外文翻译---试验研究钢筋混凝土柱改造方法(编辑修改稿)

外文翻译---试验研究钢筋混凝土柱改造方法(编辑修改稿)内容摘要：

it techniques include concrete, FRP, and steeljackets. Concrete jackets are constructed by enlarging the existing cross section with anew layer of concrete and reinforcement (Ersoy et al. 1993). This reinforcement istraditionally provided by hoop or spiral rebar, or welded wire fabric. FRP reinforcementis typically applied two ways: prefabricated jackets or wraps. Both methods have been experimentally researched (Morshed and Kazemi 2020). Steel jackets are constructed byplacing a steel tube with a slightly larger diameter around the member to be area between the existing member and steel tube is typically filled with grout(Priestley et al. 1996). Concrete Jacketing Addition of a concrete jacket is used to enhance flexural strength, ductility, and shearstrength of columns. This technique is more monly used for building columns buthas been applied to some bridge members in Japan. The enhanced confinement isachieved with the use of ties or spirals at a small pitch, or transverse reinforcementspacing (Priestley et al. 1996). Concrete jackets can be used to retrofit beams as well ascolumns (Cheong and MacAlevey 2020). Additional materials can be used to reinforce the retrofit, as long as confinement is enhanced. Rebar Reinforcement Concrete jacketed columns with hoop and spiral reinforcement effectively enhance thestructural capacity of retrofitted members. Ersoy et al. (1993) ran two series of tests tostudy the behavior of strengthened and repaired concrete jacketed columns. The firstseries pares the behavior of jacketed columns with a monolithic reference specimenunder monotonic axial loading. All the concrete for the monolithic specimen was castwith the base column and retrofit reinforcement in place, to provide a specimen withperfect interaction and bond between the base column and retrofit material. Hoopreinforcement is used in the base column and retrofit reinforcement, as shown in Figure . The jackets are applied under two conditions: after the pression loading wasapplied and removed, as well as while the axial load is still applied. It is determined thatcolumns jacketed after unloading performed well, reaching 80 to 90 percent of thestrength of the monolithic reference specimen. Repair jackets applied while the columnis still under load did not perform as well and only reached 50 percent of the axial loadcarried by the monolithic specimen. The second series of tests study the effectiveness ofconcrete jackets with columns tested under bined axial load and bending. Both repairand strengthened jackets behave adequately under monotonic and reversed cyclic loading. Steel Jacketing Steel jackets prevent concrete from expanding laterally as a result of high axial pression strains. The steel jacket is equivalent to continuous hoop reinforcement andcan be used for circular columns or rectangular columns with slight modifications, asshown in Figure . Steel jacketing of rectangular columns is not remended because while shear strength is enhanced, flexural ductility is only provided at thecorners. An elliptical steel jacket with concrete infill should be provided for rectangularmembers to fully confine all the concrete (Priestley et al. 1996). A prehensive twopart study was performed by Priestley et al. (1994 a, b) to determine the enhanced shear strength provided by steel jacket retrofitting. The first partof the research focuses on theoretical considerations and test design. It is determined thatACI design equations are overly conservative and new design equations are presented forcircular or rectangular columns in need of shear enhancement. The second part of theresearch focuses on the actual testing of the colum。