Search is not so simple

Regarding the opinions expressed in the "Letters" section of the April 2007 issue of Structural Engineer, we owe the public the duty of economical efficiency of both structures and services in addition to safety. While Mr. Ghosh’s point is well-taken that safety trumps all, Mr. Crandell’s point is also well-taken that this minimum load requirement is egregiously economically inefficient. This is so for the following three reasons: 1) It requires a completely separate analysis. 2) There are no vertical loads defined to act with this minimum horizontal load, nor is its distribution among the building surfaces defined; so it presents the building designer with a conundrum that must be thought through for each structure. 3) Because this minimum load is defined to act only on the horizontal projection of the structure, it has a built-in bias against those buildings with higher roof pitches. I have seen no scientific data which shows that this bias is justified by the actual performance of these structures.

So, I think that we can agree that some sort of minimum wind load check is prudent, but there must be a more scientifically based and better-defined one than the current 10 psf minimum on the horizontal projection.
Patrick M. McGuire, P.E.

Readers respond to "What is a bridge?"

In response to Richard G. Weingardt, P.E.’s column "What structure holds the title of the ’highest bridge in the world’?" that appeared in the June 2007 issue of Structural Engineer magazine, I offer the following opinion. From the perspective of structural design challenge and complexity, as well as construction difficulty, the walkway bridge and utility bridge should not be the record-holder for "bridge."
Yihui WU, Ph.D., P.E.

The website www.dictionary.com defines a bridge as "a structure spanning and providing passage over a river, chasm, road, or the like." It says nothing about a bridge requiring the passage of pedestrian or vehicular traffic; there are just two criteria: that it spans over something and provides passage (of something).

With this in mind, I think the records for bridges should be broken up into categories dependent upon what those bridges carry. Possible categories might include vehicular bridges, pedestrian bridges, and utility bridges. The Grand Canyon Sky Bridge, while a controversial engineering marvel, is just a cantilevered structure with no purpose other than tourism, and returns its users to essentially the same place they started from (which really isn’t a bridge at all). It does not "span" or "provide passage," and therefore, is not a bridge. The Hegigio Gorge Suspension Bridge does provide a span between two sides of a gorge and also gives passage to oil and gas. If the record books were to include categories, this would fall under the utility type.
Andrew D. Grundstrom, E.I.
Albuquerque, N.M.

I enjoyed reading Richard Weingardt’s recent column in Structural Engineer about the world’s highest bridge and would like to share some of my thoughts on this topic.

I looked at the two pictures in the article and then searched for a picture of the Millau Viaduct on the Internet. I can’t help but thinking how different they are in terms of scale. I agree the two structures are special. But they are much less magnificent than the Millau Viaduct. The Grand Canyon Sky Bridge is special due to the magnificent Grand Canyon. [There is] much less to say about the Hegigio Gorge Suspension bridge. I can barely notice it from the photo. I would imagine the Millau Viaduct is much more difficult to build. In this matter, even the Royal Gorge Bridge cannot compare.

To rank the highest bridge, I would like to borrow some ideas from the ranking of the world’s tallest building. We can compare the height of the bridge structure itself, rather than measuring how tall the deck is from the surface below. I noticed a website which has two rankings: highest bridge and tallest bridge
(www.foresthillbridge.com). Note the second group has some of the world’s most famous bridges.
Michael Day

Feedback on compensation

I just read "From the Editor" in the June 2007 edition of Structural Engineer.
I work for The Haskell Company in Jacksonville, Fla. (integrated design-build firm specializing in buildings), and we have had a heck of a time finding adequate staff to meet our workload. This has been the case the past four years. We find that it is tough to pry people with six to 15 years of experience away from their current employers. We have been hiring engineers out of school for the past few years and our experience with this past year’s graduates is that $50,000 is the minimum they are taking, and many are close to $55,000. A candidate with a master’s degree is earning $55,000 to $60,000. I think the 2007 numbers will be significantly higher for these employees.

Funny, if you think about staff salaries of other industries and compare it to the salaries of us structural engineers—we are a bargain. This is especially true when you consider the higher-level math and material behaviors that we understand and the risks we take with our work. I do believe that in 10 years, if the number of engineering graduates continues to decline, the salaries will increase significantly and finally put them where they need to be.
Thomas A. Grogan Jr., P.E., SECB
Jacksonville, Fla.