diagrams for stair platforms

I 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.

 

"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



.....................................

:I 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.
:

 

Did you consider using DDD or Feature modeling and linking to the
spreadsheets?

--
regards /Thomas V

 

Thomas:

DDD. . . . . . . Isn't that dimension driven cells?

I've never used DDD. From the little I know I think that could work, and
in large industrial and process mfg. projects the number of modified
cells for stair ramps would be nearly 100%. Far less for inhabited
buildings.

Can you outline a way to construct a DDD cell for that purpose?

For a 2D elevation drawing of the side profile the main numbers to enter
would be the fin. floor-to-fin. floor distance, or FFD. For ramps of
known numbers of risers, the fin. elev.-to-fin. elev. distance, or EED.
Landing depth could also be entered.

What is feature modeling? How does one link model features to a
spreadsheet? Would the entire stair structure considered as a 2D or 3D
model be a single data driven cell?

Once a stair general design has been established the advantages of the
linked model would be in the automation of the modifications. That would
pay for itself in the first 100% change of elevation heights. Making
drawings one at a time in scratch style would mean that both the
calculations and the drawing would have to be changed for each revision.
That's weeks of work at a probable rate of $4k per week not to mention
that the job captain has to check everything at an even higher rate and
order scratch revisions further raising the cost.

Thanks for the information.

Ralph Hertle

 

Across a language barrier, I am Swedish, I'm lost in some of your
jargong/techical terms . I do wish there could be some place on the net one
could find translations and definitions of proffesional terms and jargong.
Wikipedia/Wiktionary might be usable.

Anyway - I use Triforma and Architecture and model most in 3d and then
"calculate" the cuts for plans and elevation. The "stair maker" in TF is
awful and there is a new tool announced for Athens. And Structural have a
tool for stairs + handrails that is said to be ok for "industrial" stairs.

But a scenario with setting up base data + "rules" for a stair in a
spreadsheet and having that linked into ustn and "drivinging" the
3d-geometry, for later TF 2d-"calcualtions", is a good one. Be it with
DDD(=dimension driven desing), Feature Modeling or Generative Components
(even if that probably is to use cannons on mosquitos), or even custom
linestyles.

Feature Modeling has been around for a while in ustn v8,9. (TOOLS>FEATURE
MODELING). And you can do amazingly much in 3d with custom linestyles -
thinking of handrails.



regards /Thomas V