"ut151469"
Concerning Diagrams for Stair Platforms, Ramps and Towers
I set up the dimensional geometry matrix for more than 4000 tread levels
for
a fossil fuel exhaust gas desulfurization plant, and that had eight tall
stair towers, miscellaneous stairs, catwalks, and mezzanines. [The
project
was by Shaw Stone and Webster for PPL.]
I used MicroStation to make the plans and elevations of the precise
geometries involved. These were based upon calculations made outside
MicroStation, and they were the base of the models made in MicroStation.
I decided that after having been provided blurry red line sketches,
numbers
and ungrammatical oral instructions from the job captain, that together
the
total instructions were unintelligible during the next several days and
weeks. There were also numerous instructions amounting to more than 400,
or
possibly 800, percent aggregate total redesign during the geometry layout
stage. Confusion was the order of the day.
I placed all the information that controlled the stair structure geometry
into an Excel website replete with levels, heights, widths, depths, and
tread offsets. Formulas governed the dimensions, and all numbers for every
ramp were automatically calculated. Many more weeks with a calculator, or
doing the geometry graphically using MicroStation, would have been
necessary
if Excel had not done the calculations. The information was available
weeks
and months later, and is the best way to provide the dimensional
requirements to the stair structures manufacturer. [Scratch built stairs
are
not a good idea.]
Break the design down into blocked sections for calculation in Excel. All
working points may be included, located and numbered, and all code heights
and widths can be properly noted. Excel also provides plenty of text
capabilities for notes, headlines, and related information.
Each ramp is drawn with a geometry cell that is modified using Fence
Stretch, for example, and placed into the drawing. For the 3D geometry
model
the geometry profiles were formed using Extrude Element on the cells.
The time consuming part of the work is making the numerous revisions, and
the geometry is based upon the engineer's basic design schemes. I found
that
the design arrangements didn't often require many changes in the vertical
dimension scheme, and any vertical changes were easily handled by entering
new values into Excel and recalculating.
If it had been necessary, it would have been possible to enter "IF"
formulas
in the Excel cells. If many level changes or added levels are necessary
the
number of risers per ramp changes, and the heights vary in, or not in,
accordance with codes or practicality. In that way Excel can provide a
greater or lesser number or risers of certain heights based upon the
intended floor to floor heights.
The detailed designed structures of the selected drawing types, either of
2D
or 3D models, are easily done once the factual information has been made
available, calculated and recorded.
I would suggest that the project engineer who integrates all design
matters
be in agreement of the method to be used, e.g., using Excel and
MicroStation, and that the job captain not make those decisions. The
engineer decided the principles of design arrangement, and the job captain
gives work instructions to make deliverables. That's a critical
differentiation. Its a critical method to be decided, and that the
information is then available to all concerned.
The structural engineers and structural designer/drafters should know
where
the files are located and how to employ the geometry data and drawings for
their designs.
While the automated CAD stair layout sub-programs in CAD programs, for
example, in IGDS or TriForma, can make the drawings, it is still necessary
to have all the information notes precisely stated in a proper file.
MicroStation's drafting commands are so numerous and functional that they
make short work of the drawing; especially if there is any amount of
custom
designing involved.
To make the finished 2D or 3D model add cells that have the desired amount
of abstraction or detail. Cells may provide a high degree of
representational accuracy concerning a specific vendor's stair product. I
strongly recommend not using authoritarian stair symbols or generic
stylizations, and that specific real-world vendor's products be used for
the
finished representations of the designs. Make a deal with the vendor to
either get their MicroStation cells, or that you split the costs of
creating
the cells.
With proper Excel files and models the vendor will be able to provide a
better job, and his work of detailing and cost calculations will take less
time.
The resulting 2D and 3D models and drawings will have a properly shaped
and
dimensioned appearance that will enable other systems to be correctly
designed in accordance with the stair systems. The dimensional information
in Excel will be in a proper format that will enable the stair
manufacturer
to detail the products to be furnished.
The Excel file is a better place for the dimensions than in a complex
drawing, although a few simple dimensions may be placed in the drawing for
wayfinding purposes.
Reply if you have any questions.
Let us know who you are and how your project develops.
Ralph Hertle
ralph.hertle@[EMAIL PROTECTED]
"ut151469" <DukeDB@[EMAIL PROTECTED]
> wrote in message
news:1192139607.343516.129150@[EMAIL PROTECTED]
am designing steel stairs for platforms in power plants. Can
: someone give me an idea where I might get some information on how to
: set up working points for the elevations, etc. Any help would be
: appreciated. Also I know autoCad has a stair converter. Any
: converter for Microstation? Thanks.
:
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