Qualitative

Question 1

How does the IBC cover design of bridges?

Answer 1

IBC does not cover bridges, only buildings.

CAL trans and AASHTO publications cover bridges

Question 2

What provisions does the IBC make for buildings subject to landslides, liquefaction, subsidence, gross differential settlement, or those buildings close to major ground-breaking fault?

Answer 2

None.

IBC provides rules for buildings that will resist typical ground shaking.

IBC assumes engineer will use good judgement to avoid dangerous locations.

Question 3

What info is provided by the geotechnical engineer working on a building design team?

Answer 3

Type of soil
Depth of water table
Depth to bedrock
Proximity to fault
Maximum credible earthquake 
Likelihood of liquefaction, landslides, subsidence and differential settlement

Question 4

Which structural system resists lateral loads by flexure in members and joints?

Answer 4

Moment resisting frames

Question 5

“Secondary Stress”

Answer 5

Bending stresses that result from distortion of the frame when resisting lateral loads by flexure. (Pdelta)

Question 6

“Primary Stress”

Answer 6

Stress as a result of the compression and tensile forces that act uniformly on the cross section.

Question 7

Structural elements that transfer lateral loads to vertical elements

Answer 7

Diaphragms
Horizontal Bracing
Beams in moment resisting frames

Question 8

Structural elements that transfer lateral loads to lower levels and the foundation.

Answer 8

Lateral force resisting systems
Shear walls
Brace frames 
Moment frames 
Cantilever columns

Question 9

What types of soil are vulnerable to potential failure or collapse under seismic loading?

Answer 9

Liquefiable soil
quick/highly sensitive clays
Weakly cemented soils
Pests
Highly organic clays of 10ft or more in thickness
High plasticity clays of 25ft or more in thickness
Clays with plasticity index greater than 75
Very thick soft/medium stuff clays of 120ft or more in thickness

Question 10

Soft (weak) story

Answer 10

A floor that has a lower stiffness than (0.70 of) the above story. Or 0.8 of average stiffness.

Open cantilever column system below a shear wall system above

Question 11

What does the ‘ap’ term in the Fp Calc for non-structural components represent?
Range of values?

Answer 11

Component amplification factor
Ranges from 1 to 2.5
If rigid component, ap = 1.0

Table 13.5-1 in ASCE or empirical data

Question 12

5 Vertical irregularities

Answer 12

Soft story (stiffness) 
Mass irregularity
Geometric
In plane discontinuity (offset of lateral elements)
Weak Story (strength)

Question 13

5 Horizontal Irregularities

Answer 13

Torsional (max drift v ave drift)
Reentrant corners
Diaphragm discontinuity
Out of plane offset
Nonparallel system (diagonal SW, not orthog).

Question 14

Pounding

Answer 14

Adjacent buildings coming into contact with each other.

ASCE 710 12.2

Question 15

What structures qualify for simplified static lateral force procedure?

Answer 15

3 stories or less
No irregularities 
Risk category I or II
2 lines min of lateral resistance each direction 
Single family dwellings may comply 

12.14

Question 16

When can the dynamic analysis method he used? When can it not?

Answer 16

It can always be used!!

Question 17

Continuity Ties

Answer 17

Transfer tension across joint in wood sheathing to avoid cross grain bending.

Question 18

ASD factor applied to dead when calculating overturning

Answer 18

0.6

Question 19

Flexible diaphragms transfer horizontal shear in what way?

Answer 19

Tributary areas

Question 20

Rigid diaphragms transfer horizontal shear in what way?

Answer 20

Based on relative rigidities of vertical lateral elements.

Question 21

Max allowable aspect ratio (height to width) for vertical wood structural shear wall panel?

Answer 21

3.5:1

Question 22

Fpx(min) for floors/diaphragms?

Answer 22

0.2SdsIeWp

Question 23

Fpx(max)for floors/diaphragms?

Answer 23

0.4SdsIeWp

Question 24

Which is more life-threatening, shear cracks in seismically detailed concrete column or flexure cracks in seismically detailed concrete shear wall?

Answer 24

Flexural cracks in wall (no confinement requirements)

Question 25

Two buildings have the same mass, but one building has a shorter natural period than the other. Which building will experience larger seismic force?

Answer 25

Building with shorter period = larger accelerations and force

Question 26

For seismic design category D, is it cheaper to build a 30 story MF building out of concrete or steel?

Answer 26

Steel is cheaper.

Question 27

What consideration should be given to the design of a building that resists lateral force by a combo of braces frame and shear wall action?

Answer 27

The lateral elements must be proportioned so that the deflections are equal for both LRFS.

Question 28

For small buildings 1-2 floors, list the structural systems from most to least cost effective?

Answer 28

1. Wood panel shear wall
2. Masonry wall
3. OSBF
4. Dual systems
5. Stuff redundant steel systems
6. Concrete MRF’s
7. Steel MRF’s

Question 29

Fort all tall buildings of 10 stories or more, list the structural systems from most to least cost effective.

Answer 29

1. Stuff redundant steel systems

2. Steel MRF’s

Question 30

What’s a setback? What could it cause?

Answer 30

When the upper portion of a building is smaller in footprint than the floors below.
Could cause “whipping action” since upper portion will have different period and mode shape than lower portion.
To counteract this, the upper portion must be stiffened to match the lower portion.