橋梁畢業(yè)設(shè)計外文翻譯--碳纖維復合材料修復混凝土橋梁結(jié)構(gòu)的詳述及應用(文件)
【正文】 f NDT to investigate: (1) strength, (2) other structural properties, and (3) quality and durability. The strength methods may include。 inspection records, analyzing NDT data, and structural analysis of the bridge. The evaluation process can be summarized as follows: (1) Planning for the assessment, (2) Preliminary assessment, which involves examination of available documents, site inspection, materials assessment, and preliminary analysis, (3) Preliminary evaluation, this involves: examination phase, and judgmental phase, and finally (4) the costimpact study. If the information is insufficient to conduct evaluation to a specific required level, then a detailed evaluation may be conducted following similar steps for the abovementioned preliminary assessment, but indepth assessment. Successful analytical evaluation of an existing deteriorated concrete bridge should consider the actual condition of the bridge and level of deterioration of various elements. Factors, . actual 4 concrete strength, level of damage/deterioration, actual size of corroded rebars, loss of bond between steel and concrete, etc. should be modeled into a detailed analysis. If such detailed analysis is difficult to acplish within a reasonable period of time, then evaluation by field load testing of the actual bridge in question may be required. 5 Bridge Rehabilitation with CFRP Composites Application of CFRP posite materials is being increasingly attractive to extend the service life of existing concrete bridges. The technology of strengthening existing bridges with externally bonded CFRP posites was developed primarily in Japan (FRP sheets), and Europe (laminates). The use of these materials for strengthening existing concrete bridges started in the 1980s, first as a substitute to bonded steel plates, and then as a substitute for steel jackets for seismic retrofit of bridge columns. CFRP Composite materials are posed of fiber reinforcement bonded together with a resin matrix. The fibers provide the posite with its unique structural properties. The resin matrix supports the fibers, protect them, and transfer the applied load to the fibers through shearing stresses. Most of the mercially available CFRP systems in the construction market consist of uniaxial fibers embedded in a resin matrix, typically epoxy. Carbon fibers have limited ultimate strain, which may limit the deformability of strengthened members. However, under traffic loads, local debonding between FRP sheets and concrete substrate would allow for acceptable level of global deformations before failure. CFRP posites could be used to increase the flexural and shear strength of bridge girders including pier cap beams, as shown in Figure3. In order to increase the ductility of CFRP strengthened concrete girders, the longitudinal CFRP posite sheets used for flexural strengthening should be ancho
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