Wood Truss Council of America Presents In Conjunction With...

Wood Truss Council of AmericaWood Truss Council of America


PresentsPresents In Conjunction With... In Conjunction With...


WTCA – AZWTCA – AZ


Code IssuesCode Issues

Relating to the Manufactured Relating to the Manufactured Truss IndustryTruss Industry


IBC 2003 IBC 2003

SEI / ASCE 7-02SEI / ASCE 7-02ANSI / TPI 1-2002ANSI / TPI 1-2002

Reference StandardsReference Standards


IBC 2003IBC 2003Section 1605.3Section 1605.3

Load combinations usingLoad combinations usingallowable stress designallowable stress design

Equations 16-7 through 16-12Equations 16-7 through 16-12


Section 1605.3.1.1Section 1605.3.1.1Load reduction Load reduction

Paragraph 2Paragraph 2


Increases in allowable stresses Increases in allowable stresses specified in the appropriate specified in the appropriate

materials section of this code or materials section of this code or referenced standard shall not be referenced standard shall not be used with the load combinations used with the load combinations of Section 1605.3.1 except that a of Section 1605.3.1 except that a duration of load increase shall be duration of load increase shall be

permitted in accordance with permitted in accordance with Chapter 23.Chapter 23.


Chapter 23Chapter 23WoodWood

1.33 increase may be used for wind and 1.33 increase may be used for wind and seismic design for tooth holding. seismic design for tooth holding.

However, it However, it may notmay not be used for the metal be used for the metal connector plate shear, tension or connector plate shear, tension or compression.compression.


Section 1605.3.2Section 1605.3.2Alternative basic load Alternative basic load

combinationscombinations

Equations 16-13 through 16-18Equations 16-13 through 16-18


……When using these alternate When using these alternate basic load combinations that basic load combinations that

include wind or seismic loads,include wind or seismic loads,allowable stresses are allowable stresses are

permitted to be increased…permitted to be increased…

HoweverHowever


……Where wind loads are Where wind loads are calculated in accordance with calculated in accordance with Section 1609.6 or Section 6 of Section 1609.6 or Section 6 of

ASCE 7, the coefficient ASCE 7, the coefficient ww … shall be taken as 1.3… shall be taken as 1.3


ANSI / TPI 1 2002ANSI / TPI 1 2002

IBC 2003 Chapter 2303.4IBC 2003 Chapter 2303.4 References TPI 1References TPI 1


ANSI / TPI 1-2002ANSI / TPI 1-2002

Section 6.4.10 Wind / Seismic FactorsSection 6.4.10 Wind / Seismic Factors

Section 6.4.10 Wind / Seismic Factors Section 6.4.10 Wind / Seismic Factors (Commentary) (Commentary)


Wind / Seismic Load FactorsWind / Seismic Load FactorsAllowable shear and tension Allowable shear and tension

design values for metal design values for metal connector plates shall be connector plates shall be

permitted to be increased by permitted to be increased by 33 1/3 percent for load cases 33 1/3 percent for load cases including wind or earthquake including wind or earthquake

loads, in accordance with loads, in accordance with ASCE 7.ASCE 7.


CommentaryCommentary… it was not until 1998 edition … it was not until 1998 edition

of ASCE 7 that there was of ASCE 7 that there was effective language to prohibiteffective language to prohibit

the application of the 1.33 the application of the 1.33 increases that have increases that have

customarily been permitted in customarily been permitted in the material design standards. the material design standards.


Hence, this past practice is Hence, this past practice is now prohibited from now prohibited from

application when ASCE 7-98 application when ASCE 7-98 (ASCE 7-02)(ASCE 7-02) allowable stress allowable stress design load combinations are design load combinations are

used …used …


ANSI / TPI 1 -2002 Commentary ANSI / TPI 1 -2002 Commentary & Appendices& Appendices

Non-MandatoryNon-Mandatory


ANSI / TPI 1 -2002ANSI / TPI 1 -2002

Combined Flexure and Axial LoadingCombined Flexure and Axial Loading Net Section Lumber CheckNet Section Lumber Check


ANSI / TPI 1-1995ANSI / TPI 1-1995Section 11.2.5 Combined Flexure Section 11.2.5 Combined Flexure

and Axial Loadingand Axial Loading

…Design of inter-panel splices in …Design of inter-panel splices in the top or bottom chord not the top or bottom chord not

located within 12 inches of zero located within 12 inches of zero moment shall include the moment shall include the

additional stresses caused by additional stresses caused by flexure.flexure.


ANSI / TPI 1-2002ANSI / TPI 1-2002Section 8.8 Combined Flexure Section 8.8 Combined Flexure

and Axial Loadingand Axial Loading

… The moment applied to a … The moment applied to a metal connector plate used in metal connector plate used in chord splices shall not exceed chord splices shall not exceed

the moment capacity defined as the moment capacity defined as follows:follows:


22

MMa a = 0/45t= 0/45t11RRttFu(0.5WFu(0.5Wpp +y +ycc) +) + 22

0.15d0.15d22C(0.5dC(0.5d11 – y – ycc) -P) -Pttyycc

wherewhere


yyc c = (0.25d= (0.25d11dd22CC ) + ) + 2.22P 2.22P t t -- (t (t11WWppRRttFFuu))__________________________ __________________________

(2t (2t11RRttFFuu) + (0.5d) + (0.5d22C)C)


TranslationTranslation

Much larger bottom chord, off panel, Much larger bottom chord, off panel, splice plates. splice plates.

Especially on scissor trusses.Especially on scissor trusses.


ANSI / TPI 1-2002ANSI / TPI 1-2002Section 8.9 Net Section Lumber Section 8.9 Net Section Lumber

CheckCheck

ANSI / TPI 1-1995 Section 11.2.6ANSI / TPI 1-1995 Section 11.2.6


Section 8.9.2 For wood thickness Section 8.9.2 For wood thickness greater than 2 inches with plates greater than 2 inches with plates embedded only on the surface embedded only on the surface

normal to the thickness, the normal to the thickness, the tension, T, introduced by a single tension, T, introduced by a single joint into a wood member, shall joint into a wood member, shall

not exceed 1600 pounds per not exceed 1600 pounds per square inch wood width …square inch wood width …


Areas the Truss Industry Areas the Truss Industry could use the assistance could use the assistance Local Building OfficialsLocal Building Officials


1)1) Pressure the ICC to Pressure the ICC to change the code cycle change the code cycle

from three years to from three years to five or six yearsfive or six years


2) Help interpret the 2) Help interpret the wording in the various wording in the various codes and standardscodes and standards


3) Help identify and work to 3) Help identify and work to eliminate discrepancies eliminate discrepancies between the codes and between the codes and

standardsstandards


4) Work with the local 4) Work with the local WTCA chapter in its WTCA chapter in its

interaction with other interaction with other local jurisdictions to local jurisdictions to

adopt the same adopt the same (or very similar)(or very similar)

amendmentsamendments


5) Invite WTCA and other 5) Invite WTCA and other similar organizations similar organizations

to attend open to attend open structural committee structural committee

meetings.meetings.


Questions?Questions?Comments?Comments?


Thank YouThank You

Wood Truss Council of America Presents In Conjunction With...

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