IN DESIGN WE TRUSS DESIGN METHODOLOGY OF A TIMBER FRAME ROOF SYSTEM

MATHIEU DERASPE | LUKE LARSEN | ARCH 562 | STRUCTURAL DESIGN GTF LAURA LEVENBERG (TUESDAY 10:00-12:00) | WINTER 2014

ITERATIONS AND DESIGN DESIGN INTENT: THE SCISSOR TRUSS A truss translates roof loads into more readily resolvable member axial forces. Traditionally a bottom chord, when pulled into tension, resolves the external thrust generated in a pitched roof structure. In an effort to create larger vaulted spaces, builders break bottom chords. The report that follows is a strucrtural analysis of a simple scissor truss which spans a meeting hall. Employing the finite element analydis software Multiframe, we built, tested, sized, and evaluated this age old manner of making. Scissors cut volumes to create compelling space. Truss systems support bending loads by translating them into axial loads. Wood has a higher capacity when loaded as such and as a result leads to more efficient structural systems. IN DESIGN WE TRUSS.

ELEVATIONS

LONGITUDINAL

TRANSVERSE

ITERATIONS AND DESIGN

INITIAL SKETCHES

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Structural Deflection = 6.262 inches Allowable Deflection = L/250 = (30ft. x 12 inches) / 250 = 1.44 inches Actual Deflection (6.262 in.) > Allowable Deflection (1.44 in.) therefore, structure is NOT sound

CHEVRON

All members are 2” x 6” Load = 0.4 kip/ft Moment = 5.253 kip ft Deflection = 6.262 inch

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KLINGON

Structural Deflection = 7.710 inches Allowable Deflection = L/250 = (30ft. x 12 inches) / 250 = 1.44 inches Actual Deflection (7.710 in.) > Allowable Deflection (1.44 in.) therefore, structure is NOT sound

NOT FOR COMMERCIAL USE

All members are 2” x 6” Load = 0.4 kip/ft Moment = 7.081 kip ft Deflection = 7.710 inch NOT FOR COMMERCIAL USE

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DESIGN ITERATIONS All loads

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Structural Deflection = 2.246 inches Allowable Deflection = L/250 = (30ft. x 12 inches) / 250 = 1.44 inches Actual Deflection (2.246 in.) > Allowable Deflection (1.44 in.) therefore, structure is NOT sound

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All members are 2” x 6” Load = 0.4 kip/ft Moment = 5.011 kip ft Deflection = 2.246inch

CURVE

NOT Academic FOR COMMERCIAL Version USE

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y x

NOT FOR COMMERCIAL USE

Structural Deflection = 0.798 inches Allowable Deflection = L/250 = (30ft. x 12 inches) / 250 = 1.44 inches Actual Deflection (0.798 in.) < Allowable Deflection (1.44 in.) therefore, structure is sound

y x

y x

SCISSORS

NOT FOR COMMERCIAL USE

All members are 2” x 6” Load = 0.4 kip/ft Moment = 2.38 kip ft Deflection = 0.798 inch

LOAD DIAGRAM 6.77 kips

6.77 kips

6.77 kips

6.77 kips

6.77 kips

6.77 kips

6.77 kips

3.38 kips

3.38 kips

27.071 kips

27.071 kips

LOAD CALCULATIONS Load calculation: Pg = Ground Snow Load = 35 p.s.f. Ce = Exposure Factor Ct = Thermal Factor Cs = Slope Factor I = Importance Factor

= 1.2 (sheltered) = 1.0 (all other structures) = 0.65 pitch (12:12) = 1.1

S = Pf = .7 Ce • Ct • I • Pg = .7 (1.2) (1.0) (1.1) (35) = 32 p.s.f.

LOAD CALCULATIONS Decking 24’ rafter x 54’ total length of building 24’ x 54’ = 2,592 sq.ft 1.5 inch (1 ft/12 inches) x 2,592 sq.ft. = 324 cubic feet 324 cubic feet (34 lbs per cubic foot) = 11,016 lbs 11,016 lbs of decking / 2592 sq.ft. = 4.25 psf Standing Seam Roofing 24’ rafter x 54’ total length of building 24’ x 54’ = 2,592 sq.ft. 3 lbs. x 2,592 sq.ft. = 7,776 total lbs. 7,776 lbs of standing seam roofing / 2,592 sq.ft. = 3 psf Furring Strips 2’ O.C. TYPICAL running vertically 24’ furring strip x 28 members running length of building = 672 board feet 672 feet x 2 roof pitches = 1374 board feet 1” x 3” = 3 sq/inches (1ftsq /144 sq.inch) = 0.02 sq.ft. 0.02 sq.ft. x 24 feet = 0.5 feet cubed per purlin 0.5 cubic ft. x 34 lbs per cubic ft. = 17lbs per purlin 17 lbs per purling x 28 purlins = 476 total lbs per roof slope 476 total lbs x 2 = 952 total lbs 952 lbs of furring strips / 2,592 sq.ft. = .36 psf Liquid Applied Membrane 1lbs per square foot Total Dead Load

8.61 psf 8.61 psf x 2,592 sq.ft. = 22,317 lbs

MEMBER FORCES: OVERVIEW Academic Version

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AXIAL

x

21.071

21.071

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y

SHEAR

x

21.071

21.071

NOT FOR COMMERCIAL USE

MOMENT

y x

21.071

21.071

MEMBER FORCES: OVERVIEW

y

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DEFLECTION CHECK OF TRUSS

DEFLECTON

NOT FOR COMMERCIAL USE y

-0.291 x

21.071

21.071

Structural Deflection = 0.291 inches Allowable Deflection = L/250 = (30ft. x 12 inches) / 250 = 1.44 inches Actual Deflection (0.291 in.) < Allowable Deflection (1.44 in.), therefore, structure is sound NOT FOR COMMERCIAL USE

ROOF LAYOUT & TRIBUTARY WIDTHS 17’√2 17’

24’

24’

17’

30’ (CENTER TO CENTER)

EDGE PURLIN Tributary Area = 3 sq.ft. =40.6 psf (3 ft tributary area) =121.8 lbs/ft. =0.122 kip/ft Reaction Transferred to Truss = 3.31 kip/ft

COMMON PURLIN Dead and Snow Load = 32 lbs. + 8.6 lbs = 40.6 lbs per sq.ft. (6 ft tributary area) = 240 lbs/ft. =0.24 kip/ft Mmax = 3.47 kip/ft Vmax = 2.52 kip/ft Reaction Transferred to Truss = 4.782 kip/ft

RIDGE PURLIN Tributary Area =6 sq.ft. =40.6 psf (6 ft tributary area) =240 lbs/ft. =0.24 kip/ft Reaction Transferred to Truss = 2.41 kip/ft @ Ridge

ROOF PLAN 24’

Tributary Area between two common purlins (6 ft)(8.61 psf) = 45.91 plf 45.91 # per linear feet = 0.04591 kip lf

24’

50’

STRESS CHECKS: PURLIN Academic Version

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FREE BODY DIAGRAM PURLIN FBD

MOMENT

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y x

2.695

2.695 4.782

4.260

4.260

4.782

SHEAR

y 2.695

x 4.782

4.260

NOT FOR COMMERCIAL USE 4.260

2.695 4.782

STRESS CHECKS: STRUT

STRUT

L. Larsen M. Deraspe Laura Levenberg March 1, 2014

Name: GTF/Section: Date:

Member Information

Design Values

Fb

Fb2

Douglas Fir - Larch, Sel. Struc.

Fb

1,500 psi

CD

Two months

1.15

1.15

bending + tension

Ft

1,000 psi

CM

MC<19%

1.00

1.00

lumber

Fv

180 psi

Ct

T<100

1.00

1.00

Fc

625 psi

CL

xx

c - uniformly dist

1.00

yy

Section Properties

Fc

nominal dimensions (in.)

E Emin

4 dressed dimensions 3.5 glulam timber dim.

x

4

in

x

3.5

in

x

NA

1.00 RB

1,900,000 psi

CF

Size

1.00

1.00

690,000 psi

Cfu

Flat Use

Ci Cr CP Ke1

Incising

1.00 0.80 1.15 x

1.00 0.80 1.15 x

1,700 psi

Allowable Stresses Fb1' 1,581 psi Fb2' 1,587 psi

in

Ke2

Repetitive Memb.

1.00 1.00

=

x

x

unbraced length

axis1

120

in

Ft'

1,380 psi

CT

NA

in

x

x

unbraced length

axis2

96

in

Fv '

166 psi

Cb

NA

in

x

x

Fc'

625 psi

Glulam Factors CV NA

in

1.00

1.00

in in

1.00

1.00

1.05

1.06

in2

Area

12.250

Sxx Ixx

7.146 12.505

in3 in4

Syy Iyy

7.146 12.505

in 4 in

Fc ' E' Emin'

431 psi 1,805,000 psi 655,500 psi

CC

t NA R 400

3

Actual Stresses fb1

Maximum Forces xx-axis

27 psi

Results bending1

OK

fb2

NA psi

bending2

NA

ft

566 psi

tension

OK OK

Moment

M1

Shear

Vy

13

lb

fv1

2 psi

shear1

Axial

Px

6930

lb

fv2

NA psi

shear2

NA

fc

566 psi

compression

NA

fr

NA

bending +T

OK

bending + C

NA

192 lb-in

yy-axis Moment

M2

Shear

V2

1000 lb-in 250

lb

STRESS CHECKS: STRUT Academic Version Thursday, March 13, 2014 Multiframe Advanced 64-bit 17.00.01.59

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Mz'

MOMENT SHEAR

4

6

Vy' 4

6

dy' 4

DEFLECTION

6

Wy' 4

Mz' Vy' dy' Wy' Dist

6

-0.016kip-ft -0.002kip -0.212in -0.003kip/ft 3.953ft

4

6

Max Mz' Max Vy' Max dy' Max Wy' Dist

0.016kip-ft 0.013kip 0.213in 0.003kip/ft 3.953ft

NOT FOR COMMERCIAL USE

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C

AXIAL: COMPRESSION

Px'

4

6

T

Px' Dist

6.926kip 3.953ft

4

6

NOT FOR COMMERCIAL USE

Max Px' Dist

6.930kip 3.953ft

STRESS CHECKS: TOP CHORD

TOP CHORD

L. Larsen M. Deraspe Laura Levenberg March 1, 2014

Name: GTF/Section: Date:

Member Information

Design Values

Douglas Fir - Larch, Sel. Struc.

Fb

Fb

Fb2

1,600 psi

CD

Two months

1.15 1.15

bending uniaxial + compression

Ft

950 psi

CM

MC<19%

1.00 1.00

timber

Fv

170 psi

Ct

T<100

1.00 1.00

625 psi

CL

xx

c - uniformly dist

yy

NA

1.00 1.00 RB =6

Fc Section Properties

Fc

nominal dimensions (in.)

E Emin

6 dressed dimensions 5.5 glulam timber dim.

x x

12

in

11.5

x

1,100 psi 1,600,000 psi

CF

Size

1.00 1.00

580,000 psi

Cfu

Flat Use

Ci Cr CP Ke1

Incising

1.00 1.00 0.80 0.80 1.15 1.15 x x

Allowable Stresses Fb1' 1,686 psi Fb2' 1,693 psi

in in

Ke2

Repetitive Memb.

1.00 1.00

x

x

unbraced length

axis1

60

in

Ft'

874 psi

CT

NA

in

x

x

unbraced length

axis2

96

in

Fv '

156 psi

Cb

NA

in

x

x

Fc'

625 psi

Glulam Factors CV NA

Area

63.250

in2

Sxx Ixx

121.229 697.068

in in4

Syy Iyy

57.979 159.443

in in4

3

Fc ' E' Emin'

977 psi 1,520,000 psi 551,000 psi

CC

t R

NA 400

in

1.00 1.00

in in

1.00 1.00

3

Maximum Forces xx-axis

1.05 1.06 Actual Stresses fb1

732 psi

Results bending1

fb2

NA psi

bending2

NA

ft

556 psi

tension

NA OK

OK

Moment

M1

Shear

Vy

1171

lb

fv1

28 psi

shear1

Axial

Px

35137

lb

fv2

NA psi

shear2

NA

fc

556 psi

compression

OK

fr

NA

bending +T

NA

bending + C

OK

88716 lb-in

yy-axis Moment

M2

Shear

V2

1000 lb-in 250

lb

STRESS CHECKS: TOP CHORD Academic Version Thursday, March 13, 2014 Multiframe Advanced 64-bit 17.00.01.59

MOMENT SHEAR

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Mz' 4

8

3

8

3

8

3

8

3

Vy' 4

dy'

DEFLECTION

4

Wy' 4

-5.469kip-ft -2.379kip -0.406in -0.011kip/ft 5.303ft 10

Mz' Vy' dy' Wy' Dist Member

3

Max Mz' Max Vy' Max dy' Max Wy' Dist

8 4

7.301kip-ft 2.437kip 0.409in 0.011kip/ft 5.303ft

NOT FOR COMMERCIAL USE

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MOMENT SHEAR

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Mz' 5

7

4

7

4

7

4

7

4

Vy' 5

dy'

DEFLECTION

5

Wy' 5

Mz' Vy' dy' Wy' Dist Member

-9.108kip-ft 1.693kip -0.302in -0.011kip/ft 5.303ft 4

4 7 5 NOT FOR COMMERCIAL USE

Max Mz' Max Vy' Max dy' Max Wy' Dist

9.108kip-ft 1.751kip 0.369in 0.011kip/ft 5.303ft

STRESS CHECKS: LOWER CHORD

BOTTOM CHORD

L. Larsen M. Deraspe Laura Levenberg March 1, 2014

Name: GTF/Section: Date:

Member Information

Design Values

Douglas Fir - Larch, Sel. Struc.

Fb

1,500 psi

CD

Two months

1.15 1.

bending + tension

Ft

1,000 psi

CM

MC<19%

1.00 1.

Fv

180 psi

Ct

Fc

625 psi

CL

lumber Section Properties

Fc

nominal dimensions (in.)

E Emin

4 dressed dimensions 3.5 glulam timber dim.

x x

8

in

7.25

x

1,700 psi

in

unbraced length

axis1

60

in

unbraced length

axis2

96

in in2

Area

25.375

Sxx Ixx

30.661 111.148

in3 4 in

Syy Iyy

14.802 25.904

in in4

T<100

1.00 1.

xx

c - uniformly dist

yy

NA

1.00 1. RB

CF

Size

1.00 1.

690,000 psi

Cfu

Flat Use

Ci Cr CP Ke1

Incising

1.05 1. 0.80 0. 1.15 1. x x

Ke2

Repetitive Memb.

1.00 1.00

x

x

Ft'

1,196 psi

CT

NA

in

x

x

Fv '

166 psi

Cb

NA

in

x

x

625 psi

Glulam Factors CV NA

Fc' Fc ' E' Emin'

1,457 psi 1,805,000 psi 655,500 psi

CC

t R

NA 400

in

1.00 1.

in in

1.00 1.

3

1.11 1. Actual Stresses fb1

Maximum Forces xx-axis

72 psi

Results bending1

OK

fb2

NA psi

bending2

NA

ft

943 psi

tension

OK OK

Moment

M1

Shear

Vy

46

lb

fv1

3 psi

shear1

Axial

Px

23921

lb

fv2

NA psi

shear2

NA

fc

943 psi

compression

NA

fr

NA

bending +T

OK

bending + C

NA

2196 lb-in

yy-axis Moment

M2

Shear

V2

1000 lb-in 250

lb

F

1,900,000 psi

Allowable Stresses Fb1' 1,658 psi Fb2' 1,666 psi

in

Fb

STRESS CHECKS: LOWER CHORD Academic Version Thursday, March 13, 2014 Multiframe Advanced 64-bit 17.00.01.59

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Mz'

MOMENT SHEAR

5

6

Vy' 5

6

dy' 5

DEFLECTION

6

Wy' 5

6

Mz' Vy' dy' Wy' Dist

-0.183kip-ft 0.000kip -0.211in -0.006kip/ft 7.906ft

Max Mz' Max Vy' Max dy' Max Wy' Dist

6 5

0.183kip-ft 0.046kip 0.340in 0.006kip/ft 7.906ft

NOT FOR COMMERCIAL USE

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C

Px'

5

6

AXIAL: TENSION T

Px' Dist

-24.037kip 7.906ft

5

6

NOT FOR COMMERCIAL USE

Max Px' Dist

24.053kip 7.906ft

STRESS CHECKS: KING POST Academic Version

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AXIAL: TENSION

Px'

6

3

T

Px' Dist

-20.223kip 5.000ft

3

Max Px' Dist

6

King Post

20.739kip 5.000ft

NOT FOR COMMERCIAL USE

Member Information

Design Values

Douglas Fir - Larch, Sel. Struc.

Fb

axial tension

timber Section Properties

Fc

nominal dimensions (in.)

E Emin

x x

6

in

5.5

x

in

unbraced length

axis1

120

unbraced length

axis2

120

Two months

1.15 1.1

Ft

950 psi

CM

MC<19%

1.00 1.0

Fv

170 psi

Ct

T<100

1.00 1.0

625 psi

CL

xx

c - uniformly dist

yy

NA

1.00 1.0 RB

1,100 psi 1,600,000 psi

CF

Size

1.00 1.0

580,000 psi

Cfu

Flat Use

Ci Cr CP Ke1

Incising

1.00 1.0 0.80 0.8 1.15 1.1 x x

NA

Cb

NA

Fc'

625 psi

Fc '

677 psi

Glulam Factors CV NA

Fv'

Sxx Ixx

27.729 76.255

in3 4 in

Syy Iyy

27.729 76.255

in in4

1.00

156 psi

in in2

1.00

874 psi

in

30.250

Ke2

Repetitive Memb.

CT

Ft'

Area

E' Emin'

1,520,000 psi 551,000 psi

CC

t NA R 400

0 psi

Results bending1

NA

NA psi

bending2

NA

0 lb-in

ft

686 psi

tension

OK

Shear

Vy

0

lb

fv1

0 psi

shear1

NA

Axial

Px

20739

lb

fv2

NA psi

shear2

NA

fc

686 psi

compression

NA

fr

NA

bending +T

NA

bending + C

NA

Shear

V2

1000 lb-in 250

lb

x

x

x

1.00 1.0

M1

M2

x

in in

Moment

Moment

in in

1.00 1.0

fb2

yy-axis

x

1.05 1.0 Actual Stresses fb1

xx-axis

x

in

3

Maximum Forces

Fb2

CD

Allowable Stresses Fb1' 1,688 psi Fb2' 1,693 psi

in

Fb

1,600 psi

Fc

6 dressed dimensions 5.5 glulam timber dim.

L. Larsen M. Deraspe Laura Levenberg March 1, 2014

Name: GTF/Section: Date:

CONNECTION ANALYSIS THAR AIN’T NO JOINTERY WITH OUT JOINTS!

APPROACHES TO JOINERY

Steel dowles sized for efficient axial capacity

steel strap woven into a decorative bearing plate

Structural Doug Fir notched to locate assembly

The bottom chord is joined to the top chord at the heal of the truss with a steel spline plate. The concealed detail leaves a 1/2â&#x20AC;? reveal proud ot the joining members.

To generate the required axial bearing capacity a network of steel straps are forged into a woven pattern. At critical bearing locations the straps overlay one another and provide a double thickness plate. This strategy allows for a high load to support the king post with only two large dowels. Welds laid in the gap on the backside of the overlaped seam provide ridgidity to the strap network.

KING JOINT CAPACITY

Name:

Laura Levenberg 3.15.14

GTF/Section:

Bottom Chord At king post

Date:

Connection Information

Adjustment Factors 2 6 3

# of Shear Planes # of Fasteners (N) # of Fasteners in a Row

Dowel Information Dowel Diameter (D)

3/4

Dowel Bending Yield Strength (Fyb) Actual End Distance Ctr to Ctr

L. Larsen M. Deraspe

Diameters Inches

Member Information Main Member Side Member Douglas Fir - Larch, Sel. Struc Steel G 0.5 G ? degrees 0 deg ? degrees

in

CD CM

1.15 1.00

Two Months

Ct Cg

1.00 0.99

<=100

C?

0.98

Tension

<=19

any

Softwood

45,000

psi

5.13 4.0

in D

Min. End Dist. (CD)

req. distance (in) edge*

end

req. spacing (in) fasteners

rows

3.000

in

0.50

1.125

2.625

2.250

1.125

1.00

1.125

5.250

3.000

1.125

N*Z'

7.85 0

deg

Cd Ceg Cst Cdi Ctn

NA 1.00

No

NA NA

gray do not

0.00

0.00

Fe Fe para Fe perp

4,650 5,600 2,600

psi

87,000 87,000 87,000

psi

psi

Fe Fe para Fe perp

Fem

5,600

psi

Fes

87,000

psi

Z

Z'

3.50

in

ts

0.38

in

Im

3,675

4,072 24,432

lbs

Em

1,900,000

psi

Es

29,000,000

psi

Is

12,234

13,556 81,336

lbs

Am

25.38

2

As

1.50

2

II

1,794

1,988 11,927

lbs

Am /As

16.92

As /Am

0.06

IIIm

2,244

2,486 14,915

lbs

k1 k2

0.26 0.55

IIIs IV

3,716 4,417

4,117 24,703 4,894 29,364

lbs

0.06 9.33 1.00 FALSE

k3

7.79 4,072 24,432

lbs

tm

Re Rt K? KD

psi

in

2 steel straps each 2.5" wide by 3/8" thick per side Each strap accepts a row of bolts (.375")(5") = 1.5in^2 4 straps altogether make for 2 shear planes

NA 1.11

psi

Yield Limit Eq.'s

psi

in

critical

lbs

P = 23,921 lbs

Joint Utilization

98%

KING JOINT CAPCITY

Name: Date:

Connection Information

2 3 3

# of Shear Planes # of Fasteners (N) # of Fasteners in a Row

Dowel Information Dowel Diameter (D)

5/8

Dowel Bending Yield Strength (F yb) ctr to ctr fastener spacing

Laura Levenberg 3.15.14

GTF/Section:

STRUT At king post

Actual End Distance

L. Larsen M. Deraspe

Diameters Inches

Member Information Main Member Side Member Douglas Fir - Larch, Sel. Struc Steel G 0.5 G ? degrees 0 deg ? degrees

in

1.15 1.00

Two Months

Ct Cg

1.00

<=100

C?

1.00

<=19

any

0.97 Tension

Softwood

45,000

psi

5.00 4.0

in D

Min. End Dist. (CD)

req. distance (in) edge*

end

req. spacing (in) fasteners

rows

2.500

in

0.50

0.938

2.188

1.875

0.938

1.00

0.938

4.375

2.500

0.938

Z'

N*Z'

7.85 0

deg

Cd Ceg Cst Cdi Ctn

0.00

0.00

Fe Fe para Fe perp

4,650 5,600 2,800

psi

87,000 87,000 87,000

psi

psi

Fe Fe para Fe perp

Fem

5,600

psi

Fes

87,000

psi

psi

CD CM

NA 1.00

No

NA NA

gray do not

NA 1.11

psi

Yield Limit Eq.'s

psi

Z

3.50

in

ts

0.38

in

Im

3,063

3,412 10,237

lbs

Em

1,900,000

psi

Es

29,000,000

psi

Is

10,195

11,360 34,079

lbs

Am

12.25

in2

As

1.50

in2

II

1,495

1,666

4,997

lbs

As/Am

0.12

IIIm

1,776

1,979

5,937

lbs

IIIs IV

2,776 3,067

3,093 9,280 3,418 10,253

lbs

3,093

lbs

tm

Am/As Re Rt K? KD

8.17 0.06 9.33

k1 k2

0.26 0.52

1.00 FALSE

k3

6.99

2 steel straps each 2.5" wide by 3/8" thick per side Each strap accepts a row of bolts (.375")(5") = 1.5in^2 4 straps altogether make for 2 shear planes

critical

9,280

lbs

P = 6,930 lbs

Joint Utilization

75%

the bolt diameters are reduced due to lower loads The end distances could be reduced but they are left the same to match the lower chord

KING JOINT CAPACITY

Name:

L. Larsen M. Deraspe Laura Levenberg 3.15.14

GTF/Section:

KINGPOST At bottom chord

Date:

Connection Information

2 2 2

# of Shear Planes # of Fasteners (N) # of Fasteners in a Row

Dowel Information

CD CM

1.15 1.00

Two Months

Ct Cg

1.00

<=100

C?

1.25

<=19

any

0.94 Tension

Softwood

Dowel Diameter (D)

1

Dowel Bending Yield Strength (F yb)

45,000

psi

Diameters

24.00 5.0

in D

Min. End Dist. (CD)

req. distance (in) edge*

end

req. spacing (in) fasteners

rows

Inches

5.000

in

0.50

1.500

3.500

3.000

1.500

1.00

1.500

7.000

4.000

1.500

Z'

N*Z'

Actual End Distance ctr to ctr fastener spacing

Member Information Main Member Side Member Douglas Fir - Larch, Sel. Struc Steel G 0.5 G ? degrees 0 deg ? degrees

in

7.85 0

deg

Cd Ceg Cst Cdi Ctn

NA 1.00

No

NA NA

gray do not

0.00

0.00

Fe Fe para Fe perp

4,650 5,600 2,250

psi

87,000 87,000 87,000

psi

psi

Fe Fe para Fe perp

Fem

5,600

psi

Fes

87,000

psi

5.50

in

ts

0.75

in

Im

7,700

10,458 20,916

lbs

Em

1,900,000

psi

Es

29,000,000

psi

Is

32,625

44,312 88,623

lbs

Am

30.25

in2

As

3.75

in2

II

3,983

5,410 10,821

lbs

IIIm

4,485

6,092 12,184

lbs

IIIs IV

7,962 7,852

10,814 21,629 10,665 21,330

lbs

10,458 20,916

lbs

tm

psi

Am/As

8.07

As/Am

0.12

Re Rt K?

0.06 7.33

k1 k2

0.22 0.53

1.00 FALSE

k3

6.26

KD

2 steel straps each 2.5" wide by 3/8" thick per side The straps overlay at the doweling point to effectively double their thickness The back seam of the forged detail can be welded for rigidity and unified capacity (.75")(5") = 3.75in^2

NA 1.36

psi

Yield Limit Eq.'s

psi

Z

Critical

lbs

P = 20,739 lbs

Joint Utilization

99%

Two massive dowels lock the assembly together The center to center distance drives the curved form of the woven strap assembly Larger dowel spacing will increase the joint's capacity

HEEL JOINT CAPACITY

Name: Date:

Connection Information

2 6 2

# of Shear Planes # of Fasteners (N) # of Fasteners in a Row

Dowel Information Dowel Diameter (D)

3/4

Dowel Bending Yield Strength (F yb) ctr to ctr fastener spacing

Laura Levenberg 3.15.14

GTF/Section:

TOP CHORD At bottom chord

Actual End Distance

L. Larsen M. Deraspe

Diameters Inches

in

CD CM

1.15 1.00

Two Months

Ct Cg

1.00

<=100

C?

1.05

<=19

any

0.97 Compressio

Softwood

45,000

psi

5.50 5.0

in D

Min. End Dist. (CD)

req. distance (in) edge*

end

req. spacing (in) fasteners

rows

3.750

in

0.50

1.125

2.625

2.250

1.125

1.00

1.125

5.250

3.000

1.125

Z'

N*Z'

Member Information Main Member Side Member steel Douglas Fir - Larch, Sel. Struc. G 7.85 G 0.5 ? degrees 26.5 deg ? degrees 0 deg

Cd Ceg Cst Cdi Ctn

NA 1.00

No

NA NA

gray do not

0.46

0.00

Fe Fe para Fe perp Fem

87,000 87,000 87,000 87,000

psi

Fe Fe para Fe perp Fes

4,650 5,600 2,600 5,600

psi

0.25

in

ts

2.63

in

Im

3,799

4,451 26,707

lbs

Em

29,000,000

psi

Es

1,900,000

psi

Is

5,135

6,017 36,101

lbs

Am

2.50

2

As

30.25

2

II

1,229

1,440

lbs

Am/As

0.08

As/Am

12.10

IIIm

1,557

1,824 10,946

lbs

IIIs IV

3,522 4,114

4,127 24,762 4,821 28,926

lbs

4,127 24,762

lbs

tm

Re Rt K? KD

psi psi psi

in

15.54 0.10

k1 k2

0.43 10.52

1.07 FALSE

k3

0.62

A 1/4" steel spline plate connects members The plate is 10" long to be able to accept 4 rows of bolts (.25")(10") = 2.5in^2 Side members are adjusted for the removed material

psi

Yield Limit Eq.'s Z

psi psi

in

NA 1.17

Critical

8,638

lbs

p = 23,921 lbs

Joint Utilization

97%

The bolts need to be located beyond the member midpoint because the force has a component perpendicular to the grain which needs to be resolved as an internal bearing compression as opposed to as perpendicular tension at the edge of the member which is extremely weak and prohibited by code

HEEL JOINT CAPACITY

Name: Date:

Connection Information

2 6 3

# of Shear Planes # of Fasteners (N) # of Fasteners in a Row

Dowel Information Dowel Diameter (D)

3/4

Dowel Bending Yield Strength (F yb) Actual End Distance

Laura Levenberg 3.15.14

GTF/Section:

Bottom Chord At Top Chord

ctr to ctr fastener spacing

L. Larsen M. Deraspe

Diameters Inches

in

CD CM

1.15 1.00

Two Months

Ct Cg

1.00

<=100

C?

0.90

<=19

any

0.98 Tension

Softwood

45,000

psi

4.75 4.0

in D

Min. End Dist. (CD)

req. distance (in) edge*

end

req. spacing (in) fasteners

rows

3.000

in

0.50

1.125

2.625

2.250

1.125

1.00

1.125

5.250

3.000

1.125

Z'

N*Z'

Member Information Main Member Side Member steel Douglas Fir - Larch, Sel. Struc. G 7.85 G 0.5 ? degrees 0 deg ? degrees 0 deg

Cd Ceg Cst Cdi Ctn

NA 1.00

No

NA NA

gray do not

0.00

0.00

Fe Fe para Fe perp Fem

87,000 87,000 87,000 87,000

psi

Fe Fe para Fe perp Fes

4,650 5,600 2,600 5,600

psi

0.25

in

ts

3.25

in

Im

4,078

4,170 25,021

lbs

Em

29,000,000

psi

Es

1,900,000

psi

Is

6,825

6,979 41,875

lbs

Am

2.50

2

As

25.38

2

II

1,592

1,628

lbs

Am/As

0.10

As/Am

10.15

IIIm

1,671

1,709 10,255

lbs

IIIs IV

4,274 4,417

4,371 26,224 4,517 27,100

lbs

4,170 25,021

lbs

tm

Re Rt K? KD

psi psi psi

in

15.54 0.08

k1 k2

0.42 10.52

1.00 FALSE

k3

0.57

psi

Yield Limit Eq.'s Z

psi psi

in

NA 1.02

9,767

A 1/4" steel spline plate connects members

Critical

The plate is 10" long to be able to accept 4 rows of bolts

Joint Utilization

(.25")(10") = 2.5in^2 Side members are adjusted for the removed material

lbs

p = 23,921 lbs 96%

The end distance is a driving variable which can be dialed in to establish a high utilization

Structural Design (Timber Frame Truss System)

Structural analysis of a simple scissor truss system. Graduate source work Winter 2014.