Cambridge University professor of soil mechanics Malcolm Bolton called for engineers to use objectivity when applying factors of safety rather than arbitrary figures suggested by Eurocode 7 during last night’s Rankine Lecture.
Bolton delivered the 52nd Rankine Lecture on the subject of Performance-based design in Geotechnical Engineering in which he explained the benefits of using Mobilisable Strength Design (MSD) principles over the Limited State Design (LSD) approach used in the Eurocodes.
Bolton drew on previously published material to demonstrate how MSD provides a better view of the actual deformations and strength of the soil than LSD.
In his conclusions, Bolton said that design to EC7 is too formulaic and ultimately wasteful. “EC7 relies on safety factors rooted in the 1960s,” he said. “This creates a built in Rumsfeldian factor, rather than using insurance against risk. We need to rethink LSD and base decisions on deformation.”
According to Bolton, deformation based decisions will result in better performance and more sustainable solutions.
“I am not advocating reducing safety factors - I am advocating replacing arbitrary safety factors,” he said.