The Research On Mechanical Properties Of Concrete-filled Rectangular Steel Tubular Composite Members

The concrete filled steel tubular compsosite T-beam and concrete filled steel tubular compsosite truss beam are the new concrete filled steel tubular composite members.Both of them make full use of the advantages of concrete filled steel tubular and solve the I-beam instability of of steel-concrete compsosite beam,the lack of aesthetics and complex joint of steel truss.Meanwhile,the two new composite beams can implement rapid assembly construction and the use of stainless steel instead of common steel can be applied in harsh climate area,which have a good application prospect in bridge engineering.On the basis of the National Technology Support Program “Key techniques of steel-concrete composite urban bridges”(Grant No.2011BAJ09B02),the mechanical properties of concrete-filled stainless steel tubular members under axial compression,the flexural behavior of concrete-filled(stainless steel)steel tubular composite T-beam and concrete-filled(stainless steel)steel tubular composite truss are studied through the combination of experimental research and finite element analysis.The main works are as follows:(1)The analysis of 3D solid finite element models of 162 concretefilled stainless steel tubular members under axial compression relying on the verification are carried out.It is revealed that the law of stainless steel tube has stronger restraint on core concrete than common steel tube.A practical formula for calculating the bearing capacity of rectangular stainless steel tubular members under axial compression considering the shape constraint coefficient is proposed.(2)The experimental research on the flexural behavior of 2 concretefilled rectangular steel tubular composite T-beams and the analysis of the shell-solid finite elemnet models of 99 concrete-filled rectangular(stainless steel)steel tubular composite T-beams are carried out.The effects of stirrup on the flexural behavior,failure mode and relative slip of concrete-filled rectangular(stainless steel)steel tubular composite Tbeams are studied.It is revealed that the laws of stirrup reducing the interface slip between steel tube and core concrete and rectangular(stainless steel)steel tubular composite T-beams improving the flexural rigidity and ulitimate bearing capacity.The influence of correlative factors on the flexural rigidity and ulitimate bearing capacity of rectangular(stainless steel)steel tubular composite T-beams are discussed.The practical formula for calculating the flexural stiffness and bearing capacity of concrete-filled rectangular(stainless steel)steel tubular composite Tbeams are proposed.(3)The experimental research on the flexural behavior of 2 concretefilled rectangular steel tubular composite truss beams and the analysis of the 3D solid finite elemnet models of 129 concrete-filled rectangular(stainless steel)steel tubular composite truss beams are carried out.The effect of stirrup on the flexural behavior is studied.It is revealed that the laws of the change of neutral axis and the full curve of rectangular(stainless steel)steel tubular composite truss beams.The technical indicators of concrete-filled rectangular(stainless steel)steel tubular composite truss beams is analyzed.The influence of correlative factors on the flexural rigidity and ulitimate bearing capacity of rectangular(stainless steel)steel tubular composite truss beams are discussed.The practical formula for calculating the flexural stiffness and bearing capacity of concrete-filled rectangular(stainless steel)steel tubular composite truss beams are proposed.In this dissertation,it contains 156 figures,40 tables and 140 references.