Research On Eccentric Compression Experiment And Load-bearing Capacity Calculation Of Steel Tube-reinforced Concrete Column

Steel tube-reinforced concrete column is a kind of superimposed member setting with steel tube concrete in the middle of the reinforced concrete column section. This structure system has been developed independently by our own country and applied in engineering practices. Based on the eccentric compression test of superimposed column and theoretical analysis, the compression-bending performance of superimposed column is studied in this thesis. The main completed works are as follows:1. The eccentric compression test program of steel tube-reinforced concrete column has been designed in terms of specimen design, data acquisition program, loading method etc. A total of 13 superimposed columns are made and divided into 3 groups in accordance with 3 parameters of eccentricity, replacement coefficient (steel tube diameter/section width) and longitudinal reinforcement ratio.2. Based on the eccentric compression test of superimposed column, the thesis does a study of the whole progress from loading to failure of the superimposed columns and investigates the failure modes of specimens. Meanwhile, the effects of various parameters on compression-bending performance of superimposed columns are also discussed. The test results demonstrate that as follows:(1). Steel tube-reinforced concrete columns show different failure modes subjected to loads with different eccentricities that is large eccentric compression and small eccentric compression. Large eccentric compression members are characterized by better ductility.(2). With eccentricity increasing, the ultimate load-bearing capacity of superimposed column drops.(3). Under the condition of equal steel content, it is limited to improve the ultimate load-bearing capacity of steel tube-reinforced concrete column by increasing replacement coefficient.(4). By the way of increasing longitudinal reinforcement ratio, the ultimate load-bearing capacity of superimposed column can be improved and the failure mode can also be changed.(5). The residual load-bearing capacity existed in columns plays the role of anti-collapse when structures are subjected to earthquake.3. On the basis of the test data, the thesis does an analysis of load-bearing capacity calculation. Referring to related current codes, stability improving factor y and strength improving factor (3 introduced in calculation formula of reinforced concrete are put forward by regression analysis after making load-bearing capacity calculation values in comparison with test values of steel tube concrete and external reinforced concrete, thus to obtain a load-bearing capacity calculation method of steel tube-reinforced concrete column. The test results indicate that the load-bearing capacity of columns calculated by this method can agree well with the test values. In addition, it can be used as a reference for engineering practice.