joint connections

7/28/2019 joint connections

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Intermediate Joints

Condition in making intermediate joints

1. Timber joints shall be within the centerline of the members meeting

on a common point so as to prevent rotation at the joint.

2. For structures with smaller stresses, wood connections shall be providedwith dapping or notching at the strut to the adjoining member using dowels,

lag screw or nails to keep the member in the design position.


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5. When the strut is at right angle with the top chord, a 20mm dowel or

16mm lag screw should be used to hold the strut securely in place.

When the strut carries a large stresses, the following joints may be

employed.

a. Butt block or angle block

b. Steel S-Shaped bearing plate

c. Cast iron solid angle bear block

d. Cast iron angle bearing block with web

3. Metal bearing plate bolted connections or bearing blocks shall be specified

for structure with large stresses.

4. Pocket joints that will collect moisture shall be avoided.


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Steel S-Shaped Bearing Plate should be the same width as the top cord

Butt Block is hard wood with the same thickness as the top chord.

Cast Iron Solid Bearing Block as a solid block covering the whole width

of the top chord cast at holes not less than 16 mm thick provided with a lug

into the top chord.

Cast Iron Bearing Block with the web should have a minimum thickness

of 20mm.


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Center Joint of Howe Truss- this type of joint is provided with a butt

or angle block at the center intermediate joint.

Peak Joint has various types depending upon the design as shown on

the following illustration.


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End Joints

There are five types of Rafter and Truss End Joints:

1. Pinning the top chord into the bottom chord.

2. Notching the top chord into the lower chord with bolts.

3. Using bent strap or shoe plate with lugs or flats.4. Using the side plates with flats or tables.

5. Using malleable cast iron shoe.


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Notching Top Chord and Lower Chord

1. Notching with bolts.

2. Notching with bolts and wood key.


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3. Using bent strap with lugs or flat.

4. Using steel side plate with flats or tables riveted to the plates.

5. Using malleable cast iron shoe.


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Splicing

Splicing is the process of joining two pieces of materials in their longitudinal

direction in order to transmit stresses from one member to the other

Splicing is of three different ways:

1. By Lapping

2. Scarfing and

3. By Fishing


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Lapping is simply joining one member to the other

Fishing is joining two ends using two side blocks sometimes

called splice pads.


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Scarfing is cutting away the opposite sides of two members the lap-jointed to obtain a continuous piece of uniform thickness.

This is popularly termed as half-lap.


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Types of Splicing tension members

Bolted wooden fish plate splice

Bolted steel fish plate


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Wooden tabled fish plate splice

Shear pin splice


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Steel tabled fish plate

Tension bar splice

Timber connector splice


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Glued Laminated Lumber

Glued laminated wood is a stress rated product of timber produced

in laminating plant from selected wood.

In forming any length, each wood layer is bended slowly to a designed

curve and shape.

Lumber intended for lamination do not exceed 5 cm in thickness.

However, when bending to a radius that is too sharp to permit the use of 5 cm

thick, a nominal thickness of 2 cm is used.


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Various Example of Laminated Structures

Double tapered curve straightDouble tapered straight

Single tapered

pitchedcurve

3 centered

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