Coastal Construction Manual - National Ready Mixed Concrete ...

IDENTIFYING HAZARDS 3
non-ductile connections, especially at welded connections. Bolted connections have performed better than
welded connections under seismic loads. Modern concrete construction can be dimensioned and reinforced
to provide sufficient strength and ductility to resist earthquakes; older concrete structures are typically more
vulnerable. Elements of existing concrete structures can be retrofitted with a variety of carbon-fiber, glassfiber,
glass-fiber-reinforced or fiber-reinforced polymer wraps and strips to increase the building’s resistance
to seismic effects, although this is typically a costly option. Failures in concrete masonry structures are likely
to occur if reinforcing and cell grouting do not meet seismic-resistant requirements.
3.3.3 Tsunamis
Tsunamis are long-period water waves generated by undersea shallow-focus earthquakes, undersea crustal
displacements (subduction of tectonic plates), landslides, or volcanic activity. Tsunamis can travel great
distances, undetected in deep water, but shoaling rapidly in coastal waters and producing a series of large waves
capable of destroying harbor facilities, shore protection structures, and upland buildings (see Figure 3-12).
Tsunamis have been known to damage some structures thousands of feet inland and over 50 feet above
sea level.
Coastal construction in tsunami hazard zones must consider the effects of
tsunami runup, flooding, erosion, and debris loads. Designers should also
be aware that the “rundown” or return of water to the sea can also damage
the landward sides of structures that withstood the initial runup.
Tsunami effects at a site are determined by four basic factors:
Magnitude of the earthquake or triggering event
Location of the triggering event
Configuration of the continental shelf and shoreline
Upland topography
NOTE
Information about
tsunamis and their
effects is available
from the National
Tsunami Hazard
Mitigation Program
Web site: http://
nthmp.tsunami.gov.
Figure 3‐12.
Damage from the 2009
tsunami (Amanave,
American Samoa)
SOURCE: ASCE, USED WITH
PERMISSION
COASTAL CONSTRUCTION MANUAL
3-19