Experimental Investigation Of Bending Behavior For Steel And High Performance Concrete Composite Girders With Concrete Filled Tubular Up-flanges

Based on the references from both domestic and overseas, an innovative composite section of steel and concrete is put forward in this thesis. The upper flange of conventional I girder is substituted by steel tube filled with high performance concrete, which is self-compact. Then, the concrete filled tubular up flange composite girder (CFTFG) is formed, which shows significant advantages. When comparing with conventional I girders, the CFTFG is superior in strength, rigidity and stability under the same amount of steel. The capacity can be enhanced and the amount of steel can be reduced at the same time, if the I girder is substituted by CFTFG In this way, the steel is saved and the high of the girder is reduced. It is clearly that such CFTFG can be used effectively in bridge in city which has a strict requirement in clearance. At the same time, this innovative section is superior in ductility and safety storage, and thus can be used in high seismic regions. To sum up, this innovative composite girder can make an effective use of both steel and concrete and thus has a bright future market.At present, the relevant research about CFTFG is rare in international level. To study its bending behavior in static, two CFTFG specimens were tested and the numerical analyze was conducted. By comparison between experimental and numerical result, the bending behavior of CFTFG was analyzed thoroughly. This thesis can be valued as an elementary study of the behavior of CFTFG, which serves as the basis of its application in bridge engineering.The following research tasks were conducted in this thesis:1. Two specimens were tested to evaluate their bending capacity. The content included the design and fabrication of specimens, the distribution of tested points, and the procedure of the test. Then, the test results were analyzed to evaluate the bending capacity, deformation and strain.2. The finite element software ANASYS was used for a numerical study of the specimen. Based on the linear static calculation, the dimension of the specimen was determined. Then, the dimension was checked by calculation considering material nonlinear. Compared with the experimental and finite elemental result, the bending parameters were analyzed and the impaction of inner concrete in tube, the yielding strength of stress, the steel ratio of upper flange to bending behavior were analyzed.3. Through the experiment and numerical analyze of the bending capacity of CFTFG, the characters of bending failure were attained. On the basis of the result from experiment and finite element, the provisions concerning the design of such innovative composite girder were proposed.4. The theatrical analyze about the behavior of CFTFG was conducted according to the results of finite element and experiment. Then the simplified bending formula was supplied and it can be illustrated that the calculation is in good accordance with the test.