Die Querzugfestigkeit bei Öffnungen im Auflagerbereich von Brettschichtholz: Einfluss der Feuchtigkeit und Betrachtung von Ingenieurmodellen

Abstract

In the case of openings and notches in glulam beams, unplanned moisture can reduce the relevant transverse tensile strength. Such effects in the case of humidification and subsequent dehumidification, including improvement of the transverse tensile behaviour through the arrangement of reinforcing screws – were investigated in several test series with special framework conditions in the form of glued beams with realistic dimensions and a round opening in the support area. The tests showed that the moisture-treated beams have lower limiting loads and the reinforcements for these beams have an effect and practically restore the full load bearing capacity. However, the screw reinforcement also reduces the appearance of further cracks and the ratio of crack initiation load to cracking load is higher. The non-moisture treated beams have slightly higher limiting loads and the screw reinforcement is less effective here. Based on the test results, the engineering models of the design-relevant transverse tensile strength were evaluated with regard to standard regulations, the size effect according to the Weibull criterion and on the basis of the Tsai/ Wu criterion.