Response of Members Subjected to Shear Flashcards

1
Q

What happens to the shear stress as flexural capacity increases?

A

It decreases

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2
Q

What is the cause of shear in a member?

A

Change of moment

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3
Q

How many equations does the Compression Field Theory require you to solve to predict the response of a member in shear

A

10

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4
Q

How many equations does the Modified Compression Field Theory require you to solve?

A

15

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5
Q

What software package can you use to solve the equations in the MCFT?

A

MEMBRANE

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6
Q

What cross-sectional property is influenced by the size effect factor between the depth and width of a member?

A

The depth

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7
Q

Do larger members fail at comparatively lower stresses than smaller members?

A

Yes, this is why the size effect matters

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8
Q

What is the difference between the CFT and MCFT?

A

The inclusion of tensile stresses in the concrete after cracking
In CFT f1=0
In MCFT f1 not zero

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9
Q

If there is no reinforcement in the Z direction what is vci (shear stress on crack interface) equal to?

A

Applied shear stress v

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10
Q

What is the difference between a web-shear crack and a flexure-shear crack?

A

Web-shear cracking is a diagonal crack due to shear stresses in previously uncracked sections

Flexure-shear cracks form due to an extension of a flexural crack in cracked section

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11
Q

What changed between Morsch’s maximum shear stress formula and the ACI Code’s nominal shear stress formula for reinforced concrete beams

A

The lever arm from jd to d
Morsch v=V / bw j d
ACI Code v=V / bw d

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12
Q

Is the formula for cracking shear stress the same for web-shear cracks and flexure-shear cracks?

A

Nope

Two different formulas required

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13
Q

What 2 phenomena ensures that shear stresses are transmitted across flexural cracks?

A

1- Aggregate interlock

2- Dowel forces in flexural reinforcement

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14
Q

Does one type of diagonal crack occur before the other?

A

No, web-shear cracking can occur near the support first or flexure-shear cracking near the quarter of the span first

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15
Q

Cracking is a function of what strength?

Tensile or compressive strength of a member?

A

Tensile strength

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16
Q

What does f1 represent?

A

Principal tensile stress in concrete

17
Q

What does f2 represent?

A

Principal tensile stress in concrete

18
Q

According to the MCFT, what is the relationship between the principal stresses, f1 & f2, the inclination of diagonal cracks theta and the stages of concrete before and after cracking

A

Before cracking, f1 = f2 acting at 45 degrees

After cracking f1 and f2 not equal but act together at a different angle to cause further cracking