The following words and terms shall, for the purpose of this chapter, have the meanings shown herein.
-- Allowable Stress Design:
A method of proportioning structural members, such that elastically computed stresses produced in the members by nominal loads do not exceed specified allowable stresses (also called “working stress design”).
-- Balcony, Exterior:
An exterior floor projecting from and supported by a structure without additional independent supports.
-- Base Shear:
Total design lateral force or shear at the base.
-- Basic Seismic-Force-Resisting Systems:
• Bearing Wall System: A structural system without a complete vertical load-carrying space frame. Bearing walls or bracing elements provide support for substantial vertical loads. Seismic lateral force resistance is provided by shear walls or braced frames.
• Building Frame System: A structural system with an essentially complete space frame providing support for vertical loads. Seismic lateral force resistance is provided by shear walls or braced frames.
• Dual system: A structural system with an essentially complete space frame providing support for vertical loads. Seismic lateral force resistances is provided by a moment frame and shear walls or braced frames.
• Inverted pendulum system: A structure with a large portion of its mass concentrated at the top; therefore, having essentially one degree of freedom in horizontal translation. The columns acting as cantilevers provide seismic lateral force resistance.
• Moment-resisting frame system: A structural system with an essentially complete space frame providing support for vertical loads. Seismic lateral force resistance is provided by moment frames.
• Shear wall-frame interactive system. A structural system which uses combinations of shear walls and frames designed to resist seismic lateral forces in proportion to their rigidities, considering interaction between shear walls and frames on all levels. The same shear walls and frames provide support of vertical loads.
-- Boundary Members:
Strengthened portions along shear wall and diaphragm edges (also called “ boundary elements”).
• Boundary element: In light-frame construction, diaphragms and shear wall boundary members to which sheathing transfers forces. Boundary elements include chords and drag struts at diaphragm and shear wall perimeters, interior openings, discontinuities and reentrant corners.
-- Cantilevered Column System:
A structural system relying on column elements that cantilever from a fixed base and have minimal rotational resistance capacity at the top and are used for lateral resistance.
-- Collector Elements:
Members that serve to transfer forces between floor diaphragms and members of the lateral-force-resisting system.
-- Confined Region:
The portion of a reinforced concrete component in which is confined by closely spaced special transverse reinforcement restraining the concrete in directions perpendicular to the applied stress.
-- Dead Loads:
The weight of materials of construction incorporated into the building, including but not limited to walls, floors, roofs, ceilings, stairways, built-in partitions, finishes, cladding and other similarly incorporated architectural and structural items, and fixed service equipment, including the weight of cranes. All dead loads are considered permanent loads.
-- Deck:
An exterior floor supported on at least two opposing sides by an adjacent structure, and/or posts, piers or other independent supports.
-- Deformability:
The ratio of the ultimate deformation to the limit deformation.
• High deformability element. An element whose deformability is not less than 3.5 when subjected to four fully reversed cycles at the limit deformation.
• Limited deformability element. An element that is neither a low deformability or a high deformability element
• Low deformability element. An element whose deformability is 1.5 or less.
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-- Deformation:
• Limit deformation. Two times the initial deformation that occurs at a load equal to 40 percent of the maximum strength.
• Ultimate deformation. The deformation at which failure occurs and which shall be deemed to occur if the sustainable load reduces to 80 percent or less of the maximum strength.
-- Design Strength:
The product of the nominal strength and a resistance factor (or strength reduction factor).
-- Diaphragm:
A horizontal or sloped system acting to transmit lateral forces to the vertical-resisting elements.
• Diaphragm, blocked. In light- framed, diaphragms in which all sheathing edges not occurring on a framing member are supported on and fastened to blocking.
• Diaphragm boundary. In light-framed construction, a location where shear is transferred into or our of the diaphragm sheathing. Transfer is either to a boundary element or to another force-resisting element.
• Diaphragm chord. A diaphragm boundary element perpendicular to the applied load that is assumed to take axial stresses due to the diaphragm moment.
• Diaphragm, rigid. A diaphragm is rigid for the purpose of distribution of story shear and torsional moment when the lateral deformation of the diaphragm is less than or equal to two times the average story drift.
-- Duration of Load:
The period of continuous application of a given load, or the aggregate of periods of intermittent applications of the same load.
-- Element:
• Ductile element. An element capable of sustaining large cyclic deformations beyond the attainment of its nominal strength without significant loss of strength.
• Limited ductile element. An element that is capable of sustaining moderate cyclic deformations beyond the attainment of its nominal strength without significant loss of strength.
• Non-ductile element. An element having a mode of failure that results in an abrupt loss of resistance when the element is deformed beyond the deformation corresponding to the development of its nominal strength. Non-ductile elements cannot reliably sustain significant deformation beyond that attained at their nominal strength.
-- Equipment Support:
Those structural members or assemblies of members or manufactured elements, including braces, frames, lugs, snugger, hangers or saddles, that transmit gravity load and operating load between the equipment and the structure.
-- Essential Facilities.
Buildings and other structures that are intended to remain operational in the event of extreme environmental loading from flood, wind, snow or earthquakes.
-- Factored Load:
The product of a nominal load and a load factor.
-- Flexible Equipment Connections:
Those connections between equipment components that permit rotational and/or transnational movement without degradation of performance.
-- Frame:
• Braced frame. An essentially vertical truss, or its equivalent, of the concentric or eccentric type that is provided in a building frame system to resist lateral forces.
• Concentrically braced frame (CBF). A braced frame in which the members are subjected primarily to axial forces.
• Eccentrically based frame (EBF) A diagonally braced frame in which at least one end of each brace frames into a beam a short distance from a beam-column or from another diagonal brace.
• Ordinarily concentrically braced frame (OCBF) A steel concentrically braced frame in which members are connections are designed for ductile behavior.
• Moment frame. A frame in which members and joints resist lateral forces by flexure as well as along the axis of the members. Moment frames are categorized as “intermediate moment frames” (IMF) “ordinary moment frames” (OMF), and “special moment frames” (SMF).
-- Impact load:
The load resulting from moving machinery, elevators, crane ways, vehicles and other similar forces and kinetic loads, pressure and possible surcharge from fixed or moving loads.
-- Joint:
A portion of a column bounded by the highest and lowest surfaces of the other members framing into it.
-- Limit State:
A condition beyond which a structure or member becomes unfit for service and is judged to be no longer useful for its intended function (serviceability limit state) or to be unsafe (strength limit state).
-- Live Loads:
Those loads produced by the use and occupancy of the building or other structure and do not include construction or environmental loads such as wind load, snow load, rain load, earthquake load, flood load or dead load.
--
Live Loads (Roof)
Those loads produced (1) during maintenance by workers, equipment and materials; and (2) during the life of the structure by moveable objects such as planters and by people.
-- Load and Resistance Factoring Design (LRFD)
A method of proportioning structural members and their connections using load and resistance factors such that no applicable limit state is reached when the structure is subjected to appropriate load combinations. The term “LRFD” is used in the design of steel and wood structures.
-- Load Factor:
A factor that accounts for deviations of the actual load from the nominal load, for uncertainties in the analysis that transforms the load into a load effect, and for the probability that more than one extreme load will occur simultaneously.
-- Loads:
Forces or other actions that result from the weight of building materials, occupants and their possessions, environmental effects, differential movement an restrained dimensional changes. Permanent loads are those loads in which variations over time are rare or of small magnitude, such as dead loads. All other loads are variable loads (see also” Nominal loads”).
-- Loads Effects:
Forces and deformations produced in structural members by the applied loads
-- Nominal Loads:
The magnitudes of the loads specified in this chapter (dead, live, soil, wind, snow, rain, flood, and earthquake).
Notations:
D= Dead load
E= Combined effects of horizontal and vertical earthquake introduced forces as set forth in Sections 1617.1.
Em= Maximum seismic load effect of horizontal and vertical seismic forces as set forth in Sections 1616.4.1 and 1617.1.
F= Load due to fluids
Fa=Flood load.
H=Load due to lateral pressure of soil and water in soil.
L= Live load, except roof live load, including any permitted live road
reduction.
Lr= Roof live load including any permitted live load reduction.
P= Pounding load.
R= Rain load.
S= Snow load.
T= Self-straining force arising from concentration or expansion resulting from temperature change, shrinkage, moisture change, creep in component materials, movement due to differential settlement or combinations thereof.
W= Load due to wind pressure
-- Other Structures:
Structures, other than buildings, for which loads are specified in this chapter.
-- P-Delta Effect:
The second order effect on shears, axial forces and moments of frame members induced by axial loads on a laterally displaced building frame.
-- Panel (Part of a Structure).
The section of a floor, wall or roof comprised between the supporting frame of two adjacent rows of columns and girders or column bands of floor or roof construction.
-- Resistance Factor:
A factor that accounts for deviations of the actual strength from the nominal strength and the manner and consequences of failure (also called “strength reduction factor”).
-- Shallow Anchors:
Shallow anchors are those with embedment length-to-diameter ratios of less than eight.
-- Shear Pane:
A floor, roof or wall component sheathed to act as a shear wall diaphragm.
-- Shear Wall:
A wall designed to resist lateral forces parallel to the plane of the wall.
-- Space Frame:
A structure composed of interconnected members, other than bearing walls, that is capable of supporting vertical loads and that also may provide resistance to seismic lateral loads.
-- Special Transverse Reinforcement:
Reinforcement composed of spirals, closed stirrups or hoops and supplementary crossties provided to restrain the concrete and qualify the portion of the component, where used, as a confined region.
-- Strength, Nominal:
The capacity of a structure or member to resist the effects of loads, as determined by computations using specified material strengths and dimensions and equations derived from accepted principles of structure mechanics or by field tests or laboratory tests of scaled models, allowing for modeling effects and differences between laboratory and field conditions.
-- Strength, Required:
Strength of a member, cross section or connection required to resist the factored loads or related internal moments and forces in such combinations as stipulated by these provisions.
-- Strength Design:
A method of proportioning structural members such that the computed forces produced in the members by factored loads do not exceed the member design strength [also called “load and resistance factor design” (LRFD)]. The term “strength design” is used in the design of concrete and masonry structural elements.
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Wall, Load Bearing.
Any wall meeting either of the following classifications:
1. Any metal or wood wall that supports more than 100 pounds per linear foot (plf) (1459 N/m) of vertical load in addition to its own weight.
2. Any masonry or concrete wall that supports more than 200 plf (2919N/m) of vertical load in addition to its own weight.
-- Wall, Non-load Bearing:
Any wall that is not a load-bearing wall.
National Partitions designs utilize non-load bearing walls. We place
loads greater than 100 PLF on independent structural steel columns.
Others use their walls as structural elements and therefore must meet
certain fire endurance requirements.