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Fax.d

5. Modification factors

Factor for short-duration loading and kmod.short = 0.90 service class 2, £mod.short (Table 2.4 (EC5, Table 3.1))

6. Embedment strength of timber

Characteristic embedment strength of the timber parallel to the grain, /h.k: (equation (10.35); EC5, equation (8.32))

(The equation incorporates dimension factors for Mathcad.)

/hk = 0.082 ■ f 1 - 0.01 ■ ■ (pk- ■ Nmm-2 /U = 25.65N/mm2

7. Yield moment of a coach screw

Characteristic yield moment of a coach screw (equates to a bolt):

(The equation incorporates dimension factors for Mathcad.)

8. Tension strength of the screwed connection

Minimum spacing of the coach screws, spha = 4 d spha = 32 mm spha

spha

Check the spacing ratio -= 0.89

Ratio of minimum to actual < 1; therefore spacing for tension stresses is OK

MyRk = 0.3 /uk--- - ■ Nmm MyRk = 2.07 x 104 ■ Nmm

Characteristic pointside withdrawal strength, /ax . k

(The equation incorporates dimension factors for Mathcad.)

/ax'k = 3-0 x 10-3 ■ Pk ■ — ■ Nmm-2 U.k = 22-57 N/mm2

Characteristic strength of connection in tension, based on the withdrawal strength, iTax.Rk

(The equation incorporates dimension factors for Mathcad.)

p1ax.Rk = n0 9 ■ [n ■ (d ■ mm-1) ■ [(£ef - d) ■ mm-1]]0'8 ■ (/„.k ■ mm2 ■ N-1) ■ (N)

Characteristic tensile strength of the coach screws, Fsax Rk

(conservative assessment, based on the strength of a bolt in tension in EN1993-1-8 and ignoring the k factor and the benefit from the lower partial factor associated with the coach screw)

Because of the thickness of the steel bracket, its failure strength will exceed the tensile strength of the coach screws, so head pull-through failure will not be considered.

Characteristic strength of the connection in tension in the lesser of F 1ax.Rk and

Design strength of the connection in tension, Fax Rd k-mod.short

9. Lateral load-carrying capacity of the screws

Steel plate thickness factor (10.3 (EC5, 8.2.3(1)))

coeff d

coeff 1

coefficient — 1 and tolerance for screw hole is less than 0.1d; therefore it is a thick steel plate

For a steel-to-timber connection with coach screws in single shear, the characteristic lateral resistance per shear plane is the smallest value of equations (10.13)-(10.15) in Table 10.3 (EC5, equations (8.10)), where:

Failure mode (c):

Failure mode (d):

Fv . Rk. d — 2 . 3 ■ J My. Rk ■ fh. k ■ d + ——— v 4 • n

Failure mode (e): Fv Rk e — fh.k ■ t1 ■ d Fv Rk e — 2.5 x 104N

10.3.5 requires Fax/4 to be less than 100% of the Johansen yield equation (EC5,8.2.2(2)):

/ / 4- My.Rk ^ Fv.Rk.cc — 2 ■ fh.k ■ t1 ■ d ■ I 2 + —--—2 — 1

Rk.c

On this basis, the characteristic lateral resistance per shear plane per coach screw will be:

Effective number of coach screws in a line parallel to the grain, nef (equation (10.45) (EC5, 8.5.1.1(4)))

0 0

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