Seismic Rehabilitation of Non-ductile Concrete Columns Using Advanced Composite Jacketing

在美国的许多地区，有几个钢筋混凝土框架结构建于1950年代和1096年，主要是为重力荷载效应而设计的。 在地震荷载作用下，这些结构中使用的构造细节可能导致非延性结构破坏。 因此，这些结构的性能被认为是可疑的中度到严重的地震荷载。 本研究的重点是这些框架柱的抗震加固，这是他们的非延性行为的主要原因。 这些柱在弯曲铰区的搭接接头不足，沿构件长度方向沿着缺少横向钢筋，使其易于发生搭接接头、剪切和轴向弯曲压缩失效。 先进的纤维-环氧树脂复合护套将用于增强这些柱的强度和延性：（1）在搭接-拼接区，以在拼接上产生围压;（2）沿构件沿着，通过桁架机制增强剪切承载力;（3）在塑性铰区，通过将混凝土限制在压缩状态并增加剪切承载力来提供延性。 将进行实验测试，以评估先进的纤维-环氧复合材料导管架改造设计，考虑材料类型、纤维方向、导管架刚度、主动与被动导管架压力系统以及循环单轴侧向载荷与轴向载荷相结合的参数。 在循环荷载作用下，将导管架改造的性能与相应的已建成非延性柱的性能进行比较。 该研究计划将开发使用纤维环氧树脂包裹复合材料成功改造柱的实用方法，并将开发可由执业工程师应用的非延性柱改造指南。 ***

9422245 Ricles In many regions of the United States there exists several reinforced concrete frame structures constructed in the 1950's and 1096's which were designed primarily for gravity load effects. The construction details used in these structures can cause non-ductile structural failure under seismic loading. As a result, the performance of these structures is considered suspect for moderate to severe seismic loadings. This study focuses on seismic retrofit of the columns of these frames, which are the major reason for their non-ductile behavior. These column have insufficient lap splices in the flexural hinge zone as well as a lack of transverse steel reinforcement along the length of the member, making them prone to lap-splice, shear, and axial-flexural compression failures. Advanced fiber-epoxy composite jackets will be used to enhance the strength and ductility of these columns: (l) in the laps- splice zone to create a confining pressure on the splice, (2) along the member to enhance the shear capacity through a truss mechanism, and (3) in plastic hinge zones to provide ductility by confining concrete in compression and increasing shear capacity. Experimental testing will be conducted to assess adtanced fiber- epoxy composite jacket retrofit designs considering the parameters of material type, fiber orientation, jacket stiffness, active vs. passive jacket pressure systems, and cyclic uniaxial lateral loading combined with axial load. The performance of the jacket retrofit will be compared with that of corresponding as-built non-ductile columns under cyclic loading. The research program will develop practical methods for successfully retrofitting columns using the fiber-epoxy wrap composite material, and will develop guidelines for retrofitting non-ductile columns that can be applied by practicing engineers. ***