Chapter 9

Question 1

Irregular Structures, what is a re-entrant corner

Answer 1

An interior corner, that requires the building corner to be either strengthened or treated as separate buildings.

Question 2

What is Stiffness irregularity

Answer 2

Variable length columns can reveal a stiffness irregularity between floors, this can cause buckling of weaker columns and lead to total building failure.

Question 3

What is a weak story?

Answer 3

A story of the building that is more susceptible, to failure do to improper design. Where lateral strength is less than 80% of that in the story above.

Question 4

Irregular mass?

Answer 4

Mass of a story greater than 150% of an adjacent story.

Question 5

Vertical structure irregularity?

Answer 5

Irregularity exists if the dimension of the lateral force resisting system at any story is more than 130% of that for any adjacent story.

Question 6

In plane discontinuity?

Answer 6

Vertical structure irregularity occurs when the offset is greater than the width or there exists a reduction in stiffness of the story below.

Question 7

What is accidental torsion?

Answer 7

When diaphragms are not flexible, the design shall include the torsional moment resulting from the location of the structure masses plus the accidental torsional moments caused by assumed displacement of the mass, each way from its actual location by a distance equal to 5% of the dimension of the structure perpendicular to the applied forces

Question 8

Diaphragm deflection?

Answer 8

The deflection in the plane of the diaphragm, anything not apart of the building must be designed for the gravity load effect and seismic forces , or any movement induced by horizontal displacement.

Question 9

What is a PAI35?

Answer 9

Is a tension tie that connects the wall to the diaphragm and prevents cross grain bending of wood the ledger.

Question 10

Non-structural Components vs. Brace Cantilever Parapets.

Answer 10

Critical when designing in high seismic areas, bracing occurs at the parapet height in order to prevent the parapet from toppling over.

Question 11

In seismic deformation what is the P Delta effect?

Answer 11

The secondary effect on shears and moments of the structural members due to the action of the vertical loads induced by horizontal displacement of the structure resulting from various loading conditions.

Question 12

In a weak story what is an extreme irregularity?

Answer 12

An irregularity that exists if the lateral strength of any story is less than 65% of the strength.