CIE4115 - Exam 1 November 2013 v3-Final

7/23/2019 CIE4115 - Exam 1 November 2013 v3-Final

http://slidepdf.com/reader/full/cie4115-exam-1-november-2013-v3-final 1/9

Delft University of Technology EXAM STEEL STRUCTURES 2: CIE4115

Faculty of Civil Engineering and Geosciences Friday, November 1, 2013

Steel & Timber Structures 14.00 - 17.00 hrs

This package contains 7 pages with questions and 5 pages with equations on connections.

It also contains a page that gives the points that you get if the answer is OK. 100 points gives as end

result the mark 10.

Please fill in on each answering sheet and on the cover of this package:

Your name and student number.

Please fill in your name etc. below. The strip will be collected in about 10 minutes after the start of

the examination.

CIE4115 Student Number

EXAM STEEL STRUCTURES 2

Thursday, November 1, 2013

Name: _______________________________ Initial(s) : __________________

Address: _______________________________ City: __________________






QUESTION Question Points

1 Plasticity1a 21b 21c 21d 31e 21f 2

2 Stress strain relationship2a 22b 22c 3

3 0,2 % Yield limit and residual stress3a 23b 23c 23d 23e 2

4 Stability4 4

5 Beam to column connection5a 45b 35c 2

5d 55e 35f 3

6 Welded connection6a 36b 26c 56d 3

7 Miscellaneous7a 37b 27c 2

7d 37e 3

8 Rectangular Hollow Section Joints8a 38b 28c 4

9 Fatigue9a 29b 39c 39d 3

Total points 100






- 1 -

PLASTICITY AND STABILITY

QUESTION 1 Plasticity

All members of the framehave cross section class 1.

Both columns have hingesupports at A and B.

Figure 1: Portal frame loaded by a vertical force 3F and a horizontal force 2F.

1a. Why is it necessary to use class 1 cross sections when plastic theory is used?

1b. - What is meant by the shape factor α of a cross section?

- Give the value of the shape factor of a rectangular cross section.

- Give the value of the shape factor of an I-shaped cross section.

1c. Draw the possible plastic failure mechanisms for the frame given in Figure 1.

1d. Calculate the plastic collapse load of each mechanism drawn in question 1c.

1e. Prove that the lowest collapse load determined in question 1c and 1d is the real collapse load of theframe.

1f. Via questions 1c, 1d and 1e the lowest collapse load is based on the formation of a mechanism

only. Which other criterion can you mention to base the collapse load on? Motivate your answer.

A

M pl

2l

2F

F

l

2l

C D

B

E M pl

M pl

2l

4l

3M pl

2M pl

M pl

2M pl

2F

3F






- 2 -

QUESTION 2 Stress-strain relationship

Figure 2: Rectangular cross section loaded in bending.

2a. Calculate the bending moment in the cross section for the given strain distribution.

2b. Calculate the curvature in a beam with this cross section for the given strain distribution.

2c. Calculate the maximum moment M in the rectangular cross section when in addition to the

moment a compressive normal force F is acting equal to F = 0,30 h b f y .

QUESTION 3 0,2 % Yield limit and residual stress

3a. What is the 0,2% yield limit 0,2?

3b. What is residual stress and explain two origins of residual stresses?

3c. Does residual stress influence the deformations of a steel structure? Explain your answer.

3d. Does residual stress influence the static strength of a steel structure? Explain your answer.

3e. Does residual stress influence the stability of a steel structure? Explain your answer.

f y

= 3 y

= 3 y

-

+

ε = 3εy

ε = 3εy

+

-

b

h

εy ε






- 3 -

QUESTION 4 Stability

(a) (b)

Figure 4: Portal frames.

All members have a cross section A and a moment of inertia I (with respect to in plane bending of the

frames).

4. Give an estimate of the buckling length of the columns AB and FE in frame (a) and in frame (b)

with respect to in plane buckling of the frames. Give a motivation of your answer.

3 L

L

L

A

B

C D

E

F

3 L

L

L

A

B

C D

E

F

Fd Fd Fd Fd Fd Fd

F F FF F F

ℓ

3ℓ

ℓ

3ℓ

4ℓ 4ℓ






- 4 -

CONNECTIONS

QUESTION 5 Beam to column connection

Steel S235

End plate thickness is20 mm.

Bolts are M20 quality8.8 in holes withnormal clearance (2mm), not preloaded.

Figure 5: Bolted beam to column connection.

IPE400 HEB 200

A 8446 mm2 7808 mm

2

h 400 mm 200 mm

b 180 mm 200 mm

tf 13,5 mm 15 mm

tw 8,6 mm 9 mm

r 21 mm 18 mm

IPE400 HEB 200

Iy 23128•104 mm

4 5696•10

4 mm

4

Iz 1318•104 mm

4 2003•10

4 mm

4

It 50,3 •104 mm

4 59,6 •10

4 mm

4

Wy;el 1156•103 mm

3 569,6•10

3 mm

3

Wy;pl 1307•103 mm

3 642,5•10

3 mm

3

Wz;el 146,4•103 mm

3 200,3•10

3 mm

3

Wz;pl 229,0•103 mm

3 305,8•10

3 mm

3

5a. For the calculation of the strength in the tension zone, T-stub modelling is used. Sketch the three

possible failure modes of a T-stub, and explain under what circumstances each failure mode willoccur.

5b. Which failure mode gives the most deformation capacity. Explain why.

5c. What checks should be performed to determine the strength of the tension zone (only mention

them, no calculations).

5d. Determine the strength of bolt row 1 for the end plate.

5e. Which bolt row will have the greatest strength for the end plate, number 1 or number 2. No

calculations needed; explain your answer.

5f. Strength is an important requirement for the connection. What are the other requirements and

explain why.

Boutrij 1

4 0

3 0

5 5

IPE400 H E 2 0 0 B

100

M

tf

Boutrij 4

Boutrij 2

Lassen: a = 5

40 40

100

Bolt row 1

Bolt row 2

Bolt row 4

Welds a = 5






- 5 -

QUESTION 6 Welded connection

- HEA 300:

h = 290 mm, b = 300 mm,

tf = 14 mm, tw = 8,5 mm,

r = 27 mm, A=11250 mm2,

Iy = 18263104 mm4,

Wy;el = 1260103 mm

3,

Wy;pl = 1383103 mm

3.

- F = 200 kN

(factored load)

- Steel S355 met

f y;d = 355 N/mm2 en

f t;d = f t;rep = 510 N/mm2

- Weld thickness a = 6 mm

Figure 6: Plate welded to a column HEA 300.

6a. Calculate and draw the stresses over the cross-section in the plate near the welds (the cross- section

at 300 mm from the load introducing point of the force F).

6b. Check whether the plate is sufficiently strong to carry the calculated stresses.

6c. Check whether the welds are strong enough. Apply the combined stress method. If you could not

calculate the stresses according to question 6a, then assume a tensile stress of 260 N/mm2 and a

shear stress of 55 N/mm2.

6d. Check whether the weld thickness a = 6 mm is sufficient to provide ductile behaviour of the

construction.






- 6 -

TUBULAR STRUCTURES AND FATIGUE

QUESTION 7 Miscellaneous

7a. Why are restrictions given for the corners of cold-formed rectangular hollow sections and what are

these restrictions?

7b. Compare respectively to the strength, stiffness and

deformation capacity of a multi-planar X joint,

loaded only by compression loads F1 on the

vertical braces.

7c. Give the effect of additional compression loads

F2 = F1 on the out of plane braces on:

- the strength for F1

- the stiffness for F1

- the deformation capacity for F1

Figure 7: Multi-planar X joint.

7d. Consider a K joint with an I-section chord. Why is the contribution b0t0 (of the flange in the gap)

in the equation for the shear area larger for rectangular hollow section braces than for circular

hollow section braces?

Eq.:

000000 22 t r t t bt b A A wv

7e. Do welds of hollow section joints in lattice girders have to be designed on the brace member forces

or on the member capacities, explain why?






- 7 -

QUESTION 8 Rectangular Hollow Section Joints

For a lattice girder with rectangular hollow

sections the joints are drawn as shown in Figure 8.

The checking engineer does not accept this design

and has a conflict with the detail-designer.

8a. In general, which failure (modes) have to be

checked for rectangular hollow section

joints?

8b. Which failures are never allowed and how

can these be avoided?

8c. Are there other aspects or criteria which have

to be checked? Is there a criterion which is

not met in this joint?

Figure 8: Joint in a lattice girder with rectangular hollow sections.

QUESTION 9 Fatigue

Figure 9 shows a joint detail of a harbour crane

which is subjected to fatigue loading.

In this joint a brace (left) and a stub (right) are

connected to the leg (through member Φ1219 -

9.5). The "designer" did not check the joints

correctly.

After a short time in service fatigue cracks were

observed at the joint locations.

The welds were properly designed and

executed.

Figure 9: Joint detail of a harbour crane.

9a. If the brace member would be predominantly loaded by an axial load, where would you expect that

the cracks would start (saddle, crown or in-between location and in the brace or in the leg)?

9b. If the stub member would be predominantly loaded by an in-plane bending moment, where would

you expect that the cracks would start (saddle, crown or in-between)?

9c. What is the mean reason (with regard to geometry) why this joint detail has a low fatigue life?

9d. What is your opinion about the suitability of the joint for static loading?

200 x 200 x 8

100 x 100 x 6

= 40o

g = 10

= 40og = 10

braces

CIE4115 - Exam 1 November 2013 v3-Final

Documents

Transcript of CIE4115 - Exam 1 November 2013 v3-Final