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

9422245在美国的许多地区，有几个建于1950年的S和1096年的S的钢筋混凝土框架结构，它们主要是为重力荷载效应而设计的。这些结构中使用的构造细节可能会导致非延性结构在地震荷载下失效。因此，对于中等到严重的地震荷载，这些结构的性能被认为是可疑的。本文研究的重点是框架柱的抗震加固，这是造成其非延性性能的主要原因。这些柱在弯曲铰链区没有足够的搭接拼接，并且沿构件长度缺乏横向钢筋，使得它们容易发生搭接、剪切和轴向-弯曲压缩破坏。先进的纤维-环氧复合材料夹套将被用来提高这些柱的强度和延性：(L)在搭接-拼接区产生围压，(2)沿构件通过桁架机制提高抗剪能力，以及(3)在塑性铰区域通过约束混凝土受压和提高抗剪能力来提供延性。将进行试验测试，以评估改进的纤维-环氧复合材料夹套加固设计，考虑的参数包括材料类型、纤维取向、夹套刚度、主动与被动夹套压力系统以及循环单轴横向荷载和轴向荷载组合。将套筒加固后的性能与相应的已建非延性柱在反复荷载作用下的性能进行比较。该研究计划将开发使用纤维-环氧纤维缠绕复合材料成功加固柱的实用方法，并将制定可供执业工程师应用的非韧性柱加固指南。***

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. ***