The human spine has inspired chairs, trainers and flexible batteries, and now it’s the muse of civil engineers designing an innovative bridge pier.
A team of researchers from the University of Southampton in the UK is using the backbone as the design basis for a durable, low-maintenance and low-cost bridge pier.
Bridges undergo a lot of wear and tear, whether that’s from traffic, the elements or naturally occurring events.
“When bridges are under dynamic loading, because of the fixed way they are constructed they tend to crack, and when concrete cracks it accelerates the deterioration,” said project lead Dr Mohammad Mehdi Kashani, who specialises in structural mechanics, design and earthquake engineering at the University of Southampton.
“So after an earthquake [for example], they cannot be used; they either have to be demolished or repaired significantly, or during their service life they deteriorate due to the concrete cracking,” he said in an interview with New Civil Engineer.
Strong yet flexible
The relationship between the spine’s vertebrae and discs were the main attraction for Kashani and his team. The spine is made up of a number of vertebrae cushioned by intervertebral discs, which allows it to have more freedom of movement. The intervertebral discs act as shock absorbers and help dissipate energy from the movement of the body.
In the case of this bridge, the ‘vertebrae’ will be precast composite segments. The team is developing a new composite material from entangled polymer fibres to act as the ‘intervertebral discs’, which they say will prevent rubbing, transfer shear forces through friction, absorb impacts and provide damping under dynamic loading. According to Kashani, entangled materials based on titanium or metal alloys are already used in aerospace engineering for vibration damping.
“We want to do something similar, but using a polymer base,” Kashani said.
The two elements will be tied together with a pre-tensioned, un-bonded composite ‘tendon’ that’s designed to act like the spine’s longitudinal ligament. This will help pull the piers back into their central position if the bridge is subjected to lateral forces.
Kashani plans to use off-site manufacturing and pre-cast composite segments to reduce construction time and make maintenance easier.
“Moving toward the future, we need to do things differently, that’s the whole idea behind this project,” he said.
Kashani and his team will continue to develop the concept over the next two years through a series of experimental testing and numerical modelling.
“The aim of our research is to help infrastructure become sustainable and resilient to short-term and long-term stressors, and provide services that are more reliable, affordable, accessible and usable to the whole population,” he has previously said.