| Compared with ordinary RC structure, the one with special-shaped columns have many different characteristics because of the special section shape of its columns. During the each sdage of development and application, there are different design regulations in the standard of special-shaped columns structure with different versions, such as material selection, reinforcement construction, application scope, axial compression ratio, and so on. In the past few years, the structural seismic strengthening technology is developed and popularized rapidly. However, the related research on RC special-shaped columns structure is comparatively less.In order to study the seismic strengthening mathod of RC special-shaped column and perfect its technology, 23 RC special-shaped columns (7 of them adoped L-shaped sections, 7 of them adoped T-shaped sections, 4 of them adoped +-shaped sections and 5 of them adoped Z-shaped sections) are designed and producted. 19 of them are strenthened respectively by the mathods of bonding steel plate, sticking carbon fibre sheet and complex with the two.The experimental studies of 23 special-shaped columns bearing horizontal reversed cyclic loads are completed. The failure process and pattern of all members are observed. The hysteretic curves of horizontal load -displacement are measured. The strain development process of reinforced bars, steel plates and carbon fibre sheets are obtained. The test results indicate that: when the mathod of bonding steel plate is used, the horizontal ultimate load of special-shaped columns can be increaced more than 40%, the ductility and aseismic consumed energy behavior can not be improved obviously; when the mathod of sticking carbon fibre sheet is used, the horizontal ultimate load can be increaced about 30%-40%, the ductility factor average value of positive and negative improved more than 60%; when the mathod of complex strenthenment is used, the reforcement effects of two mathods can all be realized, and the way of carbon fibre sheet full wrapping is better than bands wrapping.The un-strenthened and complex strenthened RC special-shaped columns under horizontal load are calculated, using the mathod of finite element analysis. The calculation results are satisfactorily uniform with experement. So the calculation model and constitutive relation are reasonable, calculation mathod is dependable and can be spread and applicated ulteriorly. Based the test researches and finite element analysis, the mechanism of complex strenthenment on special-shaped columns is discused. The role of bands wrapping carbon fibre sheet is similar with hoop reinforcement, it can improve the ductility of column; the effects of full wrapping carbon fibre sheet, not only are same with bands wrapping, but also can increase concrete strength because of constraining its lateral deformation, and can directly increase normal section bearing capacity because of its vertical tensile strength. According to these study results, the normal section bearing capacity calculation formulas of complex strenthened spacial-shaped columns at the direction of engineering axis are given.This article innovation mainly has: Proposes for the first time and develops the strengthening mathod of bonding steel and CFRP, that is used by RC special-shaped columns; through the experimental study on seismic behavior of complux strengthened columns under horizontal reversed cyclic loads, the destruction characteristic is observed, the bearing capacity, ductility and earthquake resistance are analyzed; based the experimental study and finite element analysis, the practical formulas for bearing capacity of narmal section are presented.
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