ASTM WK63676

    Revision of D5456 - 17e1 Standard Specification for Evaluation of Structural Composite Lumber Products

    (What is a Work Item?)

    Active Standard: D5456 - 19

    Developed by Subcommittee: D07.02 | Committee D07 | Contact Staff Manager



    WK63676


    Keywords

    accelerated aging; allowable design stresses; binder; durability; mechanical properties; non-binder; quality assurance; structural composite lumber;;

    Rationale

    The attached ballot was developed by an ASTM D07.02.03 task group to improve the clarity and intent of the D5456 Section 10.6.3 provisions related to the periodic re-assessment of product variability for volume effects considerations. The changes were intended to address the attached shortcomings with the existing 10.6.3 provisions: 1.A strict application of the existing coefficient of variation (COV) limits independently to each product/mill/grade/species for an SCL technology each year could result in a complex suite of constantly migrating volume effects. The procedures are not considered precise enough to warrant that level of precision/maintenance. Structural products outside the scope of D5456 and used in similar applications are not subjected to a similar ongoing review and adjustment. 2.The current text does not explicitly permit corrective action or additional rationalization as a means to address short-term variability surges. 3.An out of compliance bending COV triggers a mandatory correction for both bending and tension volume effects (Equations 3 and 4), even if tension complies. 4.An out of compliance tension COV doesnt trigger a review for either parameter. 5.The corrective action mandates use of the default single-sized volume effect provisions, even if a manufacturer has developed their size effects using the more detailed/accurate multiple-sized approach. It is not clear why a manufacturer should not be permitted to redevelop their volume effects with multi-sized testing. 6.Even though the text does not explicitly address tension COVs, the 1.5% tolerance has been commonly applied. As illustrated by comparison between Tables 1 and 2, due to the difference between models, a 2.0% limit for tension would provide a limit for tension that is similar to flexure. 7.The current mandated corrective action does not permit the possibility of re-evaluation or empirical verification using multi-size testing permitted for a new material qualification. 8. The current text does not explicitly permit the use of tail-fitting procedures for the purpose of COV compliance, even though they are currently allowed for model development. The attached ballot items are intended to address these shortcomings. In addition, a provision is being proposed for Section 7.1.4.3 to specifically memorialize the typical practice of developing a volume effect for one grade and applying it to all grades of a given technology that demonstrate similar variability.

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    Work Item Status

    Date Initiated:
    05-25-2018

    Technical Contact:
    Ned Waltz

    Status:
    Draft Under Development