MOMENT DEVELOPED BY ECCENTRIC BOTTOM CHORD SPLICE BOARD ON WOODEN TRUSSES

Truss analysis methods may assume that bottom chords without ceiling l oads are only axially loaded and no moment is developed. However, on w ide span wooden trusses, the bottom chord is occasionally spliced with an additional board on the top edge of the bottom chord (fig. 1) whic h adds eccentricity to the splice that may develop additional moment s tress within the bottom chord. If significant moments develop because of forces being transferred through the top splice board, they need to be documented and accounted for in design practice. It was found that under snow load conditions, the bottom chord and tension splice board develop bending moments as well as axial load. Various simple Purdue Plane Structures Analyzer (PPSA) analogs were compared to determine ho w well they estimated axial forces and moments in the bottom chord and the splice board.