Effects of the semi-rigidity coefficients on numerical analysis results in chair side frame joints

In this study, it is aimed to determine the semi-rigidity coefficients related to joints of chair side frame and to use them numerical analyses with finite element method (FEM). Turkish beech (Fagus orientalis L.) and Scotch pine (Pinus sylvestris L.) were used for preparing the specimens; and glued dowel joint was preferred as jointing technique. T-type and L-type specimens were utilized for representing the side frame joints. Different diameters and lengths of dowels were used in the specimens, and effects of dowel these factors on semi-rigidity coefficients of joints were determined. Specimens were tested under static bending and semi-rigidity coefficients were determined by considering the elastic region of moment-rotation graphs. Then, numerical analyses were performed using these semi-rigidity coefficients and effect of defining the joints as rigid or semi-rigid on moment distribution and deflections at the joints was determined. As a result of study, it was understood that the chairs consisting of joints with high semi-rigidity coefficients, deflections decreased and joints deformed less, and these results were consistent with the deformation charactheristics results obtained from real tests. The highest semi-rigidity coefficients were obtained from the Turkish beech T-type joints connected with 10 × 35 or 40 mm (4905 Nm/rad) dowels while the lowest values were obtained from the Scotch pine L-type joints connected with 8 × 40 mm (1892 Nm/rad) dowels.