Impact of Bolt Pattern on the Fire Performance of Protected and Unprotected Concealed Timber Connections

  • Aba OwusuEmail author
  • Osama (Sam) Salem
  • George Hadjisophocleous
Conference paper


The fire performance of concealed timber beam connections has been studied over the years, and it has been shown that such connections do not perform as well as exposed and seated connections mainly due to the reduction of the beam’s cross section to accommodate the concealed steel plate. The main objective of the study presented in this paper is to investigate the performance of fully protected and unprotected concealed glued-laminated timber (glulam) beam connections when subjected to fire. For the protected connection configuration, the steel plate and bolts were fully protected from fire using wood strips and plugs, respectively. This research also studied the effect of bolt pattern on the fire performance of concealed glulam connections. Four full-size concealed glulam beam end connections: two protected and two unprotected connections were exposed to CAN/ULC-S101 standard fire, while being loaded to 100% of the ultimate design moment capacity of the weakest connection configuration. In pattern one, two rows of bolts, each of two bolts, were symmetrically positioned near the top and bottom sides of the beam cross section. While, in bolt pattern two, the bottom bolt row was shifted upward to be located at the mid height of the beam section.


Concealed connections Glulam beams Fire protection Bolt pattern Failure time 


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Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Aba Owusu
    • 1
    Email author
  • Osama (Sam) Salem
    • 2
  • George Hadjisophocleous
    • 1
  1. 1.Carleton UniversityOttawaCanada
  2. 2.Lakehead UniversityThunder BayCanada

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