General Flashcards

1
Q

What is the hierarchy of stiffnesses in stability calculations?

A

Axial
Bending
Torsional

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2
Q

Why are end fixings important for long beams?

A

Bolt slippage can cause large deflection in longer beams

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3
Q

How are wind loads applied to a structural model?

A

As points on beam-column connections which represent the area around that point

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4
Q

What size of bolts are required for moment connections?

A

8.8

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5
Q

Why is there no k in PC1 & PC2 for prestressed concrete?

A

There are no losses at transfer

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6
Q

Which inequalities bound the profile of bowed reinforcement bars?

A

PC1 & PC4

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7
Q

What is the stiffness at the upper end of a column which is attached to two beams either side (bl & br) and a column above (cu)?

A

Ku = (Kc + Kcu)/(Kc + Kcu + Kbl + Kbr)

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8
Q

How does a plate girder bear loads?

A

Top flange takes compression moment
Web takes shear
Bottom flange takes tension moment

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9
Q

What are the limits of depth to web thickness ratio for plate girders?

A

100-250

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10
Q

How is a prestressed concrete beam analysed and what does this mean?

A

Serviceability limit state so no factors are used

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11
Q

What is the minimum limit for steel stress at the bottom of a composite beam?

A

165N/mm2

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12
Q

What must you remember when finding the stress in the top of the concrete?

A

Convert values back from steel to concrete

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13
Q

What must you do for a composite beam question?

A

Draw a diagram of all forces and lever arms

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14
Q

What is the limit for c in a plate girder?

A

Epsilon x flange thickness where epsilon is in the Eurocodes

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15
Q

What is depth d of a plate girder?

A

Height y - flange thickness

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16
Q

What must always be done for point loads on a plate girder?

A

Stiffeners are positioned under them

17
Q

What is a in plate girder stiffener calculations?

A

Spacing between stiffeners

18
Q

What is the approximation for the moment at the end and centre of a rigid portal beam?

19
Q

What diagrams must be drawn in a rigid steel portal frame question?

A

A full dimensioned frame and a section of the bays with half of the columns above and below

20
Q

If there is a wind load of 28kN per floor on a 6 storey building (including ground floor and roof), what is the total?

A

0 x 14 + 4 x 28 + 1 x 14 = 126kN

21
Q

What is the short term concrete conversion factor for a composite section?

A

E of steel / E of concrete

22
Q

What is the long-term concrete conversion factor of a composite section?

A

2 * E of steel / E of concrete

23
Q

What must be found to compute the elastic stresses for short term and long term in a composite section?

A

The second moment of Area (I) for both short and long term

24
Q

What moment is used to calculate the short-term elastic stresses?

A

Live load only

25
What moment is used to calculate the long-term elastic stresses?
Sum of dead load and self weight
26
In principle, what is the equation for elastic stress?
(Moment x distance of outermost fibre to n/a) / (second moment of area) Divided by conversion factor if concrete
27
How do you determine the horizontal load on the mid height of wind loaded columns above a target floor?
Total wind load above target floor / number of half-beams Inner columns have larger values to match the total wind load
28
How do you determine the horizontal load on the mid height of wind loaded columns below a target floor?
Total wind load above and including target floor / number of half-beams Inner columns have larger values to match the total wind load
29
How does a rigid frame structure resist wind moment?
A force of Total wind moment / width of frame base Is carried in both outer columns, one upward, one downward
30
How is effective length of a column in a rigid steel frame determined
A chart gives the fraction Le/L from upper and lower limits of column stiffness
31
What is the lower limit for column stiffness if the base is fixed?
0.5
32
What is Wply of a plate girder?
Wply = Med/fy
33
How can you estimate the flange area for a plate girder?
Af = Med/(y * fy)