古建木结构"松动+虫蛀"燕尾榫力学性能试验OA

To investigate the degradation pattern of the mechanical properties of mortise-tenon joints in Chinese historic timber structures under the combined effects of different damage types,the typical damage form of"loosening+insect infestation"was selected.A total of four dovetail joint specimens with a scale ratio of 1:3.2 were designed and fabricated,including one intact specimen and three specimens with different degrees of"loosening+insect infestation"damage.Low-cycle reversed load-ing tests were conducted on these specimens.Based on the test observations and measured data,the mechanical properties of the specimens were analyzed,including failure characteristics,hysteretic be-havior,bearing capacity,deformation performance,and stiffness and strength degradation.The re-sults showed that the mechanical properties of the dovetail joints exhibited more pronounced degrada-tion with an increased degree of damage.All specimens exhibited a"pinching"effect in their hysteretic curves,with the shape gradually transitioning from an inverted-S shape to a Z shape.As the degree of damage increased,the deformation performance and bearing capacity of the damaged joints decreased to varying degrees.Compared with the intact joint,the bearing capacity of the damaged joints de-creased by 18.70％to 39.72％,and the displacement ductility coefficient decreased by 16.26％to 31.62％.When the rotation angle was less than 0.025 rad,the stiffness of each specimen degraded rap-idly;when the rotation angle was greater than 0.03 rad,the strength of each specimen degraded rapid-ly.It is recommended that necessary strengthening measures be implemented for loosening-damaged mortise-tenon joints in engineering practice to prevent instability-induced collapse.