Fracture Mechanics Models for Brittle Failure of Bottom Rails due to Uplift in Timber Frame Shear Walls

Table 4

Measured failure loads and horizontal crack lengths for failure mode 2 for specimens with the pith oriented downwards (PU) for single- and double-sided sheathing. is the length of the horizontal crack before it changes direction. End 1 and End 2 indicate the two bottom rail ends.

(a) Study A

⁢Series 1						⁢Series 2									⁢Series 3
Set 3			Set 4			Set 1			Set 2			Set 3			Set 1			Set 2
Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]
	End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2
⁢Single-sided
21.0	15	13	23.8	12	—	21.2	22	27	21.8	20	16	27.1	5	—	19.9	11	—	27.1	20	—
—	—	—	—	—	—	21.9	16	—	20.6	16	14	—	—	—	—	—	—	—	—	—

(b) Study B

⁢Series 1						⁢Series 2									⁢Series 3
Set 3			Set 4			Set 1			Set 2			Set 3			Set 1			Set 2
Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]		Failure load [kN]	[mm]
	End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2		End 1	End 2
⁢Single-sided
—	—	—	—	—	—	—	—	—	17.1	—	18	26.3	26	13	16.5	12	—	—	—	—
—	—	—	—	—	—	—	—	—	15.4	—	17	25.5	—	22	—	—	—	—	—	—
—	—	—	—	—	—	—	—	—	—	—	—	19.7	22	—	—	—	—	—	—	—
—	—	—	—	—	—	—	—	—	—	—	—	22.2	—	12	—	—	—	—	—	—
⁢Double-sided
34.1	17	—	32.4	—	20-20	—
37.4	14	—	38.0	23–15	—
—	—	—	50.0	—	10
—	—	—	37.8	22–16	—
—	—	—	39.5	—	10
—	—	—	39.0	—	23-23
—	—	—	43.8	21	—
—	—	—	35.3	—	16

Horizontal crack on both edges of the bottom rail. Uncertain whether failure was mode 2 or 3.