Fan-shaped Shear Dampers Strengthen Mortise-tenon Joints in Chinese Traditional Timber Structures

Figures & data

Table 1. Details of specimens.

Specimens No.		WT (mm)		Tightness	Tree species	Loading way	Uniform size (mm)
unreinforced	reinforced	WTF	WTN
SJ-22	SJ-29	49	39	loose	hemlock	cycle	HT & HM	175
SJ-21	SJ-38	50	40	moderate	hemlock	cycle	LT & LM	53
SJ-20	SJ-41	51	41	tight	hemlock	cycle	WMF	50
							WMN	40

Notes: The subscript “T”, “M”, “TF”, “TN” “MF” and “MN” denote the abbreviation of “tenon”, “mortise”, “tenon frontal”, “tenon neck” “mortise frontal” and “mortise neck”, respectively; the “W”, “H” and “L” represent the dimensions of members in “width”, “height” and “length”, respectively.

Table 2. Material properties of Canadian hemlock.

EL (N/mm^2)	ER (N/mm^2)	ET (N/mm^2)	νLR	νLT	νRT	GLR (N/mm^2)	GLT (N/mm^2)	GRT (N/mm^2)	MC	ρ (g/cm^3)
11580	890	493	0.43	0.49	0.37	220	680	920	12.2%	0.506

Notes: The subscript “L”, “R”, and “T” denote the longitudinal, radial and tangential directions of wood, respectively; the “E”, “ν” and “G” represent the elastic modulus, Poisson ratio, and the shear modulus of wood material, respectively. MC is moisture content, ρ is density of wood.

Figure 1. Schematic diagram of dovetail mortise-tenon joint model.

Table 3. Material properties of damper.

Project	Material properties	Values
rubber	Tensile strength (MPa)	17.3
	Elongation at break (%)	549
	Tensile permanent distortion at break (%)	23.16
	300%/500% tensile stress (MPa)	9.39/16.3
	Shore A hardness	66
	Equivalent damping ratio (%)	8.04
	Shear modulu (MPa)	0.63
Q235 steel	Yield Strength (MPa)	256

Figure 2. Damper construction.

Figure 3. Damper stalled on the column-beam joint.

Figure 4. Damper test setup.

Figure 5. M-θ hysteretic loops of the three damper specimens (a) Deformation characteristic curve (b) Frequency characteristic curve (c) Fatigue characteristic curve.

Figure 6. Wood joint test setup (all dimensions in mm) (a) Test design (b) Overview of the test setup.

Figure 7. Loading schedule.

Figure 8. The sticking location of the strain gages.

Figure 9. Failure mode of SJ-22 (a) Deformation of tenon neck on the upper side (b) Deformation of tenon neck on the lower side.

Figure 10. Failure mode of SJ-21 (a) Deformation of tenon neck on the lower side (b) Deformation of tenon neck and tenon forehead on the upper side.

Figure 11. Failure mode of SJ-20.

Figure 12. Failure mode of SJ-29 (a) Pulled out of bolts (b) Residual pullout of tenon.

Figure 13. Failure mode of SJ-38 (a) Pulled out of bolts (b) Indentation on the column.

Figure 14. Failure mode of SJ-41.

Figure 15. Comparison of hysteresis curves between joint models (a) Loose joint (b) Moderate joint (c) Tight joint.

Figure 16. Comparison of the M-θ skeleton curves between the joint models (a) Loose joint (b) Moderate joint (c) Tight joint.

Figure 17. Comparison of the stiffness degradation curves between joint models (a) Loose joint (b) Moderate joint (c) Tight joint.

Figure 18. A diagram showing the calculation of h_e.

Figure 19. Analysis of equivalent viscous damping coefficient curves in the joint models (a) Loose joint (b) Moderate joint (c) Tight joint.