Design and perpendicular to grain tensile stress in double-tapered glulam beams

Författare

Henrik Danielsson

Summary, in English

Design and stress analysis of regular double-tapered beams and double-tapered beams with a flattened apex region is considered, focusing on perpendicular to grain tensile stress in apex region. Double-tapered beams with flattened apex region are analyzed since the geometry is such that the perpendicular to grain tensile stress may be reduced compared to a regular double-tapered beam of corresponding geometry.

The Eurocode 5 design criteria for regular double-tapered beams regarding bending stress, shear stress and perpendicular to grain tensile stress are reviewed. Design with respect to perpendicular to grain tensile stress is based on an approximate solution for maximum stress and Weibull type considerations for influence of size of stressed volume and heterogeneity in stress distribution on the strength.

The maximum stress, the size of the stressed volume and heterogeneity in stress distribution are analyzed by linear elastic finite element analysis for regular double-tapered beams and for double-tapered beams with a flattened apex region. For both geometry types, loading by a uniformly distributed load and point loads in the two quarter points of the beam is considered.

Based on the FE-analysis, proposals for design criterion with respect to perpen\-dicular to grain tensile stress are also presented. The proposals consist of modifications of the Eurocode 5 design approach for regular double-tapered beams.

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