Clamp press bonding Prebena, Uetendorf

The starting position

By joining wood components, composite cross sections can be produced. These cross-sections have better structural properties than their individual cross-sections. The so-called screw press bonding has established itself on the market and is approved according to the DIN 1052 standard. Clamp press bonding and its static properties are unknown today. Prebena AG is a leader in the manufacture and sale of pneumatic tools, nails and staples. It sees great potential in the field of staple press bonding and commissioned Timbatec AG engineers to develop a staple bonding system with the aim of using it for hollow box girders or ribbed slabs and to provide a system verification.

Test specimen and methodology

Four different box girder elements with dimensions of 1.25 x 5.0 meters were manufactured, taking into account given manufacturing conditions and defined material components. A total of 630 test specimens were manufactured from these and subjected to shear testing. The adhesive joints of the test specimens were subjected to shear stress until fracture. In order to distinguish a fiber fracture from a cohesive fracture, the fracture surfaces were treated with a solution which discolors on contact with the wood.

Research result Based on the test results, a statement was made about the joint strength achievable with clamp bonding. After statistical evaluation, practical design values could be derived from the measurement results.