1 - Modern Steel Construction

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Technical
Design of Highway Bridge
Girders on the PC
The American Institute of Steel Construction,
Inc., IS cooperating With Bridge Software
Development International, Ltd.. of
Coopersburg, Pa .. In an effort to provide software
for computer-aided deSign of steel
bridge girders, BSDI has developed the Line
Girder System (LGS) package of computer
programs, whICh enables the design engineer
to take full advantage of today's desktop personal
computers (PC's) Most software can
perform qUickly computations that were always
required, but the LGS goes further- It
permits a new level of decision-making
through lIS Interaclive and user control fealures
Designers can scrutInize results of their
decisions, so a contmual learnmg process
occurs With LGS. The user becomes, In a
fashion, his own "optimizer," For example,
through Interaction With the LGS, the user
can examine the relationship between
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fatigue, Yield stress and girder depth, or the
relationship between compression flange
buckling and diaphragm arrangement. ThiS
level of Investigation can be perlormed
Without the uncertainty 01 cosls and turnaround
associated With mainframe computing,
be Ihey time-sharing or In-house. A
profeSSional , Investigative approach to
bridge deSign no longer has to be balanced
against computing and man-hour costs
The ability to investigate a three-span
girder In less than 30 minutes permits confidence
In review of in-house work as well as
the ability to qUickly develop hard Information
for proposals and to perform type, size
and localion studies. These speedy Invesl/gations
Include much more than an analy5ls
purely for adequacy-they Include evaluation
of Important variables such as girder depth,
flange Sizes and girder handling Information
such as field section lengths and weights.
Hardware Requirements
The LGS programs run on Industry-standard
MS-DOS microcomputers, which have a
parallel port receiving RS232 shaped attachments.
The programs are prOVided on
5V. -/n 360K floppy diSks. All 10 executable
programs of the LGS can be Installed uSing
less than two megabytes of disk space If disk
space IS limited, the programs can be run
from floppies or from a RAM drive_
Capabilities
The LGS programs prOVide the tools to
deSign straight girders haVing.
• Up to 20 continuous spans
• Composite or non-composite action
• Composite or non-compoSite action In
negative moment regions
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