FEMA Ch. 5

Question 1

What type of forces do shear walls receive during a seismic event?

Answer 1

Lateral Forces

Question 2

What type of forces do braced frames receive during a seismic event?

Answer 2

Lateral Forces

Question 3

In a eccentric braced frame the braces are designed to meet in the middle of the beam with some distance separating them. What is the part of the beam between the two braces called, and what is its purpose?

Answer 3

1. ) Link beam

2. ) The purpose of the link beam is to provide ductility to the system

Question 4

What is a moment frame?

Answer 4

A moment resistant frame is a frame with no diagonal bracing in which the lateral forces are resisted primarily by BENDING in the beams and columns mobilized by strong joints between columns and beams.

Question 5

What is the advantage of a moment frame?

Answer 5

No bracing and shear walls, allow for greater flexibility within the architectural design

Question 6

What is the difference between concentric and eccentrically braced frames?

Answer 6

Concentric braced frames do NOT have a link beam

Question 7

What is a diaphragm?

Answer 7

A diaphragm is the horizontal resisting members (roof, floors) that transfer lateral loads to the vertical elements (walls, frames)

Question 8

What are the edges in a diaphragm called that are perpendicular to lateral forces.

Answer 8

Chords

Question 9

What are the two types of diaphragms?

Answer 9

1. ) Flexible

2. ) Rigid

Question 10

What is a flexible diaphragm?

Answer 10

A diaphragm made of pieces, like wood or steel. They can be made of precast concrete panels as long as movement can occur between.
(NO TORSION)

Question 11

What is a rigid diaphragm?

Answer 11

Typically all concrete decking, flooring roofing function as rigid diaphragms.
(TORSION OCCURS)

Question 12

T/F Collectors and drag struts are the same thing.

Answer 12

True

Question 13

What are the 4 Building attributes that are desirable in a seismic zone?

Answer 13

1. ) Continuous load path.- Uniform loading of structural elements and no stress concentrations.
2. ) Low height-to base ratio - Minimizes tendency to overturn.
3. ) Equal floor heights - Equalizes column or wall stiffness, no stress concentrations.
4. ) Symmetrical plan shape - Minimizes torsion.

Question 14

What is a re-entrant corner?

Answer 14

A re-entrant corner is an interior corner that occurs between buildings that are L shaped, T shaped etc.

Question 15

Do to the lack of symmetry a building with Re-entrant corners creates what type of force on the building?

Answer 15

Torsional Force

Question 16

What is an example of a solution if the design requires a re-entrant corner?

Answer 16

1. ) structurally to separate the building into simpler shapes
2. ) Tie the building together more strongly with elements positioned to provide a more balanced resistance ( For Smaller Shapes)

Question 17

In regards to seismic design what is the P-Delta effect?

Answer 17

The P-Delta effect is where P is the gravitational force, and Delta is the eccentricity or the extent to which the force is offset.