Prediction of withdrawal resistance for a screw in hybrid cross-laminated timber

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 3 Specimens and test results depending on the test configurations

Group	Wood material		Screw		Repetition	Withdrawal resistance			Withdrawal strength^c (MPa)
Group	Type	Thickness (mm)	Diameter × length (mm)	Penetration depth (mm)	Repetition	Average (kN)	COV^a	5th percentile value^b (kN)	Withdrawal strength^c (MPa)
Solid-6.5^d	Solid wood	24	6.5 × 65	24	30	4.32	0.20	2.85	5.81
Solid-8.0	Solid wood	24	8.0 × 100	24	32	4.49	0.19	3.19	5.29
Plywood-6.5	Plywood	24	6.5 × 65	24	30	5.43	0.07	4.77	9.74
Plywood-8.0	Plywood	24	8.0 × 100	24	30	6.10	0.06	5.47	9.07
Ply-lam-6.5	Ply-lam (25-24-25-24-25)^e	123	6.5 × 65	33	32	5.30	0.17	3.76	6.72
Ply-lam-8.0	Ply-lam (25-24-25-24-25)^e	123	8.0 × 100	70	32	13.96	0.10	12.00	8.16

^aCoefficient of variation
^bLower 5th percentile value
^cLower 5th percentile value divided by the contact area between the screw inserted in the wood material and the wood material (Eq. 2)
^dDiameter of screw (mm)
^eParentheses show thickness of each layer (from bottom to top)