The Effective Number Of Fasteners In A Row In A Moment Connection

When a connection is subjected to a moment the direction of the force in each fastener in the connection will vary and where the fastener configuration is such that:

(a) no row exists where a force component from two or more fasteners in the row is parallel to the grain in any of the connected members,

(b) or there are rows where the above situation will arise but the spacing between the fasteners parallel to the member grain complies with the criteria given in Table 12.2, the full number of fasteners in the connection can be used.

Where the above conditions do not apply, for all design checks on the capacity of fasteners loaded parallel to the grain of a member, the effective number of fasteners

Table 12.2 Criteria at which the full number of fasteners in a row can be used in strength calculations

Fastener type Criteria for fasteners in a row with a force component parallel to the grain of a member

Nails (<8 mm in diameter) and screws (<6 mm in diameter)

Nails (>8 mm in diameter), screws (>6 mm in diameter), bolts or dowels

Toothed-plate connectors

Ring and shear plate connectors

The spacing between adjacent fasteners having a component parallel to the grain must be >14d (Table 10.10)

The function n0'9,4/ must exceed 1

Y 13d

(Equation 10.45)

Always use the full number of connectors

Where there are no more than two connectors per shear plane a row having a component parallel to the grain.

d is the fastener diameter (in mm); n is the number of fasteners in the row with a component parallel to the grain; a1 is the distance parallel to the grain between adjacent fasteners in the row.

Table 12.3 Minimum edge, end and spacing criteria for fasteners used in moment connections using timber to timber*

Fastener

Edge distance** (a4,t and a3,c)

Loaded end distance** (a3,t)

Lateral spacing** (a1 and a2)

Nails, screws': pk < 420 kg/m3

d > 5 mm; 10d d < 5 mm; Id

d > 5 mm; 15d d < 5 mm; 15d

d > 5 mm; 12d d < 5 mm; 10d

Nails, screws': 420 kg/m3 <pk < 550 kg/m3

d > 5 mm; 12d d < 5 mm; 9d

d > 5 mm; 20d d < 5 mm; 20d

d > 5 mm; 15d d < 5 mm; 15d

Nails, screws': with pre-drilled holes

d > 5 mm; Id d < 5 mm; 5d

d > 5 mm; 12d d < 5 mm; 12d

d > 5 mm; 5d d < 5 mm; 5d

Bolts, dowels and screws*

4d

The greater of Id or 80 mm

6d

Toothed-plate connectors

dc

2dc

2dc

Ring or shear plate connectors

dc

2dc

2dc

Pk is the characteristic density of the timber (in kg/m3); d is the diameter of the nail, bolt or dowel (in mm); dc is the dimension of the fastener given in BS EN 912:2000 [2] (in mm).

* When using panel or steel gusset plates connected by nails, it is proposed that the criteria given in Chapter 10 for nailed timber-to-timber connections should apply.

'Only applies to screws <6d.

*Only applies to screws >6d.

** Spacing Symbols are as shown in Fig 10.11.

Pk is the characteristic density of the timber (in kg/m3); d is the diameter of the nail, bolt or dowel (in mm); dc is the dimension of the fastener given in BS EN 912:2000 [2] (in mm).

* When using panel or steel gusset plates connected by nails, it is proposed that the criteria given in Chapter 10 for nailed timber-to-timber connections should apply.

'Only applies to screws <6d.

*Only applies to screws >6d.

** Spacing Symbols are as shown in Fig 10.11.

in a row, as defined in Chapter 10 for metal dowel type fasteners and Chapter 11 for connectors, must be used.

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