ISSN: 1945-7553
Page Count: 9

Qualitative Assessment of Failure in Bolted Connections: Tsai-Wu Criterion

Patton-Mallory, M
Assistant director, USDA,

Pellicane, PJ
Professor of wood engineeringprofessor of mechanical engineering, Colorado State University, Fort,

Smith, FW
Professor of wood engineeringprofessor of mechanical engineering, Colorado State University, Fort,

(Received 8 April 1997; accepted 5 March 1998)

Abstract

In a companion paper, a characterization is presented of stress fields in a single-shear bolted connection subjected to tension loading. Numerous stress contours are presented that illustrate the magnitude of the parallel-to-grain compression and shear stresses, as well as the perpendicular-to-grain tension stresses. In addition, regions of potential failure in the selected specimens are identified based on a maximum stress failure criterion.

The work presented in this paper represents additional efforts to identify the effect of stress interactions on the strength of the previously mentioned connections. The Tsai-Wu criterion, quantified by its failure index, is used as the tool to identify stress interactions between the aforementioned stress components. Connection geometries similar to those discussed in the companion paper [end distance/bolt diameter (e∕d)=4; and length of bolt in main member/bolt diameter (aspect ratio) (l∕d)=2,5,and7] are studied. In addition, several other geometries are discussed that illustrate the effects of changing aspect ratio and end distance.

A number of significant findings are reached in this study. As is the case in the companion study, all connections with (l∕d)=2 have nearly uniform distributions of the Tsai-Wu failure index (FI) through the specimen thickness. No significant pin bending is associated with this geometry. Connections with l∕d>4 have a failure mode (interpreted from the numerical model) that includes substantial pin bending due to steel yielding, wood crushing, and localized cracking.

Keywords:
bolted connection, wood, finite element model, Tsai-Wu failure criterion, stress interaction

Paper ID: JTE12694J
DOI: 10.1520/JTE12694J
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