Composite Bridge Designed to Resist the Elements with Algor Software

In many parts of the United States, springtime brings a blossom of potholes and road repairs. If you have ever sat in road construction traffic and wondered why modern technology can put a man on the moon but has yet to build a bridge that won't crack after a few months of ice and salt, you will be interested in the work of Stephen Gill at Kansas Structural Composites, Inc., (KSCI) in Russell, Kansas. With Algor software, Mr. Gill designed and analyzed the first composites bridge of its kind to resist the elements.

The No Name Creek Bridge

In November 1996, a composite bridge KSCI designed was erected over the No Name Creek in Russell County, Kansas, in just one day. With no curing necessary, the bridge was open on the day after its installation to traffic that often includes the tanker trucks which service local oil fields. Avoiding the expenses and inconveniences that would have resulted from the more lengthy process of laying a traditional steel and concrete bridge probably made up for the additional material costs alone. However, this 23-foot, resin and fiberglass bridge also promises lower maintenance costs because it will not rust or crack the way steel, concrete or asphalt does.

Photo by John Gaudio Courtesy of Alpha/Owens Corning

Composites for Civil Engineering

At KSCI, Mr. Gill researches and develops "sandwich"-type composite material products primarily for civil engineering applications. A composite material consists of two or more independent materials. Many composite materials contain a large amount of one substance combined with fibers, flakes or layers of another. Greater strength and lighter weight can be obtained compared to what the individual materials acting alone can achieve. Composites have been widely used in the aerospace industry where the combination of strength and light weight is necessary. KSCI uses composites to stand up against the elements and reduce construction labor. With many of our bridges in a state of disrepair, the market for composites in the infrastructure industry is extremely promising.

The concept is so promising that Mr. Gill's work on the No Name Creek Bridge project was underwritten by the Transportation Research Board's IDEAS project. Materials were donated by several regional companies including Alpha/Owens Corning (resins), Vetrotex-Certainteed (glass fibers) and Brunswick Technologies (glass textiles).

Analyzing to Determine the Best Composite

Mr. Gill began by modeling the bridge and creating a finite element mesh in Superdraw using type 16 "sandwich" elements. Composite finite elements are types of plate/shell elements which employ special element formulations for the purpose of replicating the behavior of layered composite materials.

The "sandwich" type of composite developed by Mr. Gill has a fiberglass casing around a honeycomb core. A material which inhibits the effects of ultraviolet light is included in the resin and coats on the top layers which are exposed to the sun.

Mr. Gill experimented with panel thicknesses varying from 2 to 22 inches. The depth of the core was also varied. Laboratory testing at Kansas State University determined the material's stiffness coefficients, which were specified in the processor's input. Linear stress analyses were then conducted to determine the best composite material for the bridge.

Bending Stresses Resulting from Wheel Loads		Deflections Resulting from Wheel Loads
Models of No Name Creek Bridge, Russell, Kansas Courtesy of Kansas Structural Composites, Inc.

About Algor

Mr. Gill's bridge weathered the winter and now he is using Algor on two other bridge projects. He is designing composite panels for the Kansas Department of Transportation which will replace asphalt decks on two steel bridges in Crawford County, Kansas. The other project involves re-decking for a California drawbridge which has been experiencing rusting caused by exposure to salt water.

"I like Algor because it is easy to use," said Mr. Gill. "Especially with the Windows version, I don't have to be a programmer to understand and use the software."

"The speed of analyses is also a big advantage," continued Mr. Gill. "Each analysis of the bridge in Russell took just 5 minutes on my Pentium 166."