Size and spacing of holes in beams key to avoiding failure

Making beams shorter may not stave off buckling.

Engineers often make structures such as buildings and bridges lighter by incorporating beams containing holes. But over the past decade, theoretical work and lab experiments have shown that ‘holey’ beams may be subject to buckling in unusual patterns. When force is applied to such beams, every other hole deforms vertically, and the remaining holes deform horizontally, leading to the beam’s collapse.

Chris Johnson at the University of Manchester, UK, and his collaborators have produced a theoretical explanation for this phenomenon that leads to a surprising conclusion. Making a beam shorter — which ordinarily reduces buckling — does not necessarily prevent failure in hole-studded beams.

The good news, the authors say, is that by fine-tuning the size and spacing of the holes, such beams can be made more resistant to buckling than beams without holes. The team hopes to validate the predictions experimentally.