| Reinforced concrete (RC) structure with special-shaped columns, in which the conventional rectangular columns are replaced with the special-shaped columns to form an"implicit frame", is a kind of new residential structural system and has wide prospect of development.The paper investigates the seismic behavior of RC frame with special-shaped columns and analyze the seismic behavior of special-shaped columns, beam-column joint, RC frame . But on the point of seismic capacity of the whole structure in seismic regions with earthquake intensity of degree 8, the test and theoretic analysis on the frame structure with special-shaped columns are deficient. Therefore, the forward study of this topic should be more necessary and has a great theoretical and practical value.The difference between the behavior of the reinforced concrete(RC) structures with special shaped columns and of structures with conventional rectangular columns focuses research's attention on it's seismic performance, especially on the applicable coverage in high intensity seismic zones. Several tests of such structure have been done in recent years, but most of them were based on seismic fortification intensity 7 zone. In concert with the development of national Technical Specification on the employment and suitability of such structure in higher intensity area, a three-storey RC frame with special-shaped columns in seismic fortification intensity 8zone and type 3 site was designed for low-cycle lateral loading test. The test puts emphasis on the global seismic performance and damage mechanism of structure. The numerical results of structural design and experimental phenomena reveal the pros and cons of this structure system, that is the easy attainment for drift control requirement and predomination of beam hinge mechanism under major shock, and more attention to joint capacity for its application in high intensity zones.At the same time, the author take nonlinear finite element analysis of RC frame with special-shaped column is proposed in the paper to research the seismic behavior of this type structure under low-reversed cyclic loading. Compared with the experimental hysteresis curve and stiffness degradation curve ,the computational results are found to be accurate, which shows that this model proposed in this paper can be applied in structure analysis of RC frame with special-shaped column .From the analysis of test results and theoretical calculation ones ,it can be concluded thatRC frame with special-shaped column has good seismic performance. The nonlinear finite element analysis for the corner and interior joints of RC frame with special-shaped column are performed under monotonic loading, considering the influence of the flanges. The failure mechanism, the developing process of cracks, the stirrup stress and the influence of the width of flange on the behavior of joint are further analyzed. The results show that the bearing capacity, the shear compression ratio and the sliding deformation of longitudinal bar at the end of beam of the joints with flange are much better than those of the joints without flange. In addition, the mathematical representation for the stirrup and concrete of flange participating in joint core is obtained, which may be extended to the calculation of seismic behavior for the ordinary joints of frame with special-shaped columns with unequal flanges. Based on the summation and investigation for the obtained results, the calculation formulas for the bearing capacity of joints of the frame with special-shape columns are proposed, which will provide an important reference to work out the relevant design code. Finally, some suggest for design and structural measures for residence system of RC frame with special-shaped columns are mentioned from the above study.
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