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Curtin University of Technology

STRUCTURAL DESIGN 266

Steel Design ASSIGNMENT ONE

Original due date: Thursday, 24th September 2009, 4:00 pm

Extension given until: Tuesday, 29

th

September 2009, 4:00 pmSubmission to: Assignments office building 204, level 2

Kerri Bland 1Lecturer

This assignment is worth eight (8)% of the assessment for Structural Design 266.This assignment can be done singly or in groups ofno more than four(only one assignment to be

handed in per group). If it is to be done in a group, I encourage all members to fully participate in the

assignment as any portion may be similar to questions in the end of semester exam.

Show the names of all group members on this cover sheet. Attach this cover sheet to the front of your assignment, but behind your

assignment office submission sheet.

Fill out the summary sheets and attach directly behind this cover sheet. All

working should follow the summary sheet. Assignments with summary sheets filled out in pencil will be penalised.

Marks will be allocated for clarity, logic and correctness of calculations, and for overall presentation.

Marks will be deducted for failure to comply with all instructions given. Each group member will

receive the same mark. Late submission will attract a penalty of 10% per day.

Student Number / Name:

____________________________ _____________________________________________________________

____________________________ _____________________________________________________________

____________________________ _____________________________________________________________

____________________________ _____________________________________________________________

Marking Key:Question 1 (20)

Question 2 (20)

Question 3 (40)

Question 4 (20)

Total Marks (100)

Penalty for failure to followinstructions,or late submission

Final Recorded Mark(100)

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SUMMARY PAGES(to be located directly after cover sheet)

Insert question answers on these pages.

All working to support the answers given heremust also be attached.


Question 1

Combinations of Actions considered:

Design Actions to be used: N*t = ________________ kN

N*c = ________________ kN

UC selected: _____________________

Member data:

Nt Nc

kt Le

fy kf

fu fy

Ag b

An n

c

An

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Question 2

Member data:

Nt Nc

kt Le

fy kf

fu fy

Ag b

An ry

n

c

An

Sketch the failure paths considered and state the calculated net area for each of the

failure paths shown:

Is the non-standard steel section suitable? __________

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Question 3

a) UB selected: _____________________

member data:

kf fy rx An b

Column A Column B

Lex Lex

c c

Ncx Ncx

b)

Column A Column B

c required c required

n required n required

Max Ley to providesufficient lateral restraint

to column A

Max Ley to providesufficient lateral restraint

to column B

Logical lateral restraint

placement for Column A

restraints

Logical lateral restraint

placement for Column B

restraints

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c) UB selected: _____________________

member data:

kf fy ry An b

Column A Column B

Ley Ley

c c

Ncy Ncy

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Question 4

VR Md Mz,cat Ms Mt

Vsit, Design Wind Pressure: (in terms of Cfig)

Internal Pressure Coefficients (Cp,i):

Possible Openings:

Potential combinationsof openings:

Internal Pressure Coefficients (for each combination) : Cp,i

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External Pressure Coefficients (Cp,e ):

Windward Wall (W)

Leeward Wall (L)

Side Walls (S)

Roof

List the possible combinations of internal and external pressures that should be

considered

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Original due date: Thursday, 24th September 2009, 4:00 pmExtension given until: Tuesday, 29th September 2009, 4:00 pm

Submission to: Assignments office building 204, level 2


Question 1

A member in a large mining structure in Karratha is to be used to provide lateral

support to the structure. The member in the truss is 5.0 metres long (effectively

pinned at both ends), and will be subjected to the following unfactored actions:

Permanent Actions (compression) 80 kN

Imposed Actions (compression) 50 kN

Ultimate Wind Actions (compression) 200 kN

Ultimate Wind Actions (tension) -650 kN

It is required to select a grade 300PLUS UC member to satisfy all the relevant

loading combinations. Assume the UC member is connected to the structure with an

M16 bolt in each flange outstand (in the fracture plane cross section) as shown in

Figure 1.

Hints:

1. Calculate the ultimate action combinations and determine the worst ultimatetension action and the worst ultimate compression action.

2. Determine the lightest UC member required to resist the worst tension action.

3. Determine the lightest UC member required to resist the worst compressionaction. Assume that the member is pinned at both ends.

4. Choose the member that will satisfy both tension and compression requirements.

5. Show the capacity (tension and compression) of the selected member.

Figure 1

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Question 2

A non-standard lightly weldedsteel section (shown below) is available for use in the

structure in Question 1 at a substantial cost saving. Using the same length and

actions as in Question 1, determine whether this member would be suitable. Assume

it will be connected by M20 bolts in the flanges, as shown in the elevation and plan

views below.

Note: Bolt holes will be 22mm in diameter

Determine fy and fu using Table 2.1 of AS4100, assuming the steel elementsused to fabricate this steel section are standard grade 300 flats

Elevation:

Plan view:

Flanges: 200*6 FL

Web: 200*6 FL3030

40 40

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Question 3

A series of steel frames (as shown in Figure 3) are to be used to support a boardwalk

structure across uneven ground. The ultimate design actions on the frame are shown

in Figure 3.

Assume that the same section will be used to fabricate the beam and all of the

columns. Assume that the webs of all members lie in the plane of the frame.

Column A can be assumed to have a fixed base, and column B can be assumed to

have a pinned base. The members shall be a standard grade 300 UB or WB section.a) Determine the member size required for the columns and beam assuming

lateral restraint is to be provided for the columns against buckling about the

weak axis wherever necessary.

b) Determine the required lateral restraint spacing of each column to preventbuckling about the weak axis.

c) Determine the member required if lateral restraint is not provided.

Note:

1. Assume that the base condition of each column is the same in all directions, (ie if

it is pinned, it is pinned about the x and y axis, and if it is fixed it is fixed aboutboth axes). However, assume that the connection between the column and the

beam at the top is pinned when considering buckling about the y-axis (weak axis)

(ie out of the page) but it is a rigid connection when considering buckling about

the x-axis (strong axis) (ie in the plane of the frame and the page).

2. The boardwalk structure itself can prevent sway into the page (ie lateral restraintat the top of the column), but cant prevent sway in the plane of the frame.

4.5m

5.0 m

A B

350 kN 850 kN

8.0m

FIGURE 3

Not to scale

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Question 4

A small warehouse is to be constructed in a well developed industrial area of

Karratha, Western Australia (Wind Region D). The design wind actions that the

structure in subjected to need to be calculated to enable analysis of the structure.

Using the information given below, calculate the following data only:

1. The design wind pressure (in terms of Cfig). Assume Cdyn = 1.02. The internal wind pressure coefficients for different potential opening

combinations. Tabulate.3. The external wind pressure coefficients. Tabulate or sketch the possible cases.4. Disregarding the other coefficients used to calculate Cfig list the different

combinations of pressure coefficients that should be considered. (eg: Wext1+Wint1)

Design Information

For this assignment (and contrary to the requirements of the Wind ActionsCode), it is only necessary to calculate the wind actions associated with a

westerly wind(referred to as direction 1 in Figure 4).

Refer to Figure 4 for the dimensions of the structure.

Refer to Figure 4 for the location and dimensions of two openings in thestructure. During any wind event it cannot be assumed that either opening willbe open or closed, so all possible circumstances must be considered. Assume

there are no other openings and that there is negligible cladding permeability.

Assume there is no change in terrain category that needs to be considered.

Assume that no other nearby structures will provide any shielding to the structure

Assume that the structure is located on fairly flat terrain (ie: no hills orescarpments in the near vicinity).

Disregard any local pressure factors (assume we are obtaining wind actions todesign major structural elements, not cladding or purlins/girts).

Disregard any frictional drag forces.

30m6m2m

4.6m

0.8m

3.5mWind direction 1

(Westerly)

FIGURE 4

Not to scale

Opening

1

5.5m

Opening

2

3.5m

10m

3.0m

Opening 1 Opening2

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