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

Post on 23-Feb-2016

87 views 0 download

description

Wood Truss Council of America Presents In Conjunction With. WTCA – AZ. Code Issues. Relating to the Manufactured Truss Industry. IBC 2003 . SEI / ASCE 7-02 ANSI / TPI 1-2002 Reference Standards. IBC 2003 Section 1605.3 Load combinations using allowable stress design. - PowerPoint PPT Presentation

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

Wood Truss Council of AmericaWood Truss Council of America

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

WTCA – AZWTCA – AZ

Wood Truss Council of AmericaWood Truss Council of America

Code IssuesCode Issues

Relating to the Manufactured Relating to the Manufactured Truss IndustryTruss Industry

Wood Truss Council of AmericaWood Truss Council of America

IBC 2003 IBC 2003

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

Reference StandardsReference Standards

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

Section 1605.3.1.1Section 1605.3.1.1Load reduction Load reduction

Paragraph 2Paragraph 2

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

Section 1605.3.2Section 1605.3.2Alternative basic load Alternative basic load

combinationscombinations

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

Wood Truss Council of AmericaWood Truss Council of America

……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

Wood Truss Council of AmericaWood Truss Council of America

……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

Wood Truss Council of AmericaWood Truss Council of America

ANSI / TPI 1 2002ANSI / TPI 1 2002

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

Wood Truss Council of AmericaWood Truss Council of America

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)

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

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 …

Wood Truss Council of AmericaWood Truss Council of America

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

Non-MandatoryNon-Mandatory

Wood Truss Council of AmericaWood Truss Council of America

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

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

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

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:

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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

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

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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 …

Wood Truss Council of AmericaWood Truss Council of America

Wood Truss Council of AmericaWood Truss Council of America

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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

Wood Truss Council of AmericaWood Truss Council of America

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.

Wood Truss Council of AmericaWood Truss Council of America

Questions?Questions?Comments?Comments?

Wood Truss Council of AmericaWood Truss Council of America

Thank YouThank You