Abstract

The paper presents a description and results of the research concerning one of the scarf joints, so-called ‘lightning sign’ (also described as ‘Bolt of lightning’ or ‘Trait-de- Jupiter’). This joint has been used and can be commonly found in wooden historical structures and is considered to be an interesting example of carpentry longitudinal joints. In the experimental part timber beams with this type of joint shaped in the different planes, horizontal and vertical, reinforced with spindle fasteners (metal bolts), were subjected to four-point bending tests. As a result, the static equilibrium paths and the bending capacities of individual beams were obtained. They were compared to the load-bearing capacity of the continuous reference beam. Moreover, a simplified numerical analysis based on FEM was carried out for comparison the rigidity of individual beams. A comparison of the results for series of beams is discussed and some conclusions and possible directions of the future actions in the subject are presented.

Abstract

This work concerns structural and sensitivity analysis of carpentry joints used in historic wooden buildings in south-eastern Poland and western Ukraine. These are primarily sacred buildings and the types of joints characteristic for this region are saddle notch and dovetail joints. Thus, in the study the authors focus on these types of corner log joints. Numerical models of the joints are defined and finite element simulations of their statics are carried out. Moreover, a sensitivity analysis is performed in order to describe how the uncertainty of material properties including humidity of some structural members, caused during potential repairs, affect the structural behaviour of the whole connection. This represents the situation when some degraded logs are exchanged into new wood combining old, and often damp, wood with new and dry logs. A non-intrusive probabilistic approach to the sensitivity analysis is applied and regression-based Polynomial Chaos (PC) expansion method is used to propagate uncertainties.