Experimental Research On H Steel Partially Encased Composite Short Columns Subjected To Seismic Behaviors

With the development of modern construction, the height and the span of building are on the increase,the traditional structures of reinforced concrete can not meet requirements of the modern construction. If reinforced concrete columns are still applied in the high-level, ultra-high-rise buildings, it will result in increased size of columns section because of big axial compression and limits of axial compression ratio. This not only affects service function, but also may become short columns whose seismic behavior is poor. The composite structure of steel and concrete has developed fast in our country in recent decades, its excellent performance and technical economical index make it have a wider range of applications. A new composite column is described in this paper, which is named partially encased composite (PEC) column. The new partially encased composite column consists of a H type steel column with steel tie bars welded between the column flange tips and the concrete is in two blocks separated by the web. The column has advantages of the in-plant prefabrication of steel, the quick and convenient concrete formwork and pouring and the fire resistance property.In order to research this new composite column, in this text, research is carried on five H steel partially encased composite columns, under low frequency cyclic load. The parameters include ratio of axial compression force,steel ratio and slenderness ratio. The experiment results showed that the partially encased composite columns have the plump hysteretic curve,no significant reduction of the pinch phenomenon; Good deformation ability after the specimens reaches ultimate loads,the ductility coefficients are between 3.40and 4.40, the columns can meet the requirement of ductile specimens; The rigidity degradation of columns is low,the specimens have good energy dissipation capacity; The results indicate that H steel partially encased composite (PEC) column has excellent earthquake resistant properties. By analyzed, axis pressure coefficient on the impact of seismic performance component is the most significant. Based on some basic assumption, limited values of axial compression coefficient of H steel partially encased composite columns are put forward through calculating.Based on the experiment, according to constitutive relations of materials, the relationship of moment and curvature is derived by the method of dividing strips, compared with experiment; two results are in good agreement.