Lecture 2

Question 1

Highways with 1-2 lanes have a ______width

Answer 1

12’

Question 2

Highways with 4 lanes have a ______wide right shoulder

Answer 2

10’

Question 3

Highways with 4 lanes have a ______wide right shoulder

Answer 3

10’

Question 4

Highways with 4 lanes have a ______wide left shoulder

Answer 4

4’

Question 5

Highways with 6-8 lanes have a ______wide left shoulder

Answer 5

10’

Question 6

The minimum median width is obtained by…

Answer 6

adding two left shoulder width in table 3.10 AASHTO to give 10’ for 4 lane and 22’ for 6 and 8

Question 7

for freeways and arterial systems a minimum vertical clearance is

Answer 7

16’ plus an allowance for about 6 inches of resurfacing

Question 8

A general statement for assuring safety in design is that

Answer 8

the resistance of the components supplied must exceed the demands placed on them by the loads

Question 9

A limit state can be defined as

Answer 9

a condition beyond which a bridge system or component ceases to fulfil the function for which it was designed

Question 10

The value to be used for the strength limit state ductility factors in non ductile components and connections is…

Answer 10

η_d = 1.05

Question 11

The value to be used for the strength limit state ductility factors in ductile components and connections is…

Answer 11

η_d = .95

Question 12

Ductility is importannt to the safety of the bridge because

Answer 12

If ductility is present, overloaded portions of the structure can redistribute the load to other portions that have reserve strength.

Question 13

What is the redistribution of the load from ductility dependent on?

Answer 13

the ability of the overloaded component and its connections to develop inelastic deformations WITHOUT failure

Question 14

When is a structure statically indeterminant?

Answer 14

When it has more restraints than necessary to satisfy conditions of equilibrium

Question 15

Benefits of Redundancy in a bridge system

Answer 15

To increase its margin of safety and its reflected strength limit state redundancy factors

Question 16

What is the redundancy factor for non-redundant members?

Answer 16

η_R= 1.05

Question 17

What is the redundancy factor for redundant members?

Answer 17

η_R= .95

Question 18

What is the redundancy factor for conventional redundant members?

Answer 18

η_R= 1.00

Question 19

True/False Single load paths or non redundant bridge systems are encouraged

Answer 19

False, they are not

Question 20

Extreme limit state and strength limit state have a importance factor of ________for non ductile components

Answer 20

η_i= 1.05

Question 21

Extreme limit state and strength limit state have a importance factor of ________for ductile components

Answer 21

η_i= .95

Question 22

Limit states to consider in bridge design

Answer 22

1. service limit state
2. fatigue limit state
3. strength limit state
4. extreme limit state

Question 23

Service limit state pertains to?

Answer 23

restrictions on stresses, deflections, and crack width of bridge components

Question 24

For service limit state resistance factor Φ and load factor γ_i are =

Answer 24

1.0

Question 25

How many service limit state conditions are there?

Answer 25

4

Question 26

Define service limit state 1

Answer 26

refers to the load commination elating to normal operational use of the bridge with 55 mph wind

Question 27

Define service limit state 2

Answer 27

this service limit state refers to the load combination relating to steel structures and is intended to control yielding and slip critical connections

Question 28

Define service limit state 3

Answer 28

This limit state refers to the load combination relating to tension in pre-stressed concrete superstructure with the objective of crack control.

Question 29

Define service limit state 4

Answer 29

This limit state refers to the load combination relating to tension in pre-stressed concrete substructure with the objective of crack control.

Question 30

AASHTO defines __#____ fatigue limit states

Answer 30

2

Question 31

The fatigue limit state refers to restrictions on…

Answer 31

stress range caused by a design truck

Question 32

The fatigue and fracture limit state Φ

Answer 32

1.0

Question 33

What limit state defines ΦR_n >= η Σ Υ_i Q_i

Answer 33

Strength limit state

Question 34

Strength limit state defines the evaluation of the resistance to…

Answer 34

Bending
Shear
Torsion
Axial Load

Question 35

Define strength limit state 1

Answer 35

this is the basic load combination relating to the normal vehicular use of the bridge without wind

Question 36

Define strength limit state 2

Answer 36

this is the basic load combination relating to use of the bridge by permit vehicles without wind

Question 37

Define strength limit state 3

Answer 37

This strength limit is the basic load combination relating to the bridge exposed to wind velocity exceeding 55mph

Question 38

Define strength limit state 4

Answer 38

This strength limit is the basic load combination relating to very high dead load/live load force effect ratios

Question 39

Define strength limit state 5

Answer 39

This strength limit is the basic load combination relating to the normal vehicular use of the bridge with wind of 55mph velocity. It differs from strength 3 b the presence of the live load on the bridge, wind on the live load and reduced wind on the structure.

Question 40

Extreme event limit state defnes

Answer 40

Refers to the structural survival of a bridge during a major earthquake or floods or when collided by a vessel, vehicle or ice flow. (apply separately)

Question 41

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