REPORTERS:
CLEMENTE, JOHN ANDREI
DE PEDRO, JOHN PAUL
FAJARDO, XANDRA ALE
SORIANO, ALGERNON
I. TYPES OF WOOD CONNECTORS
1. Dowel Type Connectors
Transmits either lateral or withdrawal loads
Examples are nails, screws and bolts
Lateral loads – transmitted by bearing stresses developed between the fastener and
the members of the connection
Withdrawal loads – axial loads parallel to the fastener axis transmitted through
friction or bearing connected materials
2. Bearing Type Connectors
Transmits only lateral loads
Transmits shear forces trough bearing on the connected materials
Examples are shear plates and split ring connectors
II. CONNECTOR HARDWARES
1. Nails
Sharpened metal pins that are driven into wood with a hammer or mechanical nail
gun
Resists either lateral or withdrawal forces or combination of the two
Parts of the nail: point (sharpened end), shank (shaft of the nail) and head (flattened
part of the nail)
Nail Sizes – denoted by penny or “d”
Nail Types
a. Common Nail – used primarily for fastening rough framing
b. Finishing Nail – virtually headless; used for fastening finish woodwork
c. Box Nail – used for toe nailing and other light framing connections where
lumber splitting is concern
d. Casing Nail – used for attaching finish components of the building
e. Spiral Shank Nail – very resistant to withdrawal from the wood; used for
attaching floor underlayment
f. Roofing Nail – has a large head; used for applying sufficient holding power
in the soft material of which asphalt shingles are made
Methods of Nailing
a. Face Nailing – directly nailing to the face of the wood; strongest of all
methods
b. End Nailing – used for holding frame members in alignment until gravity
forces and applied sheathing make a stronger connection
c. Toe Nailing – can carry about five-sixths as much loads as face nail; used as
substitute for end nailing
Types of Nail Shanks
a. Ring Shank – straight shaft and contains no threading
b. Spiral Shank – has threading along the shaft and commonly used in
hardwood
2. Screws
Type of fastener characterized by a helical ridge, known as an external thread or
just thread, wrapped around a cylinder
Screw Point Types
a. Self-drilling Tapping Screws – externally threaded fasteners with the ability
to drill their own hole and form or cut their own internal mating threads
into which they are driven without deforming their own thread and without
breaking during assembly
b. Self-piercing Tapping Screw – externally threaded fasteners with the ability
to self-pierce metallic material, form a sleeve by extruding metallic material,
and “tap” their own mating threads when driven
Screw Head Types
Screw Slot Types
Standard Screw Sizes
Screw Designation
3. Bolts
Most common wood fastener for connections with most high lateral strength is
required
Used in tension connections where forces are applied parallel to the bolt axis
Usually used for securing wood-to-steel or wood-to-concrete connections
Bolt Connections
Bolt Types
a. Carriage bolt – bolts that need no washers since they have square shoulder
under the head that prevent the bolt from turning as the nut is being
tightened
b. Lag bolt – used to anchor metal, or wood, to wood in areas inaccessible to
the placement of a nut for a through bolt, or where an especially long bolt
would be needed to penetrate a joint fully
c. Machine bolts – same with carriage bolts except they have a hexagonal
head
d. Anchor Bolts – often called J-Bolts and are used for connecting wood to
concrete
Typical Bolt Types
Washers – used with bolts to keep a bolt head or nut from causing crushing
when tightening is taking place
Side Plates – frequently used to transfer load from one wood member to
another by allowing a butt joint rather than an overlapping joint
Washer Types Used with Bolts
Lag Bolt Typical Connection
4. Specialty Connection Hardwares
Sill Anchors – used in lieu of foundation anchor bolts
Joist Hangers – used to attach single or multiple joists to the sides of the girders
or head joists
Rafter Clip or Roof Tie Down – brackets that connect roof framing members to
wall framing to resist roof uplift loads
Hold Down Brackets – brackets that are bolted, nailed or screwed into wall
studs or posts and anchored to the construction below to “hold down” the end
of a member or assembly
Epoxy Set Anchors – anchor bolts that are drilled and installed with epoxy
adhesives into concrete
Strap Ties – prepunched strap or coils of strapping that are used for variety of
connections to transfer tension loads
Glulam Rivets/ Timber Rivets – high strength fastener which resembles a nail
but has a flattened oval shank with a wedge shaped head
Split Rings and Shear Plates – load transferring devices that rely on bolts to
restrain the assembly; transfers shear either between faces of two timber
members or between a timber member and a metal side plate
Shear Plates Split Rings
Assembly of Split Rings and Shear Plates
Adhesives – primarily used in factory settings and panelized construction; used
between floor joists and floor sheathing and between wall studs and wall
covering
III. JOINT CONNECTIONS
Type of connection that always meet at an angle
1. Butt Joint
Made by placing a squared-butt end of a timber to a smooth face of another
timber
Butt end of timbers are cut with same angle and are connected to each other.
Commonly used in roof connections and door jambs
2. Lap Joints
Made by removing parts of the timber members that are to be connected and
lapping them together
Connecting timbers should fit together and no additional thickness should be
done
3. Dovetail Joints
Noted for its strong tensile strength compared to other methods of joinery
Does not rely on mechanical fasteners and are often used in walls
4. Box Joint
An alternative design for dovetail joint where connecting fingers are rectangular
5. Mortise and Tenon Joint
Made by inserting one end of a member to a hole cut in the other member
6. Bridle Joint
Made by cutting the receiving timber member to full width of the other timber
7. Tounge and Groove
Made by joining two flat pieces strongly together, end to end, to make a single
flat surface
Mainly used in flooring and paneling
IV. SPLICE CONNECTIONS
Connections that extend in the same line
Vertical supports (longitudinal stress) require splices that resist compression
Trusses, braces, and joists (transverse and angular stress) require splices that
resist tension
Horizontal supports, such as girders or beams, require splices that resist bending
tension and compression
Splice Stresses
1. Compression Resistant Splices
a. Butt Splice - constructed by butting the squared ends of two pieces of timber together
and securing them in this position with two wood or metal pieces fastened on opposite
sides of the timber
b. Halved Splice - constructed by cutting away half the thickness for equal distances from
the ends of two pieces and fitting the complementary tongues together
2. Tension Resistant Splices
a. Square Splice - modification of the compression halved splice; notches are cut in the
tongues or laps to provide an additional locking shoulder
b. Long, Plain Splice - long overlap of two pieces is desirable to provide adequate bearing
surface and enough room for fasteners to make up for the lack of shoulder lock
3. Bend Resistant Splice
Complementary Lap Splice - constructed by cutting oblique complementary tongues or
laps in the ends of two pieces of timber
REFERENCES:
Mechanical Connections in Wood Structures 1996 by American Society of Civil Engineers
Connectors for Timber and Masonry by Simpson Strong – Tie, United Kingdom
Wood Mechanical Fasteners by D.R. Rammer
Wood and Steel Details – Builder’s Guide by Hybrid Builders
Carpentry and Building Construction 1960 by US Department of Army
Structural Engineering Handbook: Timber Structures by Kenneth Fridley
