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Denavit Authors Design Guide on Ponding

Mark Denavit.Associate Professor Mark Denavit occasionally receives random text messages from engineers that include photos of large pools of water collecting on a flat roof.

The engineers aren’t seeking any advice about how to fix anything. They just always think of Denavit and figure he would want to see the images because Denavit is an expert in ponding, which is the accumulation of water on roofs that can cause progressively increasing deformations and even collapse.

Denavit’s knowledge is well known in the industry, and he was recently asked to write a design guide for the American Institute of Steel Construction and Steel Joist Institute on ponding. The guide, which Denavit co-authored with James M. Fisher, a consulting engineer, is expected to be released in March. AISC has produced more than 35 design guides to provide detailed information on topics related to steel design and construction.

The most common method for assessing roofs for ponding was developed more than 50 years ago and has many limitations. A new design method, that is required in the latest building codes, uses nonlinear analysis to capture the behavior of roofs under ponding conditions more accurately.

Under ponding conditions, insufficient strength or stiffness of the roof system can lead to instability or collapse. Denavit developed practical nonlinear analysis methods and tools and worked on the code committee to help upgrade the standards to account for the ponding effect directly in the rain load.

“It makes things safer when they need to be safer and it makes things more efficient when they need to be more efficient,” Denavit said. “It’s just a far more accurate approach.”

Denavit hopes the updated design guide will provide clarity on ponding and help avoid any disastrous outcomes for roof construction.

“Number one, it’s important because collapses can happen,” Denavit said. “But No. 1B is because ponding doesn’t matter for a lot of roofs, but it’s been hard to deal with for engineers. I want designs to be safe, but I also want ponding easy to deal with while still being technically rigorous.”

Denavit’s work in ponding has made distinct and visible impacts on the profession of structural engineering. His work on ponding provides UT with more recognition in the field nationwide.

“I think it is good for the University of Tennessee to have people being engaged in practical issues of structural engineering and advancing the profession as it is now,” Denavit said.


Rhiannon Potkey (865-974-0683,