High modulus carbon fiber materials for retrofit of steel structures and bridges
This paper summarizes the research work dealing with the use of high modulus carbon fiber reinforced polymer (HM CFRP) materials for the retrofit of steel structures and bridges. The research work included selection of an appropriate adhesive for bonding HM CFRP materials to steel and the performance of Large-scale steel-concrete composite beams tested to examine the behavior of different strengthening schemes. The research findings demonstrate the effectiveness of the proposed HM CFRP strengthening system.
Proposed design guidelines for strengthening of steel bridges with FRP materials
Abstract This paper focuses on the use of externally bonded high modulus carbon fiber reinforced polymer (HM CFRP) materials to strengthen steel bridges and structures. Proper installation of the CFRP materials is necessary to prevent premature failure due to debonding. The paper proposes guidelines and installation techniques based on the best practice reported in the literature and the extensive practical experience in bonding of composite materials. The surface preparation of the materials, the application of the adhesive and the detailing of the strengthening are provided in detail. The design guidelines include the structural design criteria for the use of high modulus CFRP materials as flexural strengthening system of typical steel–concrete composite bridge girders. The flexural design procedure is based on a moment–curvature analysis and a specified increase of the live load carried by the bridge to satisfy specific serviceability requirements. A bond model is also described which can be used to calculate the shear and peel stresses within the adhesive thickness. To prevent a premature debonding failure of the strengthening system, the criteria specify a maximum principle stress in the adhesive which cannot be exceeded for a given characteristic strength of an adhesive. A worked example is presented to illustrate the proposed flexural design approach. The research findings conclude that high modulus CFRP materials provide a promising alternative for strengthening steel bridges that can be easily designed and installed to increase their strength and stiffness.
Non-linear analysis and optimization of adhesively bonded single lap joints between fibre-reinforced plastics and metals
Abstract Non-linear finite element methods are applied in the analysis of single lap joints between fibre-reinforced plastics (FRP) and metals. The importance of allowing for both geometric and material non-linearities is shown. The optimization of single lap joints is done by modifying the geometry of the joint ends. Different shapes of adhesive fillet, reverse tapering of the adherend, rounded edges and denting are applied in order to increase the joint strength. The influence of the joint-end geometry is shown for different metal adherend/FRP adherend/adhesive combinations. The results of the numerical predictions suggest that with a careful joint-end design the strength of the joints can be increased by 90–150%.