Ductwork (D8)

This section comprehensively addresses the restraint of Ductwork for seismic applications. It is extremely practical in nature. It avoids the basic sizing of components (which is explained in Chapter D4) and focuses on layout, hardware arrangements, installation options and other issues critical to the installation contractor. Addressed in the section are floor mounted and suspended systems.

This chapter is recommended reading for Installation contractors, design support for contractors and field inspection personnel.

Seismic Forces Acting on Ductwork (D8.1)
This section provides a brief overview of the forces encountered by ductwork exposed to seismic forces and how they generate loads in restraint systems.

BBasic Primer for the restraint of Ductwork (D8.2)
This section addresses different kinds of duct systems, variations between them and provides some general direction in getting started with a restraint plan.

Pros and Cons of Struts versus Cables (D8.3)
While Struts and Cables are often used to perform the same restraint function and because they appear similar to the casual observer, there are significant differences between them that need to be accounted for in the field. This section addresses these issues.

Layout Requirements for Duct Restraint Systems - Definitions and Locations (D8.4.1)
The basic installation "Rules" for the appropriate restraint of duct systems along with basic definitions of terms used in later sections of this manual make up this section of the manual.

Ceiling Supported Duct Restraint Arrangements (D8.4.2)
Illustrated here are widely ranging options for the installation of both lateral and axial restraint arrangements acceptable for use on Ductwork. Isolated, non-Isolated, single and multiple trapezed ducts are all addressed in this section.

Floor or Roof supported Duct Restraint Arrangements (D8.4.3)
This section is similar to the one above except that it covers ductwork that is supported from below, either on floors or for roof mounted applications.

Attachment Details - Transferring Forces (D8.5.1)
A key element in the effectiveness of a restraint is the details of the connection. Basic parameters required to ensure that these connections are appropriate for seismic applications are included in this paper.

Attachment Details - Cable Clamps (D8.5.2)
There are several end connection details that are suitable for cable restraints. Both appropriate and inappropriate connections are identified in this section along with proper installation techniques.

Attachment Details - Duct Attachment (D8.5.3)
The connection between the cable or strut and a duct can be accomplished in a wide variety of ways and through the use of a wide variety of hardware. A wide variety of acceptable arrangements applicable to a broad variety of possible applications are shown and discussed in this section.

Attachment Details - Attachment to Structure (D8.5.4)
Similar to the connection between the cable or strut and the ductwork is the connection between the cable or strut and the structure. Cautions are required to ensure that the structure is not weakened by the connection and that the connection is adequate to transfer the design load. As in the section above, this segment illustrates a wide variety of acceptable arrangements that can accomplish this feat.

Non-Moment Generating Connections (D8.5.5)
Under some conditions, restraints can be avoided if the duct support hanger is fitted with a "Non-Moment" generating connection. Additional input on this subject is available in this section.

Connection options for Awkward Situations (D8.6)
Virtually every application will have situations where the basic connection arrangements won't fit or simply are not suitable. This section illustrates several typical "Awkward" situations and offers guidance on possible configurations to incorporate restraints in these areas.