Jiří Kunecký

Structural assessment of a lapped scarf joint applied to historical timber constructions in central Europe

ABSTRACT The article deals with assessment of suitable applications of all-wooden lapped scarf joints intended for use in retrofitting of existing historical timber structures in Central Europe. The first part of the article addresses the bearing capacity and stiffness of a lapped scarf joint. In the second part, four types of roof structures typical for the region were analyzed and potential application of the joints is discussed. The third part of the article describes the influence of the application of the lap joints on the force distribution of the repaired structure, since lower stiffness of one member induces forces elsewhere in the structure as it is transmitted by the other members to the rest of the structure. Extent and influence of the stiffness change on the force distribution is briefly discussed.

Torsional Shear Testing of Mortar

This paper presents a complex multidisciplinary approach to characterize the torsional shear on thin-walled cocciopesto lime mortar tubes. The approach employs (i) an in-house developed biaxial electro-mechanical loading frame designed for torsional loading, (ii) an optical measurement setup based on the digital image correlation technique to monitor and record the deformation during loading and (iii) a numerical model using finite element simulation to assess localization of shear failure. Prior to torsional loading, the mortar specimen needs to be firmly secured into the loading frame without exposing it to unwanted tensile or bending loading and possible crushing at fixture points. During the torsional loading, the mortar tube must be able to freely move axially. An optical measurement setup based on the digital image correlation technique allowed to quantify deformation measurements during torsional testing and provided the strain field on the observed surface. The mode of torsional failure was finally assessed from finite element simulations and compared to experimental measurements.