing deformed shapes

A

B

C


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Question 4 (continued) PART B Understanding structural behaviour

Q4B - 3 Choose the bending moment diagram (BMD) that matches the structure shown (2 marks)

A

B

C D

Q4B - 4 Choose the diagram (A, B, C or D) that shows the structural model that

matches the shear force diagram (SFD) shown (2 marks)

A

B

C

D



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Q4B - 5 Choose the bending moment diagram (BMD) that matches the structure

shown (2 marks)

A

B

C

D

Q4B - 6 Choose the bending moment diagram (BMD) that matches the structure

shown. (3 marks)

A

B

C D



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Q4B - 7 Choose the bending moment diagram (BMD) that matches the pin jointed structure shown. Consider the values of the bending moments given in the answer choices (3 marks)

A

B

C D

(Total 28 marks)

End of Questions Please turn the page

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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:

Questions Circle the correct answers

Marks (please

leave this column blank)

Q4B - 1 A B C D 2

Q4B - 2

1 A B C 1

2 A B C 1

3 A B C 1

Q4B - 3 A B C D 2

Q4B - 4 A B C D 2

Q4B - 5 A B C D 2

Q4B - 6 A B C D 3

Q4B - 7 A B C D 3

TOTAL 17

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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ab9

Typewritten Text

ab9

Typewritten Text

APPENDIX A: DATA SHEET TO BE USED WITH QUESTION 2

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