9501b195-48a0-475e-bb90-23cdce66e70c 3 2 5 decimal

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Project:

11 Tom Scmidt Ct, Mt Samson

Job Number:

10033

Date:

01.06.11

Joint Design Check

References AS1720 & TFEC 1-2010

Joint:

King post at Rafters

Consider peg failure:

Double shear through the peg section, perpendicular to the grain

must satisfy the yield Limit equations of TFEC 1-2010:

Yield Mode

Capacity

Yield Mode

Capacity

Z.1 D l.m * F.em * (R.d1 / :

Z.3 2 k.3 * D * l.s * F.em * (2 R.e + (R.d3 * / :

I.m

III.s

Z.2 2 D * l.s * F.es * (R.d2 / :

Z.4 π D 2^* F.yv * (2 R.d4 * / :

I.s

V

R.d1 4 K.θ1 * :

R.d3 3.2 K.θ3 * :

R.d2 4 K.θ2 * :

R.d4 3.5 K.θ4 * :

K.θ1 1 θ.1 360 / (+ :

K.θ2 1 θ.2 360 / (+ :

K.θ3 1 θ.3 360 / (+ :

K.θ4 1 θ.4 360 / (+ :

F.yv 4850 G.p * G.t 0.75^* psi * :

D= peg diameter (in)

F.yb

= yield strength of peg in bending (psi)

R.e F.em F.es / :

l.m

= tenon breadth(in)

l.s

= minimum mortice side wall thickness on one side of tenon (in)

F.em

= tenon dowel bearing strength parallel to the grain (psi)

F.es

= mortice side wall dowel bearing strength perpendicular to the grain (psi)

θ

= maximum angle (0<θ<90) of load to grain for any member in a connection (deg)

F.yv

= effective yield strength of the peg in shear(psi)

G.p

= specific gravity of the peg material

G.t

= specific gravity of the timber material

k.3 21 R.e + (* (R.d3 / 2 F.yb * 2 R.e + (* D 2^* 3 F.em * l.s 2^* / + sqrt 1 - :

Pegs are Messmate where,

D 0.75 in * :

F.yb 5801 psi * :

40 MPa * (

l.m 2 in * :

l.s 1 in * :

F.em 6527 psi * :

45 MPa * (

F.es 2176 psi * :

15 MPa * (

where,

R.e 2.9995

θ.1 25 :

θ.2 0 :

θ.3 25 :

θ.4 90 :

G.p 1.1 :

(Messmate)

G.t 1.25 :

(Ironbark)

where,

Z.1 10180.5928 N *

Z.2 3629.7488 N *

Z.3 2547.7258 N *

Z.4 5665.8842 N *

Z Z.1 abs Z.2 abs Z.3 abs Z.4 abs 41 mat min :

and

Z #

the joint capacity is modified by capacity reduction factors:

C.D

= Load duration factor

C.M

= Timber seasoning factor

C.t

= Temperature factor (sustained temps over 65 degrees C)

C.g

= Group action factor, for multiple pegs parallel to the line of force

C.`

= Reduced end distance factor

where,

Z.mod C.D C.M * C.t * C.g * C.` * (n * Z * :

take,

C.D 0.86 :

(Short term load AS1720 T2.7)

C.M 1.10 :

(unseasoned timber AS1720 T2.9)

C.t 1.0 :

(enclosed structure & south of Fraser Island)

AS1720 Cl 2.4.3

C.g 1.0 :

C.` 0.75 :

n 4 :

(4 pegs)

for,

Z.mod #

from analysis,

N 14130 N * :

Very close.. use four pegs

Design Decision: Construct as detailed