Terms Flashcards
Stress
The resistance of a body to a load aka internal force and measured in kips
Factor of safety
Ratio of the ultimate strength of material in psi or ski
Strain
The deformation of a material caused by external loads. Tensile loads stretch, and compressive loads shorten.
Section modulus
Is the ratio of a cross sections second moment of area to the distance of the extreme compressive fiber from the neutral axis
Center of gravity
The point at which the mass of a member is concentrated is called what
Shear
Two pushing or pulling adjacent forces, acting close together but not directly opposing each other
Centroid
The actual point at the center of gravity that measurements are taken
Yield strength
is the lowest stress that produces a permanent deformation in a material.
Shear wall
A wall with in-plane rigidity
redundancy
Having the ability to redistribute loads to another part of the structure
lamella
a series of parallel arches, skewed with respect to the building, which intersects another series of skewed arches
bracketed duration
The time between the first and last peaks of motion that exceeds this threshold value of 0.05g
Frequency
Is the inverse of period or the number of cycles that will occur in a second abd is measured in hertz
Response spectrum
A site response spectrum is a graph that plots the maximum response values of acceleration, velocity and displacement against period.
Dynamic amplification
The increase of the structural movement over that of the ground motion
Drift
Deflection of vertical structural members like columns and walls
Eccentricity between the center of mass and the center of resistance
Torsional forces are created in a building by a lack of balance between the location of the resisting elements and the arrangement of the building mass
Soft story
Are less stiff or more flexible than stories above
Weak stories
Have less strength than stories above
P-delta effect
P is the gravity force or weight and delta is the eccentricity or the extent to which the force is offset. All objects that overturn do so as a result of this phenomenon.
Moment of inertia
directly proportional to the amount of deflection. If the deflection is high
Liquefaction
Soil liquefaction describes a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.
Resonance
It causes amplification of damage for instance when the buildings period matches the soils period
Slenderness Ratio
The ratio of a structural members unsupported height to its thickness
Space frame
A structural system consisting of trusses in two directions rigidly connected at their intersections
Two way structural slab system
Composed of concrete members usually spaced 24 or 36 inches apart, running in one direction and framing into larger beams