Norma astm d-2555

Designation: D 2555 – 98e1

Standard Test Methods for

Establishing Clear Wood Strength Values1
This standard is issued under the fixed designation D 2555; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e)indicates an editorial change since the last revision or reapproval.

e1 NOTE—Table 1 footnotes were corrected editorially in May 2003.

INTRODUCTION

The development of safe and efficient working stresses for lumber, laminated timber, plywood, round timbers, and other solid wood products, each with its own special requirements has, as a common starting point, the need for an authoritativecompilation of clear wood strength values for the commercially important species. Also required are procedures for establishing, from these data, values applicable to groups of species or to regional groupings within a species where necessitated by marketing conditions. This standard has been developed to meet these needs and to provide, in addition, information on factors for consideration in theadjustment of the clear wood strength values to the level of working stresses for design. Since factors such as species preference, species groupings, marketing practices, design techniques, and safety factors vary with each type of product and end use, it is contemplated that this standard will be supplemented where necessary by other appropriate standards relating to specific work stresses for eachsuch product. ASTM Practice D 245 is an example of such a standard applicable to the interpretation of the clear wood strength values in terms of working stresses for structural lumber. A primary feature of this standard is the establishment of tables presenting the most reliable basic information developed on the strength of clear wood and its variability through many years of testing andexperience. The testing techniques employed are those presented in Methods D 143. Among the recognized limitations of such strength data are those resulting from the problems of sampling material from forests extending over large regions, and the uneconomical feasibility of completely testing an intensive sample. A practical approach to the improvement of strength data is through the application of theresults of density surveys in which the specific gravity of the entire forest stand for each species is determined on a sound statistical basis. Through regression equations derived from presently available strength data, revised strength values are established from the specific gravity-strength relationship for clear wood. This procedure greatly extends current capabilities to develop new estimates ofstrength and to improve or verify estimates made in the past. 1. Scope 1.1 These test methods cover the determination of strength values for clear wood of different species in the unseasoned condition, unadjusted for end use, applicable to the establishment of working stresses for different solid wood products such as lumber, laminated wood, plywood, and round timbers. Presented are: 1.1.1Procedures by which test values obtained on small clear specimens may be combined with density data from extensive forest surveys to make them more representative,
1 These test methods are under the jurisdiction of ASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental Test Methods and Properties. Current edition approved July 10, 1998. Published March 1999.Originally published as D 2555 – 66 T. Last previous edition D 2555 – 96e1.

1.1.2 Guidelines for the interpretation of the data in terms of assigned values for combinations of species or regional divisions within a species to meet special marketing needs, and 1.1.3 Information basic to the translation of the clear wood values into working stresses for different solid wood products for...