Experimental Study on Seismic Behavior of Full Encased Steel-Concrete Composite Columns

With the rapid development of high-rise buildings in China, the steel-concrete composite structure is widely used because of its excellent seismic performance. So far, all of the high-rise buildings that rise more than 300 m in China are of a steel-concrete composite structure, which are designed based on Chinese codes. During the construction process, two main problems are encountered, as follows: (1) minimum stirrup ratio, and (2) embedded depth ratio for steel-concrete composite columns, which are strictly limited by Chinese codes. To solve those problems, 26 steel-concrete composite columns were tested under low cyclic reversed loading to simulate an earthquake load. By analyzing the failure patterns, hysteresis loops, skeleton curves, energy-dissipation capacity, and ductility of such specimens, the influence of the axial compression ratio, stirrup ratio, steel section shape, and steel embedded depth ratio on the seismic behavior of steel-concrete composite members are discussed. In accordance with the test results, the minimum stirrup ratio and embedded depth ratio for steel-concrete composite columns can be reduced relative to the limiting value given by Chinese codes. A formula for minimum stirrup ratio and a minimum embedded depth ratio for steel-concrete composite columns are recommended in accordance with an analysis of the test results.