The Fritz Legacy: Materials scientist honored for 'bridging' disciplines

It takes about three years to build a steel bridge, spanning from one side of a stream, river or ditch, to the other. It takes much longer for that bridge to deteriorate, rust, wear down and possibly collapse. And when it does, civil engineers work for months to find out why – and decades to form steps to prevent it from happening again.

Several Lehigh professors have dedicated that time – given their entire careers, in fact – to researching steel bridges and their inevitable fatigue and failure. Well into the fourth and fifth decades of their decorated research careers, they run tests on the reliability of large structures, inspect aging structural elements and high-profile structural failures, advise on how to keep them standing tall, and guide the construction of newer, more resilient elements of our national and global infrastructure.

Last month, at the 5th New York City Bridge Conference, Al Pense, professor and provost emeritus in materials science and engineering, was acknowledged for his outstanding contributions to bridge safety and repair, the topical focus of the 2009 conference.

The conference theme was deemed appropriate in the shadow of the I-35W Bridge collapse in Minneapolis, MN, on August 1, 2007, the experts in attendance spent time discussing the current bridge inspection and monitoring practices and formulated ways to improve them. The proceedings are published in Safety and Reliability of Bridge Structures.

For his efforts to prevent future bridge failures, Pense was awarded the Bridge Engineering Association’s Bridge Engineering Research Award.

The award was completely unexpected, but I am glad to know they recognize the significant amount of work that still needs to be done with steel and bridges, said Pense, an expert in the welding of iron and steel and co-author of the proposal for the National Science Foundation’s Engineering Research Center for ATLSS (Advanced Technology for Large Structural Systems).

ATLSS, a renowned facility based at Lehigh and focused on cutting-edge research in civil infrastructure, has housed numerous industry-leading experiments on the life cycle and materials of bridges and other large structures since its conception in 1986.

Pense, who began his post doctorate work with pressure vessels, said his welding experience caught the attention of his bridge-research colleagues at Lehigh. When someone needed an opinion on steel fatigue or the welding of two steel plates, they asked Pense for advice. His expertise grew to include welding and materials for failure in bridges, forensic and failure analysis of fallen bridges and the legal issues that accompanied it.

I fell in among bridge engineers, and I became their Good Samaritan, says Pense, who collaborates with Lehigh professors emeritus Ben Yen and John Fisher to solve bridge issues and teach the next generation of bridge engineers. They are the first ones who got me to look under bridges. They put me in a snooper to examine the pins under an eyebar bridge, and I liked it – except for the time when a heavy fire truck drove overhead and caused the bottom of the bridge deck to hit me on the head.

Today, Pense is renowned for his work with stressed and fatigued bridges. He has inspected numerous suspect, cracked and failed bridges, including the Liberty Bridge and I-79 Bridge in Pittsburgh in 1979 and the second Silver Bridge in West Virginia in 1985. The original Silver Bridge collapsed in 1967, killing 40 people. Lehigh investigators did the forensic analysis of that failure also.

Pense’s knowledge of the first Lehigh experience with the Silver Bridge allowed him to spot a similar problem with the pin connection on the Liberty Bridge, possibly identifying and correcting a quandary that could have caused a comparable bridge collapse in the steel city. He also examined the fractured pieces of the gusset plates from the I-35W Bridge in Minneapolis that infamously fell in 2007. Investigators found it fell due to the fact that the gusset plates – steel pieces used to reduce stress on other structural elements – were undersized.

Currently, he is inspecting the pieces of a wrought iron bridge dismantled in northern Pennsylvania. Authorities face the question of reusing the members or replacing them to update the bridge, and Pense will help determine what is safest to do. His experience as an international consultant to private companies and government agencies also continues to expand, and has led him to receive numerous other awards, including the Hillman Service Award in 1997.

Pense is an elected member of the National Academy of Engineering and is a Fellow of the American Welding Society and the American Society Metals. He served as Lehigh’s provost and vice president for academic affairs from 1990 to 1997.