An innovative approach for the on-site
reinforcement and rehabilitation of timber
structures

The timber beam was cambered
prior to the installation of the FRP lamella.
The prestress force in the FRP is not constant. It
peaks in the middle of the beam and is zero towards the ends were high
stress would cause delamination.

Steckbrief

  • Departement BFH | Architektur, Holz und Bau
  • Forschungsschwerpunkt Holzbau, Tragwerke und Architektur
  • Forschungsfeld Holzbau, Bauen im Bestand und Denkmalpflege
  • Förderorganisation SBFI
  • Laufzeit 06.09.2004 - 31.12.2007
  • Projektverantwortung Frédéric Pichelin
  • Projektleitung Martin Lehmann
  • Projektmitarbeitende Martin Lehmann
    Milena Properzi
  • Mitwirkende Projektpartner Wirtschaft SIKA
  • Mitwirkende Projektpartner Forschungsinstitutionen inkl. BFH EMPA
  • Schlüsselwörter Bonding, reinforcement, rehabilitation, timber, epoxy, FRP, prestressing

Ausgangslage

In this project timber beams were cambered prior to the installation of the FRP lamella. This cambering was done using a in the height adjustable prop placed in the middle of the beam. The prestress force in the FRP is not constant. It peaks in the middle of the beam were it is mostly needed and is zero towards the ends were high stress would cause delamination. Furthermore, a calculation model was developed and verified with structural sized 4-point bending tests.

Ziel

The aim of the study was to develop a method for on-site reinforcement of structural timber beams using CFK-strips.

Kernkompetenzen

Numerical and analytical calculation of composite constructions FEM calculation of the stress distribution in gluelines

Ergebnis

The estimated increase of the load bearing capacity in bending of 30% on the structural sized beams is a significant contribution to the ultimate limit state. The cambering due to prestressing has a significant contribution in the service limit state and justifies the prestressing, especially because the described method is very easy and fast to apply. The total contribution (including the chamber) of the reinforcement to the service limit state is around 40%.

Ausblick

A building for a case study is being sought.