The influences of moisture content variation, number and width of gaps on the withdrawal resistance of self tapping screws inserted in cross laminated timber

Catarina Silva*, Jorge Branco, Andreas Ringhofer, Paulo B. Lourenco, Gerhard Schickhofer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A large experimental campaign comprised of 470 withdrawal tests was carried out, aiming to quantify the withdrawal resistance of self-tapping screws (STS) inserted in the side face of cross laminated timber (CLT) elements. In order to deeply understand the “CLT-STS” composite model, the experimental tests considered two main parameters: (i) simple and cyclic changes on moisture content (MC) and (ii) number and width of gaps. Regarding (i), three individual groups of test specimens were stabilized with 8%, 12% and 18% of moisture content and one group was submitted to a six month RH cycle (between 30% and 90% RH). Concerning (ii), different test configurations with 0 (REF), 1, 2 and 3 gaps, and widths equal to 0 mm (GAP0) or 4 mm (GAP4), were tested. The influences of MC and number of gaps were modeled by means of least square method. Moreover, a revision of a prediction model developed by Uibel and Blaß (2007) was proposed.

The main findings of the experimental campaign were: the decrease of withdrawal resistance for specimens tested with MC = 18% in most configurations; the unexpected increase of withdrawal resistance as the number of gaps with 0 mm increased; and, the surprising increase of withdrawal resistance for REF specimens submitted to the RH cycle.
Original languageEnglish
Pages (from-to)1205-1215
Number of pages11
JournalConstruction and Building Materials
Volume125
DOIs
Publication statusPublished - 9 Sep 2016

Keywords

  • Cross Laminated Timber (CLT)
  • Self-tapping screws
  • Moisture content variation
  • Withdrawal resistance
  • Axial loading

Fields of Expertise

  • Advanced Materials Science
  • Sustainable Systems

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