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

Wood Truss Council of America WTCA – AZ

Wood Truss Council of America Code Issues Relating to the Manufactured Truss Industry

Wood Truss Council of America IBC 2003 SEI / ASCE 7-02 ANSI / TPI Reference Standards

Wood Truss Council of America IBC 2003 Section Load combinations using allowable stress design Equations 16-7 through 16-12

Wood Truss Council of America Section Load reduction Paragraph 2

Wood Truss Council of America 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 except that a duration of load increase shall be permitted in accordance with Chapter 23.

Wood Truss Council of America Chapter 23 Wood 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.

Wood Truss Council of America Section Alternative basic load combinations Equations through Equations through 16-18

Wood Truss Council of America …When using these alternate basic load combinations that include wind or seismic loads, allowable stresses are permitted to be increased… However However

Wood Truss Council of America …Where wind loads are calculated in accordance with Section or Section 6 of ASCE 7, the coefficient w … shall be taken as 1.3

Wood Truss Council of America ANSI / TPI IBC 2003 Chapter IBC 2003 Chapter References TPI 1 References TPI 1

Wood Truss Council of America ANSI / TPI Section Wind / Seismic Factors Section Wind / Seismic Factors Section Wind / Seismic Factors (Commentary) Section Wind / Seismic Factors (Commentary)

Wood Truss Council of America Wind / Seismic Load Factors Allowable 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.

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

Wood Truss Council of America Hence, this past practice is now prohibited from application when ASCE 7-98 (ASCE 7-02) allowable stress design load combinations are used …

Wood Truss Council of America ANSI / TPI Commentary & Appendices Non-Mandatory

Wood Truss Council of America ANSI / TPI Combined Flexure and Axial Loading Combined Flexure and Axial Loading Net Section Lumber Check Net Section Lumber Check

Wood Truss Council of America ANSI / TPI Section 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.

Wood Truss Council of America ANSI / TPI Section 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:

Wood Truss Council of America 2 M a = 0/45t 1 R t Fu(0.5W p +y c ) d 2 C(0.5d 1 – y c ) -P t y c 2 M a = 0/45t 1 R t Fu(0.5W p +y c ) d 2 C(0.5d 1 – y c ) -P t y c where

Wood Truss Council of America y c = (0.25d 1 d 2 C ) P t - (t 1 W p R t F u ) __________________________ (2t 1 R t F u ) + (0.5d 2 C) y c = (0.25d 1 d 2 C ) P t - (t 1 W p R t F u ) __________________________ (2t 1 R t F u ) + (0.5d 2 C)

Wood Truss Council of America Translation Much larger bottom chord, off panel, splice plates. Much larger bottom chord, off panel, splice plates. Especially on scissor trusses. Especially on scissor trusses.

Wood Truss Council of America ANSI / TPI Section 8.9 Net Section Lumber Check ANSI / TPI Section ANSI / TPI Section

Wood Truss Council of America Section 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 …

Wood Truss Council of America

Areas the Truss Industry could use the assistance Local Building Officials

Wood Truss Council of America 1)Pressure the ICC to change the code cycle from three years to five or six years

Wood Truss Council of America 2) Help interpret the wording in the various codes and standards

Wood Truss Council of America 3) Help identify and work to eliminate discrepancies between the codes and standards

Wood Truss Council of America 4) Work with the local WTCA chapter in its interaction with other local jurisdictions to adopt the same (or very similar) amendments

Wood Truss Council of America 5) Invite WTCA and other similar organizations to attend open structural committee meetings.

Wood Truss Council of America Questions? Comments?

Wood Truss Council of America Thank You