Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Possible Enercalc Load Combination Problem

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Conrad, I agree with you on all fronts here.  The problem (for me) is having the time to create something presentable and at least semi-automated.  Or convincing the bosses that it would be cost effective to hire an intern for this purpose... (most fresh grads ought to be able to create anything you need with minimal direction)  In most cases I don't even have the time to deal with formatting something on the computer - it's just plain faster to do it by hand... just not in the long run of course.  But I have a few half-working spread sheets, created specifically for one job and massaged from there to add extra shapes etc. for the next job it was used on... but they are still only 'almost' capable of saving time in most cases. 

But I think something else is at work here: as far as I understand, Enercalc used to be just a set of spreadsheets with a nice UI and presentable reports, and it wasn't too expensive.  So it was likely cost effective at that time to just buy something already complete, rather than recreating it.... From there we've just gotten hooked on using it.  

As a side, something I can't stand is the "black box" math of softwares.  As far as I'm concerned, computer reports shouldn't be different than what we would create by hand - content-wise.  Input variables stated (or not if we're talking constants like E_steel) controlling load case *only*, maybe a free-body diagram, a formula, the input value shown in the formula immediately after, and then the result.  Unfortunately, a software that can be used to create such automation doesn't exist.  Excel isn't good with stating formulas - sure you can use math type to insert pictures of the formulas, but I've hit a number of formatting issues doing this, plus the formulas can't be made to be dynamic - and creating something that moves/hides pictures for all of the various failure modes and possibilities becomes cumbersome, and usually ends in a heavy/slow piece of s_oftware. Mathcad works well, but it doesn't show the values in-formula and with a large number of variables it begins to look like computer code.  Plus with some of the advanced features it begins to break easily - just move something slightly and for no apparent reason it claims the variable is no longer defined... TEDDS appears to be a good solution and has canned data tables for beam sizes etc. but I have yet to own it, so that is just theory.  Speaking of which, as I'm sure Mr. Newton is reading, why not offer the creation portion of TEDDS for free in the lite version to make it more functional - just limit the developer tools and advanced functions for the purchased version - I think people would be more likely to buy if (A. it were a common name, like enercalc, and (B. they were better exposed to what they *could* do with it, if only they had the full version.  It is kind of a Microsoft approach to marketing, but apparently it works.  

As for the wasted time on formal calcs and submittals... the lawyers have to have something to work with, right?

-----Original Message-----
From: Conrad Harrison [mailto:sch.tectonic(--nospam--at)] 
Sent: Tuesday, June 29, 2010 3:11 AM
To: seaint(--nospam--at)
Subject: RE: Possible Enercalc Load Combination Problem

I'm curious as to what attracts people to software like EnerCalc in the
first place.

You have pencil, and paper and say slide rule, along with various drawing

You notice that a large proportion of what you write and draw is highly
repetitive. Multiple copies of drawings are required for production and
tracers and copy drafters produce these copies. With no other copying
technology available, not sure how calculations were copied in triplicate:
carbon paper maybe. Or maybe there was less need for such waste.

Any case along comes new fangled device in the form of a photocopier: less
trouble and better quality prints than any previous copying process. So take
pen and good quality paper and in your best hand writing produce a master
template for all that repetitive writing and drawing. Then take copies each
time need to replicate and fill in the blanks. New recruits have guidelines
as to the correct procedure as they follow the template and fill in the

The calculations are repetitive enough that move over to tabulating the
results and input parameters, and produce an appendix with one sample of
worked calculations. Most of the numerical calculations are carried out on a
scratch pad aside from the main body of the report in any case.

Then the electronic calculator comes along and the scratch pad calculations
to work out the numbers and fill in the blanks is discarded. Then
programmable calculators arrive and getting the final numerical results and
making the design decision becomes even faster: documentation is however now
a bottle neck. Largely because documenting decisions has become an end in
itself. For not only is the generic form of the calculations highly
repetitive but so are the input parameters.

Then desktop computers arrive, but when it comes to programming: 80% of the
effort is required for the user interface: getting numbers in and out of the
program: the calculations are easy. Then arrives the electronic spreadsheet.

Now instead of pushing numbers onto the stack of your HP/RPN calculator, can
type the values into a spreadsheet, and the elements of the stack can now be
readily labeled. The problem of programming input and output is taken care
of by the spreadsheet. So within the time it takes to push the numbers
through a calculator now have a simple program: that can be used over and
over again: whilst fill in the numbers on that photocopied master.

With all the time saved by the photocopier those highly repetitive
calculations, can be transformed into pre-engineered prescriptive solutions
for specific applications. In general only need to know maximums and
minimums: the basic limitations of the structural components and whether
fit-for-function for the current application. The loads are standardized the
sections are standardized, and the applications are largely established:
that is we are not at the frontiers of science and technology.

With the time saved by standardization and the calculation of limits, time
can be spent transforming that spreadsheet calculator into a more readable
report that can be printed out and displace the master template. No more
transcribing substitution of numbers into formula and calculated results.
Just input the parameters into the spreadsheet, and printout.

Further more the results of one spreadsheet calculation can be linked into
the parameters of another spreadsheet calculation: so can build a model of
an entire project. Change one parameter everything dependent also changes.
Calculations can be copied in blocks, assembled together or if have one
large model to suit the typical project, delete that not required for the
simpler project: so deliberately delete that which choose to ignore rather
than forget. The calculation can be rearranged, or if simple just use goal
seek to change a single parameter to achieve the desired result. You do the
calculations to suit the task at hand. If need a table of values or graph,
then easy to do.

You are not constrained by the limitations of the commercial software
produced for a specific purpose. For example if want to produce span tables
for a given application (say series of carports), then with most commercial
software would have to carry out multiple iterations manually, and manually
assemble results into a table. With a spreadsheet can produce the table
directly, and plot a curve to check has the correct trend. Also if have the
calculations in Excel/VBA can also provide client with something better than
just span tables: can eliminate the error in reading span tables by
providing a custom application program: which produces a specification
drawing which they can use to check the input parameters.

Further more why are we churning out all this paper for calculations which
serve no real purpose? It is in the main just paper shuffling, the
structures have been built a thousand times or more previously. The
calculations are not telling us anything new.

If the designer can push numbers through Enercalc and get results in say a
few minutes, then why print out any calculation reports? The certifying
authority only needs to know the input parameters, the controlling
characteristics for the proposal so that they can assess its compliance with
the code. They can push these parameters through the software in a few
minutes also and get the results: and reach a decision. No detailed
calculation reports with pretty pictures required: just a simple summary
would suffice. The detail of the calculations needs to suit the importance
of the structure and the importance of the component to the structure. Most
commercial software doesn't really accommodate for this, and pages and pages
of unwarranted detail are printed out: which people have to copy, transport,
check and store. If print to pdf, still got to copy, check, transmit and
store. The software defines the structural model, if it is relevant to the
proposed building, then just need to store the input parameters, and have a
summary report that: all was ok!

How did we get to a point where by calculations in the majority of cases are
done to produce a document simply to satisfy a regulator and no other

Here in SA most hot rolled steel design is mostly done using design capacity
tables, not by direct calculation to the code. When permissible stress code
was displaced by the limit state steel code, the main complaint was that now
they would have to do the calculations: they wanted to return to permissible
stress to continue using the available safe load tables. Once limit state
design capacity tables were introduced the opposition to limit state
basically disappeared.

But there are no design capacity tables for cold-formed steel, the
calculations have to be done to the code: the only exception is load
capacity tables for cee and zed/zee section girts and purlins. More general
assessment however has to be done to the code and few people do so. There is
little available software to Australian codes, if there is any there is
little variety: choice of one. So typically have little choice but to write
own computer applications or complete calculations manually.

Though the more common approach is to declare impossible cannot do that in
coldformed steel, and try to get the client to accept hot rolled steel or
what ever material they can easily design: timber from span tables. Timing
may be a problem, with quick answers wanted.

That aside, why would someone who's job involves determining the
calculations to suit a specific task, choose to become dependent on software
from someone else?

For example as far as I understand the AISC/ASI design capacity tables were
produced using a customized version of LimSteel. The two main frame analysis
programs used have LimSteel integrated and available as stand alone. Whilst
it achieves consistency, who is checking that LimSteel is valid? No real
forum in Australia debating error in capacity tables, span tables or
software, or codes. Regulatory notices criticizing software for manufactured
timber trusses, and specifying requirements for. But no debate.

There is also that issue of everyone saying how do you check the software?
Well the simplest and fastest way is to build an Excel calculator, not
concerned about the presentation just the number crunching. Check that Excel
can get the numbers right, and check that the calculator gets the numbers
right, and the slide rule, the log tables and the counting board. On the
other hand building and testing a prototype more reliable than mathematical
model. Just depends on how critical getting it right is: what ever right is?

When doing a value-analysis how does software like EnerCalc and similar
become a preferred option?

Writing a graphical user interface for frame analysis or finite element
analysis is not something would want to do: but if have a special purpose
then maybe it is. In which case open source code, or GPL licensed
preprocessor and post processor software would be a benefit.

As far as I understand EnerCalc, is not open source, nor open architecture,
therefore stuck with what it does. And from what I gather it does relatively
routine calculations. If it supported COM automation, and could be linked
into Excel, and therefore greater control over the sequence of calculations,
and the input parameters and output presentation, then potentially useful.

Don't want to be limited by what design capacity tables permit, nor limited
to what software like EnerCalc and similar permit. Nor limited to how fast
can do the job with the software: bottle necks with respect to what goes
into the software and what need to do with what comes out. With COM
automation can automate the input and output to the specialist application.

Put another way those using Excel and similar may be, depending on the
nature of the project, completing their work significantly faster than those
using off-the-shelf engineering software.

Secondly there are builders and manufacturers who have products which are
largely standardized and don't want to be using off-the-shelf software for
the few parametric variations permitted: nor employ people to drive such
software. Writing custom software to better suit their needs is another
market for engineering services, if have suitable computing skills as well.

So if you are the engineer using off-the-shelf engineering software then
your toolbox is some what limiting: like having your hands tied behind your
back. But that may be just what is needed to best serve your market.

Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
South Australia

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ******** 

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ********