Engineering / Construction Definitions

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D

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 equipment, including the weight of cranes. All dead loads are considered permanent loads.

Decking – Lumber from 2” to 4” (nominal) thick, tongued and grooved or grooved for spline on the narrow face, and intended for use as a roof, floor or wall membrane. Decking is graded for application in the flatwise direction, with the wide face of the decking in contact with the supporting members, as normally installed.

Diaphragm – A horizontal or sloped system acting to transmit lateral forces to the vertical-resisting elements. When the term “diaphragm” is used, it shall include horizontal bracing systems.

Diaphragm Aspect Ratio  – The ratio of length to width of a diaphragm.

Diaphragm Chord  – A diaphragm boundary element perpendicular to the applied load that is assumed to take axial stresses due to the diaphragm moment.

Diaphragm Length – The dimension of a diaphragm in the direction perpendicular to the application of force and is measured as the distance between vertical elements of the lateral-force-resisting system (in many cases, this will match the sheathed dimension).

Diaphragm Width – The dimension of a diaphragm in the direction of application of force and is measured as the distance between diaphragm chords (in many cases, this will match the sheathed dimensions).

Duration of Load – The period of continuous application of a given load, or the aggregate of periods of intermittent applications of the same load.