Investigation Of Compression Membrane Action In GFRP Reinforced Concrete Deck Slabs

In recent years, deterioration of reinforced concrete bridge deck slabs caused by corrosion of reinforcement has become increasingly evident. Glass Fiber-Reinforced Polymers (GFRP) is developing to be promising alternative reinforcement construction materials as an effective solution of corrosion problems. However, traditional design methods exaggerated the influences from the low elastic modulus and the brittle behaviours in GFRP. Therefore, construction costs of exsiting GFRP reinforced concrete bridge deck slabs were increased, which restrict the application of these non-metallic structures in practical engineering. In the previous research, it was found that the presence of the longitudinal steel beams and the unloaded area of concrete slab cause the loaded deck slabs to be restrained against lateral expansion. As a result, a compressive membrane thrust is developed, which enhances the loading capacities of bridge deck slabs.Currently, many bridges have been built as composite structures with decks of reinforced concrete that are supported by longitudinal steel beams. This structural type reinforced with GFRP bars was selected as the physical model in this thesis. With consideration of compressive membrane action (CMA), the structural behaviours of GFRP reinforced concrete slabs in this composite structure were studied. The details are shown as follows:(1) A series of one-third scaled experimental tests of steel-concrete composite bridge structures were carried out. In this study, some structural parameters, such as applied load, stress & strain, cracking conditions, were measured in different stages. Furthermore, the influences from some structural variables were analysied, which included steel supporting beams, reinforcing materials, reinforcement percentages and concrete strengths.(2) The structural behaviours of bridge deck slabs under static patch loads was studied, including the deflections, cracking patterns and failure modes. The analytical results were used to investigate the CMA conditions and the effects of this structural phenomenon.(3) A finite element software named ABAQUS was used in the numerical analysis of this structure type. The accuracy of established finite element model was validated with the comparison between numerical and experimental results. Therefore, a further study of failure mechanism and stress & strain distribution was developed. A series of parametric study was conducted and the results were presented. (4) The prediction results of loading capacities by modified methods were presented. In the comparison of current design standards, it was shown that the proposed method provided more accurate predictions of loading capacites in bridge deck slabs.In this study, influences from CMA on structural behaviours of GFRP reinforced concrete bridge deck slabs was investigated by experimental tests and finite element analysis. Thereafter, the arching effects were reveals and the working mechanism of these non-metallic structures was studied. With the consideration of material properties of GFRP and CMA, the structural behaviours of GFRP reinforced concrete deck slabs in composite bridges was analysed, which could be used to improved the durability of this structural type without the influences of loading capacities and construction costs.