Seismic, Wind and Flood Resistant Design
ASHRAE Technical Committee 2.7

TC 2.7 History

The first engineering study of damage to building nonstructural systems (components attached to the building frame) occurred after the 1964 Alaska earthquake.  Similar studies were reported following the 1971 San Fernando earthquake. California passed laws designed to protect hospitals from these destructive earthquakes. This led to the development of new construction standards and stimulated the growth of the seismic restraint industry.

The ASHRAE members in California and other seismically active regions were extremely interested in the seismic resistive design, but this was not true on a national level. It took 15 years, several additional earthquakes, and the urging of Jeffrey Rands from New Zealand, before ASHRAE agreed that there was enough interest to form a Task Group on Seismic Restraint Design (TGSRD).

ASHRAE announced the formation of the TG, and with the help of Jeffrey Rands and others identified potential members.  Pat Lama was a member of TC 2.6 for many years and helped write the seismic paragraphs that appeared in the ASHRAE Applications Handbook chapter on Sound and Vibration.  The first meeting of the new TGSRD took place in Dallas in 1988. A group of five individuals attended the first meeting.  They were Jeffrey Rands, Ralph Robson, Jim Carlson and Marx Ayres. Pat Lama was elected chairperson, and the first task was to see if it was possible to produce a practical seismic restraint design chapter for the Handbook.

During the TGSRD meetings in Ottawa and Chicago in 1989, several other key members were recruited, Bill Staehlin a structural engineer from the State of California, Paul Hollenbach an anchor bolt expert, Warren Blazier an acoustician, Fred Kohloss past ASHRAE president, Dr. William Iwan from Cal Tech, and Robert Voelz, a practicing mechanical engineer.  With this core group, the TG had a good representation of both practicing mechanical, structural, and civil engineers, an acoustician and a professor of earthquake engineering.  By the 1990 Atlanta meeting, Bill Staehlin and Jim Carlson completed the first draft of the seismic chapter that appeared in the ASHRAE 1991 Applications Handbook.  The rest of the committee added the required artwork, polished the text and provided the tables for this new chapter.

From the first meetings of TGSRD it was agreed that the chapter needed to fill several basic functions.  One was to explain to the practicing HVAC system design engineers how code dictated seismic inputs effects their systems.  Another purpose was to show how the seismic equations found in all codes can be applied to the various types of equipment. The chapter had to stay in line with the structural engineering community and keep up with new technology that was emerging.  Numerical examples were to be provided to illustrate how the forces translated from the center of gravity of the equipment down to the support base for the equipment.  Application of various types of hardware along with post drill anchors would be explained.  Numerous generic details were included so that the HVAC system design engineer would have a practical working document which, when followed, would prevent loss of equipment and associated piping and ductwork during a seismic event.  This all assumed that the building itself survived.  This document was in effect prior to the 1994 Northridge earthquake. It was observed that the HVAC systems installed according to the chapter guidelines performed much better than other installations that did not.  The TG was convinced that this document worked, and continues to update the text to keep the chapter up to date with current codes.  
                                
The chair of the TG moved from Pat Lama to Jim Carlson, Bill Staehlin, Doug Valerio and Doug Fitts.  The TG became a permanent Technical Committee (TC), and is now fully staffed with acousticians, mechanical, structural and civil engineers.  A key to the success of this committee lies in the tremendous amount of help from members.

In December 1999, the scope of TC 2.7 was expanded to include wind effects, which sometimes exceeds seismic forces on rooftop equipment.  Chapter 53 of the 1999 ASHRAE Handbook was expanded to include both seismic and wind restraint design information. The present handbook chapter is chapter 55 in the 2011 HVAC Applications Handbook.

The Practical Guide to Seismic Restraint is an ASHRAE special publication, with the first edition published in the fall of 1999. The second edition was published in January 2012.  This book was developed in research project RP-812.  It contains technical background, code requirements, and practical design information for typical installations in the HVAC industry.  It serves as a useful guide to mechanical, electrical, and structural engineers.