Technical note on the determination of strength reduction factors using ASTM D245

Bather, Mike ORCID: 0000-0002-6725-6815 (2022) Technical note on the determination of strength reduction factors using ASTM D245 [Report]

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Executive Summary

The US standard ‘Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber’ ASTM D245 is based on the assumption that knots act as voids and presents a simplified way to account for the reductions in bending capacity due to these voids. It is worthwhile considering the equations given in the code and comparing them with a similar approach based on first principles. The first principles approach compares (i) reduced sections with knots with (ii) entire sections without knots. The basis for the comparisons is their elastic section moduli, assuming that knots can transmit zero tension forces and so act as voids below the neutral axis. It is assumed that knots can transmit compressive forces, which would be above the neutral axis for a typical timber joist in normal vertical bending.

Item Type:	Report
Uncontrolled Keywords:	in situ timber, structural timber, strength reduction, SR, mechanical properties, physical properties, timber
Divisions:	Faculty of Science & Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	14 Jan 2022 11:20
Last Modified:	18 Jan 2023 21:16
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3146813
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