Design Team Communication Helps Minimize Natural Hazard Loss
April 2006
Natural disasters, such as the Gulf Coast
hurricanes in 2005, typically focus attention on how structures perform when
subjected to extreme loads. Material specifications, building codes, and construction
practices are often scrutinized to determine if there are changes that should
be made to improve performance. The methodology by which a project site is selected
and how the project design team communicates throughout the design process is
often ignored in discussions of natural hazard loss.
by Nathan
C. Gould, D.Sc., P.E., S.E.
ABS Consulting
and Gregory L. Hempen, Ph.D., P.E., R.G. URS Corporation
A new paradigm for design team communication is required to minimize natural
hazard losses while maintaining a cost efficient design.
Site Selection
When selecting a site for a new building or industrial facility, there are
many issues to be addressed prior completing the site selection process. Issues
related to transportation and local infrastructure are often paramount to the
site selection process, while other issues, such as the risk from natural hazards,
are considered secondary. In many instances, the person who is responsible for
making decisions related to site selection may not have the background or resources
to understand the risk that various natural hazards present. The developer and/or
owner of the potential site may engage an architect prior to site selection,
while other design professionals such as a geotechnical and structural engineer
are typically not consulted until later in the design process.
If the prospective site is located in a region of extreme wind hazard, consideration
should be given to issues such as the orientation of the new building or facility,
the structure's elevation relative to potential storm surges or other flooding
hazards, and the potential exposure to wind-borne debris that can result in
extensive nonstructural damage in the event of extreme winds.
For sites located in regions of moderate or high seismicity, it is important
to consider seismic risk from both an ongoing business perspective, and the
immediate implications directly related to the cost of the new building or facility.
Unrecognized hazards—such as soil liquefaction and lateral spreading, which
may have profound risk implications in the future—may be addressed by the design
professionals early in the site-selection process. Subsurface conditions—such
as soft soils, poor bearing capacity and/or potential slope instability—will
present an immediate issue for the design team in the form of increased design
costs. The geotechnical and structural engineers can also address these potential
problems during the site-selection process that will save design and construction
costs later.
Communication
Once a site has been selected, and the design process moves forward, it is
important that the owner and architect understand the benefits of early interaction
with the geotechnical and structural engineers who are part of the project team.
Early interaction between the architectural, structural, and geotechnical professionals,
along with the project owner, will result in a project that incorporates the
most current natural hazard design provisions, while minimizing any related
cost impact.
In the case of seismic design, significant savings can be realized if site-specific
technical information, most commonly shear-wave velocities, is developed utilizing
the borings obtained as part of a standard soil investigation program. The differential
cost to the owner for collecting the additional data related to seismic design
can be fairly minor. However, if these shear-velocities are not obtained during
the standard boring phase of the project, the additional cost to acquire this
information at a later date can be significant.
The figures provided illustrate different approaches to communication within
the project team relative to interaction between the design professionals and
the owner. In the first approach, illustrated in Figure 1, the geotechnical engineer is hired by either the owner or architect,
and then delivers information back to the architect and structural engineer.
There is typically minimal feedback from the structural engineer to the geotechnical
engineer, and from the geotechnical engineer back to the owner. The second approach,
which is illustrated in Figure 2, is the recommended
protocol, whereby all members of the project teams work together early in the
design process to optimize the value that can be provided by the design professionals.
As discussed above, under this organization the owner would involve all of the
design professionals during the site selection. The geotechnical engineer, structural
engineer, architect, and owner would also confer early in the process to determine
what site-specific, geotechnical information will be critical to the design
process. This discussion should occur prior to commencing any work in the field.
Figure 1: Typical Project Team Communication Structure
Figure 2: Preferred Project Team Communication Structure
Summary
A new paradigm for design-team communication is highly desirable, as natural
hazards become more costly and design criteria are incorporated into building
codes to address the hazards. Under the proposed design-team communication structure,
the full design team works together early in the site selection and design process
to minimize the issues posed by natural hazards while maintaining a cost-efficient
design.
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