ETABS Recovered Loads

When designing a structure, you as the structural engineer must keep in view the big picture. What are the ‘vital signs’ of the structure? What do you tell your supervisor when they ask for a quick status?

ETABS, like other analysis programs, doesn’t provide a quick answer to these questions. Enter the “Recovered Loads” spreadsheet, which provides a 30,000-foot view of your building on one printed page.

ETABS Recovered Loads.xlsxETABS Recovered Loads

At a glance, this tool tells you what you need to know about the building:

  • Area
  • Mass and Weight
  • Dead, Superimposed Dead, and Live Loads (total and per area)
  • Steel and concrete weight per area
  • Base Shears for all loads
  • First three building periods

Instructions are found on the first tab of the spreadsheet. Questions? Let me know via the comments.

Posted in ETABS, software, tools | 5 Comments

ETABS 2013

The eternally-pending release of ETABS 2013 is a recurring topic of conversation in my office these days. As a major factor in my productivity and thus my bringing home the necessary bacon, I have a great deal of interest in the new release myself.

etabs_2013_4

Timing

Overheard in my office: “2013? We said 2030.” It was late 2005 when ETABS 9.0.0 was released; more than seven years later, CSI has been promising ETABS 2013 in “the next few weeks” for some time. Recent support inquiries have been answered with “wait for the next version, coming soon.” CSI has told me that for the last few years, other sectors (bridges, oil and gas) have been hot while buildings have decidedly not been, which has certainly slowed the development. I expect that the new version will actually and finally be released this spring.

What to Expect

  • “SAPification” – If you use SAP v15 or SAFE v12, you should not be surprised by anything in the new interface. Improved graphics will be appreciated so long as they don’t make the program seem less snappy.
  • “Web-activated licensing schema” – This info comes from a recent support response. ETABS 2013 will apparently be the first CSI product licensed via the web, a la Bentley. If done well, this will be helpful, particularly if it allows occasional over-usage for deadline days (as RAM products do).
  • Advanced shear wall design tools – This was in the works all the way back in 2009. I expect better visualization of bars and the ability to more easily check boundary zones.
  • Improved composite beam design – Check this under-construction page on CSI’s website for more info.
  • Goodbye to keyboard shortcuts – I use custom keyboard shortcuts in ETABS incessantly and will be chagrined to see ETABS 2013 follow the “what we give you is all you get” path of SAP and SAFE.
  • A few problems – Past experience with major upgrades says that one might do well to wait a few months to make the jump, unless you want to be the one wrestling with the bugs. At the very least, test ETABS 2013 against the current release as much as necessary to develop trust.

What are you looking forward to in ETABS 2013?

 

 

Posted in ETABS, software | 6 Comments

Hard Lessons

Dear Young Engineer,

A friend and I were talking not long ago and I mentioned my “I’ll never do that again” list. He asked if he could see it for his own benefit and I told him that it wasn’t written down, although my boss seemed to enjoy quoting from it. Even though these have been hard lessons and are not flattering, I trust that publishing some of them here can help you avoid the same problems.

erase

  • Remember the Live Load – I performed a preliminary design of a two-story structure using RAM Structural System, dutifully adding 20psf of roof live load. After returning from a week away, I learned that my boss had found a small problem: the general criteria in the program were set such that roof snow load was considered rather than roof live load. Fortunately, this was early in design and did not cause any more problems beyond my embarrassment. Ironically, it was yours truly that had warned the entire office of this possibility some months prior to this incident.
  • Watch the Hatch – Strictly speaking, this was not my error, but I was responsible for catching it and did not. A metal deck roof diaphragm was properly designed with tighter weld patterns at the perimeter, which were shown with a hatch pattern on the drawing. However, the legend was switched such that the tighter spacing was shown in the field. This wasn’t noticed by anyone until a site observation during construction. We were able to show that the existing pattern did work at the perimeter, thankfully. Lesson: just because it looks right doesn’t mean it is.
  • Dicey Splice – I designed a moment frame lateral system for a small parking structure. I failed to notice that the typical detail shown for the column-to-footing detail specified a compression lap splice. The saving grace here was the ample conservatism in the generic code splice lengths, allowing a much shorter length to suffice in a particular situation such as this one.

Note that none of these errors has led to dramatic consequences, let alone danger to the public. They have, however, increased my humility and my near-paranoia about checking my work in every way possible. They’ve also brought home the absolute necessity of another set of eyes on a set of drawings. As project engineer, you are incapable of seeing your own design clearly, making even basic errors more likely to be missed.

Remember that you are not perfect. Be humble enough to seek out feedback and correction, and not just of your drawings. Over time, you will become a far better engineer with this attitude than one of overconfidence.

So, do you have any ‘lessons learned’ you can share?

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A Structural Engineer’s Toolbox

How does a structural engineer work well? The same way as any other professional: by using the right tools. Here are the basics in my toolbox:

  • Pencil and paper – start here, always. You should be able to explain a design via a hand sketch and brief calculations before running to the computer. For a recent long-span truss installed in an existing building, the proof of concept filled just one sheet of paper. I’ve found that having a really good pencil and crisp paper makes it much more satisfying to put graphite on wood pulp.
  • Calculator – I take for granted how easy it is to outsource the grunt work of basic math. I highly recommend using one that is allowed on the SE exam. I switched from a graphing calculator to the TI-30X IIS a year before I took the SE, fully expecting to switch back. I never did and am still happily using this simple but powerful model every day.
  • Triangle and scale – these simple drafting tools allow you to create much better hand sketches and also give you credibility with the older engineers. You can’t draw pretty lines – you’re not an architect – so use the triangle.
  • Codes – these seem to be behaving in the manner of rabbits, with new editions coming out before you’ve even seen the previous one. But they are indispensable to our work, as they both provide the minimum requirements and in many cases explain how to do the design. The steel manual is the clearest of all the codes and contains excellent design aids and examples. For concrete, I use the PCA Notes on ACI 318 alongside the code.
  • Excel – the Swiss Army knife of calculations. I use Excel 2010 for any number-crunching that involves using the same equation more than once. Tables changed my life; I can work only in the first row of a table without a thought of the thousands of rows below.
  • MathCAD – Excel may be powerful, but it has two very significant drawbacks: it is hard to back-check (impossible when printed to paper) and it is not savvy with units. Most of my linear calculations are done in MathCAD 15, which does both the math and the unit conversion while displaying everything in the same form as a hand calc. The unit awareness is particularly useful when working on international projects, as results can be shown both in the native units (say kN-m) and more familiar units (kip-feet).
  • AutoCAD – although my office is using Revit Structure to produce drawings, I use AutoCAD 2012 every day for many tasks: sketching details, measuring dimensions in an architectural drawing, overlaying two drawings for coordination, or building a file to import to the analysis model. It will serve you well to develop skill in a 2D drafting program, at least for the foreseeable future.
  • 3D analysis program – every engineer should have a go-to analysis software. Mine is ETABS, which I’ve used in the design of everything from high-rise buildings to aluminum trusses. I know the program inside and out, including what it should not be asked to do. Pick a program and become expert at using it.
  • Special-purpose software – need to design an anchor? Hilti Profis will help you immensely. Have a single composite steel beam to size? RAM SBeam can’t be beat. There are many trustworthy, simple tools to help with routine design chores. Never let them replace engineering judgment; always find ways to check the results by hand or against a table in the manual.
  • Dropbox – all of the project files in my office are stored and shared with two other offices effortlessly via Dropbox. The best feature: unlimited version history. Saved over that important file? No worries – a few clicks and the previous version is back.
  • Workflowy – the newest addition to my toolbox. This online list tool stores my notes and to-do lists for most of my active projects and allows me to easily share them with coworkers.

Those are a few of my favorite tools. How about you? What do you find useful and why?

Posted in musings, software, tools | 2 Comments

The Missing Manual

No career comes with a manual. There is truly no substitute for experience in any field, most especially structural engineering. As I near the end of my first decade as an engineer, I have learned a few things that I wish I knew before I began. I would still have chosen to do this – I consider structural engineering my vocation – but I would have been far more effective. I plan to share those things here, using the following broad categories:

  • Practical Tips – how to ‘hack’ your work, leverage software, become more productive, and get more done.
  • Letters to a Young Engineer – encouragement for those considering or just joining the profession.
  • Musings – thoughts on how things are and how they could be better.

A note to the esteemed engineer with more experience: you’re welcome to read along with us. The more I learn, the smaller my knowledge seems and the more eager I am to listen to those older and wiser than me. Please, join the conversation. Tell us what you wish you had known when you began.

Together, with experience and fresh ideas, we can build the “missing manual” for our profession.

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