Typically this attachment is the 'weakest link' of the overall design, especially when post-installed concrete anchors are used. Cables can only be loaded in tension, which means the hanger rod and its anchorage are not part of the seismic load path. The Eng-Tips staff will check this out and take appropriate action. Therefore, extra care must be used when restraining them.
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SEI Supplements and Errata | ASCE
Generally the structural engineer is responsible for determining the seismic design category for a project. One problem in the past was the lack of enforcement of seismic and wind restraint code provisions. Even the failure of domestic water, sanitary and roof drain lines can flood a building and render it uninhabitable.
Mechanical and electrical equipment knocked off of its supporting structure due to earthquake-related building movement can threaten both life and property.
Typical beam clamps rely strongly on friction to hold their position and are designed to support primarily vertical loads. Applicable building code, or codes 2. There are six seismic design categories that vary from A, the least stringent seismic restraint requirement to F, the most stringent,level of restraint required. Unless specified otherwise, typical restraints are selected to resist psf horizontal and psf vertical wind loads.
Image courtesy of Kinetics Noise Control. The and IBC require that non-isolated mechanical equipment over 10 HP will require undercut anchors that fit into a groove cut at the base of ascf anchor pocket, chaptef anchors that are adhered in the anchor pocket using a seismically qualified adhesive material.
Example of a connector that fastens cables used in the seismic restraint of 31, duct, electrical cable trays, and suspended equipment. In addition, the use of struts subjects the anchorage for the hangers at the strut locations to become part of the seismic restraint system; this means that the struts will need to be fitted with seismically rated anchors. In both cases above, if the hangers are attached to concrete, wedge-type expansion anchors must be used. Several factors determine the need for seismic restraints: What Determines Seismic Restraint Requirements?
Codes Relating to Seismic and Wind Restraints.
This article pertains to nonbuilding structures which are not similar to buildings and focuses on the determination of when the design rules of ASCE Chapter 15 or ASCE Chapter 13 apply. Click Here to join Eng-Tips and talk with other members!
Discuss the selection and certification of seismic and wind restraints for MEP equipment and components. Seismic forces load the strut in compression resulting in a tensile load on the hanger rod.
If a component importance factor has not been assigned to an MEP system, the designer chaptr assume that it is equal to 1.
Understanding Seismic and Wind Restraints
Because struts subject hanger rods to tensile loads in conjunction asc the static weight loads, the number of restraint points needed on a given run of piping will typically be considerably higher for a strut-restrained system than for the cable-restrained system. Since they can be fitted to one side only, struts allow for a more narrow packaging arrangement. The worst case will be assigned to the project.
I don't see in chapter 13 of ASCE 7 an equation for vertical seismic forces. It is critical that the restraint system design specifies a particular anchor by size and source and that the anchor used conforms to this specification.
non structural Components and Nonbuilding Structures
Few production environments have the luxury of ordering new equipment to replace existing machines on their shop floor. Nonstructural Components Traditionally, nonstructural components have been identified as architectural, mechanical and electrical components found in buildings. I found that "Seismic Design Review", by the author Steven Hiner has an example problem that assisted with load combinations of vertical and horizonatal siesmic forces at the reactions anchors. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.
SEI Supplements and Errata
It is most cost effective to locate heavy equipment at lower levels within the building envelope wherever feasible. Piping and systems or equipment that could normally have a component importance factor of 1. MEP components mounted inline with the duct system and hard connected to the duct on at least one end, weighing lbs or less, may be restrained as though they were part of the duct system.
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An added factor to consider when selecting a restraint system is that once a decision is reached on the type to use for a particular run, code requirements state that the same type of system must be used for the entire run all cable or all strut.