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Study On Behaviors Of Rectangular Concrete Filled Steel Tube Members Based On Unified Theory

Posted on:2015-04-01Degree:MasterType:Thesis
Country:ChinaCandidate:X L LiFull Text:PDF
GTID:2272330479989947Subject:Architecture and Civil Engineering
Abstract/Summary:PDF Full Text Request
The rectangular concrete filled steel tube(RCFST) members are used wider and wider and the study of them are deeper and deeper. Because they have beautiful apperance, simple nodes with beam, and can improve the ductility effectively and provide a powerful axis. However, the study of RCFST members based on unified theory focuses more on circular and square cross members than the large aspect ratio ones. Furthermore, the consideration of the present theory to the ferrule effect of RCFST members with large aspect rotio are not enough, so they need to be researched deeper.The distribution rule of RCFST between steel tube and core concrete under axial load is discovered by static analysis and finite element simulation. Then put forward the assumption of parabolic equation of core concrete zone and the derivation of the core concrete area with ferrule effect. The influence of cross section aspect ratio on the ferrule effect is analyzed based on the ideology of unified theory and the existing unified formula of bearing capacity of square concrete filled steel tube(SCFST) members under axial compression. Finally, the unified calculation formula of practical strength for RCFST members is obtained.In consideration of benefit of concrete to stable performance, the more economy stability factor formula is obtained by use of test reslts from the international database. Then the stability capacity formula of RCFST members can be obtained by use of the modified axial compression strength formula. At the end, the obtained formula is verified by experimental data.Based on unified theory, the theoretical calculation formula of ultimate flexural capacity for RCFST members around long axis and short axis is derived form the limit equilibrium theory. Then practical calculation formula of flexural capacity for RCFST of different aspect ratio is obtained by modifing that of SCFST. Under the guidance of unified theory, through modifing the limit equilibrium theory, the related equations of RCFST members under eccentric compression is correct.The unifited theory is verified to be inaccurate by the experiement database published by the internatinal assocition of composite structure and the European Code 4. The criterion and standard indicate that the uited theory is not suitable for RCFST members with lengh-width ratio beyonds 1.5, but the errors are relatively small for small length-width ratio. The article makes use of the database based on kinds of empirical experiments to prove the validity of the following formulas deduced in the main body of the essay:the axial compression strength formula for RCFST, the flexural bearing capacity formula for RCFST around long and short axis and the related equations for RCFST members under eccentric compression. And the data are from the internatinal database.
Keywords/Search Tags:unified theory, rectangular concrete filled steel tube, axial compression bearing capacity, stability bearing capacity, bending bearing capacity
PDF Full Text Request
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