Southern Pine Lumber Research Articles

WITHDRAWAL STRENGTH OF RING-SHANK NAILS EMBEDDED IN SOUTHERN PINE LUMBER

Ring-shank nails are used extensively in post-frame construction due to their superior performance, yetsurprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests thatpublished allowable design values for ring-shank nails may be overly conservative and need revision. The goal of theresearch reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pinelumber. Three sizes of galvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ringshanknails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizingslightly reduced withdrawal strength (approximately 8%) due to partial filling of the threads. Nail head pull-through wasstudied as a possible failure mode. Even allowing for galvanizing and head pull-through, strong evidence is presented forincreasing withdrawal design values for ring-shank nails.

Comparison of flexural and shear properties of southern pine LVL and lumber from young plantation and natural stands

Des poutres en bois massif reconstitue (LVL) sont realisees a partir de placages deroules (section 5,08 x 10,16 cm 2 ) de pin (Pinus taeda L). Trois type de poutres sont testees en flexion sur chant et en cisaillement. Elles sont realisees i) a partir de placages deroules dans des pins de plantation âges de 20 ans, ii) a partir de placages d'arbres âges de 28 et 40 ans provenant de peuplements naturels et iii) en melangeant des placages d'arbres de plantation et des placages d'arbres de 40 ans. Les mesures de flexion obtenues sont correlees a l'epaisseur des placages et a leur classement ainsi qu'a l'âge des arbres. Les proprietes de flexion et de cisaillement du LVL sont comparees aux proprietes du bois massif mesurees sur des arbres comparables en âge et qualite. Les distributions de contrainte admissible (Fb) et de module d'elasticite admissible (E) qui sont definies dans les regles de classement du LVL (SPIB91) sont determinees et presentees.

Effects of CCA Treatment and Drying on Tensile Strength of Lumber

Approximately 50% of the southern pine lumber produced in the United States is subsequently pressure treated with chromated copper arsenate (CCA) preservative. This report discusses the influence of initial kiln‐drying temperature, CCA preservative treatment, post‐treatment redrying temperature, and grade on the tensile properties of southern pine dimension lumber. Tensile strength was not significantly affected by initial kiln‐drying temperature, but it was reduced when CCA treatment was followed by high‐temperature redrying. When comparing No. 2 and better southern pine nominal 2‐ by 4‐in. (actual 38‐ by 89‐mm) lumber initially kiln dried at either 91 °C or 113 °C, a consistent reduction in tensile strength of 7–10% was noted when initial kiln drying at 113 °C was followed by CCA treatment and any level of redrying. This effect is consistent with previously reported results for bending strength.

Compression Testing of Lumber: A Comparison of Methods

Abstract A study was conducted to compare compression strength values obtained using short segments cut from full-length lumber and tested in accordance with ASTM D 4761-87 with those values obtained using full-leagth specimens and tested in accordance with ASTM D 198-84. Tests were conducted on Southern Pine lumber conditioned to a target moisture content of 9%. To obtaim a short-segment compression strength estimate within a factor of about 1.05 of those obtained by testing full-length (3-m [10-ft]) specimens, it is necessary to select two of the apparent worst strength-reducing defects in the full-length specimen using ASTM D 245-84 sorting criteria.

Tensile Strength and Stiffness of Spliced Mechanically Laminated Posts

Thirty, spliced, mechanically laminated posts were evaluated in tension to determine their tensile strength and stiffness. The 30 posts consisted of five replicates of six designs fabricated with No. 1 Dense Southern Pine lumber. The strength of all six designs was controlled by the strength of the mechanical fasteners used to laminate the assemblies. The allowable tensile strength of unspliced posts, as calculated according to NFPA National Design Specifications, was shown to be 6.6 to 7.4 times greater than the calculated design tensile strength of spliced nail-laminated posts without butt joint reinforcement. With proper use of butt joint reinforcement, post strength was substantially increased. Finite element methods of analysis can be used to predict the distribution of tensile forces in spliced posts. However, the accuracy of such predictions was shown to be highly dependent on the load-slip parameters used to model the behavior of mechanical connections.

COMPARISON OF TWO, GLUE-LAMINATED, CONSTRUCTION POST CONHGURATIONS

ABSTRACT Allowable structural properties were determined for three composite, glue-laminated timber construction posts. The posts consisted of three or four glue-laminated plies of 50 mm (2 in.) nominal No.2 southern pine lumber fabricated by splicing preservative-treated and untreated sections. The splice consisted of lamina end finger joints oriented horizontally (or parallel) with the wide edge of the lamina. Full size specimens through the joint sections of three sizes of posts were tested to determine allowable structural material properties. The allowable bending stress, compressive stress parallel to the grain and apparent elastic modulus determined for the 150x150 mm (6x6 in.) nominal size category were 13.8, 14.8, and 16 900 MPa (2000, 2150, and 2.47x106 psi), respectively. The allowable bending and compressive stress and apparent elastic modulus for the 150x200 mm (6x8 in.) nominal size category were 14.1, 14.8, and 11 400 MPa (2050, 2150, and 1.66x106 psi), respectively. The allowable bending stress and the apparent elastic modulus were 15.5 and 13 900 MPa (2250 and 2.03x106 psi), respectively, for the 200x200 mm (8x8 in.) nominal size category. These results are compared to a product of similar construction. The allowable values determined may not be representative of the entire population of posts using similar materials and resin systems.

Spectroscopic Analysis of Southern Pine Treated with Chromater Copper Arsenate. I. X-Ray Photoelectron Spectroscopy (XPS)-17

Abstract The amount of southern pine lumber treated with chromated copper arsenate annually is considerable, yet the association of this preservative with the wood structure is not clear. The current study was undertaken to elucidate the nature of chemical reactions occurring between the components of the treating solution and the constituents of wood. Small, clear Southern pine samples were treated with six different preservative solutions (Cr; Cr/Cu; Cr/As; CCA-A; CCA-B; CCA-C), at 6.4 and 40 Kg/m3 (0.4 and 2.5 pcf) retentions, and compared to water treated and untreated controls. Samples were dried following treatment and analyzed by X-ray photoelectron spectroscopy (XPS). Evaluation of XPS data indicated that the preservative components reacted with wood, through aromatic and possibly alkene substitution, while oxidation of hydroxyl groups was not detected. The proposed wood/CCA bonding also offers an explanation for differences in hardwood and softwood durability following treatment.

A Comparison of Five Laminated Wall Column Designs

FOUR nail-laminated wall column designs previously reported in the literature are compared with new results from a fifth study. A wide range of strength values are achieved by the five wall column designs. This study uses 2X6 No. 1 Dense KD15 southern pine lumber and two splice-type truss plates applied to the outside wide faces of the three laminate assembly at the butt joints between the treated and untreated lumber. Twenty wall columns were tested to failure in bending under a two point loading arrangement. An allowable normal duration bending strength of 13.25 MPa (1,921 psi) was estimated from the load tests. The effective modulus of elasticity, MOE, of the 3.66 m (12 ft) jointed section was also measured. The mean MOE was 8,660 MPa (1.256 million psi) with a coefficient of variation of 8.1%

High-temperature drying of southern pine 2 by 4's: Effects on strength and load duration in bending

Southern pine lumber specimens dried by conventional (82 °C maximum) and high temperature (116 °C for less than 1 day) schedules were tested to determine if high-temperature drying affects load duration. Results show that high-temperature drying has no appreciable effect on load duration, probably because it has no appreciable effect on static strength. Results from combining the data from both kinds of drying suggest that the load duration effect is less severe for lumber than for small clear specimens.

A spatial equilibrium analysis of Southern Pine lumber pricing and allocation

The objective of this paper is to determine the optimum allocation and pricing pattern of Southern Pine lumber as well as to evaluate the current and future demand-supply situation. With regard to the latter, spatial equilibrium of the Southern Pine lumber market is analyzed, and a comparative statics approach involving two equilibrium points is employed. The year 1981 is chosen as the initial point in time. The future date of 1984 is selected to be used for comparative statics analysis. A spatial solution—the optimal allocation and pricing pattern—will be obtained by using the Takayama-Judge and the Liew-Shim quadratic spatial equilibrium models. In estimating regional demand and supply functions, which are critical for the analysis, the two-stage least-squares estimation method will be used, based on apooled sample of cross section and time series for the period 1971–1981. As a result of comparing the optimum 1984 solution with the 1981 solution, it is expected that some of the areas under study can experience a tight supply of Southern Pine lumber, and consequently, lumber production-consumption balances will result in deficit production.

The adjustment of output-inventory process under linear decision rules

Linear decision rule models which allow adjustment of output, inventory and unfilled orders in order to absorb fluctuations in demand are empirically estimated here for three representative industries: Southern pine lumber, printing paper, and softwood plywood. The empirical results show a more stabilizing influence in the recent period for the three industries in general and the cyclical tendencies appear to have been dampened out. For the plywood sector, the introduction of futures trading by the end of 1969 has helped considerably in exerting a stabilizing influence and in reducing considerably or even eliminating the sources of cyclical instability.

Climatic Limitations for Tree Growth Potential in Southern Forests

CLIMATIC LIMITATIONS FOR TREE GROWTH POTENTIAL IN SOUTHERN FORESTS Chelvadurai Manogaran* The role of the southern United States as a supplier of forest products will have to be even greater in the future than at present although this region possesses the most rapidly growing trees in the nation. Pines form the predominant part of the pulpwood, plywood, and lumber production of the southern states. The forest resources of the South produce more than 63 percent of the nation's plywood and about 17 percent of the United States' total plywood production. (1) A 50 percent increase in southern pine lumber production is expected as a result of the urgent need for the construction of 26 million houses during the next eight years. (2) If forest production is not increased beyond the present level, harvest will catch up with growth by 1990. Although field experiments relating to the role of irrigation in forestry have yielded significant findings , the results have application limited to certain localities. These studies do not provide estimates of how much more growth would be realized on a regional scale if adequate moisture were made available to trees during the growing season. Potential growth of trees is not realized in many areas of the southern United States because of the prevalence of soil moisture deficits in summer; the effect of this environmental feature has been largely overlooked. The purpose of this paper is to develop a model of tree growth that estimates the depressing effect of drought. Potential growth might be estimated empirically if appropriate environmental factors were selected to predict tree growth. Such methods consider energy, moisture , and drought as factors of the environment that work together, and not independently as in a laboratory or controlled experiment, in promoting or retarding potential growth of trees. If the model predicts growth under specified conditions of soil moisture deficit, the same model could be utilized to estimate potential growth under conditions of no soil moisture deficit, which irrigation could assure, and naturally occurring moisture deficits. The additional growth, estimated as the difference between these conditions, is considered the quantity of growth that would result from the use of irrigation in forestry. A regional evaluation of additional growth resulting * Dr. Manogaran is assistant professor of geography at the University of WisconsinParkside in Kenosha. This paper was accepted for publication in March 1973. 72Southeastern Geographer from the use of irrigation in forestry is possible since the independent climatic data are available for the entire area where forests grow in the South. DERIVING A MODEL OF CLIMATE'S POWER FOR FOREST GROWTH. An equation which employs climatic variables and growth data is produced so that two kinds of projections can be made: 1) the growth under actual weather conditions which results from variable limitations due to moisture deficit; and 2) the potential growth that could occur if moisture deficit were prevented by irrigation. Data Utilized to Generate a Predictive Model. Diameter increments recorded during 1960 and 1961 on naturally occurring loblolly pines by Bassett and Moehring in southeast Arkansas and northeast Louisiana, respectively, are utilized to develop the model of tree growth. (3) (4) The pines were at maturity and varied in age from 30 to 41 years. Although the trees sampled by Bassett were homogenous with respect to age and species, the sample plots varied in stand density. The trees sampled by Moehring varied greatly with respect to age and stand density. The plots consisted of mixed stands of hardwoods and pines. The trees sampled in these two areas were combined to determine the extent to which the factors of climate explain the monthly growth of loblolly pines. One hundred seventy observations on the diameter growth of pines were utilized to generate the predictive model. The data on climate and growth were used to compute a sequence of multiple linear regression equations in a stepwise manner to identify the climatic variables that are most significantly correlated with tree growth. The readily available data on temperature and precipitation for the study areas were transformed into water budget parameters utilizing the water budget procedure developed by Thornthwaite. (5) Thornthwaite's water budget is an accounting of the continuous budget of energy's demand...

Discussion: Factors Influencing the Consumption of Southern Pine

The paper we have just heard brings together a number of the contributions Professor Zaremba has made in the area of timber products demand, price, and consumption. He has directed the attention of forest economists to a number of significant relationships that bear substantially on forest resource development and planning. Zaremba indicated that the demand for southern pine, in the form of both lumber and pulp products, can be expected to rise. The basis for this tendency lies chiefly in the anticipation of upward trends in population and income. A third determinant of demand, consumer preference, is critical, but can be forecast with less assurance. In the case of pulp and paper products, preference may add to the upward pressures on demand exerted by rising population and income. For lumber, on the other hand, weakening preferences may tend to modify the effect of other determinants. It remains to be seen how the lumber industry's recent aggressive measures to improve and promote their product will affect the demand for southern pine lumber. While the prospect of rising demand for southern pine was established, Zaremba's paper went well beyond the subject of demand. In turning from demand to consumption, that is bringing supply into the picture, the prospect we are given for southern pine lumber is drastically altered. Because of lagging productivity in the industry, supply is expected to continue to diminish. Even though demand will tend to rise, it is not anticipated that consumption will change appreciably. Unless rather drastic technological changes occur, consumption will be severely inhibited by steadily rising prices. Thus, the position of the southern pine lumber industry differs appreciably from the pulp and paper industry in which a fairly steady flow of technological advancements have the effect of increasing supply as demand rises. On the whole, the evidence Zaremba has brought together seems to indicate growing consumption of southern pine roundwood. Pulp products will undoubtedly comprise an increasing proportion of the volume of southern pine utilized. Within the lumber category, structural and similar applications may assume increasing significance relative to finish materials. In early projections of demand for timber products, greatest emphasis was placed upon population as the principal determinant of demand. Such estimates tended to be in error, generally on the conservative side, largely because forecasts of population growth were low and the positive effects of other factors were disregarded. On the basis of a rather limited

Phytosociological Studies in the Pinelands of Southeastern Louisiana

The Florida Parishes of Southeastern Louisiana include hardwood uplands, mixed shortleaf and hardwood uplands, longleaf pine hills and longelaf pine flats. The longleaf pine flats, which are the subject of this investigation, are at the southwestern edge of the longleaf-slash pine forest which extends along the seaboard as far north as North Carolina. This forest is very important economically since it not only produces the finest southern pine lumber but also most of the naval stores produced in the United States. It is also the most-important of our southern range due to its well-developed herbaceous cover of grasses, legumes and other palatable plants.