Posted on

Large truck collisions with bridge piers

I am giving a short talk on Tuesday about designing pier columns to meet the AASHTO 400 kip collision load.

I found this new paper, “ANALYSIS OF LARGE TRUCK COLLISIONS WITH BRIDGE PIERS: PHASE 1. REPORT OF GUIDELINES FOR DESIGNING BRIDGE PIERS AND ABUTMENTS FOR VEHICLE COLLISIONS” FHWA/TX-10-4973-1,  online from the Texas Transportation Institute, which gives an overview of the design process.

The paper has Mathcad examples in the back but I think there are some inconsistencies in their use of beta /theta and tensile strain factors.

I think the most important point in the paper was the discussion of the shear failure mechanism due to an impact force. Two shear planes should be used in an analysis, which boils down to multiplying the column shear strength by a factor of two. This really boosts the shear capacity of our typical pier columns and helps them meet the AASHTO requirements.  I will post some of my talk later…..

Posted on

Businesses worry as bridge closure looms

Closing a bridge is always a concern for local businesses, so it is important that all aspects of the rehabilitation is carefully planned out.

Oregon City has already adapted to a 14-ton load limit imposed in March 2009 after inspectors found cracked concrete that had allowed water to penetrate and degrade the internal steel girders holding up the bridge. The original concept of a $3 million project expanded to $10 million, while a nine-to-12-month bridge closure expanded to the current expected closure of two years.

Posted on

Teaching Concrete Design

I just found out I will be teaching concrete design, at our local University, starting on Monday! Talk about a short time frame to get ready…

I’m sure the class will be well over a hundred students and I will have to shove them into groups of 3-4 for homework assignments. I think this semester I am going to make them develop spreadsheets for major topics, such as single reinforced beam, double reinforced beam, interaction diagrams for square columns, etc.

The biggest headache for me (its all about me) is grading exams. It takes about eight hours to grade an exam and I have four of them this fall, yikes!

On a side note, does anyone know a good free image site I can use to add interesting photos to my blog?

Posted on

Painting Progress 8/14

It is slow going in the painting department….but I am trying different things. Typically, when I want to learn something new I read as much as I can (which I am doing) but with painting it seems practice is the most important variable.

Right now I like about one in every ten painting attempts. I hope to improve on that ratio because it is very frustrating to spend two or more hours painting and end up with mud!

For example this study of flowers my wife gave me about ten years ago. (It is still alive!) I had a ton of colors on my palette so I mixed them together (to save paint) and got that awful orangey background.

A detail of the flower shows the paint application. (click for close up)

Then I tried a “folk Art” style of my friend’s house. I think it came out a little cartoony…onwards and upwards!

Posted on


Okay our mini crisis may be winding down depending on how much rain we get today. So to recap, I tend to over react in periods of uncertainty. For example, when I heard our city water may not be drinkable I drove for an hour to pick up enough bottled water for a week. I was also calculating how I could use the water from our dehumidifier to flush our toilets.

I worried about how I was going to get my family, 3 dogs, 3 cats, a guinea pig and horse to a hotel in another city. (I must be an engineer. My kids say I always look for the worst scenario.) And when the eventual riots broke out, how I was going to defend our hoard of canned goods. (And you know everyone was going to become a zombie, it’s just common sense.)

The other thing that occurred to me is how easy we have it. Imagine the inconvenience of 2-5 days of boiled water compared to nations without water to boil! When I was in Moscow, I did not understand how people survived when times were relatively good and now with the heat wave / environmental disaster looming, who do they turn to? And don’t get me started on Haiti or Pakistan….

So, bottom line, we have it good, I can stand to wear clothes two days in a row, the world is not ending. (not until 2012!)

If you can donate to those truly in need and as engineers donate as much skill as you can.

Posted on


Well the flood is over but now we have to boil our water to drink! At least I was smart enough to go and get six flats of bottled water before the end of times comes…we can bath in the city water but no drinky. The power also went out at my wife’s biotech company and all her chemicals / anti-bodies may have been compromised. We took what we could to another location, so we will have to wait and see what survives…

Sooo, this is a very minor annoyance for us but it put me to thinking what I would do in a major crisis. (Shopping at the local walmart with empty water shelves was surreal…I kept thinking about Omega Man!) Imagine if the water supply went down completely, no toilets, no showers and no fresh Popsicles!

Next time I will be ready with my high powered anti looting device! With optional orange spotting light!

Posted on


We had 11 inches of rain in the last three days. Couple that with near 100 degree temperatures and you have some fun. Now all the rivers and creeks are flooding and I am on an island at work.

Click on the image for a larger view.