Stress Distribution Among Laminates in Laminated Posts in Region Near Abrupt Section Change

Abstract

Four unspliced laminated posts were strain gaged and loaded in bending to determine how stresses are shared among the laminates around abrupt section changes. The posts were mechanically laminated 26s constructed from three full-length boards plus one half-length board which ended abruptly at the center of the post length. The posts were tested to simulate both simply supported and cantilever beams. The posts were also simulated with FEAST (Finite Element Analysis of Spliced Timber; Bohnhoff, 1987) to compare test results with theoretical analysis. In the region near an abrupt change, the full length laminate nearest the abrupt change had 11% more stress than would be predicted if the designer assumed that all laminates shared the load equally. The half-length board did not develop its share of the post stress until around 1000 mm below the abrupt change. FEAST predicted stresses in an abrupt section change post within 7% of measured stress.