| Reinforced concrete (RC) structure with special-shaped columns, in which theconventional rectangular columns are replaced with the special-shaped columns toform an "implicit frame", is a kind of new residential structural system and has wideprospect of development. Based on the existed achievements, the theoretical and experimental researcheson the RC structural system with special-shaped columns are systematically andprofoundly performed in this dissertation, and the primary innovative work andachievements are included as follows. (1) The limited values for the axial compression ratio of the special-shaped RCcolumn are systematically studied. Through the theoretical and numerical analysis, thelimited values of the axial compression ratio and the relevant constructionrequirements for the special-shaped column are determined for 4 seismic fortificationgrades. It is suggested that in order to assure the better seismic behavior of thespecial-shaped RC columns in case of the 1st seismic fortification grade, thestrengthened zone must be set along the edge of flanges for the bottom and cornercolumns, and the relevant construction requirements are given in detail. The limitedvalues for the axial compression ratios of the special-shaped RC columns in case of the1st and 4th seismic fortification grades and the corresponding requirements for theratio of stirrup spacing to diameter of longitudinal bar and the diameter of stirrup aregiven for the first time, which provides an important theoretical reference to completethe relevant design code. (2) Through the nonlinear element analysis for the special-shaped columns andthe statistic analysis for the tested data, the limited values of the elastic andelastic-plastic interstory drifts for the RC frame or frame - shear wall structure withspecial-shaped columns are proposed. The results show that the axial compressionratio, the loading angle, the stirrup ratio, the ratio of reinforcement, the slendernessratio and the ratio of section height to section thickness are the primary influencefactors on the maximum interstory drift. And in order to prevent the destabilization ofthe special-shaped columns in certain loading angles because of the higher slendernessratio, the limited value for the slenderness ratio is suggested for the special-shaped RCcolumns. (3) The tests on the full-scale models of the top joints, five with L-shaped and six 2with +-shaped columns with various flange width, are carried out under cyclic loading,in which the displacement at the end of beam and the strains in the joint core and at theend of beam are measured at the cracking, yielding, maximum and ultimate stages, andthe properties of the dissipation of energy, the changing of stiffness and the developingof cracks of the joints are investigated. The tested results show that the flange has agreat effect on the behavior of the top joints of frame with special-shaped columns,such as: â‘ The failure pattern of the joint is directly affected by the flanges, in whichthe failure at the core area of the joint with flange occurs after the plastic hinge at theend of beam, while that of the joint without flange happens first. â‘¡The shear bearingcapacity of the joint core may be obviously improved by the flanges. â‘¢The shearcompression ratio is also remarkably affected by the flanges. (4) The planar nonlinear finite element analysis for the top corner and interiorjoints of RC frame with special-shaped column are performed under monotonicloading, considering the influence of the flanges. The calculated results are muchcoincided with the tested results, which proves the generated program is correct andproper. The failure mechanism, the developing process of cracks, the stirrup stress andthe influence of the width of flange on the behavior of joint are further analyzed. Theresults show that the bearing capacity, the shear compression ratio and the slidingdeformati...
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