PSAD Flashcards
energy stored in a material due to its deformation.
Strain energy
it indicates the maximum amount of strain-energy the material can absorb just
before it fractures (ability to absorb energy in plastic range).
Modulus of toughness:
represents the largest amount of internal strain energy per unit volume the
material can absorb without causing any permanent damage to the material (ability to absorb
energy in the elastic range).
Modulus of Resilience:
refers to the property of a material which makes it return to its original dimension when the
load is removed.
Elasticity:
refers to the ability of a material to deform in the plastic range without breaking.
Ductility:
or ability to resist a deformation within the linear range.
Stiffness:
material’s resistance to fracture.
Toughness:
material’s resistance to indentation.
Hardness:
Any material that can be subjected to large strains before it fractures
Ductile Materials:
Materials that exhibit little or no yielding before failure
Brittle Materials:
has the same physical and mechanical properties throughout its volume or
material has the same composition at any point.
Homogeneous material:
has same physical and mechanical properties in all directions.
Isotropic material:
has material properties at a particular point, which differ along three mutually-
orthogonal axes.
Orthotropic material:
all cross sections are the same throughout its length.
Prismatic:
When a material has to support a load for a very long period of time, it may continue to deform
until a sudden fracture occurs or its usefulness is impaired.
Creep:
When a material is subjected to repeated cycles of stress or strain, it causes its structure to break
down, ultimately leading to fracture.
Fatigue:
lateral deflection that occurs when long slender members are subjected to an axial compressive
force.
Buckling:
A slight increase in stress above the elastic limit will result in a breakdown of the material and
causes it to deform permanently.
Yielding:
When yielding has ended, an increase in load can be supported by the specimen, until
it reaches a maximum stress referred to as the ultimate stress.
Strain Hardening:
Just after the ultimate stress, the cross-sectional area will begin to decrease in a localized region
of the specimen, until the specimen breaks at the fracture stress.
Necking:
It is the space between two adjacent floors
Story:
rigid horizontal planes used to transfer lateral forces to vertical resisting elements.
Diaphragms:
wall designed to resist lateral forces acting in its own plane, typically wind and seismic loads.
- stiffened walls and are capable of transferring lateral forces from floors and roofs to the
foundation.
Shear wall:
is the point where the object “suffers” no torque by the effect of the gravitational force
acted upon it.
Center of gravity:
center of resistance of a floor or diaphragm against lateral forces
- It is the point through which the resultant of the resistance to the applied lateral force acts.
Center of rigidity:
point through which the resultant of the masses of a system acts.
- It is the point through which the applied lateral force acts.
Center of mass:
The point through which the resultant of the restoring forces of a system acts.
Center of stiffness:
distance between the center of rigidity and the center of mass.
Eccentricity:
It is the total design lateral force at the base of a structure.
Design seismic base shear:
is the lateral displacement of one level relative to the level above or below.
Story drift:
is the lateral displacement of the story relative to the base
Story displacement:
Discontinuities in a lateral force path
Out-of-plane offsets:
occurs when the structure’s center of mass does not coincide with its center of
rigidity
Torsional shear stress:
It occurs when a building period coincides with the earthquake period.
Resonance:
time period of undamped free vibration of a structure.
Natural period:
rate at which natural vibration is absorbed.
- The effect of internal friction, imperfect elasticity of material, slipping, sliding, etc in reducing
the amplitude of vibration
Damping:
The geographical point on the surface of earth vertically above the focus of the earthquake.
Epicenter:
The originating earthquake source of the elastic waves inside the earth which cause shaking of
ground due to earthquake.
Focus:
the capacity to undergo large inelastic deformations without significant loss of strength or
stiffness.
Ductility:
is a state in saturated cohesionless soil wherein the effective shear strength is reduced to
negligible value.
- condition when soil tends to behave like a fluid mass.
Liquefaction:
a measure of the strength of shaking during the earthquake
Intensity:
a measure of energy released in an earthquake.
Magnitude:
are instruments used to record the motion of the ground during an earthquake.
Seismographs:
It is one in which the lateral stiffness is less than 70 percent of that in the storey above or less
than 80 percent of the average lateral stiffness of the three storeys above.
Soft Storey:
It is one in which the storey lateral strength is less than 80 percent of that in the storey
above.
Weak Storey:
Inverse of stiffness.
Flexbility
The deformation that occurs
in yielding.
Plastic Deformation
