Guide to the Design of Diaphragms, Chords and Collectors: Based on the 2006 IBC and ASCE/SEI 7-05 (PDF Download)

Authored by NCSEA.
Many publications on lateral design do not address the design of diaphragms, chords and collectors in much detail. This Guide fills that void by explaining the role that diaphragms, chords and collectors play in buildings and providing detailed examples of how to determine the seismic forces and design the diaphragm, chords and collectors for various types of buildings located in Seismic Design Category (SDC) B and D.

This guide is based on the 2006 International Building Code® (IBC) and the American Society of Civil Engineers Minimum Design Loads for Buildings and Other Structures (ASCE/SEI 7-05) standard. The book's design examples also apply to the 2009 IBC® because it references ASCE/SEI 7-05 as well. Although the 2009 IBC® references the 2008 edition of the ACI 318 standard, there are only minor changes from ACI 318-05 in regards to the design of concrete diaphragms, chords and collectors. The design examples presented in this publication are based on seismic load effects. However, lateral forces due to wind loads also produce loads in the diaphragms, chords and collectors, and the basic principles involved in the design of these elements are essentially the same.

Detailed design examples are provided for the following:

• Four-story concrete office building with concrete diaphragms
• Three-story office building with CMU walls, glue-laminated beams on steel columns and wood-frame roof and floor diaphragms
• Four-story steel-braced frame building with steel beams and columns and steel deck roof diaphragm
• Four-story steel-braced frame building with steel beams and columns and concrete-filled steel deck floor diaphragms

Each design example includes analysis and design of the diaphragm, determination of chord forces, determination of collector forces and design of collectors to resist combined axial and flexural loads.