PSAD TERMS (Sir Ferry)

Oldest measure of earthquake strength based on damage and observed human/building effects:

Intensity

The tensile stress that develops on a diagonal surface of a member:

Diagonal Tension

The ratio of the failure stress to allowable stress is:

Factor of Safety

The property enabling a material to undergo considerable plastic deformation under compressive load:

Malleability

The stress at which a marked increase in strain occurs without an increase in stress:

Yield Stress

The greatest stress a material can withstand without permanent elongation upon complete unloading:

Elastic Limit

What condition occurs when a structure's center of mass does not coincide with its center of rigidity?

Torsional Shear Stress

What phenomenon occurs when a building's natural period coincides with the earthquake period?

Resonance

When a material deforms continuously under a long-term sustained load until fracture occurs, it is called:

Creep

When a material is subjected to repeated cycles of stress or strain leading to eventual failure, it is called:

Fatigue

A material having different elastic properties in perpendicular directions is classified as:

Orthotropic

The term that refers to the flexibility of a structure:

Reciprocal of Stiffness

The point through which the applied seismic force acts on a structure:

Center of Mass

A sudden drop in the shear strength of a soil under seismic action is best described as:

Liquefaction

The lateral displacement of one level relative to the level above or below:

Story Drift

A story in which the lateral stiffness is less than 70 percent of the stiffness of the story above:

Soft Story

The distance between the Center of Rigidity and the Center of Mass is called:

Eccentricity

The point through which the resultant of the resistance to applied lateral force acts:

Center of Rigidity

The ability of a material to absorb energy in the plastic range up to its fracture point is:

Modulus of Toughness

The ability of a material to absorb energy in the Elastic Range is:

Modulus of Resilience

The loss of stress that takes place over time when concrete is held at a constant strain is known as:

Relaxation

Stressing high-strength steel after concrete has been cast and attained sufficient strength:

Post-Tensioning

Stressing high-strength steel wires before concrete hardens is described as:

Pre-Tensioning

The property of a material enabling it to undergo large permanent strains/deformations before failure is called:

Ductility

What is the retarding force acting opposite to the direction of a body in motion?

Kinetic Friction

A structural member with an unsupported height-to-least lateral dimension ratio not less than 3, used primarily to support axial load:

Column

What is the constant of proportionality that defines the linear relationship between stress and strain?

Young’s Modulus

What is the ratio of lateral strain to longitudinal strain?

Poisson’s Ratio

What principle states that stress is proportional to strain within the elastic region?

Hooke’s Law

Which force determines whether the body will be in equilibrium or will have a varying state of motion?

Kinetic Friction