archive.floridadisaster.orgarchive.floridadisaster.org/mitigation/rcmp/wind loss/condolr5...appendix...

APPENDIX B:

EXAMPLE DESIGN CALCULATIONS BY FBC, SBC 88, AND SBC 76

APPENDIX B: EXAMPLE DESIGN CALCULATIONS BY ASCE 7-98, SBC 88, AND SBC 76

This appendix contains one sample set of design calculations of the analysis completed in Section 4 of this report. This sample is for a Group I building designed according to Florida Building Code Section 1606 (based on ASCE 7-98), Standard Building Code 1988, and Standard Building Code 1976.

The dimensions of the building, and other key parameters such as truss spacing are defined on page B-3 under the section called “Geometry of Building”. A sample of the sizes of the windows, and doors are defined on page B-9. Once the configuration of the building is established, these calculations compute the design parameters for the following:

• Roof deck nailing,

• Fenestration design pressures,

• Roof-wall connection design,

The input parameters are the design wind speed and terrain exposure, and the internal pressure condition (Enclosed vs. Partially Enclosed), as appropriate. Note that SBC 76 and SBC 88 do not have an exposure variable.

This particular sample design has been prepared for 130 mph gust design wind speed in Terrain Exposure C for an Enclosed Building condition under FBC and 110 mph fastest mile wind speed under SBC. Recall that 110 mph fastest mile wind speed is equivalent to about 130 mph gust wind speed.

This set of calculations was repeated for each of the FBC/SBC combinations of wind speed, terrain exposure, and internal pressure condition listed in Table 2-1 for each

of the modeled buildings. The results of these calculations are summarized in Appendix A of this report.

One may note that the nailing patterns for wood decks on Group I buildings appear to be slightly weaker than those reported in the single family report, even though the wind loads are higher for two story than single story structures. This design calculation is based on a higher wood density, which is more common on commercial and large-scale residential projects. This higher wood density yields a higher nail pullout strength and thus the Group I designs reported here will use slightly fewer nails.

Version 1.3 – August 2002

B-2

FBC

W 38ft 2 o⋅+:= dimensions of buildingIntPressure in0 2⟨ ⟩:= IntPressure 0= L 192ft 2 o⋅+:=

∆ 24 in⋅:= Truss spacingCase 1:= Case 1 = C&C and

MWFRS for low rise bldgsRoof cover: Shingle

hwall 9 ft⋅:= Height of Wall, single story

Dead load of roof

DLroof 9 psf⋅:= Hip roof, shingle, trusses, underlayment (from SBC Appendix A)

DLsheath 0.5 in⋅( )0.4psf.125 in⋅

⋅:= DLsheath 1.6 psf=

Dead load of roof is composed of following: Truss/Sheathing (7 psf), Tile (10psf). If shingles are used, use 2 psf instead of 10 psf.

Lattic 30 psf⋅:= SBC Table 1604.1 φ 0.6:= Fraction of DeadLoad used in combination with Wind Load

Lfloor 40 psf⋅:=

Lroof 16 psf⋅:=

Miscellaneous: Contents, carpet, cabinets, fixtures)Wood Frame wall weight

Masonry Wall WeightDLmisc 15 psf⋅:=DLwall

10

55

psf⋅:=

ASCE7-98 (FBC) Loads on single story building with flat roof slope (less than 10 degrees)

Variables for Exposure

Variables for Enclosed/Part Encl.Input Parameters

in0 130 C Enclosed( ):= Enclosed 0≡

PartEnclosed 1≡Define design parameters

A

B

C

D

0

1

2

3

≡

Geometry of Building: Building Name: 0023 - Condo projectDesign Parameters

h22.18 22.18+

2

ft⋅:= ht of building h 22.18 ft=

V in0 0⟨ ⟩ mph⋅:= V 130mph=

I 1.0:= Importance for Class II Building θ atan012

:= θ 0deg= roof slope

Exp in0 1⟨ ⟩:= Exp 2= o 0.0 ft⋅:= overhang widthog 0 ft⋅:=

B-3Version 1.3 - Aug 2002

FBC

Dummy value in Case Int Pressure is invalid

posneg 0 1..:=GCpi0.18−

0.18

=GCpi0.18−

0.18

IntPressure Enclosed=if

0.55−

0.55

IntPressure PartEnclosed=if

20−

20

otherwise

:=

internal pressure range variable

Internal Pressure coefficient

Dynamic Wind Pressureqh 33.9 psf=qh .00256slug

2.15111ft3Kz h( )⋅ Kzt⋅ Kd⋅ V2⋅ I⋅:=

Directionality factor (0.85 used when doing combination loads - with dead load)Kd 0.85:=

No topographic speedupKzt 1.0:=

Kz h( ) 0.92=

hminExp15 ft=

Kz h( ) 2.0115 ft⋅zgExp

2

α Exp⋅ h 15 ft⋅<( )if

2.01hminExp

zgExp

2

α Exp

⋅ h hminExp≤( )if

2.01h

zgExp

2

α Exp⋅ otherwise

:=hmin

100

30

15

15

ft⋅ Case 1=if

15

15

15

15

ft⋅ otherwise

:=

hmin

60

30

15

7

ft⋅:=α

5.0

7.0

9.5

11.5

:=zg

1500 ft⋅

1200 ft⋅

900 ft⋅

700 ft⋅

:=Exposures = A,B,C,D

Terrain Exposure Constants

Dynamic Wind Pressure


FBC

Gust Factor (Eqn 6-2)G 0.88=G 0.9251 1.7 gQ⋅ Iz⋅ Q⋅+

1 1.7 gv⋅ Iz⋅+

⋅:=

gv 3.4:=gQ 3.4:=

Q 0.92=Background Response (Eqn 6-4)Q

1

1 0.63W h+

Lz

0.63⋅+

:=

Integral Length Scale of Turbulence (Eqn 6-5)

Lz 427.06 ft=Lz lExpze

33 ft⋅

εExp

⋅:=

Turbulence Intensity (eqn 6-3)Iz 0.23=Iz cExp33 ft⋅

ze

1

6⋅:=

Equivalent height of structureze 15 ft=ze max ze( ):=ze0.6 h⋅

zminExp

:=

zmin

60

30

15

7

ft⋅:=c

0.45

0.3

0.2

0.15

:=ε

12

13

15

18

:=l

180

320

500

650

ft⋅:=

Terrain Exposure Constants from Table 6-4

Gust Factor:


FBC

Zone 3, ohang

Zone 2, ohangZone 3, overhang

Zone 1 , ohangZone 2, overhang Zone 5

Zone 4Alim_10deg

0

10 100 1000( )

10 100 1000( )

10 100 1000( )

10 500 1000( )

10 500 1000( )

10 100 500( )

10 100 500( )

10 100 1000( )

ft2⋅:=Zone 1 , overhangZone 3

Zone 2Zone 5

Zone 1 GCp_10deg

0

1−

0.3

0.9−

0.2

0.9−

0.2

1.8−

0.3

1.1−

0.2

1.1−

0.2

2.8−

0.3

1.1−

0.2

1.1−

0.2

0.91.1−

1

0.8−

0.7

0.8−

0.7

⋅

0.91.4−

1

0.8−

0.7

0.8−

0.7

⋅

1.7−

0

1.6−

0

1.1−

0

1.7−

0

1.6−

0

1.1−

0

2.8−

0

0.8−

0

0.8−

0

:=wall coefficients, ASCE7-98 Fig 6-5A

Zone 4

Zone 3

Zone 2

roof coefficients ASCE7-98: Figure 6-5B

Zone 1

Alim is the x axis values of the change in slope of the GCP graphs in Fig 6-5 and 6-4

If slope is less than 10 degrees:

10SF neg 100SF neg, 1000SF neg10SF pos 100SF pos, 1000 SF pos

Limits of External Pressure Coefficients for each Zone in C&C loads( first row neg coefficients, second row positive coefficents)

External Pressure Coefficients: Figure 6-5B


FBC

Zone 3, overhang

Zone 2, overhang

Zone 1 , overhang - assumed same as Zone 1 no overhang

Zone 5

GCp_45deg

0

1.0−

0.9

0.8−

0.8

0.8−

0.8

1.2−

0.9

1.0−

0.8

1.0−

0.8

1.2−

0.9

1.0−

0.8

1.0−

0.8

1.1−

1

0.8−

0.7

0.8−

0.7

1.4−

1

0.8−

0.7

0.8−

0.7

1.0−

0.9

0.8−

0.8

0.8−

0.8

2.0−

0

1.8−

0

1.8−

0

2.0−

0

1.8−

0

1.8−

0


Zone 4

Zone 3Alim_45deg

0

10 100 1000( )

10 100 1000( )

10 100 1000( )

10 500 1000( )

10 500 1000( )

10 100 1000( )

10 100 1000( )

10 100 1000( )

ft2⋅:=

Zone 2


Zone 1

If slope is 30 to 45 degrees:

Zone 3, overhang

Zone 2, overhang

Zone 1 , overhang - assumed same as Zone 1 no overhang

Zone 5

GCp_30deg

0

0.9−

0.5

0.8−

0.3

0.8−

0.3

2.1−

0.5

1.4−

0.3

1.4−

0.3

2.1−

0.5

1.4−

0.3

1.4−

0.3

1.1−

1

0.8−

0.7

0.8−

0.7

1.4−

1

0.8−

0.7

0.8−

0.7

0.9−

0.5

0.8−

0.3

0.8−

0.3

2.2−

0

2.2−

0

2.2−

0

3.7−

0

2.5−

0

2.5−

0


Zone 4

Zone 3Alim_30deg

0

10 100 1000( )

10 100 1000( )

10 100 1000( )

10 500 1000( )

10 500 1000( )

10 100 1000( )

10 100 1000( )

10 100 1000( )

ft2⋅:=

Zone 2


Zone 1



FBC

Select appropriate set of parameters according to slope of roof:θ 0deg=

GCp GCp_10deg θ 10 deg⋅≤( )if

GCp_30deg 10 deg⋅ θ< 30 deg⋅≤if


0 otherwise

:= Alim Alim_10deg θ 10 deg⋅≤( )if

Alim_30deg 10 deg⋅ θ< 30 deg⋅≤if


0 otherwise

:=

Calculate slopes of parts of pressure coefficient graphs for interpolation:

slopeGCp Zone( )GCpZone( ) 1⟨ ⟩ GCpZone( ) 0⟨ ⟩−

logAlimZone( ) 1⟨ ⟩

ft2


ft2

−

:=

Slope of first section of line

slope of secondary section of line (usually flat)slopeGCp2 Zone( )

GCpZone( ) 2⟨ ⟩ GCpZone( ) 1⟨ ⟩−


ft2


ft2

−

:=

GCp Area Zone,( ) GCpZone( ) 0⟨ ⟩ Area AlimZone( ) 0⟨ ⟩<if

slopeGCp Zone( )( ) logArea

ft2


ft2

−+

...

⋅

GCpZone( ) 0⟨ ⟩+

...

AlimZone( ) 0⟨ ⟩ Area≤ AlimZone( ) 1⟨ ⟩<if

slopeGCp2 Zone( )( ) logArea

ft2


ft2

−+

...

⋅


...


GCpZone( ) 2⟨ ⟩ otherwise

:=

For Example:

GCp 11 ft2⋅ 4,( ) 0.98−

0.89

= GCp 10 ft2⋅ 5,( ) 1.26−

0.9

= GCp 50 ft2⋅ 1,( ) 0.93−

0.23

=


FBC

DP 4⟨ ⟩ 38.87−

35.82

psf=for example window : Design pressures are:

DP0 1 2 3 4 5 6 7 8 9

01

-38.87 -38.87 -38.04 -38.04 -38.87 -38.04 -38.87 -38.04 -38.87 -38.8735.82 35.82 34.99 34.99 35.82 34.99 35.82 34.99 35.82 35.82

psf=

Effective Area of fenestrations are set according to the area of the element resisting the load, as opposed to the area of the entire fenestration. For example, a sliding glass door is made of 3 doors spanning vertically, each door is 4x8. The doors do not transfer wind load horizontally, therefore the wind loads are correlated only over the single door, and thus instead of an effective area of 96 square feet, the effective area is 32 square feet.

DP j⟨ ⟩ qh GCp Fen Size⟨ ⟩( )j 1+ ft2⋅

→

Fen Zone⟨ ⟩( )j 1+

→ ,

GCpi+

⋅ Fen Zone⟨ ⟩( )

j 1+ 45≠if

qh GCp Fen Size⟨ ⟩( )j 1+ ft2⋅

→

5,

GCpi+

⋅ Fen Fraction⟨ ⟩( )

j 1+⋅

qh GCp Fen Size⟨ ⟩( )j 1+ ft2⋅

→

4,

GCpi+

⋅ 1 Fen Fraction⟨ ⟩( )

j 1+−

⋅+

...

otherwise

:=

j 0 rows Fen( ) 2−..:=

Fen

0 1 2 3 40123456789101112131415

0 0 0 0 00 1 1 14 40 2 2 14 40 3 3 20 40 4 4 20 40 5 5 14 40 6 6 20 40 7 7 14 40 8 8 20 40 9 9 14 40 10 10 14 40 11 11 20 40 12 12 20 40 13 13 14 40 14 14 20 40 15 15 14 4

=

rows Fen( ) 196=

Number of windows/doors

Zone 4:=Fen

D:\..\fen dp.xls

:= Size 3:=

Dummy Width and Height

The following input table was imported from an excel sheet that had a list of fens for this building. Each column represents the width, height, area, and zone of each fen respectively.

Window Design Pressure


FBC

GCp Area 3,( )1.94−

0.25

=

ppanel qh GCp Area 2,( ) GCpi+( )⋅:= ppanel55.13−

14.56

psf=

Resistance of single 8d Nail Load Case : Wind + 60% of dead load

qr 41lbfin

⋅:= 8d common nail, NDS 1997, page 30, diameter 0.131", specific Gravity 0.55 (Southern Pine)

lnail 2.5in:= length of nail, 8d

t .5 in⋅:= Plywood thickness = 1/2" (min thickness of code) Southern Pine SG - 0.55 on page 29, Table 12A of NDS-S97

lp lnail t−:= lp 2 in= penetration length

CD 1.6:= Duration factor for short term loads - wind = 10 minutes

Cm 1.0:= Condition Factor = assume that wood moisture content at time of construction is same as long term value

Rnail qr lp⋅ CD⋅ Cm⋅:= Rnail 131.2 lbf=

Design of Nailing Pattern for Roof DeckTributary area for single fastener: Area 10 ft2⋅:=

Zone1 Zone 2 Zone 3

GCp Area 1,( )1−

0.3

= GCp Area 2,( )1.8−

0.3

= GCp Area 3,( )2.8−

0.3

=

Design load: Zone2

psingle qh GCp Area 2,( ) GCpi+( )⋅:= psingle67.12−

16.27

psf=

Tributary area for single sheet of plywood fastener: Area 32 ft2⋅:=

One 4x8ft sheet of plywood/OSB = 32 FT tributary area

Zone1 Zone 2 Zone 3

GCp Area 1,( )0.95−

0.25

= GCp Area 2,( )1.45−

0.25

=


FBC

PASS = 1, FAIL = 0StatusRoofNail 1=StatusRoofNail Rtotal Lpanel>:=

Rtotal 4723.2 lbf=Rtotal Rnail Nnails⋅:=

upliftLpanel 1733.42 lbf=Lpanel ppanel00.6 DLsheath⋅+( ) 32⋅ ft2:=

Check whole panel resistance

Nnails 36=Nnails 248inse

1+

⋅ 348in

si1+

⋅+:=

interior spacingsi 9.6 in=edge spacingse 6in:=

USE the following spacing:

si spossibleIIs:= NailSched

4.36 124.8 11

5.33 106 9

6.86 88 7

9.6 612 516 424 348 2

=IIs floor linterp spossible II, At,( )( ):=

lookup nailing pattern to meet Zone2/3

ceil linterp spossible Npossible, At,( )( ) 6=

practical number of nails that meets nailing spacing criteria listed above (Zone 2/3)

spacing, nailsSelect nailing pattern that meets max spacing criteria

maximum required spacing of fastenersAt 11.9 in=AtRnail

psingle00.6 DLsheath⋅+ 2⋅ ft⋅( )

:=

Maximum Spacing for 8d nail:


FBC

Aeff

W ∆⋅

WW3

⋅

:= Aeff

76

481.33

ft2= Aeff max Aeff( ):= GCp Aeff 1,( ) 0.9−

0.2

=

Aeff 481.33 ft2= GCp Aeff 2,( ) 1.1−

0.2

=

k 1 3..:= pk GCp Aeff k,( )0 GCpi0+( ) qh⋅:=

GCp Aeff 3,( ) 1.1−

0.2

=

V 130mph=p

0

36.61−

43.39−

43.39−

psf= Design Pressures for Zones 1, 2, and 3Exp 2=

Overhang pressures, Zone 2

po GCp Aeff 7,( )0( ) qh⋅:= GCp Aeff 7,( ) 1.11−

0

= po 37.69− psf=

ROOF STRAPS DESIGN (Uplift): Design of Typical Truss at Center of Building

The ARA roof-strap model simulates failure of the entire roof assembly as a whole, and not any one specific truss connection. Therefore, strap size in model should be based on strap representative of the majority of the connections, and therefore is based on section at middle of structure.

We have considered the C&C loads that are acting on a single truss in the middle of the roof.

Edge zone

LeastHorDim min W L,( ):= LeastHorDim 38 ft=

a0.1 LeastHorDim⋅

0.4 h⋅

:= a3.8

8.87

ft= a min a( ):= a max

a

0.04 LeastHorDim⋅

3 ft⋅

:= a 3.8 ft=

lrW

2 cos θ( )⋅:= lr 19 ft= length of top chord of truss

aθa

cos θ( ):= length of edge zones along roof slope - assume that "a" in ASCE7 figures are widths in plan.

Method 1: Center Roof Truss Design based on Components and Cladding loads from ASCE 7-98

Effective wind area of a truss equals maximum of actual area and span times 1/3 span length External Gust Factors


FBC

P2

Pa* Pb*

Pc*

P1 P1

θ

R1 R2

WIND

wo o

PoPo

WIND Perpendicular to Ridge: Loading pattern according to ASCE 7-98 guide by K. Metha

Set pa and Pc equal to p1, because ASCE7-98 guidebook indicates that truss loads should follow patterns where Zone2 is not applied simultaneously to all locations according to wind tunnel tests.

Pattern is slightly different for low slope roofs

pa p1 θ 10 deg⋅<if

p1 otherwise

:=

pb p1 θ 10 deg⋅<if

p2 otherwise

:=

θ 0deg=pc p1:=

Sum Moments: about R2 reaction point

R11

W 2 o⋅−po

ocos θ( )⋅ ∆⋅ cos θ( )⋅ W o−

o2

−

⋅

p2 aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅ W o−a o−

2− o−

⋅+

...

pb aθ⋅ ∆⋅ cos θ( )⋅W2

o−aθ

2cos θ( )⋅−

⋅+

...

pa aθ⋅ ∆⋅ cos θ( )⋅ W o− lraθ

2−

cos θ( )⋅−

⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅12

aθo

cos θ( )−

cos θ( )⋅

⋅

+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ cos θ( )⋅ W o−lr2

cos θ( )⋅−

W2

o−lr2

cos θ( )⋅−

+

⋅

+

...

po−o

cos θ( )⋅ ∆⋅ cos θ( )⋅o2

⋅+

...

poo

cos θ( )⋅ ∆⋅ sin θ( )⋅o

2 cos θ( )⋅sin θ( )⋅

⋅

−+

...

p2 aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅

−+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅

−+

...

pa aθ⋅ ∆⋅ sin θ( )⋅ lraθ

2−

⋅ sin θ( )

−+

...

poo

cos θ( )⋅ ∆⋅ sin θ( )⋅o


⋅+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅+

...

pb aθ⋅ ∆⋅ sin θ( )⋅ lraθ

2−

⋅ sin θ( )⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅+

...

φ DLroof⋅ ∆⋅ W⋅W2

o−

⋅+

...

⋅:=

Dead load factor, ASD

φ 0.6=

R1 1234.86− lbf=


FBC

Sum Forces in Vertical

R2 2 poo

cos θ( )⋅ cos θ( )⋅ ∆⋅

⋅

p2 aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅

+

...

pb aθ⋅ cos θ( )⋅ ∆⋅( )+

...

2 p1⋅ lr 2 aθ⋅−( )⋅ cos θ( )⋅ ∆⋅+...

pa aθ⋅ cos θ( )⋅ ∆⋅+

...

pc aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅+

...

φ DLroof⋅ ∆ W⋅( )⋅+

R1−:=

R2 1188.49− lbf=

P1 P1

θR1 R2

wo o

WIND Parallel to Ridge

R3∆

W 2 o⋅−p1 lr⋅ cos θ( )⋅ W o−

lr2

cos θ( )⋅−

lr2

cos θ( )⋅ o−

+

⋅

φ DLroof⋅ W⋅W2

o−

⋅+

...

⋅:=

R4 2 p1⋅ lr⋅ ∆⋅ cos θ( )⋅ R3− φ DLroof⋅ ∆⋅ W⋅+:=

R3 1185.92− lbf=

R4 1185.92− lbf=

Wind perpendicular to ridge, applied at all edge zones simultaneously (note that this is an unrealistic condition, but is one that may be checked by a designer).

P2

Pa* Pb*

Pc*

P1 P1

θ

R1 R2

WIND

wo o

PoPo

If slope less than 10 degrees, pa and pb do not exist

pa p1 θ 10 deg⋅<if

p2 otherwise

:=

pb p1 θ 10 deg⋅<if

p2 otherwise

:=

pc p2 θ 10 deg⋅<if

p2 otherwise

:=


FBC

R11

W 2 o⋅−po

ocos θ( )⋅ ∆⋅ cos θ( )⋅ W o−

o2

−

⋅

p2 aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅ W o−a o−

2− o−

⋅+

...


o−aθ

2cos θ( )⋅−

⋅+

...


2−

cos θ( )⋅−

⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅12

aθo

cos θ( )−

cos θ( )⋅

⋅

+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ cos θ( )⋅ W o−lr2

cos θ( )⋅−

W2

o−lr2

cos θ( )⋅−

+

⋅

+

...

po−o

cos θ( )⋅ ∆⋅ cos θ( )⋅o2

⋅+

...

poo

cos θ( )⋅ ∆⋅ sin θ( )⋅o


⋅

−+

...

p2 aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅

−+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅

−+

...


2−

⋅ sin θ( )

−+

...

poo

cos θ( )⋅ ∆⋅ sin θ( )⋅o


⋅+

...

p1 lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅+

...


2−

⋅ sin θ( )⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅+

...


o−

⋅+

...

⋅:=

p2 43.39− psf=

p1 36.61− psf=

po 37.69− psf=

pa 36.61− psf=

pb 36.61− psf=

pc 43.39− psf=

aθ 3.8 ft=

W 38 ft=

lr 19 ft=

∆ 2ft=

R1 1237.44− lbf=

R2 2 poo

cos θ( )⋅ cos θ( )⋅ ∆⋅

⋅

p2 aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅

+

...

pb aθ⋅ cos θ( )⋅ ∆⋅( )+

...

2 p1⋅ lr 2 aθ⋅−( )⋅ cos θ( )⋅ ∆⋅+...

pa aθ⋅ cos θ( )⋅ ∆⋅( )+

...

pc aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅+

...


R1−:=

R2 1237.44− lbf=


FBC

RU2774.96−

277.5−

lbf=

Shear on Roof-Wall Connectors

Lateral shear loads on connectors are assumed to be adequate.

SUMMARY:Design Parameters: V 130mph= IntPressure 0= Exp 2=

Nail Spacing:se 6 in= edge of plywood si 9.6 in= interior of plywood

Straps: C&C loads Rdesign 1237.44− lbf= RU2774.96−

277.5−

lbf=

Window Design Pressure: max DP( ) 36.61 psf= min DP( ) 39.66− psf=

The theorectically correct loading pattern produces maximum uplifts that are only ~6-7% lower than the full pattern loading. Therefore, since ASCE7 doesn't clearly indicate the which pattern loading is appropriate, and since the difference is relatively minor, then default to full pattern loading.

Compared to theoretically correct loading pattern:

Pattern_LoadFull_Zone_Load

R1

R11=

R2

R20.96=

R1 R1:= R2 R2:= Use full pattern loading

Summary of Strap Design

Strap Design of interior zone truss:

Components and Cladding: Interior Truss

R

0

1237.44−

1237.44−

1185.92−

1185.92−

lbf= min R( ) 1237.44− lbf= Rdesign min R( ):=

Convert from 5%ile of Ultimate Distribution to Mean and SD of Ultimate

ratio5%UltMean 1.196:=

ratio5%UltSD 0.1196:=

Ultimate Failure CapacityRU

Rdesign

1.63

ratio5%UltMean

ratio5%UltSD

⋅

⋅:=


SBC 88

L 192ft 2 o⋅+:=

∆ 24 in⋅:= Truss spacing

Roof cover: Shingle


Dead load of roof

DLroof 9 psf⋅:= Hip roof, Tile, trusses, underlayment (from SBC Appendix A)



Dead load of 17 psf is composed of following: Truss/Sheathing (7 psf), Tile (10psf). If shingles are used, use 2 psf instead of 10 psf.

Lattic 30 psf⋅:= SBC Table 1604.1

Lfloor 40 psf⋅:=

Lroof 16 psf⋅:=

Wood Frame wall weightMasonry Wall Weight

Miscellaneous: Contents, carpet, cabinets, fixtures)DLwall

10

55

psf⋅:= DLmisc 15 psf⋅:=

SBC88 Wind Loads by SBC 1988 version

Design Parameters Variables for Enclosed/Part Encl.

in0 110 1 Enclosed( ):= Enclosed 0≡

PartEnclosed 1≡

V in0 0⟨ ⟩ mph⋅:= V 110mph=

Geometry of Building: Building Name: 0023 - condo project

h22.18 22.18+

2

ft⋅:= ht of building

IntPressure in0 2⟨ ⟩:=θ atan

012

:= θ 0deg=

o 0.0 ft⋅:= overhang widthog 0 ft⋅:=

W 38ft 2 o⋅+:= dimensions of building


SBC 88

dummy value

GCpi0

0

=GCpi0

0


0.4−

0.1

IntPressure PartEnclosed=if

20−

20

otherwise

:=

Internal Pressure coefficient

length of top chord of trusslr 19 ft=lrW

2 cos θ( )⋅:=

aθ 3.8 ft=

length of edge zones along roof slope - assume that "z" in Figures 1205 are widths in plan not along roof

aθa

cos θ( ):=

a 3.8 ft=a max

a

0.04 LeastHorDim⋅

3 ft⋅

:=a 3.8 ft=a min

0.1 LeastHorDim⋅

0.4 h⋅

:=

h 22.18 ft=LeastHorDim 38 ft=LeastHorDim minW

L

:=Edge zone

qh 28.415 psf=

Dynamic Wind Pressure( Table 1606.2A)qh .00256 V2⋅h

30 ft⋅

2

7⋅

slug

2.15111 ft3⋅⋅

h hmin>( )if

.00256 V2⋅15 ft⋅30ft

2

7⋅

slug

2.15111 ft3⋅⋅ otherwise

:=

hmin 15 ft⋅:=



SBC 88

Zone c, overhang

Zone c, overhangZone s, overhang

Zone s, overhang

Zone r, overhangZone r, overhangZone e

Zone wAlim_10deg

10 100 1000( )

10 100 1000( )

63 100 1000( )

63 100 1000( )

10 100 1000( )

10 500 1000( )

10 500 1000( )

10 100 1000( )

48 72 1000( )

10 100 1000( )

ft2⋅:=Zone eZone cZone seZone w Zone siZone re GCp_10deg

1.3−

0

1.15−

0

1.15−

0

1.3−

0

1.15−

0

1.15−

0

1.7−

0

1.4−

0

1.4−

0

1.7−

0

1.4−

0

1.4−

0

2.9−

0

1.4−

0

1.4−

0

0.91.3−

1.3

1.1−

1.0

1.1−

1.0

⋅

0.91.5−

1.3

1.1−

1.0

1.1−

1.0

⋅

1.3−

0

0.95−

0

0.95−

0

1.5−

0

1.2−

0

1.2−

0

2.7−

0

0.95−

0

0.95−

0

:=Zone r wall coefficients,

Figure 1205.2C (reduced by 10% when roof slope less than 10deg)

Zone c

Zone se

Alim is the x axis values of the change in slope of the GCP graphs

Zone si

roof coefficients Table 1205.2D

Zone re

Zone r

If slope is less than 10 degrees:

10SF neg 100SF neg, 1000SF neg10SF pos 100SF pos, 1000 SF pos

Limits of External Pressure Coefficients for each Zone in C&C loads( first row neg coefficients, second row positive coefficents)

External Pressure Coefficients: Components and Cladding


SBC 88

Zone c wall coefficients, Figure 1205.2C (reduced by 10% when roof slope less than 10deg)

Zone c, overhang

GCp_30deg

1.2−

0

1.1−

0

1.1−

0

1.2−

0

1.1−

0

1.1−

0

1.4−

0

1.2−

0

1.2−

0

2.1−

0

1.8−

0

1.8−

0

2.7−

0

1.8−

0

1.8−

0

1.3−

1.3

1.1−

1.0

1.1−

1.0

1.5−

1.3

1.1−

1.0

1.1−

1.0

1.0−

0

0.9−

0

0.9−

0

1.2−

0

1.0−

0

1.0−

0

2.5−

0

1.6−

0

1.6−

0

:=

Zone w

Zone e

Zone r, overhang

Zone s, overhang

Zone c, overhang

GCp_45deg 0:=Dummy Values for high slope roofs: Not part of this study

Alim_45deg 0:=

θ 0deg=Select appropriate set of parameters according to slope of roof:

GCp GCp_10deg θ 10 deg⋅≤( )if



0 otherwise

:= Alim Alim_10deg θ 10 deg⋅≤( )if



0 otherwise

:=


Zone r Zone r Zone re

Zone re roof coefficients Table 1205.2D

Zone siZone seZone c

Zone si Alim_30deg

10 100 1000( )

10 100 1000( )

10 100 1000( )

48 100 1000( )

10 100 1000( )

10 500 1000( )

10 500 1000( )

10 100 1000( )

10 100 1000( )

10 100 1000( )

ft2⋅:= Zone w

Zone eZone r, overhangZone seZone s, overhang


SBC 88

Calculate slopes of parts of pressure coefficient graphs for interpolation:

slopeGCp Zone( )GCpZone( ) 1⟨ ⟩ GCpZone( ) 0⟨ ⟩−


ft2


ft2

−

:=

Slope of first section of line

slope of secondary section of line (usually flat)slopeGCp2 Zone( )

GCpZone( ) 2⟨ ⟩ GCpZone( ) 1⟨ ⟩−


ft2


ft2

−

:=

GCp Area Zone,( ) GCpZone( ) 0⟨ ⟩ Area AlimZone( ) 0⟨ ⟩<if

slopeGCp Zone( )( ) logArea

ft2


ft2

−+

...

⋅


...


slopeGCp2 Zone( )( ) logArea

ft2


ft2

−+

...

⋅


...


GCpZone( ) 2⟨ ⟩ otherwise

:=

For Example:

GCp 72 ft2⋅ co,( ) 1.2−

0

= GCp 10 ft2⋅ r,( ) 1.3−

0

= GCp 50 ft2⋅ e,( ) 1.202−

1.059

=

GCp 200 ft2⋅ e,( ) 1.074−

0.963

=GCp 510 ft2⋅ si,( ) 1.4−

0

=


SBC 88

min DP( ) 33.246− psf=max DP( ) 33.246 psf=

DP0 1 2 3 4 5 6 7 8

01

0 -32.806 -32.806 -32.34 -32.34 -32.806 -32.34 -32.806 -32.340 32.586 32.586 31.886 31.886 32.586 31.886 32.586 31.886

psf=

DP j⟨ ⟩ qh GCp Fen Size⟨ ⟩( )j ft2⋅

→

Fen Zone⟨ ⟩( )j

→ ,

GCpi+

⋅ Fen Zone⟨ ⟩( )

j 45≠if

qh GCp Fen Size⟨ ⟩( )j ft2⋅

→

e,

GCpi+

⋅ Fen Fraction⟨ ⟩( )

j⋅

qh GCp Fen Size⟨ ⟩( )j ft2⋅

→

w,

GCpi+

⋅ 1 Fen Fraction⟨ ⟩( )

j−

⋅+

...

otherwise

:=

pwall33.246−

33.246

psf=GCp 10 ft2⋅ e,( ) 1.35−

1.17

=pwall qh GCp 10 ft2⋅ w,( ) GCpi+

⋅:=

j 1 rows Fen( ) 2−..:=

rows Fen( ) 196=Number of Fens:

Fraction 5:=

Zone 4:=Fen

0 1 2 3 4 50123456789101112

0 0 0 0 0 00 1 1 14 5 00 2 2 14 5 00 3 3 20 5 00 4 4 20 5 00 5 5 14 5 00 6 6 20 5 00 7 7 14 5 00 8 8 20 5 00 9 9 14 5 00 10 10 14 5 00 11 11 20 5 00 12 12 20 5 0

= Size 3:=

Dummy Width and Height

Fen

D:\..\fen dp SBC88.xls

:=

The following input table was imported from an excel sheet that had a list of fens for this building. Each column represents the widht, height, area, and zone of each fen respectively.



SBC 88

t .5 in⋅:= Plywood thickness = 1/2" (min thickness of code)

lp lnail t−:= lp 1.5 in= penetration length



Rnail0qr lp⋅ CD⋅ Cm⋅:=

8d common nail

lnail 2.5in:= length of nail, 8d, Southern Pine (SG=0.55), NDS 97-S Table 12.2Aqr 41

lbfin

⋅:=t .5 in⋅:= Plywood thickness = 1/2" (min thickness of code)


Resistance of single Nail, 6d and 8d respectivelyRnail1

qr lp⋅ CD⋅ Cm⋅:= Rnail84

131.2

lbf=

Design of Nailing Pattern for Roof DeckLoad on one nail: use 10 SF as effective area

Area 10 ft2⋅:= GCp Area r,( )1.3−

0

= GCp Area si,( )1.7−

0

= GCp Area c,( )2.9−

0

=

Design Load: Zone si

psingle qh GCp Area si,( ) GCpi+( )⋅:= psingle48.306−

0

psf=

Tributary Area of single sheet of plwood: (4ftx8ft)

Area 32 ft2⋅:= GCp Area r,( )1.224−

0

= GCp Area si,( )1.7−

0

= GCp Area c,( )2.142−

0

=

ppanel qh GCp Area si,( ) GCpi+( )⋅:= ppanel48.306−

0

psf=

Resistance of Single Nail

6d common nail

qr 35lbfin

⋅:= 6d common nail, Southern Pine (specifig gravtiy =0.55) NDS 1997-S Table 12.2A



SBC 88


edge spacing se 6in:=

interior spacingsi si8 si6 12 in⋅<if

si6 otherwise

:= nailsize 8 si6 12 in⋅<if

6 otherwise

:=

nailsize 8= si 16 in=


Nnails 248inse

1+

⋅ 348in

si1+

⋅+:= Nnails 30=

Lpanel ppanel0DLsheath+( ) 32⋅ ft2:= Lpanel 1494.589 ft2 psf= uplift

Rtotal Rnail nailsize 6−2

Nnails⋅:= Rtotal 3936 lbf=

StatusRoofNail Rtotal Lpanel>:= StatusRoofNail 1= PASS = 1, FAIL = 0

Maximum Spacing for nails:

maximum allowable spacing of fastenersAt

Rnail

psingle0DLsheath+ 2⋅ ft⋅( )

:= At10.791

16.854

in=

Select nailing pattern that meets max spacing criteria

Check 6d nail first spacing, nails

number of nails that meets nailing pattern criteria for Zone si

ceil linterp spossible Npossible, At0,( )( ) 6=


IIs floor linterp spossible II, At0,( )( ):= IIs 6=

NailSched

4.364 124.8 11

5.333 106 9

6.857 88 7

9.6 612 516 424 348 2

=si6 spossibleIIs

:= si6 9.6 in=

check 8d nail



si8 spossibleIIs:= si8 16 in=


SBC 88

φ 1.0:=Negative pressures for r, ri, si, se and c zone

p

00123456789

-32.678-32.678-39.781-39.781-39.781-28.181-28.231-26.994-34.098-26.994

psf=pk GCp Aeff k,( )0 GCpi0+( )qh:=

GCp Aeff c,( ) 1.4−

0

=

Note there is no combo load case that has a reduction in dead load in SBC (section 1609)

GCp Aeff si,( ) 1.4−

0

=

k 0 9..:=GCp Aeff r,( ) 1.15−

0

=

External Gust Factors

Since Aeff is greater than 100SF, Use 100SF for GCp values

Aeff max Aeff( ):=Aeff76

481.333

ft2=Aeff

W ∆⋅

WW3

⋅

:=

Effective wind area of a truss equals maximum of actual area and span times 1/3 span length

Roof Truss Design should be based on Components and Cladding loads

ROOF STRAPS DESIGN


SBC 88

STRAP RESISTANCE used in ARA modelWIND Perpendicular to Ridge at section A-A

Sum Moments (note that in the mathcad formulas p0 is zone r pressures and p2 is zone si pressure)

pa pr θ 10 deg⋅<if

psi otherwise

:=

pc pr:=pb pr θ 10 deg⋅<if

psi otherwise

:=

P2

Pa* Pb*

Pc*

P1 P1

θ

R1 R2

WIND

wo o

PoPo

R01

W 2 o⋅−pso

ocos θ( )⋅ ∆⋅ cos θ( )⋅ W o−

o2

−

⋅

psi aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅ W o−a o−

2− o−

⋅+

...


o−aθ

2cos θ( )⋅−

⋅+

...


2−

cos θ( )⋅−

⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ cos θ( )⋅12

aθo

cos θ( )−

cos θ( )⋅

⋅

+

...

pr lr 2 aθ⋅−( )⋅ ∆⋅ cos θ( )⋅ W o−lr2

cos θ( )⋅−

⋅

+

...

pr lr 2 aθ⋅−( )⋅ ∆⋅ cos θ( )⋅W2

o−lr2

cos θ( )⋅−

⋅+

...

pso−o

cos θ( )⋅ ∆⋅ cos θ( )⋅o2

⋅+

...

psoo

cos θ( )⋅ ∆⋅ sin θ( )⋅o


⋅

−+

...

psi aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅

−+

...

pr lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅

−+

...


2−

⋅ sin θ( )

−+

...

psoo

cos θ( )⋅ ∆⋅ sin θ( )⋅o


⋅+

...

pr lr 2 aθ⋅−( )⋅ ∆⋅ sin θ( )⋅lr2

sin θ( )⋅

⋅+

...


2−

⋅ sin θ( )⋅+

...

pc aθo

cos θ( )−

⋅ ∆⋅ sin θ( )⋅ aθ12

aθo

cos θ( )−

⋅−

sin θ( )⋅

⋅+

...


o−

⋅+

...

⋅:=

R0 951.036− lbf=


SBC 88

RU2132.697−

213.27−

lbf=RURdesign

1.63

ratio5%UltMean

ratio5%UltSD

⋅

⋅:=Ultimate Failure Capacity

ratio5%UltSD 0.1196:=

ratio5%UltMean 1.196:=Convert from 5%ile of Ultimate Distribution to Mean and SD of Ultimate

Rdesign min R( ):=min R( ) 951.036− lbf=R

951.036−

902.446−

899.746−

899.746−

lbf=

Components and Cladding: Interior Truss

Strap Design of interior zone truss:

Summary of Strap Design

R3 899.746− lbf=

R2 899.746− lbf=

R3 2 pr⋅ lr⋅ ∆⋅ cos θ( )⋅ R2− φ DLroof⋅ ∆⋅ W⋅+:=

R2∆

W 2 o⋅−pr lr⋅ cos θ( )⋅ W o−

lr2

cos θ( )⋅−

lr2

cos θ( )⋅ o−

+

⋅

φ DLroof⋅ W⋅W2

o−

⋅+

...

⋅:=

WIND Parallel to Ridge

P1 P1

θR1 R2

wo o

WIND Parallel to Ridge at Section A-A

R1 902.446− lbf=

R1 2 psoo

cos θ( )⋅ cos θ( )⋅ ∆⋅

⋅

psi aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅

+

...

pb aθ⋅ cos θ( )⋅ ∆⋅( )+

...

2 pr⋅ lr 2 aθ⋅−( )⋅ cos θ( )⋅ ∆⋅+...

pa aθ⋅ cos θ( )⋅ ∆⋅+

...

pc aθo

cos θ( )−

⋅ cos θ( )⋅ ∆⋅+

...


R0−:=



SBC 88

SUMMARY:Design Parameters: V 110mph= IntPressure 0=

Nail Spacing:nailsize 8= se 6 in= edge of plywood si 16 in= interior of plywood

Straps: C&C loads Rdesign 951.036− lbf= RU2132.697−

213.27−

lbf=

Window Design Pressure: max DP( ) 33.246 psf= min DP( ) 33.246− psf=


SBC 76

dimensions of buildingL 192ft 2 o⋅+:=Use 1.0:=∆ 24 in⋅:= Truss spacing

Roof cover: Shingle


Dead load of roof

DLroof 9 psf⋅:= Hip roof, Tile, trusses, underlayment (from SBC Appendix A)



Dead load of 17 psf is composed of following: Truss/Sheathing (7 psf), Tile (10psf). If shingles are used, use 2 psf instead of 10 psf.

Lattic 30 psf⋅:= SBC Table 1604.1

Lfloor 40 psf⋅:=

Lroof 16 psf⋅:=

Wood Frame wall weightMasonry Wall Weight

Miscellaneous: Contents, carpet, cabinets, fixtures)DLwall

10

55

psf⋅:= DLmisc 15 psf⋅:=

Wind Loads by SBC 1976 versionSBC 76

Variables for Enclosed/Part Encl.

Design ParametersEnclosed 0≡

PartEnclosed 1≡in0 110 Enclosed 0( ):=

V in0 0⟨ ⟩ mph⋅:=

Geometry of Building: Building Name: 0023 - condo projectV 110mph=

h22.18 22.18+

2

ft⋅:= ht of building

IntPressure in0 2⟨ ⟩:=

θ atan012

:= θ 0deg=IntPressure 0=o 0.0 ft⋅:= overhang width

og 0 ft⋅:=

W 38ft 2 o⋅+:=Table 1606: Use factor


SBC 76

DP17.037−

34.074

psf=DP qh GCpwindow⋅:=

qh 30.976 psf=GCpwindow0.55−

1.1

=

DP is not a function of location on building, exposure, or size of opening: Single DP can be calcuated


GCp

1.1−

1.1

0.55−

1.1

1.0−

0

0.75−

0

1.5−

0


1.5−

1.1

0.55−

1.1

1.5−

0

1.25−

0

1.5−

0

otherwise

:=

extwall

window

hor_windward

hor_leeward

overhang

0

1

2

3

4

≡

Shape Factors: Tables 1205.2 to 1205.6

lr 19 ft=lrW

2 cos θ( )⋅:=

length of top chord of truss

qh 30.976 psf=

Dynamic Wind Pressure( Table 1606.2A)qh .00256 V2⋅h

30 ft⋅

2

7⋅

slug

2.15111 ft3⋅⋅

h hmin>( )if

.00256 V2⋅hmin

30ft

2

7

⋅

slug

2.15111 ft3⋅⋅ otherwise

:=

hmin 30 ft⋅:=



SBC 76

penetration length



Rnail0qr lp⋅ CD⋅ Cm⋅:=

8d common nail

lnail 2.5in:= length of nail, 8d, Southern Pine (SG=0.55), NDS 97-S Table 12.2Aqr 41

lbfin

⋅:=t .5 in⋅:= Plywood thickness = 1/2" (min thickness of code)


Resistance of single Nail, 6d and 8d respectivelyRnail1

qr lp⋅ CD⋅ Cm⋅:= Rnail84

131.2

lbf=

Design of Nailing Pattern for Roof DeckLoad on one nail: use 10 SF as effective area

GCphor_windward1−

0

=

Design Load: windward zone of horizontal surface

psingle qh GCphor_windward( )⋅:= psingle30.976−

0

psf=

Tributary Area of single sheet of plwood: (4ftx8ft)

ppanel psingle:= ppanel30.976−

0

psf=

Resistance of Single Nail

6d common nail

qr 35lbfin

⋅:= 6d common nail, Southern Pine (specifig gravtiy =0.55) NDS 1997-S Table 12.2A


t .5 in⋅:= Plywood thickness = 1/2" (min thickness of code)

lp lnail t−:= lp 1.5 in=


SBC 76

edge spacing se 6in:=

interior spacingsi si8 si6 12 in⋅<if

si6 otherwise

:= nailsize 8 si6 12 in⋅<if

6 otherwise

:=

nailsize 6= si 16 in=

Spacing cannot exceed 12 inches: si min si 12 in⋅,( ):= si 12 in=


Nnails 248inse

1+

⋅ 348in

si1+

⋅+:= Nnails 33=

Lpanel ppanel0DLsheath+( ) 32⋅ ft2:= Lpanel 940.033 ft2 psf= uplift

Rtotal Rnail nailsize 6−2

Nnails⋅:= Rtotal 2772 lbf=

StatusRoofNail Rtotal Lpanel>:= StatusRoofNail 1= PASS = 1, FAIL = 0

Maximum Spacing for nails:

maximum allowable spacing of fastenersAt

Rnail

psingle0DLsheath+ 2⋅ ft⋅( )

:= At17.157

26.797

in=

Select nailing pattern that meets max spacing criteria

Check 6d nail first spacing, nails

number of nails that meets nailing pattern criteria for Zone si




NailSched

4.364 124.8 11

5.333 106 9

6.857 88 7

9.6 612 516 424 348 2

=si6 spossibleIIs

:= si6 16 in=

check 8d nail



si8 spossibleIIs:= si8 24 in=



SBC 76

R1687.513−

228

lbf=

R1 ∆ phor_windwardW

3 cos θ( )⋅⋅ cos θ( )⋅ phor_leeward( ) 2 W⋅

3 cos θ( )⋅

⋅ cos θ( )⋅+

⋅ R0− φ DLroof⋅ ∆⋅ W⋅+

:=


R0818.301−

228

lbf=

P2

Pa* P2

Pa*

P1 P1

θ

R1 R2

WIND

wo o

PoPo

R0∆

W 2 o⋅−( )phor_windward

W3 cos θ( )⋅

⋅ cos θ( )⋅ W o−W3

0.5⋅−

⋅

phor_leeward lrW

3 cos θ( )⋅−

⋅ cos θ( )⋅ W o−W3

−W12

−

⋅+

...

phor_leeward lr( )⋅ cos θ( )⋅W4

o−

⋅+

...

phor_windward−W

3 cos θ( )⋅

⋅ sin θ( )⋅W

3 cos θ( )⋅sin θ( )

2⋅

⋅+

...

phor_leeward− lrW

3 cos θ( )⋅−

⋅ sin θ( )⋅ lrW

12 cos θ( )⋅−

sin θ( )⋅

⋅+

...

phor_leeward lr( )⋅ sin θ( )⋅lr2

⋅ sin θ( )⋅+

...

φ DLroof⋅ W⋅W2

o−

⋅+

...

⋅:=Sum Moments (note that in the mathcad formulas p0 is zone r pressures and p2 is zone si pressure)

WIND Perpendicular to Ridge at section A-ASTRAP RESISTANCE used in ARA model

φ23

:=

phor_leeward23.232−

0

psf=

phor_leeward qh GCphor_leeward⋅:= phor_windward30.976−

0

psf=

phor_windward qh GCphor_windward⋅:=Section 1205.3: StabilityIndicates: (c) the uplift forces calculation from wind pressure shall not exceed two-thirds of the resisting dead load.

This is interpreted as limiting Dead load contribution to 67%

GCphor_leeward0.75−

0

=

k 0 4..:=GCphor_windward1−

0

=External Gust Factors

Roof Truss Design should be based on Components and Cladding loads from Table 1205.5 which refers to Table 1205.3

ROOF STRAPS DESIGN


SBC 76

min DP( ) 17.037− psf=max DP( ) 34.074 psf=Window Design Pressure:

RU 1835.04− lbf=Rdesign 818.301− lbf=Straps: C&C loads

interior of plywoodsi 12 in=edge of plywoodse 6 in=nailsize 6=Nail Spacing:

IntPressure 0=V 110mph=Design Parameters:

SUMMARY:

RUs 183.504− lbf=RUsRdesign

1.63⋅ ratio5%SD⋅:=

RU 1835.04− lbf=RU

Rdesign

1.63⋅ ratio5%U⋅:=

ratio5%SD 0.1196:=

ratio5%U 1.196:=Convert from 5%ile of Ultimate Distribution Mean and SD of Ultimate distribution

Ultimate Failure Strength

Rdesign 818.301− lbf=

Rdesign min R0( ):=R

818.301−

228

687.513−

228

lbf=

Design value:


archive.floridadisaster.orgarchive.floridadisaster.org/mitigation/rcmp/wind loss/condolr5...appendix...

Documents