Experimental Investigations of Timber Beams with Stop-Splayed Scarf Carpentry Joints

Abstract

The paper presents the results of an experimental investigation of stop-splayed scarf joints, which was carried out as part of a research programme at the Wroclaw University of Science and Technology. A brief description and the characteristics of scarf and splice joints appearing in historical buildings are provided, with special reference to stop-splayed scarf joints (so-called ‘Bolt of lightning’) which were widely used, for example, in Italian renaissance architecture. Analyses and studies of scarf and splice joints in bent elements presented in the literature are reviewed, along with selected examples of analyses and research on tensile joints. It is worth noting that the authors in practically all the cited literature draw attention to the need for further research in this area. Next, the results of the authors’ own research on beams with stop-splayed scarf joints, strengthened using various methods, e.g., by means of drawbolts (metal screws), steel clamps and steel clamps with wooden pegs, which were subjected to four-point bending tests are presented. Load-deflection plots were obtained for load-bearing to bending of each beam in relation to the load-bearing of a continuous reference beam. A comparative analysis of the results obtained for each beam series is presented, along with conclusions and directions for further research.

Historical scarf and splice carpentry joints: state of the art

“…The results and conclusions from the experimental program described above are presented i.a. in [59] and will be shown in subsequent papers. [7,55] Halved and tabled tenoned scarf joint The maximum tensile force was limited by the appearance of cracks and was significantly lower than the maximum value for a solid member without joints 2012, Aira, Arriaga, Íñiguez-González, Guaita, Esteban; [54] Halved and tabled tenoned scarf joint with steel clasps or wooden pegs 2019, Ceraldi, Costa, Lippiello; [37] Stop-splayed scarf joint with wooden pegs or steel pins The most beneficial solution for 6 m beams in terms of load bearing capacity, stiffness and realisation is the 1.38 m long face-halved and bridled scarf joint with three pegs, located 1/5 of the length of the whole beam from the support 2014-2018, Kunecký, Sebera, Hasníková, Arciszewska-Kędzior, Tippner, Kloiber et al; inter alia [45,46,49] The greatest influence on stiffness is the angle of the inclined face in the joint.…”

Testing of Materials and Elements in Civil Engineering

“…The paper by [ 18 ] presents the results of an experimental investigation into stop-splayed scarf joints which was carried out as part of a research program at the Wroclaw University of Science and Technology. A brief description of the characteristics of scarf and splice joints appearing in historical buildings is provided, with special reference to stop-splayed scarf joints (so-called “bolt of lightning” joints) which were widely used, for example, in Italian Renaissance architecture.…”

“…Load-deflection plots were obtained for load-bearing to bending of each beam in relation to the load-bearing of a continuous reference beam. A comparative analysis of the results obtained for each beam series is presented, along with conclusions and directions for further research [ 18 ].…”

Timber Construction: An Experimental Assessment of the Strength of Scarf Joints and the Effectiveness of Various Adhesives for Laminated Wood

“…While more complex joints have received more attention due to their use in civil engineering [6], plain scarfs remain the prevalent option in traditional boatbuilding, and thus will be the primary focus of this investigation.…”