Theoretical Research On Uniform-Torsion Rigidity Of Steel-Concrete Composite Beam With Circular And Non-Circular Section

As we known,steel-concrete composite beam has the characteristics of high strength,large rigidity,and excellent anti-seismic property.Thus,it is applied widely in large-span,high-rise and large space structures of constructional engineering.However,due to the steel-concrete composite beam made of different materials,its torsion mechanical property is more complex than the single material beam.So,at present,the studies of steel-concrete composite beam mainly concentrate on mechanical property of axial compression,eccentric compression and pure bending,and there are rarely researches related to its torsional performance.Moreover,the torsional deformation easily occurs in the structural members that are used in large-span,high-rise complex structures under different forms load actions.Besides,the research on mechanism of torsion and calculating method of bearing loads of steel-concrete composite beam is the foundation of studying deeply its composite torsion working performance and bearing loads calculation.Therefor,to carry out the study of torsional performance of steel-concrete composite beam not only has much higher scientific significance but also is a complex engineering problem which is desiderated to solve.So,based on thought of Plate-Beam theory presented by Prof Zhang wenfu and traditional classic Saint-Venant torsion theory,the uniform-torsion rigidity of steel-concrete composite beam with circular and un-circular(including ellipse?square and rectangle)sections are researched in this paper.The main research contents of this paper include:(1)According to Plate-Beam theory and traditional classic Saint-Venant torsion theory,firstly the cross-section lateral displacement u,v and the longitudinal displacement w expression formula of uniform torsion deformation of steel-concrete composite beam with circular section are given.Next,the strain energy expressions of uniform torsion deformation of CFST composite beam built-in I-type steel with circular section and I-type steel reinforced concrete(SRC)composite beam with circular section are respectively derived by basic knowledge of elastic theory.Then,the theoretical analytical solutions of uniform-torsion rigidity of these two types of steel-concrte composite beams are given.Meanwhile,in order that uniform-torsion rigidity analytical solution of steel concrete composite beam with circular section is conveniently applied in practical engineering,the superposition composite design formula of uniform-torsion rigidity of steel composite beam with circular section is presented based on the superposition thought in this paper.(2)The finite element models of CFST composite cantilever beam built-in I-type steel with circular section and I-type steel reinforced concrete(SRC)composite cantilever beam with circular section are established by ANSYS,and torsional mechanical property of steel conctere composite beam with circular section are analyzed by ANSYS in order to verify the validity of uniform-torsion rigidity analytical solution of steel composite beam with circular section presented in this paper.(3)According to Plate-Beam theory and traditional classic Saint-Venant torsion theory,firstly the cross-section lateral displacement u,v and the longitudinal displacement w expression formula of uniform torsion deformation of steel-concrete composite beam with un-circular section(including ellipse,square,and rectangle section)are obtained.Next,the strain energy expressions of uniform torsion deformation of CFST composite beam built-in I-type steel with un-circular section and I-type steel-reinforced concrete(SRC)composite beam with un-circular section are reapectivly derived by basic knowledge of elastic theory.Then the uniform-torsion rigidity theoretical analytical solutions of steel-concrete composite beams with un-circular section are given.Meanwhile,in order that uniform-torsion rigidity analytical solution of steel-concrete composite beam with un-circular section is conveniently applied in practical engineering,the superposition composite design formula of uniform-torsion rigidity of steel-composite beam with un-circular section is presented based on the superposition thought in this paper.(4)The finite element models of CFST composite cantilever beam built-in I-type steel with un-circular section and I-type steel reinforced concrete(SRC)composite cantilever beam with un-circular section are established by ANSYS,and torsional mechanical property of steel-conctere composite beam with un-circular section are analyzed by ANSYS in order to verify the validity of uniform-torsion rigidity analytical solution of steel composite beam with un-circular section presented in this paper.