Anchoring operational and functional components (OFCs) to the building structure is a multi-dimensional topic. If equipment is floor-mounted in a non-seismic area, whether the equipment is vibration isolated or not, most do not have to be anchored to the structure (ie: horizontal forces, during operation, are insignificant relative to the gravitational weight of the equipment … so it stays in place). In many cases, from a housekeeping point-of-view, equipment is mounted on ‘housekeeping pads’ so that they are kept up, out of the way, when sweeping or protected from water contact if water from various sources should flood the structural floor on which they are located. Again, in non-seismic areas, the housekeeping pads need not be attached directly to the structure or to the equipment as gravity keeps all in place. However, whether in a low to a very high seismic area, every element in the ‘critical load path’ needs to be anchored to ensure that the system stays in place and cannot shift, causing secondary mechanical damage or bodily injury during a dynamic event. That means that every ‘element’ in the ‘critical load path’ needs to be addressed, starting with the housekeeping pad-to-structure attachment. If this critical anchoring is overlooked at the design stage, and the HKP has yet to be poured, Mason has come up with a quick solution – the HPA anchor.
The next attachment in the ‘critical load path’ is at the equipment-to-housekeeping pad interface, or the direct anchorage of equipment to the structure. Anchor type, depth of anchor embedment, inter-anchor spacing, potential bending moment, edge distance and so on, are all critical parameters that need to be considered, whether there is a seismically rated isolation mount or pad between equipment and structure, or not. Mason offers a number of seismically rated steel-to-concrete anchors.
HUNG EQUIPMENT and systems in non-seismic areas need only be anchored to the structure with anchors capable of handling two times the gravitational applied load, in tension, at each anchor location. In seismic areas, the requirement is the same but a minimum of two rigid braces or four slack cables complete with anchors capable of withstanding 4 times the calculated loads generated during a dynamic event must be used. ‘Drop-in’ type anchors may be used to support the gravitational loads of equipment and systems but MUST NOT BE USED to anchor seismic cables or braces.
Anchoring PIPING in VERTICAL RISERS can present unique challenges because of thermal expansion/contraction, particularly if this piping also has to be vibration isolated and is located in a seismically active area. In order to address this Mason developed seismically rated isolation anchors (ADA) and guides (VSG(H)). Doing so also led to incorporating spring isolators on intermediate floors in very high building structures, not necessarily to address potential vibration induced noise at the various floors within the building but rather to accommodate the significant expansion/contraction that occurs in the very long vertical piping runs that occur in these ‘skyscrapers’. This anchor/guide/ spring design has been shown to be a lot more resistant to failure during an earthquake compared to ‘expansion loops’ and telescoping and bellows-type expansion compensators that have been traditionally used in piping design for these high structures. More and more, they are being used in buildings in non-seismic areas because they require a minimal amount of space adjacent to pipe/floor penetrations and are maintenance free throughout the life of the building.
The high temperatures involved with STEAM and ENGINE EXHAUST PIPING present another challenge as the use of springs and elastomeric isolation mounts and materials would be inappropriate in many, if not most, situations. Fortunately, there are vibration isolation anchors (W302) and guides (VA50247(H)) for these high temperature applications.