A steel-glass fibre-reinforced polymer (GFRP) hybrid reinforced concrete (RC) section would benefit from the superior advantages of steel at serviceability limit states, particular advantages of GFRP at ultimate limit states, and ductility provided by steel reinforcement. Replacing some steel rebars with GFRP bars can reduce the construction costs of the project by lowering the material and labour costs. Moreover, replacing some steel rebars exposed to harsh environmental conditions, such as corners, with GFRP bars can increase the service life of the element. This thesis investigates the serviceability and flexural behaviour of steel-GFRP hybrid RC flexural members through analytical investigations and experimental studies. It also provides design recommendations for designing hybrid RC flexural members and assesses the design equations of deflection, crack width, yielding and ultimate moment capacity in North American standards and guidelines.
This research started with analytical investigations to set a platform for designing steel GFRP hybrid RC sections. Practical design charts were developed for the proposed design recommendation based on the fundamentals of section analysis. An extensive parametric study was undertaken to transform steel RC sections into alternative steel-GFRP hybrid RC sections with the same total number of bars. The study then experimentally investigated the flexural and serviceability behaviour of steel-GFRP hybrid RC beams and one-way slabs through testing and analyzing 15 RC beams and eight RC one-way slabs. The experimental results were analyzed and compared in terms of the first cracking moment and yielding moment, failure modes, flexural capacity, concrete and rebar strain, mid-span deflection, crack width, and ductility. Based on the cracked section analysis, new equations were proposed to estimate the rebar strain and maximum mid-span deflection for the post-yielding stage in the hybrid RC beams. The experimental results were also used to assess the bond-dependant coefficient, kb of the steel, GFRP, and hybrid RC beams and one-way slabs.