1. Anchor
Channel Systems
2. HAC
Portfolio
3. HAC
Applications
4. Design
Introduction
5. Base material
6. Loading
7. Anchor Channel
Design Code
8. Reinforcing
Bar Anchorage
9. Special Anchor
Channel Design
10. Design
Software
5.5 SEISMIC CONSIDERATIONS
This application chart offers a general guideline addressing environmental corrosion (direct chemical attack). Site specific
conditions may influence the decision. 5.5.1 SEISMIC CONSIDERATIONS
Aluminum fastenings (flashing / roofing
accessories, hand rails, grating panels, sign posts
and miscellaneous fixtures) Interior applications without condensation Galvanic zinc plating
Exterior applications with condensation Stainless steel, X-CR
Water treatment Not submerged HDG, Sherardized or Stainless steel
Submerged Stainless steel
Not submerged HDG or Stainless steel
Submerged Stainless steel
Non-safety critical or temporary connections HDG
High humidity with the presence of chlorides —
splash zone Stainless steel 1
On the off-shore platform or rig Stainless steel
Non-safety critical HDG
Safety critical or subjected to high concentrations
of soluble chlorides Stainless steel 1
Above grade HDG
Below grade Stainless steel
Non-safety critical HDG or Stainless steel
Safety critical or subjected to high concentration
of soluble chlorides Stainless steel
Non-safety critical HDG, Stainless steel
Safety critical Stainless steel 1
Waste water treatment
Marine (salt water environments, shipyards,
docks, off-shore platforms)
Indoor swimming pools
Pressure / chemically treated wood
Power plant stacks / chimneys
Tunnels (lighting fixtures, rails, guard posts)
1 Steel selection depends on safety relevance
In general terms, the main difference between static loading and
seismic loading of attachments is the multi-directional cyclic
loading induced by the seismic event as shown in Figure 5.5.1.1.
A seismic hazard is the probability that an earthquake will occur
in a given geographic area, within a given window of time, and
with ground motion intensity exceeding a given threshold.
The U.S Geological Survey (USGS) has produced a one-year
2017 seismic hazard forecast for the central and eastern United
States from induced and natural earthquakes that updates
the 2016 one-year forecast; this map is intended to provide
information to the public and to facilitate the development of
induced seismicity forecasting models, methods, and data. The
2017 hazard model applies the same methodology and input
logic tree as the 2016 forecast, but with an updated earthquake
catalog.
In order to ensure the adequacy of the anchor to resist seismic
loads, the seismic analysis needs to be performed, even when
at first glance, the seismic loads seem to be significant lower
than the static loads.
Figure 5.5.1.2 illustrates the different seismic design categories
in different states of the United States. Although regulations in
some state are more stringent than others, in order to provide
IBC-compliant solutions and ensure the general welfare of
citizens, seismic design verification for anchor channels is
performed for anchor channels located in structures assigned
to Seismic Design Categories C, D, E, or F.
Fastener Recommendations
14. Design
Example
No significant cyclic loading with inertia
In summary:
Figure 5.5.1.1 Comparison of loading characteristics under seismic and
static conditions (reinforcement not shown for clarity).
In addition, loading frequencies during earthquakes often lead
to resonance phenomena which result in greater vibration
amplitudes on the upper floors than on lower floors. This may
result in a need for different designs for anchor systems situated
140
• Seismic conditions can significantly change the behavior of
anchors, compared to static conditions.
• It’s important to include seismic design for both structural
and non-structural elements of a build, as research shows
that non-structural systems suffer the largest damage in
commercial buildings during an earthquake.
• Adequate seismic construction design and specification
reduces the probability of a failure of the anchorage during a
seismic event.
• Seismic events have a big impact on the loading and
behavior of anchors in the supporting material, resulting
in the possibility of some anchors being unsuitable for
seismic conditions or having a lower capacity under seismic
conditions than under static conditions.
Cast-In Anchor Channel Product Guide, Edition 1 • 02/2019
141
Figure 5.5.1.2 — U.S. seismic hazard map.
Significant cycle loading with multi-directional inertia force
Conditions
13. Field Fixes
Application
Rapid ground movement during an earthquake leads to relative
displacement of a building’s foundation. Owing to the inertia
of its mass, the building cannot follow this movement without
experiencing deformations in the building frame. In addition,
accelerations are induced in the structure. Due to the stiffness
of the structure, restoring forces result and cyclic strains are
induced in the structure. These strains are also experienced
by anchors used for attachment of nonstructural components,
such as cladding, to the structural frame. The loads acting on
these anchors can be calculated directly on the basis of the
dynamic characteristics of the building, local site seismicity,
soil characteristics, and the dynamic characteristics of the
components fastened to the building.
12. Instructions
for Use
5.4 SPECIAL APPLICATIONS
11. Best
Practices