What’s Most Important To You As A Structural Engineer?

I am attending the 2012 SEAOC-SEANM Convention in Santa Fe, New Mexico this week. I did not realize that Santa Fe is the oldest state capitol in the U.S., first inhabited by Spanish settlers in 1607, and then settled by Don Pedro de Peralta in 1609-1610. The Palace of the Governors, built in 1610, served as the main government building in Santa Fe for nearly 300 years. The current capitol building, known as the Roundhouse, is the only round state capitol building in the U.S. Our airport shuttle driver used to be a tour guide, so we learned a lot on the drive in.Continue Reading

A Little Fun with Testing

My apologies for being late with my blog post this week. We are having our once a year big sales meeting, so I’ve been traveling to the Midwest to participate. Speaking of traveling, several times each year, we invite our newest employees to our home office in Pleasanton, California for a week-long Sales and Product Orientation class. Although originally envisioned as detailed product knowledge training for our sales people, the class has evolved over the years to include people from all areas of our business such as finance, accounting, IT, purchasing, quality, marketing, and (of course) engineering.

I do one presentaton for the class explaining the importance of a continuous load path in a building, and another covering the history of innovation that led to some of our products. It is a great opportunity for me to meet my new coworkers by spending some time with them before they embark on their careers in different parts of the country (or world!).

Holdown Test Setup

My favorite training session I do for the class is about product development and testing, which includes a tour of our test lab in Pleasanton. We go over a lot of testing basics – how we select lumber, get parts made, build setups and run the tests. For a demonstration, I used to run a simple joist hanger test and also a holdown test. Usually I’ll pick a heavy holdown to test, since those make an impressive bang when the steel breaks, and then everyone jumps and gets a good laugh out of it.


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Cantilever Floor Induced Load Path Concerns

IBC Section 1604.9 requires structural members, systems, components and cladding be designed to resist forces due to earthquakes and wind, with consideration of overturning, sliding and uplift. It also states that a continuous load path be provided for transmitting these forces to the foundation. Seems obvious to engineers that a continuous load path is needed, but it’s still nice to have the code say so.

But what happens if your structure’s upper and lower story walls do not stack? How do you create the required continuous load path? As engineers, we try to steer the architect towards eliminating the offset, making things line up, and keeping construction simple. But architectural requirements cannot always accommodate simple, and non-stacking walls occur all the time.

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Confidence in Code Reports

Every building uses products that are not specifically covered in the building code. IBC Section 104.11 permits this if the “alternative material” is found to comply with the code intent by the building official after review of supporting information, such as research reports and tests.

Reviewing product data might be a challenge for some building departments, as they vary in size and expertise around the country. Some of the questions they might ask are:

1. What, if any, criteria was used to evaluate the product (e.g., test protocol, load rating methodology),

2. Was the criteria developed based on a single individual or a single company’s opinion or was there at least some involvement of others in the construction industry,

3. Are there any potential conflicts of interest in the parties wanting to use the product or the company who evaluated the product, and

4. Are there other tests or analyses that need to be completed prior to accepting the products use in the jurisdiction?

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Corrosion in Coastal Environments

An ounce of prevention is worth a pound of cure

– Benjamin Franklin

Any contractor that has ever had to replace a corroded connector or fastener will tell you this quote is an understatement. Here at Simpson Strong-Tie, we spend a lot of time refining new product designs to simplify their installation, but uninstalling a joist hanger? It never crosses our minds, and it shows by looking at all the tools you would need: claw hammer, cat’s paw, reciprocating saw, and the all-important first aid kit.

But luckily for the project owner, an ounce of prevention only costs about the price of half a pound of cure. Stainless steel connectors and fasteners are in the range of 5-10 times the cost of galvanized steel. However,  connections are usually only a small part of a project’s overall budget and are a critical part of the load path, so the argument for stainless steel is an easy one to make.

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Is Your New Hire Ready For The Working World?

It’s that time of year again: newly graduated college students are entering the workforce.  For the student, it’s an anxious time. They are often wondering how and if four plus years of college has effectively prepared them for the real working world. For the potential employer, it can be a gamble. They have decided to take a chance on someone who likely does not have any professional work experience, but expect production from day one. On a recent visit to Cal Poly San Luis Obispo, my colleague Scott Fischer got a firsthand view of what students are doing to prepare for a career.

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Is It Friday Yet? Maintaining A Positive, Motivational and Fun Work Environment

It’s not Friday yet, but I am looking forward to the obnoxious Hawaiian shirts some of my coworkers wear as part of our Engineering Department’s unofficial Hawaiian Shirt Day each week. It’s a little thing, but it definitely helps lighten the mood and gives us all an opportunity to interact with each other.Continue Reading

How We Test – Part I: Wood Connectors

If you have followed some of my earlier blog posts, you know I am passionate about testing. In my post, Testing – Then and Now, I said, “There simply is no substitute for a physical test.” Something I haven’t discussed in much detail, however, are some of the complexities involved in a good test.

LUS2 10-2 Uplift Test Setup

For wood connector testing, we follow ASTM D7147-11 Testing and Establishing Allowable Loads of Joist Hangers. The actual testing is relatively straight forward – build at least three setups, test them, measure the deflection and ultimate loads.

LUS2 10-2 Uplift Test Failure





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Top 3 Roof Deck Design Considerations for High Wind Events

Was it JFK who said, “The time to repair the roof is when the sun is shining?” He was likely using the roof as an analogy for the economy, but I take things literally and wanted to talk about roofs.  The time to think about the design of your roof and its function in a high wind event like a hurricane or tornado is right now.

Wood screw vs. common nail

During a high wind event, a roof deck is expected to perform many functions. It should prevent water intrusion from rain, withstand impacts and protect those inside from hail. It also needs to act as a diaphragm – transferring lateral loads to shear walls and resisting the vacuum effects of wind uplift forces.Continue Reading

Flexible or Rigid? Multi-Story Light-Frame Structure Design Considerations

I like to think I’m flexible, but I’ve been accused of being rigid at times. I guess that’s what therapy is for. If you were to ask a light-frame structure diaphragm that same question, you would likely get multiple conflicting answers. The 1988 UBC first introduced parameters to evaluate diaphragm rigidity. Earthquake Regulations Section 2312(e)6 stated:

Figure 1. Flexible Diaphragm Definition from ASCE 7-05

Provision shall be made for the increased shears resulting from horizontal torsion where diaphragms are not flexible. Diaphragms shall be considered flexible for the purposes of this paragraph when the maximum lateral deformation of the diaphragm is more than two times the average story drift of the associated story. This may be determined by comparing the computed midpoint in-plane deflection of the diaphragm under lateral load with the story drift of adjoining vertical resisting elements under equivalent tributary lateral load.

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