3 Flashcards
Unified Soil Classification System
The most widely used system for classifying soils. In this system, the soils are primarily classed as coarse-grained (gravels and sands), fine-grained (silts and clays), and highly organic.
precast concrete
A concrete element cast in a location other than its final position. After curing, it is moved to its final location and installed.
coefficient of thermal expansion
The ratio of unit strain to temperature change, which is constant for a given material.
concentric braced frame
A braced frame in which the center lines of intersecting members meet at a point and whose members are therefore subjected primarily to axial forces.
coefficient of friction
The ratio of the maximum frictional force between two bodies to the normal (perpendicular) for pressing the surfaces together.
moment
The tendency of a force to cause rotation about a given point or axis.
working stress
The maximum unit stress permissible in a structural member. It is also called allowable stress.
clay
A fine-grained, cohesive, inorganic soil.
volume factor
A factor used to reduce the allowable bending stress for glued, laminated beams, based on width, depth, and span.
thrust
The horizontal reaction at the base of an arch.
fill
A manmade deposit of soil.
caisson
A waterproof box-like structure in which construction work can be performed underwater. Also a pile constructed by pouring concrete into a drilled shaft.
construction joint
The joint between two successive concrete pours. Construction joints are usually located where the shear is minimum, such as at the midspan of beams.
rigid frame
A frame with rigid joints, in which members and joints are capable of resisting vertical and horizontal forces primarily by flexure. It is also called a moment/resisting frame.
p-delta effect
The secondary effect on frame members produced by vertical loads acting on a building frame which is laterally displaced by earthquake loads.
deflection
The movement of a beam from its original location when load is applied to it.
centroid
The point in a cross-section where all of the area may be considered concentrated without affecting the moment of the area about any axis. For symmetrical shapes, the centroid is the geometric center of the shape.
vertical shear (v)
The algebraic sum of the forces that are on one side of a given cross-section of a beam.
component
One of two or more forces which will produce the same effect on a body as a given force.
in situ
In place.
pile cap
A thick, reinforced concrete slab placed over a group of piles and used to distribute the structural load to all the piles in a group.
continuous beam
A beam that rests on more than two supports.
compression
Stress which tends to shorten a member or crush it.
column
A member, usually vertical, which is subject primarily to axial compressive load.
amplification
An increase in a building’s response to earthquake ground motion, resulting from the building’s period coinciding with that of the ground shaking, or other causes.
resonance
The condition that occurs when a building’s period is close to that of the predominant period of the earthquake ground shaking. Resonance causes the building’s response to be amplified, and the resulting increases in the buildings earthquake-induced forces and deformations must be considered in the design.
bearing capacity
The load per unit area which can be safely supported by the ground.
spiral column
A reinforced concrete column, usually square or round, containing longitudinal reinforcing bars enclosed by a closely spaced continuous steel spiral.
billet bars
The most commonly used reinforcing steel, rolled from steel billets made by open-hearth, electric furnace, or acid-bessemer process.
load
A force applied to a body.
reactions
Forces acting at the supports of a structure which hold the structure in equilibrium.
epicenter
The projection of the focus, where rock slippage begins, on the ground surface.
windward side
The side of a building facing the direction from which the wind is blowing.
diaphragm chord
The boundary element of a diaphragm or shear wall which is assumed to resist axial stresses, analogous to a flange of a beam.
base isolation
A method of isolating a structure from the ground by specially designed bearings and dampers which absorb earthquake forces. Also called seismic isolation.
essential facilities
Structures or buildings which must be safe and usable for emergency purposes after an earthquake or severe windstorm. Such facilities include hospitals and fire and police stations.
dynamic lateral force procedure
A method for determining earthquake forces in which a mathematical model of the structure is developed and then subjected to appropriate ground motions. This procedure is always acceptable for design.
tension
Stress which tends to stretch a member or pull it apart.
seismicity
A measure of the frequency, intensity, and distribution of earthquakes in a given area.
suction
Negative pressure.