Abstract

This practice covers sampling and analysis procedures for the investigation and evaluation of allowable properties of specified populations of stress-graded structural lumber. This practice generally assumes that the population is sufficiently large so that, for sampling purposes, it may be considered infinite. The population shall be clearly defined where it may be necessary to specify the following: (1) grade name and description, (2) geographical area over which sampling will take place, (3) species or species group, (4) time span for sampling (5) lumber size, and (6) moisture content. Two statistical techniques are described under this practice, namely: parametric and nonparametric analysis. The sampling methods include: (1) random sampling, (2) sampling with unequal probabilities, and (3) sequential sampling. Selection and method of determining sample size are detailed. The results of the tests performed shall be presented as (1) a set of summarizing statistics, and (2) an appendix of unadjusted individual test specimen results. The procedures and requirements for analysis of results are detailed and includes the following: (1) adjustment factors used to reduce the test statistics to the level of allowable properties, (2) formula for calculating apparent modulus of elasticity, sample mean, sample standard deviation, and confidence interval for the mean (3) sample nonparametric percent point estimate, (4) nonparametric lower tolerance limit, (5) parametric point estimate, (6) lower parametric tolerance limit, and (7) histogram and empirical cumulative distribution function. This practice does not specify the action to be taken after the results have been analyzed.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This practice covers sampling and analysis procedures for the investigation of specified populations of wood and wood-based structural products referred to in this standard as products. Appropriate product standards should be referenced for presentation requirements for data. Depending on the interest of the user, the population from which samples are taken may range from the products produced at a specific manufacturing site to all the products produced in a particular grade from a particular geographic area, during some specified interval of time. This practice generally assumes that the population is sufficiently large so that, for sampling purposes, it may be considered infinite. Where this assumption is inadequate, that is, the population is assumed finite, many of the provisions of this practice may be employed but the sampling and analysis procedure must be designed to reflect a finite population. The statistical techniques embodied in this practice provide procedures to summarize data so that logical judgments can be made. This practice does not specify the action to be taken after the results have been analyzed. The action to be taken depends on the particular requirements of the user of the product.

1.2 The values stated in inch-pound units are to be regarded as the standard.

1.3 This practice does not purport to address the adjustment factors needed to adjust test data to standardized mechanical and environmental conditions (that is, temperature, moisture, test span, or load duration). Additionally, it provides a basis for statistical estimates that will typically require further adjustment to determine design values for use with an accepted design methodology (that is, allowable stress, limit states, or load and resistance factor design). It shall be the responsibility of the user to seek out the appropriate adjustments in specific product standards.

1.4 This practice does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D9 Terminology Relating to Wood and Wood-Based Products

D198 Test Methods of Static Tests of Lumber in Structural Sizes

D245 Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber

D1990 Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens

D2555 Practice for Establishing Clear Wood Strength Values

D3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)

D5055 Specification for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists

D5456 Specification for Evaluation of Structural Composite Lumber Products

D6570 Practice for Assigning Allowable Properties for Mechanically Graded Lumber

E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications

E105 Practice for Probability Sampling of Materials

Keywords

confidence level; mean and median properties; parametric and nonparametric properties; sample size; standard error; Adjustment equations; Bend testing--wood products; Compression testing--wood/wood products; Sampling wood products; Conversion units/factors; Grading--wood products; Loading tests--building constructions/materials; Lumber; Modulus of elasticity--wood products; Moisture analysis--wood products; Shear testing--wood products; Stiffness; Strength--wood materials/applications; Structural building materials/applications (wood); Tensile properties/testing--wood products; Wood products (structural);

ICS Code

ICS Number Code 79.040 (Wood, sawlogs and sawn timber)

DOI: 10.1520/D2915-10

ASTM International is a member of CrossRef.

ASTM D2915