PSAD - TERMS

Is a mechanical property of a material that describes its ability to deform under tensile stress without fracturing.

Ductility

is a mechanical property of a material, and it refers to its ability to absorb energy without fracturing.

Toughness

refers to a substance or material that has uniform composition and properties throughout its structure.

homogeneous material

refers to a material's capacity to absorb impact or deformation and then recover its original shape and size when the applied load is removed.

Resilience

a material that describes its ability to deform under applied stress and return to its original shape and size when the stress is removed.

Elasticity

refers to the ability of a material to resist deformation when subjected to an applied load or force. It is a measure of the material's rigidity or resistance to bending, stretching, or compressing.

Stiffness

The ability of a material to undergo large permanent deformation in compression or property which enables a material to be beaten or rolled into thin sheets.

Malleability

is a substance or material that exhibits the same physical properties in all directions.

isotropic material

is a substance or material that exhibits different physical properties or behaviors in different directions.

anisotropic material

is a type of anisotropic material that exhibits distinct mechanical properties along different mutually perpendicular axes.

Orthotropic material

is the proportionality of stress and strain or the slope of the stress-strain diagram within the elastic range of the material.

Young's modulus

is a mechanical property that measures the energy absorbing capacity of a material under elastic deformation. It is defined as the maximum amount of energy per unit volume that a material can absorb without permanent deformation or failure.

modulus of resilience

also known as work hardening or cold working, is a mechanical phenomenon that occurs in certain materials when they are subjected to plastic deformation. It refers to the increase in hardness and strength of a material as a result of plastic deformation, while also decreasing its ductility.

Strain hardening

refers to the region in which it exhibits linear elastic behavior. In this range, the material will deform under an applied load, but it will return to its original shape and size once the load is removed.

elastic range

refers to the stress level at which the material begins to exhibit significant plastic deformation or permanent strain under an applied load.

Yield point

refers to the stress or load that a material can withstand before it breaks or ruptures. It is the point at which the material experiences complete failure under tension.

rupture strength

is the maximum stress or load that a material can withstand before it breaks or fails. It is the highest point on the stress-strain curve of the material during a tensile test.

Ultimate strength

is the greatest stress that one can still see a linear relation between stress and strain. Beyond this point, the stress is no longer proportional to the strain.

proportional limit

This is the ratio of lateral strain to longitudinal strain. The typical range of values for this quantity is between zero and 0.5.

Poisson's ratio

refers to the point along the beam's cross-section where the application of a shear load causes only shear deformation without inducing bending or twisting.

shear center

is a widely used method of prestressing in which high-strength steel tendons or cables are tensioned after the concrete has hardened.

Post-tensioning

is a method of prestressing in which high-strength steel tendons or cables are tensioned before the concrete is cast.

Pre-tensioning

Temporary force exerted by the device that introduces tension into the tendons in prestressed concrete.

Jacking force

in prestressed concrete refers to the gradual loss of prestress force in the reinforcing tendons over time.

Relaxation

refers to the distance between the axis of an applied load or force and the centroid or center of gravity of a structural element. It represents the offset or displacement of the load from the central axis of the element.

eccentricity

refer to granular materials used as a component of concrete, asphalt, or other construction materials.

Aggregates

refers to a substance added to concrete, mortar, or other construction materials during mixing to modify their properties.

admixture

is the point in a column cross-section where the resultant force acts when all the steel has yielded in compression and the entire concrete section is subjected to its maximum compressive stress.

Plastic Centroid

is a structural system composed of braced panels to counter the effects of lateral load acting on a structure. Wind and seismic loads are the most common loads that these are designed to carry.

Shear wall

is a mechanical instability phenomenon that occurs in structural elements when they undergo compressive forces. It refers to the sudden lateral deflection or deformation of a slender structure under an axial load, leading to a loss of stability.

Buckling

is the principle that states that the conditions of equilibrium or motion of a rigid body will remain unchanged if a force F acting at a given point of the rigid body is replaced by a force F' of the same magnitude and same direction, but acting at a different point, provided that the two forces have the same line of action.

Transmissibility

is the location of application of lateral load at that point will not produce rotation of that story in a building.

Center of rigidity

refers to the point within the building where the entire mass or weight of the structure can be considered to be concentrated.

center of mass

is a concept in structural mechanics that states that as a localized load is applied to a structural element, the effects of that load will become more uniformly distributed throughout the element at distances sufficiently far away from the point of application.

Saint Venant's principle

refers to a floor level within a building that is significantly more flexible or weaker in stiffness compared to the floors above it or below it.

soft storey

also known as interstorey drift or story drift, refers to the relative horizontal displacement or movement between adjacent storeys of a building during lateral loading, such as earthquakes or strong winds.

Storey drift

Pertaining to earthquake activities.

Seismic

Areas defined on a map within which seismic design requirements are constant.

Seismic Zone

The worldwide or local distribution of earthquakes in space and time; a general term for the number of earthquakes in a unit of time, or for relative earthquake activity.

Seismicity

A device, which writes or tapes a permanent, continuous record of earth motion, a seismogram.

Seismograph

The sinking of a plate under an overriding plate in a convergence zone.

Subduction

A long and narrow deep trough in the sea floor; interpreted as marking the line along which a plate bends down into a subduction zone.

Trench

To modify the period of the building beyond the range of the site period to avoid resonance. Examples include lowering the height of a building; lowering the position of weight in a building; changing materials; changing fixity of base, etc.

Tuning

A measure of earthquake size which describes the amount of energy released. The measure is determined by taking the common logarithm (base 10) of the largest ground motion observed during the arrival of a P-wave or seismic surface wave and applying a standard correction for distance to the epicenter.

Richter Magnitude Scale

Induced oscillations of maximum amplitude produced in a physical spectrum when applied oscillatory motion and the natural oscillatory frequency of the system are the same.

Resonance

is a measure of earthquake size which describes the amount of energy released.

Magnitude

refers to the subjective assessment of its effects and the level of shaking experienced at a particular location. It is a measure of the impact or damage caused by an earthquake rather than a direct measure of the earthquake's physical characteristics.

Intensity

A method using flexible bearings, whereby a building superstructure is detached from its foundation in order to reduce earthquake forces.

Base Isolation

Resultant of resistance provided by walls and frames.

Center of Resistance

The point of the earth's surface directly above the focus or hypocenter of an earthquake.

Epicenter

Depth of the earthquake (or hypocenter) below the ground surface.

Focal Depth

The point at which the rupture occurs; (It marks the origin of the kinetic waves of an earthquake).

Focus (of an earthquake) or Hypocenter

One having diagonal braces for stability and capacity to resist lateral forces.

Braced Frame

The centerlines of brace, supporting beam and column coincide.

Concentric Braced Frame

The centerlines of brace, beam and of column and do not coincide allowing deformation, thereby utilizing ductility.

Eccentric Bracing

Frames in which structural members and joints resist lateral forces by bending.

Moment Frame

Acceleration of the ground due to earthquake forces.

Ground Acceleration

The distance that ground moves from its original position during an earthquake.

Ground Displacement

A situation in which the ground does not hold together such as land sliding, mud flows and liquefaction.

Ground Failure

A general term; includes all aspects of motion: acceleration, particle velocity and displacement.

Ground Movement

Velocity of the ground during an earthquake.

Ground Velocity

Transformation of a granular material (soil) from a solid state into a liquefied state as a consequence of increased porewater pressure induced by vibration.

Liquefaction

Encasement of existing columns with steel or Kevlar to increase resistance.

Jacketing