VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Adaptive development of a lightweight composite beam prototype for a pedestrian bridge“ („Lengvos kompozitinės pėsčiųjų tilto sijos pro-totipo adaptyvusis kūrimas“) prepared by VILNIUS TECH, Mantas Garnevičius. The doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2019–2023., Supervisor – Dr Viktor Ggribniak.

The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Civil Engineering in the SRA-1 Meeting Hall of Vilnius Gediminas Technical University at 10 a.m. on 15 January 2024.

The replacement of steel elements, solving the corrosion problem, describes the primary trend in the structural application of fibre-reinforced polymers (FRP). However, the relatively low modulus of elasticity of typical FRP materials raises the structural components’ deformations. A possible solution to these problems is combining FRP composites with concrete elements. However, this fundamental improvement requires new design methodologies. Thus, this work introduces the adaptive design concept when the finite element (FE) modelling outcome defines the target reference of the design procedure. The iterative modification of the design solution, numerically identifying the disagreements between the experimentally verified model and physical test outcomes, stimulates the successive approach of the physical prototype to the reference numerical solution. Ultimately, this adaptive design concept diminishes the number of physical trials as correcting the FE model parameters helps identify the weakness of the physical prototype (without additional laboratory trials). Exemplifying the proposed adaptive design idea, this work employs a hybrid beam, which combines a polymeric fibre-reinforced concrete (PFRC) slab, a pultruded glass fibre-reinforced polymer (GFRP) profile, and a pultruded carbon fibre-reinforced polymer strip. The considered structural element utilises an efficient structural solution, which ensures the synergetic PFRC and pultruded GFRP profile effect by fixing the profile at the supports. This innovative structural solution contradicts the traditional concept of local bond improvement, e.g., employing GFRP profile perforation and mechanical anchorage systems. Furthermore, the proposed solution simplified the corresponding finite element model, ensuring the perfect bond assumption between the components. The physical tests proved the viability of the developed composite structure: the enhancement of the supports doubled the hybrid beam’s flexural stiffness and load-bearing capacity regarding the reference bridge with weak supports. The dissertation includes an introduction, three chapters, general conclusions, and a list of references. The First Chapter reviews the literature on the FRP manufacturing process, existing materials, physical characteristics, and structural design principles. The Second Chapter presents the adaptive design concept, considering the hybrid beam system’s design example. The Third Chapter describes the experimental studies, verifying the proposed adaptive design concept. The author’s list of publications on the topic of the dissertation consists of four journal articles (three with an Impact Factor from Clarivate Analytics Web of Science) and three conference presentations.