Creep leading to sag in floor joists

Structure · Concrete Floor Slabs · printed page 58 (PDF page 59)

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Floor – Creep Leading to Sag in Floor Joists Creep Leading to Sag in Floor Joists

Text in the illustration

Creep leading to sag in floor joists loads applied to joists support support resulting stress causes deflection (sagging) center cross-section of joist stress: compression stress: tension wood cells in tension at bottom of joist: stretched, flattened wood cells in compression at top of joist: shortened, crowded
loads applied to joists
support
resulting stress causes deflection (sagging)
center cross-section of joist
stress: compression
stress: tension
wood cells in tension at bottom of joist: stretched, flattened
wood cells in compression at top of joist: shortened, crowded

Generated explanation

The illustration explains creep leading to sag in a wood floor joist spanning between two end supports. Downward load arrows are shown above a straight joist diagram, followed by a deflected profile with the greatest sag near midspan. A center cross-section identifies compression at the top and tension at the bottom. Magnified wood-cell diagrams show shortened, crowded cells in compression and stretched, flattened cells in tension. The lower drawing shows a sagging wood joist bearing on brick supports.