GERTC PSAD Terms: Structural

are caused by the direct contact of one body with the surface of another.

Surface forces

is developed when one body exerts a force on another body without direct physical contact between the bodies.

body force

All cross sections are the same throughout its length.

Prismatic

has the same physical and mechanical properties throughout its volume.

Homogeneous material

has these same properties in all directions.

Isotropic material

reflect the probability that the total loading R will occur for all the events stated.

Load Factors

are determined from the probability of material failure as it relates to the material's quality and the consistency of its strength.

Resistance factors

If we select two line segments that are originally perpendicular to one another, then the change in angle that occurs between them is referred to as _________.

shear strain

A slight increase in stress above the elastic limit will result in a breakdown of the material and cause it to deform permanently.

Yielding

The stress that causes yielding is called the ________, 𝜎𝑌 , and the deformation that occurs is called _________.

yield stress or yield point and plastic deformation

When yielding has ended, an increase in load can be supported by the specimen, resulting in a curve that rises continuously but becomes flatter until it reaches a maximum stress referred to as the ultimate stress.

Strain Hardening

Up to the ultimate stress, as the specimen elongates, its cross-sectional area will decrease.

Necking

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

As a material is deformed by an external load, the load will do external work, which in turn will be stored in the material as internal energy. This energy is related to the strains in the material, and so it is referred to as ________.

strain energy

When the stress reaches the proportional limit, the strain-energy density is referred to as the _______.

Modulus of Resilience

This quantity represents the entire area under the stress-strain diagram, and therefore it indicates the maximum amount of strain-energy the material can absorb just before it fractures.

Modulus of Toughness

The ratio of modulus of toughness to the

modulus of resilience.

Ductility Factor

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 metal is subjected to repeated cycles of stress or strain, it causes its structure to break down, ultimately leading to fracture.

Fatigue

A condition where a material break down and deforms permanently even due to a slight increase in stress above the elastic limit.

Plasticity

When the plastic moment is removed from the beam then it will cause ________ to be developed in the beam.

Residual Stress

Members that are slender and support loadings that are applied perpendicular to their longitudinal axis.

Beams

The change in volume per unit volume is called the "volumetric strain" or the _________.

Dilatation

It occurs when a building period coincides with the earthquake period.

Resonance

Occurs when the structures center of mass does not coincide with the center of rigidity.

Torsional Shear Stress

Measured by a seismometer.

Ground Displacement

Reciprocal of deflection

Rigidity of a Structure

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 on its own plane, typically wind and seismic loads

Shear wall

It is the point where the object "suffers" no torque by the effect of the gravitational force acted upon it.

Center of Gravity

It is point through which the resultant of the resistance to the applied lateral force acts.

Center of Rigidity

It is point through which the applied seismic force acts.

Center of Mass

It is the distance between the center of rigidity and center of mass.

Eccentricity

It is the total design lateral force

Design seismic base shear

Inverse of stiffness.

Flexibility of a structure

It is the displacement of one level relative to the level above or below.

Story drift

Lateral displacement of the story relative to the base.

Story displacement

Rate at which natural vibration is absorbed.

Damping

Instrument use to measure the peak ground acceleration, which is one of the most important characteristics of an earthquake.

Seismometer

Instrument use to measure the strain of rock under pressure.

Magnetometer

The originating earthquake source of the elastic waves inside the earth which cause shaking of ground due to earthquake.

Focus (Hypocenter)

The point on the earth's surface directly above the focus.

Epicenter

Story drift divided by the story height.

Story drift ratio

A measure of the strength of shaking during earthquake.

Intensity

A measure of energy released in an earthquake.

Magnitude

Is a state in saturated cohesionless soil wherein the effective shear strength is reduced to negligible value.

Liquefaction

Is an oscillatory, sometimes violent movement of the ground's surface that follows release of energy in the Earth's Crust.

Earthquake

The sideways deflection of a building due to lateral (sideways) loads.

Shear Drift

The sideways deflection of axial (vertical) loads.

Chord Drift

A _________is one in which the lateral stiffness is less than 70 % of that in the storey above or less than 80 percent of the average stiffness of the three stories above.

Stiffness Irregularity - Soft Storey

It shall be considered to exist where the effective mass of any storey is more than 150 % of the effective mass of an adjacent storey. A roof that is lighter than the floor below need not be considered.

Weight (Mass) Irregularity

It shall be considered to exist where the horizontal dimension of the lateral-force-resisting system in any storey is more than 130 % of that in an adjacent storey. One-storey penthouses need not be considered.

Vertical Geometric Irregularity

An in-plane offset of the lateral-load-resisting elements greater than the length of those elements

In-Plane Discontinuity In Vertical Lateral-Force-Resisting Element Irregularity

A weak storey is one in which the storey strength is less than 80 % of that in the storey above. The storey strength is the total strength of all seismic-resisting elements sharing the storey for the direction under consideration.

Discontinuity In Capacity - Weak Storey Irregularity

Shall be considered to exist when the maximum storey drift, computed including accidental torsion, at one end of the structure transverse to an axis is more than 1.2 times the average of the storey drifts of the two ends of the structure.

Torsional irregularity

Plan configurations of a structure and its lateral-force-resisting system contain re-entrant corners, where both projections of the structure beyond a re-entrant corner are greater than 15 % of the plan dimension of the structure in the given direction.

Re-Entrant Corner Irregularity

Diaphragms with abrupt discontinuities or variations in stiffness, including those having cutout or open areas greater than 50 % of the gross enclosed area of the diaphragm, or changes in effective diaphragm stiffness of more than 50 % from one story to the next.

Diaphragm Discontinuity Irregularity

Discontinuities in a lateral force path, such as out-of-plane offsets of the vertical elements

Out of Plane Offsets Irregularity

The vertical lateral-load-resisting elements are not parallel to or symmetric about the major orthogonal axes of the lateral force-resisting systems.

Non-Parallel Systems Irregularity

Is the force which determines whether the body will be in Equilibrium or will have a varying state of motion

Resultant

The principle used in equations related to the deformation of axially loaded material.

- That the stress is proportional to the strain within the elastic region.

Hooke's Law

The ratio of the lateral to the longitudinal strain is constant

Poisson's Ratio

- It is the constant of proportionality that defines the linear relationship

Young's Modulus

A structural member that has the ratio of its unsupported height to its least lateral dimension of not less than 3 and is used

Column

Retarding force acting opposite of body in motion.

Kinetic Friction

It is the term for the value beyond which the stress is no longer proportional to the strain.

Proportional Limit

-Materials which have the same composition/compression at any point.

- Material has the same elastic properties in all directions.

Homogeneous

- Property of a material enables it to under large permanent strains before failure.

- Ability of a material to deform/ defuse in the plastic range without breaking. (2013 & 2016).

Ductility

It is described herein stressing high strength steel wires before concrete hardens.

Pre-Tensioning

It is described herein stressing high strength steel after the concrete has been cast and has attained sufficient strength.

Post-Tensioning

Is described herein loss of stress that takes place with the passage of time as concrete is held at a constant strain.

Relaxation

Ability of a material to absorb energy in the Elastic Range.

Resilience / Modulus of Resilience

- Ability of a material to absorb energy in the plastic range or fracture point. (2016)

Toughness / Modulus of Toughness

Property of a material which makes it return to its original dimension when the load is removed.

Elasticity

It is the point through which the resultant of the resistance to the applied lateral force acts. (2018)

Center of Rigidity

It is the distance between the Center of Rigidity and Center of Mass.

Eccentricity

One in which the lateral stiffness is less than 70 percent of the stiffness of the story above is called

Soft Story

A Lateral Displacement of one level relative to the level above or below is called

Story Drift

is best described as

- A sudden drop in the shear strength of a soil.

Liquefaction"

it refers to the Rigidity of a Structure

Reciprocal of Deflection

It is the point through which the applied seismic force acts.

Center of Mass

Refers to flexibility of structure.

Reciprocal of Stiffness

- The material has the same composition at every point but the elastic may not be the same in all directions.

- The composite material exhibits elastic properties in one direction different from that in the perpendicular direction.

Orthotropic

Besides the Epicenter, it describes the location of the Earthquake.

Focal Depth

It is measured by a seismometer.

Actual Displacement or Seismic/Earthquake Waves

It is measured by the Richter Scale

Magnitude of Earthquake

The material is subjected to repeated cycles of stress or strain, it causes the structure to breakdown ultimately leading to fracture.

Fatigue

When a material has to support a load for a long period of time, what causes it to continue to deform until a sudden fracture occurs.

Creep

Condition of a material when it breaks down and deforms permanently even due to a slight increase in stress above the elastic limit.

Plasticity

It occurs when a building period coincides with the earthquake period.

Resonance

It occurs when the structure's center of mass does not coincide with its center of rigidity.

Torsion/Torsional Shear Stress

The greatest stress a material is capable of developing without deviation from straight line proportionality between strain and stress *

Proportional limit

The greatest stress a material is capable of developing without a permanent elongation remaining upon complete unloading of the specimen

Elastic limit

Slope of the straight line portion of the curve or the ratio of stress over the strain

Modulus of elasticity

The ability of a material to deform in the plastic range without breakage or the ability to undergo considerable plastic deformation under tensile load before actual rupture.

Ductility

A property of a material where if the specimen be unloaded, it will not return to its original length, rather it will retain a permanent elongation sometimes called a permanent set

Plasticity

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

Yield stress

The max. stress a material is capable of developing

Ultimate stress