Load and Resistance Factor Design Rules
sign philosophies for designing structures are cur 
rently in use.  The LRFD philosophy utilizes proba 
The University of New Orleans, College of Engi 
bilistic methods as opposed to pure static and dy 
neering  teamed  with  the  University  of  Maryland,
namic formulas used in the ASD philosophy.
College Park to develop new design rules utilizing
Advantages of the LRFD philosophy include a more
probabilistic  methods  to  reduce  weight  in  future
rational  approach  for  new  designs  and  configura 
commercial and naval vessel structures.
tions; consistency in reliability with the potential of
a more economical use of materials; building codes
The University of New Orleans, College of Engi 
can be calibrated by allowing for future changes as a
neering (UNO COE) saw a need for weight reduc 
result of gained information in predicted models, and
tion in today s shipbuilding market.  The U.S. Navy
material and load characterization.
is  now  requiring  the  use  of  light  gage  plate  in
nonstructural  and  structural  bulkheads  on  their
LPD 17 and DDG 21 next generation warfighters.
On going committee studies were considered by the
team in the development of these new procedures
Advanced Composites Manufacturing
for the design of ship structures.  Initially, the Load
and Resistance Factor Design (LRFD) criteria is en 
visioned to be used in parallel with currently used
The University of New Orleans, College of En 
procedures.  The applications and limitations of this
gineering  participates  in  the  development  of  a
procedure are currently limited to the design of  fine
highly  capable  fiber  composite  system  and  con 
bow, bow with flare, or flat bottomed vessels and con 
tributes to a collaborative manufacturing environ 
ventional displacement type monohull surface ves 
ment  that  provides  considerable  economic  and
sels made of metallic materials, and with a length
educational opportunities.
between perpendiculars of 300 feet to1000 feet.
The old process to design vessels utilized Navy or
The University of New Orleans, College of Engi 
the American Bureau of Shipping rules.  New de 
neering (UNO COE), in partnership with the state
signs do not have historical information to use as a
of Louisiana, the National Aeronautics and Space
basis.  The team s objective in the first year was to
Administration (NASA), and Lockheed Martin Cor 
develop  LRFD  criteria  for  hull  girder  bending  of
poration at the Michoud Assembly Facility in New
surface  ship  structures  for  both  commercial  and
Orleans, is directly involved in the provision of re 
naval vessels.  In the second year, the team devel 
search, development, and education for manufac 
oped LRFD criteria for unstiffened panels of sur 
turing the next generation launch vehicle systems.
face  ship  structures,  and  in  the  third  year  of  the
State funding and NASA facilities have been com 
project,  it  developed  LRFD  criteria  for  fatigue  of
bined to provide UNO COE with an opportunity
surface ship structures.
to participate directly to effect an intelligent col 
The development of this new method for the struc 
laborative  manufacturing  environment,
tural design of conventional displacement type sur 
strengthen national competitiveness in aerospace/
face monohull ships is based on a structural reliabil 
commercial  markets,  develop  and  manufacture
ity theory in an LRFD format.  The LRFD rules can
composite materials, and expand regional economic
be used for early design of ship structures to check
development  and  advanced  manufacturing  tech 
adequacy in the detailed design stage.  For marine
nology education opportunities.
applications, LRFD development is based on special
Operating under the auspices of the National Cen 
and extreme analysis of wave loads with a combina 
ter  for  Advanced  Manufacturing  (NCAM),  UNO
tion of partially correlated loads.  Nominal strength
COE established significant cooperation with fed 
and load values, along with achieving target reliabil 
eral agencies, universities, the state, and industry.
ity  levels,  are  also  considered. The  LRFD  method
NCAM currently possesses and operates a highly
builds on conventional marine and structural codes.
capable fiber composites installation, and is in the
The design philosophy must provide for ship struc 
process of developing and obtaining a state of the 
tural designs that have adequate safety and allow
art system to advance this manufacturing technol 
for the proper functioning of each component.  The
ogy.  With the capability for seven axes and 24 tow
Allowable Stress Design (ASD) and the LRFD de 
fiber placements, the current composite fabrication

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