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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DESIGN ITERATIONS Academic Version Sunday, March 16, 2014 Multiframe Advanced 64-bit 17.00.01.59
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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
Academic Version
All members are 2” x 6” Load = 0.4 kip/ft Moment = 5.253 kip ft Deflection = 6.262 inch
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All loads
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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
All loads
NOT Academic FOR COMMERCIAL Version USE
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NOT FOR COMMERCIAL USE
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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SHEAR
x
21.071
21.071
NOT FOR COMMERCIAL USE
MOMENT
y x
21.071
21.071
MEMBER FORCES: OVERVIEW
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y
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LOAD
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x
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
Academic Version
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
Adjustment Factors
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
Adjustment Factors
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
Adjustment Factors
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
Adjustment Factors
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
? radians
0.00
rad
? radians
0.00
rad
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
Adjustment Factors
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
? radians
0.00
rad
? radians
0.00
rad
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
Adjustment Factors
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
? radians
0.00
rad
? radians
0.00
rad
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
Adjustment Factors
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
? radians
0.46
rad
? radians
0.00
rad
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
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 (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
? radians
0.00
rad
? radians
0.00
rad
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