News

Cullen College Engineers Bring TxDOT Bridge Ratings Up to Date

By: 

Laurie Fickman
Driving in Texas? You'll appreciate the work of (L-R) Mina Dawood, Qianmei (May) Feng and Abdeldjelil Belarbi
Driving in Texas? You'll appreciate the work of (L-R) Mina Dawood, Qianmei (May) Feng and Abdeldjelil Belarbi
Testing loads: Mina Dawood with a ruptured piece of steel
Testing loads: Mina Dawood with a ruptured piece of steel

Take a car trip from Houston and you’ll likely drive over one of the 50,000 bridges that span the great state of Texas. During your drive you probably never wondered if the weight limits on the bridges were accurate. But then, that’s why we have Mina Dawood, associate professor of civil and environmental engineering in the Cullen College.

That’s the way he thinks, and the Texas Department of Transportation (TxDOT) has taken notice, awarding him and two colleagues $260,000 over the next two years to assess bridges and bring them accurate load information. His co-principal investigators are Abdeldjelil Belarbi, professor of civil and environmental engineering, and Qianmei (May) Feng, associate professor of industrial engineering and Brij and Sunita Agrawal Faculty Fellow.

“TxDOT is by nature conservative,” said Dawood. “What we’re trying to do is allow them to safely increase the loads being carried by bridges and hopefully, in some cases, not need to post loads on bridges that are being load posted now.”

TxDOT regularly assesses its bridge inventory for safety and posts the safe load weight on older bridges that were built before the days of 18-wheelers and heavy intrastate traffic.

Historically conservative

When analyzing a bridge that was built almost a century ago, there’s a good chance the details of the material tests that were performed decades ago aren’t available, so engineers depend on guidelines set in The American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Engineering (MBE).

“We believe AASHTO provides conservative guidance on material strength and, in reality, actual materials may have strengths measurably greater than the MBE guidance or what was specified in the original plans,” said Dawood. “If you have more accurate data about the strength of the materials in a bridge you would calculate more accurately the capacity of the bridge.”

While Dawood anticipates most load-posted bridges can take more weight, some bridges in Texas were built before World War II and environmental conditions may have hastened aging.

“On the one hand, the bridges are deteriorating, and on the other hand, we need to apply more load to the bridges on a day-to-day basis,” said Dawood.

Bridging the data gap

With TxDOT the UH group will visit different historical bridges being decommissioned to gather test samples. The samples may be collected from girders, braces, gusset plates, reinforcing bars in concrete, bolts or rivets – any steel part in the structure. Back at the Structural Research Laboratory, machinists will take the test samples and create pieces small enough to hold in your hand (called tension coupons) and stress testing on those pieces will begin. Machines will actually pull apart a tension coupon to note the exact load at which it ruptures.

Aside from test samples, the group will pull information from the TxDOT historical archives and explore existing literature. And then, Feng will take all the pieces of information to make sense of it.

“I will look at the strength of the materials versus the stress or loads, to see how much stress the bridge can take based on the material strength.” said Feng.

“We definitely need Dr. Feng’s expertise with statistics,” said Dawood. Out of a thousand or more pieces of data, she will conduct a statistical analysis and identify the appropriate material strengths to be used for load ratings based on the desired reliability of bridges.

Once the work is completed and delivered to TxDOT, there’s a good chance that state officials will have their hands full: traveling Texas, changing signs and bringing load posts up to date, the way Cullen College engineers determine appropriate.

Faculty: 

Department/Academic Programs: 

Related News Stories

ASCE tabs UH student Mello for research fellowship

Livia Mello, a UH graduate student and doctoral candidate in Civil Engineering with Dr. Roberto Ballarini, was awarded the American Society of Civil Engineers' 2020 O.H. Ammann Research Fellowship to continue her work in studying progressive building collapse.

A graduate student at the University of Houston's Cullen College of Engineering has been honored by being selected by the American Society of Civil Engineers for the 2020 O.H. Ammann Research Fellowship.

Livia Mello, a UH graduate student and doctoral candidate in Civil Engineering, was awarded the fellowship to continue her work in studying progressive building collapse.

College honors 17 with yearly Faculty and Student Excellence Awards

Dr. David Shattuck of Electrical and Computer Engineering.

Dr. Joseph W. Tedesco, Elizabeth D. Rockwell Dean of the UH Cullen College of Engineering, announced that 17 students and faculty members had been selected as recipients in the 2019-2020 Faculty and Student Excellence Awards, which recognize teaching and research achievements.

Cullen College of Engineering posts new 6-Year graduation high mark

The six-year graduation rate for the Cullen College of Engineering is 71.2 percent for students that began in Fall 2014, the fourth year in a row it has increased.

The Cullen College of Engineering has set a new record for its six-year graduation rate, hitting a mark of 71.2 percent for students that began in Fall 2014, according to new information released by the department's Division of Undergraduate Programs and Student Success.

Upcoming Events / Seminars