PhD Power-Up: Structural Behaviour

This technical presentation summarises doctoral research on the structural behaviour and design of steel bolted connections strengthened locally using induction‑heat treatment. Steel connections are particularly susceptible to premature failure due to high stress concentrations around bolt holes, often leading to net‑section fracture and reduced structural integrity. A local strengthening concept is presented in which a high‑strength steel zone is selectively created around the bolt holes while conventional steel is retained in the gross section. This approach enhances bearing and net‑section capacity, promotes ductile gross‑section failure, and is achieved without altering connection geometry, making it suitable for retrofitting and design optimisation. The session combines experimental testing and numerical modelling of single‑ and multi‑bolt lap joints, supported by validated finite element models and fracture criteria for both untreated and induction‑treated S355 steel. Parametric studies are used to develop design and geometry guidelines and to inform refinements to Eurocode 3 provisions for bearing resistance, deformation limits, and failure mode control.

Speaker

Pelagia Kastiza is a Structural Engineer holding a Master in Structural Engineering from the Aristotle University of Thessaloniki and PhD in Civil and Environmental Engineering from the University of Birmingham, where her research focused on failure mechanisms in steel structures, fracture prediction, and the development of sustainable retrofitting methods for bolted connections using induction hardening techniques. Her work, supported by FEM analysis and experimental testing, contributed to proposed amendments to the EN1993‑1‑8:2024 design standards. Currently, Pelagia works at Rendel ltd. as a Graduate Engineer and applies her research expertise within the field of bridge engineering in the UK, combining advanced technical insight with practical industry application.