Free software predicts how and when steel beams will buckle

A free computer program developed by a Johns Hopkins civil engineering researcher allows designers of thin-walled structures to test their stability and safety before a single beam is put into place.

A free computer program developed by a Johns Hopkins University civil engineering researcher is said to allow designers of thin-walled structures, including buildings and bridges, to test their stability and safety before a single beam is put into place.

This modelling software, dubbed CUFSM and devised by Benjamin W. Schafer, asks designers to enter their materials, the geometry of their structure and the load it is expected to withstand. The program is said to quickly report how and under what conditions the structural components will buckle.

‘To keep costs down, many people today are looking for maximum strength with the minimum amount of materials,’ said Schafer, an assistant professor in the Department of Civil Engineering.

‘So very often, you end up with what we call thin-walled structures. But instability or buckling can cause these structures to collapse or ‘fail’,’ added Schafer. ‘Engineers need to predict how and when this will happen, so they can design buildings that won’t buckle under a particular load. This software is a tool that does just that.’

The civil engineering researcher recently updated the program, which is available in a stand-alone version for users of Windows and in another version that is compatible with MatLab software, which is available on virtually all computer platforms. The Web site also features tutorials and examples to help designers and students learn to use CUFSM.

The computer program is an extension of research Schafer began while earning his doctorate in structural engineering from Cornell University in 1997. At Johns Hopkins, Schafer’s research focuses on the behaviour and design of cold-formed steel sheet metal bent into various shapes.

Cold-formed steel is said to have become a popular structural alternative to timber and is used extensively in low-rise buildings. It is utilised in a variety of applications, supporting floors, roofs and walls in industrial, commercial and residential buildings.

‘The idea is to provide maximum strength with the minimum material,’ Schafer said. ‘The design is critical. Even small changes in the geometry can affect the strength of the structure and how it might buckle. Placing little bumps or folds in the members, using corrugated versus flat sheet metal – all of these things can make a difference.’

To test how such changes in geometry and materials will affect the stability of a thin-walled structure, an engineer can enter this data in the CUFSM software to determine how much compression and/or bending the structure can tolerate before it buckles.

Currently, civil engineers must adhere to rigid building codes that severely limit their design options, Schafer said.

‘These highly prescriptive building codes accomplished that, but they also took away the opportunity for structural innovation,’ Schafer said. ‘My software can help bring it back by giving engineers a way to predict buckling for structures that don’t fall within the rules.’

Schafer’s CUFSM software can be downloaded free from his Web site: <A href=’http://www.ce.jhu.edu/bschafer’>Thin walled structures</A>.