wood construction: connections seventeen

(1)

seventeen

wood construction:

connections

lecture

A

RCHITECTURAL

S

TRUCTURES

:

F

ORM,

B

EHAVIOR, AND

D

ESIGN

A

RCH 331

HÜDAVERDİ TOZAN

(2)

Connectors

• joining

– lapping

– interlocking

– butting

• mechanical

– “third-elements”

• transfer load at a point, line or surface

(3)

Wood Connectors

• adhesives

– used in a controlled environment

– can be used with nails

• mechanical

– bolts

– lag bolts or lag screws

– nails

– split ring and

shear plate connectors

(4)

Wood Connections

(5)

• connected members in tension cause

shear stress

• connected members in

compression cause

bearing stress

Bolted Joints

(6)

Tension Members

• members with holes have reduced area

• increased tension stress

• A

_e

is effective net area















e

t

A

T

or

A

P

f

(7)

Effective Net Area

• likely path to “rip” across

(8)

• seen when 2 members are connected

Single Shear

4

2 d

v

P

A

P

f





(9)

• seen when 3 members are connected

Double Shear

4

2

2 d

v

P

A

P

A

P

f





)

2 (

2

0 P

P

F









(10)

• compression & contact

• stress limited

by species &

grain direction

to load

• projected area

Bearing Stress

td

P

A

P

f

projected

p



F=

(11)

Bolted Joints

• twisting

• tear out

– shear strength

– end distance & spacing

Taylor & Line 2002

(12)

Nailed Joints

• tension stress (pullout)

• shear stress nails presumed to share

load by distance from centroid of nail

pattern

(13)

Nailed Joints

• sized by pennyweight units / length

• embedment length

• dense wood, more capacity

(14)

• plates with

– nails

– rivets

– bolts

• splices

• V from beam load

related to V

_longitudinal

Connectors Resisting Beam Shear

x

y

a

4”

2”

12”

8”

p

4.43”

I

VQ

p

V

_longitudin

_al



p

I

VQ

(15)

Vertical Connectors

• isolate an area with vertical interfaces

p

I

VQ

nF

_connector



connected

area



p