Stress analysis of a metal-plate-connection in a beam under 3-point-bending using digital image correlation

Abstract

Metal-plate-connected wood trusses for roofs and floors have been used in light-frame residential, industrial, and commercial construction for several decades. The behavior of a metal-plate connector (MPC) joint is very complex and is influenced by many variables, including metal-plate properties, joint geometry, and the natural variability of wood. Moreover, boundary conditions of such connectors are not well defined in practice, thus ruling out meaningful analytical or numerical stress analyses. With very little prior research on the state of stress of a MPC, this paper presents a hybrid method for stress analyzing a MPC in a beam subjected to 3-point bending using 3D Digital Image Correlation (DIC). The recorded vertical displacements in the vicinity of one of the holes of the MPC are coupled with an Airy stress function, along with imposed appropriate boundary conditions on the edge of the MPC hole. All stress components are determined from only the vertically recorded displacements. Obtaining reliable experimental data near edges can be challenging, but this is overcame here by filling the MPC holes with extremely compliant clay material and applying the speckle pattern over both materials such that measured displacements are obtained continuously throughout the perforated metal plate. © The Society for Experimental Mechanics, Inc. 2014.