Structure Flashcards
A stable assembly of structural elements desgined and constructed to function as a whole in supporting and transmitting applied loads safely to the ground without exceeding the allowable stresses in the members.
Structure
A structural member having a length that dominates its other two dimensions.
Linear Structure
A structural member having a length and width that dominates its thickness.
Surface structure
Of or pertaining to a structure or structural member having a shape that does not change appreciable under action of an applied load or changing loads.
Rigid
A structure or structural member that redirects external forces primarily through the bulk and continuity of its material, such as a beam or column,
Bulk-active structure,
A structure that redirects external forces primarily through the composition of tension and compression members, such as a truss.
Vector-active structure
A structure that redirects external forces primarily along the continuity of a surface, such as a plate or shell.
Surface-active structure
Of or pertaining to a structure or structural member characterized by a lack of stiffness and having a shape that responds to changes in loading.
Flexible
A structure or structural member that redirects external forces primarily through the form of its material, such as an arch or cable.
Form-active structure
Contraction of tensional integrity; aterm attributed to Buckminster Fuller, describing a structure whose stability is based on a balance between tensile and compressive forces.
Tensegrity
A closed skeletal structural system composed of a set of three or more discontinuous compressive struts within a network of tensile tendons; no structural member experiences bending.
tensegrity structure
One of the constituent parts into which a structure may be resolved by analysis, having a unitary character and exhibiting a unique behavior under an applied load.
Structural Member
A structural member subject primarily to compressive forces.
Compression Member
A structural member designed primarily to resist longitudinal compression.
Strut
A structural member subject primarily to tensile forces.
Tension member
A tension member designed to keep two structural members from spreading or separating.
Tie
A structural member subject primarily to transverse forces.
Bending Member
Of or pertaining to a structure or structural member having a load-carrying mechanism that acts in one direction only.
One-way
Of or pertaining to a structure or structural member having a load-carrying mechanism that acts in two or more directions.
Two-way
A discrete structure or assembly of structural members forming a spatial volume.
Structural Unit
A major spatial division, usually one of a series, marked or partitioned off by the principal vertical supports of a structure.
Bay
A grid defining the principal points or lines of support for a structural system.
Structural Grid
A structural grid having regularly repeating bays in two directions.
Regular Grid
A structural pattern consisting of two grids offset from each other and creating interstitial spaces between the bays.
Double grid
Forming an intervening space.
Interstitial
A structure mediating between two or more different structural patterns.
Transition structure
A structural grid having irregularly shaped bays in one or more directions.
Irregular Grid
A structural grid having points or lines of supports spaced uniformly in one direction but varying in the other.
Slipped Grid
The arrangement of principal vertical supports for a structure, which influences the selection of an appropriate spanning system and establishes the possibilities for the ordering of spaces and functions.
Structural pattern
The process of arranging, interconnecting, sizing, and proportioning the members of a structural system in order to safely carry a given set of loads without exceeding the allowable stresses of the materials employed.
Structural Design
A method for sizing and proportioning a structural member based on the assumption that the service load will not stress the material beyond its allowable stresses.
Allowable Stress Design, Elastic Design, Stress design, working stress design
A load used in structural design computations.
Design Load
A load inducing the allowable stresses at a critical section of a structural member.
Allowable Load
The maximum load a structure may be reasonably required to support during its useful life. Building codes specify minimum service loads for various uses, occupancies, types of construction, and environmental conditions.
Service load, working load
The process of determining the ability of a structure or any of its constituent members to safely carry a given set of loads without material distress or excessive deformation, given the arrangement, shape, and dimensions of the members, the types of connections and supports utilized, and the allowable stresses of the materials employed.
Structural analysis,
For an existing structure, this procedure is also known as STRUCTURAL RATING
A structural design method that employs statistical probabilities to establish the acceptable reliability of a structure, based on the variability of anticipated loads, the variability in the strength of the materials and types of members used, and the variability of construction,
Limit State Design,
Ultimate strength design for concrete structures, and load and resistance factor design (LFRD) for steel and timber structures in the US.
- Limite state design assumes that a factored load will not stress a material beyond its factored strength.*
- (FL) factored load*
A set of performance criteria that must be satisfied by a structure or structural component under loading, beyond which the structure or component ceases to function (serviceability limit state) due to deflection, vibrations or swaying or becomes unsafe (ultimate limit state) due to twisting, buckling or collapse.
Limite State
A design load equal to the service or nominal load multiplied by a load factor or a factor of safety.
FActored load, Ultimate load
The ratio of the maximum stress that a structural member can withstand to the maximum stress estimated for it in the use for which it is designed.
Factor of Safety, Safety Factor
Any of the factors assigned to service or nominal loads to account for unavoidable deviations in actual loads from nominal values and for uncertainties in load analysis. Load factors generally amplify service or nominal loads.
Load factor
Any of several combinations of load factors for modifying the dead and live loads applied to a structure, based on the assumption that not all live loads will act simultaneously on a structure at their full value and that their combined effect can be reasonably expected to be less tan the sum of their separate actions. After all possible load combination are considered, a structure is designed to carry the most severe but realistic distribution, concentration, and combinations of loads.
Load combination factors
Any of the factors assigned to different material properties and failure mechanism to account for the variability in the nominal strength of different types of structural members and for the manner and consequences of failure. Resistance factors generally reduce the nominal strength of structural materials and members.
Resistance factor
The capacity of a structural material or component to resist the effects of loads, as determined by computation using specified material strengths and dimensions and formulas derived from accepted principles of structural mechanics.
Resistance
The process of modeling how a structure collects, channels, and redirects the loads resulting from external forces through the hirarchy of its members to the foundation and underlying soil. The analysis usually starts at the roof level with the smallest members actually picking up the loading, and proceeds by tracing the loads through each collecting member. The reaction of each member to its loading becomes forces on the members supporting it.
Load Trace, Load Flow
The portion of a structure contributing to the load on a structural element or member.
Tributary Area, Contributary Area
Channelling into something more inclusive.
Tributary
The tributary area per unit length of a supporting structural member.
Load Strip
The load on a structural element or member collected from its tributary area.
Tributary Load
A structural member essential to the stability of a structural whole.
Primary Member, Main member
Any structural member supported by a primary member.
Secondary Member
Any structural member supported by a secondary member.
Tertiary member
A point, surface, or mass that supports weight, esp the area of contact between a bearing member, such as a beam or truss, and column, wall or other underlying support.
Bearing
The stress developed between a bearing member and an underlying support, equal to the quotient of the magnitude of the forces transmitted and the area of contact between the two elements.
Bearing Stress
Any condition, such as fracturing, buckling, or plastic deformation, that renders a structural assembly, element, or joint incapable of sustaining the load-carrying function for which it was designed.
Structural Failure
The manner in which a structural member is supported and connected to other members, affecting the nature of the reactive forces developed on the loaded member.
Support Condition
A point on a structural member at which its reaction to a load is transmitted as a force to a supporting member.
Point of Support
A structural member permitted to rotate freely about a point of support.
Unrestrained member
A structurat allows rotation but resists translation in a direction perpendicular into or away from its face.
Roller Support, Roller Joint
A cable anchorage that allows rotation but resists translation only in the direction of the cable.
Cable Support
A structural connection that allows rotation but resists translation in any direction.
Pin Joint, Hinge Joint, Pinned Connection
A slender rod driven through holes in adjacent parts to keep the parts together or to permit them to move in one plane relative to each other.
Pin
A structural connection that maintains the angular relationship between the joined elements, restrains rotation and translation in any direction, and provides both force and moment resistance.
Rigid Joint, Fixed Connection, Fixed Joint, Rigid Connection
A rigid joint connecting the end of a structural member to a support.
Fixed-end Connection
A means for binding a structural member to another or to its foundation, often to resist uplifting and horizontal forces.
Anchorage
The ability of a structure, when disturbed from a condition of equilibrium by an applied load, to develop internal forces or moments that restore the original condition.
Stability
The ability of a structure to resist lateral forces without sliding, overturning, buckling or collapsing.
Lateral Stability
The straining and distortion of a structural frame by lateral forces.
Racking
An unstable configuration of structural members susceptible to falling or breaking down under an applied load without a change in length of any individual member.
Collapse Mechanism
A structural frame of linear members made rigid by a system of diagonal members
Braced Frame
Stabilizing a structural system against lateral forces by means of diagonal or cross bracing.
Lateral Bracing
A structural element for positioning, supporting, strengthening, or restraining the members of a structural frame.
Brace
A system of inclined members for bracing the angles between the members of a structural frame and ensuring the lateral stability of the whole.
Diagonal Bracing
A diagonal member for bracing a structure against lateral forces.
Sway Brace
A pair of transverse braces for stabilizing a structural frame against lateral forces. When using cables, two are necessary to stabilize the structure against lateral forces from either direction. For each direction, one cable will operate effectively in tension while the other would simply buckle. If rigid braces are used, a certain degree of redundancy is involved since a single member is capable of stabilizing the structure.
Cross Bracing, X-bracing
A pair of diagonal braces for stabilizing a structural frame against lateral forces, meeting at some point along the length of a member of the frame.
K-brace
A diagonal member for bracing the angle between joined members, being joined to each partway along its length.
Knee Brace
A relatively thin, rigid structural member capable of withstanding shear when loaded in a direction parallel to its plane.
Diaphragm
A rigid floor or roof plane acting as a thin, deep beam in transferring lateral forces to vertical shear walls, braced frames, or rigid frames.
Horizontal Diaphragm
A vertical diaphragm acting as a thin, deep cantilever beam in transferring lateral loads to the ground foundation.
Shear Wall
A structural system characterized by the symmetrical configuration of mass and lateral force-resisting elements and having no significant discontinuities of stiffness or strength. The effects of laterals forces on regular structures may be determined by static methods.
Regular Structure
A structural system consisting of vertical planar elements for supporting gravity loads and shear walls or braced frames for resisting lateral forces.
Bearing Wall System
A structural system consisting of a three-dimensional array of interconnected linear members that functions as a complete, self-contained unit in supporting gravity loads and shear walls or braced frames for resisting lateral forces.
Frame System
A frame system designed to resist lateral forces primarily by flexure in the members and joints.
Moment-resisting frame
A structural system for resisting lateral forces, combining the ductility of a moment-resisting frame with the rigidity of a shear wall.
Dual System
A structural system characterized by any of various plan or vertical irregularities, such as a soft or weak story, a discontinuous shear wall or diaphragm, or the asymmetrical layout of mass or lateral-force resisting elements. Irregular structures generally require dynamic analysis in order to determine the torsional effects of lateral forces.
Irregular Structure
The asymmetrical layout of mass or lateral force-resisting elements, resulting in noncoincident centers of mass and resistance and causing the story drift at one end of the structure to be more than the average of the story drifts at both ends.
Torsional Irregularity
The centroid of the vertical elements of a lateral force-resisting system, through which the shear reaction to lateral forces acts.
Center of resistance, center of rigidity.
The plan configuration of a structure and its lateral force-resisting system having projections beyond a corner significantly greater than the plan dimension in the given direction. A reentrant corner tends to produce differential motions between different portions of the structure, resulting in local stress concentrations at the corner. Solutions include providing a seismic joint to separate the building into simpler shapes, tying the building together more strongly at the corner, or splaying the corner.
Reentrant Corner
A joint that physically separates two adjacent building masses so that free vibratory movement in each can occur independently of the other.
Seismic Joint
A horizontal diaphragm having a large cutout or open area, or a stiffness significantly less than that of the story above or below.
Discontinuous Diaphragm
A structural system having lateral force-resisting elements neither parallel nor symmetrical about the major orthogonal axes of the system.
Nonparallel System
A story having a lateral stiffness significantly less than that of the stories above.
Soft Story
A story having lateral strength significantly less than that of the stories above.
Weak Story
A story having an effective mass significantly greater than that of an adjacent story.
Irregular Mass
A shear wall having a large offset or a significant change in horizontal dimension.
Discontinuous Shear Wall
A tube structure having perimeter shear walls with less than 30% of the surface area perforated by openings.
Perforated Shell Tube
A tube structure having closely spaced perimeter columns rigidly conneted by deep spandrel beams.
Framed Tube
A high-rise structure having perimeter lateral force-resisting systems internally braced by rigid floor diaphragms, this structure acts as a cantilevered box beam in resisting lateral forces.
Tube Structure
A framed tube structure tied together by a system of diagonal braces.
Braced Tube
A braced tube structure having trussed wall frames of widely spaced columns tied together by diagonal or cross bracing.
Trussed Tube
A braced tube structure having perimeter frames of closely spaced diagonals with no vertical columns.
Latticed Truss TUbe
An assembly of narrow tubes tied directly to each other to form a modular structure that behaves like a multicellular box girder cantilevering out of the ground. More tubes are sometimes provided in the lower portion of a tall structure where greater lateral force resistance is needed.
Bundled TUbes
A tube structure having an inner braced tube added to the perimeter tube to improve its shear stiffness in resisting lateral forces.
Tube-in-tube structure
An interior service core braced to provide additional stiffness in resisting lateral forces.
Braced Core
To cause a decrease in amplitude of successive oscillations or waves.
damp
Any of various viscoelastic devices typically installed at structural joints to absorb the energy generated by wind or earthquake forces, progressively diminish or eliminate vibratory or oscillatory motions and prevent destructive resonances from occurring.
Damping Mechanism
A heavy mass mounted on rollers or suspended with cables and attached to the upper portion of a tall building with spring damping mechanisms, having an intertial tendency to remain at rest and thus counteracting and dissipating any building movements.
Tuned Mass Damper
Isolating the base of a building from the ground with damping mechanisms to allow the superstructure to float as a rigid body and alter the natural period of vibration of the structure so that it is different from that of the ground; thus preventing destructive resonances from occurring.
Base Isolation
The damping that naturally occurs as a building undergoes elastic or plastic deformation, such as from the internal friction of a stressed material (hysteresis damping), from the friction between two moving parts (frictional damping), or from the viscous resistance of a fluid such as air (viscous damping).
Internal Damping
The shaping of a tall building to create turbulence which generates cross-wind lift to oppose cross-wind deflections during high winds.
Aerodynamic Damping
Irregular motion of the atmosphere characterized by up-and-down currents.
Turbulence
A high-rise structure that resists lateral loads primarily through lateral-force-resisting elements located within the interior of the structure, such as a rigid frame structure of steel or concrete, or a structure braced by a core consisting of braced frames, moment frames, or shear walls constructed into a closed system that acts as a structural tube.
Interior Structure
A high-rise structure that resists lateral loads primarily through lateral-force-resisting elements located along the perimeter of the structure.
Exterior Structure
A modified braced-tube structure consisting of stacked triangulated prisms containing diagonals that connect the exterior with the interior frame. This type of structures are capable of resisting both lateral and vertical loads.
Space Truss
A high-rise structure that utilizes megacolumns, which comprise the chords of oversized braced frames at the building corners, linked by multistory trusses at 15- to 20-story intervals.
Megaframe Structure, Superframe Structure
Contraction for diagonal + grid: the exterior lattice-like framework of a building created by crosscrossing diagonal members.
Diagrid
