IMAGE CORRELATION-ANALYSIS OF MULTIPLE-BOLT WOOD CONNECTIONS

Displacement beneath the bolts in multiple-bolted wood connections was studied using digital image correlation. This method combines digital image analysis and image correlation to calculate surface displacemen ts from a set, of digitized video images of an object under an applied load. Double-sheer connections constructed of clear, straight-grained yellow-poplar were tested in compression parallel to grain. Five diff erent bolt patterns were used to analyze the effect of number of bolts irt a vertical row and number of bolts in a horizontal column on disp lacement distribution among bolts. II was discovered that for multi-bo lt patterns in a vertical row, parallel to load displacements below th e outer bolts, are higher than those below the center bolt(s) but not equal in magnitude as previously assumed and the surface displacements perpendicular to the load beneath the bolts split along the centerlin e of the bolts, Variation in material properties, rigid body motion, e ccentric loading and/or wood failure beneath a bolt are detectable wit h digital image correlation and may influence the results if not caref ully considered in experimental design.