Donald A. Bender

LATERAL RESISTANCE OF RING-SHANK NAIL CONNECTIONS IN SOUTHERN PINE LUMBER

Ring-shank nails are used in engineered structures with lateral connection design values based on theoretically derived equations which were validated only for common nails. The goal of this study was to quantify the input parameters and lateral connection strength of several types of ring-shank nails in Southern Pine lumber and critically evaluate the applicability of the theoretical equations for ring-shank nails. Two sizes of galvanized and ungalvanized, hardened steel ring-shank nails from two manufacturers were studied. The hardened, ring-shank nails carried significantly higher loads than the common wire nails studied. Because the current method of determining yield load does not give adequate credit to hardened, ring-shank nails, an alternate method is proposed.

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, yet surprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests that published allowable design values for ring-shank nails may be overly conservative and need revision. The goal of the research reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pine lumber. Three sizes of galvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ringshank nails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizing slightly reduced withdrawal strength (approximately 8%) due to partial filling of the threads. Nail head pull-through was studied as a possible failure mode. Even allowing for galvanizing and head pull-through, strong evidence is presented for increasing withdrawal design values for ring-shank nails.

Threaded-nail fasteners: Research and standardization needs

Threaded nail fasteners are commonly used in agricultural and commercial post-frame structures, yet there has been insufficient research to fully understand the effect of threads on withdrawal and lateral load resistance. The objective of this article is to review technical information on threaded nail fasteners and to identify problems facing manufacturers, designers, and users of threaded nail fasteners for engineering applications. Recommendations are given concerning research and standardization needs.

Rigid Roof Design for Post-Frame Buildings

Rigorous design methods are available to account for the effect of roof diaphragm action on post-frame buildings. These methods are computationally intensive and require sophisticated structural analysis software. This article presents a much simpler procedure for designing roof diaphragms based on the assumption that the roof diaphragm acts as an infinitely stiff, deep beam. The rigid roof method was compared with the more elaborate computer-based methods for a variety of building length-to-width ratios and diaphragm panel stiffnesses. Roof shear predictions were in good agreement with the results from the computer-based methods.

A Simple Analysis Procedure for Calculating Post Forces

A method is presented to calculate post bending moments and axial forces in a post-frame building, subject to diaphragm action. This method uses the current design standard procedures outlined by ASAE EP 484.1 (1991a), but it eliminates the need for computer-based frame analyses. The method was validated for a large class of post-frame buildings with wall heights ranging from 3.05-6.10 m (10-20 ft) and length-to-width ratios less than 3.07. This method assumes that the posts are pinned connected to the truss, the truss is symmetric, and the posts are restrained at the groundline by a concrete floor.

Reliability Indices for Bolted and Nailed Connections in Wood Structures

Recently published test data for bolted and nailed connections was evaluated to assess the structural reliability inherent in current allowable stress design procedures for connections in wood structures. Reliability indices were determined for timber connections using standard firstorder, second moment (FOSM) procedures. For the connections considered in this study, reliability indices range from 2.6 to5.1, generally providing higher levels of safety than the structural members in timber structures.