Novel Concrete Reinforcement for Wave Energy Converters
The experimental work programme developed in this study investigates the behaviour of novel concrete reinforcement for the wave energy converters. The reinforcement included fibre-reinforced polymer (FRP), synthetic fibres, steel fibres and ultra-high-molecular-weight polyethylene (UHMWPE). 24 cube specimens were tested using a pull-out test where no splitting was allowed to develop to examine the bond between FRP (glass and carbon) bars and concrete. 45 beam specimens were subjected to three-point or four-point bending tests where the beams were bent until their failure in order to study the structural behaviour of flexural concrete elements reinforced with internal FRPs, external FRPs as well as fibrous reinforcement. A large-scale WEC prototype was produced, and design of reinforcing this prototype with novel reinforcement was proposed. The bond behaviour between FRP bars and concrete as well as influence of seawater ions were investigated. The shear strength contribution of FRP-reinforced concrete beams was analysed. Also, the structural behaviour of beams reinforced or strengthened with FRPs was presented and compared with estimations using existing methods. A concept of Crack Resistance Indices (CRIs) was introduced to reflect the cracking behaviour of the beams. Appropriate methods for evaluating the flexural strength of beams externally bonded with CFRPs using epoxy resin was developed. Influence of the water and seawater exposures on the CFRP strengthening capacity was also discussed. Addition of macro-synthetic fibres to the concrete at a dosage of 20 kg/m3 significantly improved the toughness of FRP-strengthened beams. Longitudinally aligning macro-steel fibres into concrete beams could provide the latter with competitive flexural and shear strengths. The relation between the aligned fibre dosages and the beam’s flexural strength was formulised. Influence on the flexural strength from factors of the concrete strength, addition of cementitious materials and the alignment effectiveness was also studied. A circular Vierendeel-truss-type WEC prototype was designed and produced from precast concrete elements. Assembly of the prototype was accomplished whilst reinforcing with UHMWPE ropes remained at the proposal stage. A 3D printed concrete beam reinforced with UHMWPE ropes was also trialled.
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