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

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.

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

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  1. Wood Truss Council of AmericaPresents In Conjunction With...

  2. WTCA – AZ

  3. Code Issues Relating to the Manufactured Truss Industry

  4. IBC 2003 SEI / ASCE 7-02 ANSI / TPI 1-2002 Reference Standards

  5. IBC 2003Section 1605.3Load combinations usingallowable stress design Equations 16-7 through 16-12

  6. Section 1605.3.1.1Load reduction Paragraph 2

  7. Increases in allowable stresses specified in the appropriate materials section of this code or referenced standard shall not be used with the load combinations of Section 1605.3.1 except that a duration of load increase shall be permitted in accordance with Chapter 23.

  8. Chapter 23Wood 1.33 increase may be used for wind and seismic design for tooth holding. However, it may not be used for the metal connector plate shear, tension or compression.

  9. Section 1605.3.2Alternative basic load combinations Equations 16-13 through 16-18

  10. …When using these alternate basic load combinations that include wind or seismic loads,allowable stresses are permitted to be increased… However

  11. …Where wind loads are calculated in accordance with Section 1609.6 or Section 6 of ASCE 7, the coefficient w… shall be taken as 1.3

  12. ANSI / TPI 1 2002 IBC 2003 Chapter 2303.4 References TPI 1

  13. ANSI / TPI 1-2002 Section 6.4.10 Wind / Seismic Factors Section 6.4.10 Wind / Seismic Factors (Commentary)

  14. Wind / Seismic Load FactorsAllowable shear and tension design values for metal connector plates shall be permitted to be increased by 33 1/3 percent for load cases including wind or earthquake loads, in accordance with ASCE 7.

  15. Commentary… it was not until 1998 edition of ASCE 7 that there was effective language to prohibitthe application of the 1.33 increases that have customarily been permitted in the material design standards.

  16. Hence, this past practice is now prohibited from application when ASCE 7-98 (ASCE 7-02) allowable stress design load combinations are used …

  17. ANSI / TPI 1 -2002 Commentary & AppendicesNon-Mandatory

  18. ANSI / TPI 1 -2002 Combined Flexure and Axial Loading Net Section Lumber Check

  19. ANSI / TPI 1-1995Section 11.2.5 Combined Flexure and Axial Loading…Design of inter-panel splices in the top or bottom chord not located within 12 inches of zero moment shall include the additional stresses caused by flexure.

  20. ANSI / TPI 1-2002Section 8.8 Combined Flexure and Axial Loading… The moment applied to a metal connector plate used in chord splices shall not exceed the moment capacity defined as follows:

  21. 2Ma = 0/45t1RtFu(0.5Wp +yc) +20.15d2C(0.5d1 – yc) -Ptyc where

  22. yc = (0.25d1d2C ) + 2.22Pt - (t1WpRtFu)__________________________ (2t1RtFu) + (0.5d2C)

  23. Translation Much larger bottom chord, off panel, splice plates. Especially on scissor trusses.

  24. ANSI / TPI 1-2002Section 8.9 Net Section Lumber Check ANSI / TPI 1-1995 Section 11.2.6

  25. Section 8.9.2 For wood thickness greater than 2 inches with plates embedded only on the surface normal to the thickness, the tension, T, introduced by a single joint into a wood member, shall not exceed 1600 pounds per square inch wood width …

  26. Areas the Truss Industry could use the assistance Local Building Officials

  27. Pressure the ICC to change the code cycle from three years to five or six years

  28. 2) Help interpret the wording in the various codes and standards

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

  30. 4) Work with the local WTCA chapter in its interaction with other local jurisdictions to adopt the same (or very similar)amendments

  31. 5) Invite WTCA and other similar organizations to attend open structural committee meetings.

  32. Questions?Comments?

  33. Thank You

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