Flexural Analysis of Beams

Question 1

Stress due to bending

Answer 1

Flexure

Question 2

This is the concrete cracked - elastic stress stage

Answer 2

Service Stage

Question 2

Bending moment where cracks will begin to occur.

Answer 2

Cracking Moment

Question 2

This is the ultimate strength stage

Answer 2

Failure

Question 3

This is the uneconomical stage before collapse occur

Answer 3

Uncracked concrete stage

Question 3

If the steel does not yield, the concrete is still on the ______ stage

Answer 3

Elastic Stage

Question 4

It is the moment that causes the stress in the extreme tension fiber to reach the modulus of rupture

Answer 4

Cracking Moment

Question 5

Stage of Working stress design where the criteria is Ma < Mcr

Answer 5

Stage 1: Uncracked Concrete Stage

Question 6

Stage of working stress design where the criteria is Ma > Mcr

Answer 6

Stage 2: Concrete Cracked - Elastic Stresses Stage

Question 7

are the loads that are assumed to actually occur when a structure is in use or service.

Answer 7

Service Loads or Working Loads

Question 8

It is the clear distance between bars

Answer 8

Spacing

Question 9

For members with parallel layers of rebar, the minimum spacing should be ____

Answer 9

At least one bar diameter but not less than 1 in

Question 10

For members with two or more layers of rebar, the upper layers must be _____ in the bottom layers

Answer 10

directly above

Question 11

Clear spacing for members with two or more layers of rebar

Answer 11

at least 1 inch clear vertically

Question 12

For this member the clear distance between longitudinal bars must be at least 1-1/2 bar diameter but not less than 1-1/2 inch

Answer 12

Spirally reinforced and tied reinforced compression members

Question 13

In walls and slabs other than concrete joists, primarily flexural reinforcement must NOT be spaced ____

Answer 13

greater than 3 times the wall or slab thickness nor 18 inches

Question 14

For flexural members, the clear horizontal distance is ____

Answer 14

db > 1 in

Question 15

For Compression members, tied or spirally, the clear horizontal distance is _____

Answer 15

1.5 db > 1.5 inches

Question 16

d stands for

Answer 16

effective depth

Question 17

d’ stands for

Answer 17

effective cover

Question 18

ft stands for

Answer 18

tensile stress

Question 19

fr stands for

Answer 19

modulus of rupture

Question 20

h stands for

Answer 20

depth

Question 21

b stands for

Answer 21

width

Question 22

Formula for Modulus of Elasticity
(Concrete, Normal Weight)

Answer 22

Ec = 4700 √fc’

Question 23

Formula for Modulus of Elasticity
(Steel)

Answer 23

Es = 200,000 Mpa

Question 24

Formula for allowable stress on concrete

Answer 24

fc = 0.45fc’

Question 25

Formula for allowable stress on steel

Answer 25

fs = 0.5fy

Question 26

Formula for Rupture (Normal weight of concrete)

Answer 26

fr = 0.62 λ √fc’

Question 27

Formula for modular ratio

Answer 27

n = Es/Ec

Question 28

Ma stands for

Answer 28

actual moment due to load

Question 29

symbol for allowable moment of steel

Answer 29

Ms

Question 30

symbol for allowable moment of concrete

Answer 30

Mc

Question 31

nb stands for

Answer 31

number of bars

Question 32

db stands for

Answer 32

bar diameter

Question 33

To solve for cracking moment (Mcr), use formula ___

Answer 33

fr = Mcr(y) / Ig

Question 34

Specified cover (mm) for cast against and permanently in contact with ground

Answer 34

75 mm

Question 35

Specified cover (mm) for concrete exposed to weather or in contact with ground.
No. 19 through No. 57 bars

Answer 35

50 mm

Question 36

Specified cover (mm) for concrete exposed to weather or in contact with ground.
No. 16, MW200 or MD200 wire, and smaller

Answer 36

40 mm

Question 37

Specified cover (mm) for concrete not exposed to weather or in contact with ground.
Slab, joists, and wall member
No.43 and 57 bars

Answer 37

40 mm

Question 38

Specified cover (mm) for concrete not exposed to weather or in contact with ground.
Slab, joists, and wall member
No. 36 bar and smaller

Answer 38

20 mm

Question 39

Specified cover (mm) for concrete not exposed to weather or in contact with ground.
Beams, columns, pedestals, and tension ties

Answer 39

40 mm

Question 40

Reinforcement for beams, columns, pedestals, and tension ties

Answer 40

✓ Primary Reinforcement
✓ Stirrups
✓ Ties
✓ Spirals
✓ Hoops

Question 41

Reinforcement for slabs, joists, and walls

Answer 41

✓ No. 43 and No. 57 bars
✓ No. 36 and smaller bars

Question 42

3 Advantages of Concrete Cover

Answer 42

✓ Helps steel to not be exposed on weather
✓ Helps avoid corrosion
✓ Enhances fire resistance

Question 43

Three distinct stages before collapse occur:

Answer 43

1. The uncracked concrete stage (uneconomical)
2. The concrete cracked - elastic stresses stage (service stage)
3. The ultimate-strength stage (failure)