Glossary of Terms
A push (compression) or pull (tension) acting along the length of a member. Usually measured in pound, kips (1000 lb), tons (2,000 lb) or the metric equivalents.
The axial force acting at a point along the length of a member, divided by the cross sectional area of the member (usually measured in pounds per square inch).
A void deliberately set into the top of a wall to allow a beam or floor truss to bear on the wall.
A structural support, usually a wall, that occurs at the top or bottom chord or between the end points of roof or floor truss.
A measure of the bending effect on a member due to forces acting perpendicular to the length of the member. The bending moment at a given point along a member equals the sum of all perpendicular forces, whether to the left or right of the point, times their corresponding distances from the point.
A horizontal or inclined (e.g. , scissors truss) member that establishes the lower edge of a truss, usually carrying combined tension and bending stresses.
A preassembled part usually fabricated in a manufacturing plant for use in the construction of a building.
A single member composed of two wood members having the same thickness but not necessarily the same depth, which provides greater load carrying capability as well as lower deflection, e.g., garage door, stairwell and fireplace headers.
Slight vertical cut at outside edge of truss bottom chord made to insure uniform nominal span and tight joints. Usually ¼ inch.
An upward vertical displacement built into a truss bottom chord to compensate for deflection due to dead load.
Slight pitch on flat trusses
The part of the truss that extends beyond its support, exclusive of overhang.
Truss with structural support at center of truss span as well as at the heel points.
An open panel in a floor truss for the purpose of running utilities through it, such as heating and air conditioning ducts.
Horizontal distance between interior edges of supports.
The combination of axial and bending stress acting on a member simultaneously, such as occurs in the top chord (compression and bending) or bottom chord (tension and bending) of a truss.
Superimposed load centered at a given point, e.g., roof mounted air conditioners.
Any permanent load such as the weight of the truss itself, purlins, sheathing, roofing and ceiling.
Downward vertical movement of a truss (when in place) due to dead and live loads.
The dead and live loads which a truss is designed to support.
DUAL PITCH TRUSS
A truss that has two different pitches on its top chord.
DURATION OF LOAD STRESS INCREASE
A percentage increase in the stress permitted in a member, based on the length of time that the load causing the stress acts on the member. The shorter the duration of the load the higher the percent increase in the allowable stress.
Trim board applied to ends overhang.
Point on truss at which the top and bottom chords intersect.
See Butt Cut.
A structural member (typically lumber or metal) installed at right angles to a chord or web member of a truss to reduce the laterally unsupported length of the truss member. The Lateral Restraint must be properly braced to prevent lateral deformation and/or buckling of the truss member to which it is attached due to laterally imposed loads on, and/or the accumulation of buckling forces within, the truss member, respectively.
LET TAILS RUN<:p>
Top chord not cut off to specific overhang length but extended to maximum length provided by lumber used in top chord.
LEVEL RETURN Lumber filler placed horizontally from the end of an overhang to the outside wall to form a soffit.
Lumber filler placed horizontally from the end of an overhang to the outside wall to form a soffit.
Any loading which is not of a permanent nature, such as snow, wind and temporary construction loads.
Horizontal distance between outside edges of the supports.
OVERALL TRUSS HEIGHT
Vertical distance from bottom-most part of the truss to upper-most point of the peak.
The extension of the top chord of a truss beyond the bearing support.
The chord segment defined by two adjacent joints.
The center line distance between joints measured along the chords.
The point of intersection where a web (or webs) meet a chord.
Point on truss where the sloped top chords meet.
Inches of vertical rise for each twelve inches of horizontal run.
A horizontal member attached to and placed perpendicular to the truss top chord for supporting the roofing: i.e., corrugated roofing or plywood and shingles.
Point on triangular, Fink, Howe truss where the webs connect to the top chord.
Forces acting on a truss through its support that are equal but opposite to the sum of the dead and live loads.
SEALED BUILDING DRAWINGS
Drawings prepared, checked, and/or approved by and having the seal of a registered professional architect or engineer.
SHORT TERM INCREASE
Increase allowed for design loads of short duration
SHORT TERM LOADING
Live loads of a short duration, such as wind and snow loads.
End of top chord cut perpendicular to the slope of member.
Truss with the same configuration of member occurring on each side of truss centerline.
An inclined or horizontal member that establishes the upper edge of a truss.
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