Bearing Capacity Research On Cold-formed Steel Tubes Encased Concrete Stub Pier

Concrete-filled steel tubular structures have good performance and have been wildlyused in the production process. Domestic and foreign scholars have mainly focused onno more than6mm wall-thickness of Concrete-filled steel tubular structures. This paperfocused on medium-walled and cold-formed Concrete-filled steel columns，and theresearch can give references to the engineering design and the concrete-filled steeltubular structures research.Based on the experimental study of Concrete-filled steel tubular columns,the finiteelement (FE)analysis have already conducted, and the experimental results are comparedwith Concrete-filled steel tubular specimen standards. Ten columns including6mm-walland10mm-wall specimens, involving five tubular sections, were tested.According to the experimental study of the specimens under axial pressure,we havegot the ultimate bearing capacity of the specimens and the strain in the geometric centerof steel pipe; the comparison between the FE analysis and the experimental results havebeen used to study the influence of the arrangement of the stiffeners and the thickness ofsteel pipe; And the FE model is used to carry out analysis of the actual pier. In the sameway, this paper has also carried on the standards comparison. Mainly conclusions arelisted as follows:1、Cold-formed medium-walled steel stub columns have better strength with morestiffeners. And reasonable arrangement of stiffeners can get ideal effect;2、The design strength which is calculated by the standards of CECS159:2004、DBJ13-51-2003、 AISC(2005) and BS EN1994-1-1:2004,is all less than theexperimental values. The result of AISC(2005) is the most similar to the experimentalresults;3、In this paper, the FE analysis can give a very good simulation to the experimentalspecimens;4、Based on the FE analysis, the analysis of concrete-filled steel tubular pier wascarried on. And the optimal concrete-filled steel tubular section size was found, which is equal to the practical engineering of reinforced concrete bridge piers. The presence of ahorizontal force greatly reduced the concrete-filled steel tubular pier bearing performance.And the performance of piers which have stiffeners has been improved although the effectis not so obvious.5、 The standard BS5400(2005), which is used to calculate the concrete-filled steeltubular piers, needs to be modified in order to calculate bearing capacity of theconcrete-filled steel tubular with thicker tubular wall.