Experimental Research And Experimental Research On Bending-torsion Characteristics Of Curve Composite Beams With Interior Diaphragms

As the steel-concrete composite beam has the advantage of light weight, settingup easily, good seismic performance, structural stability, the medium-span bridgesand the curved bridges which have a horizontal curve has been widely used. Whencurve composite beams under load, it will generate complicated bending and torsioncoupling effects. This paper is based on national natural science foundation of chinaResearch on bending-torsion coupling mechanism and diaphragm effect of curvedcomposite bridges stiffened by diaphragm (51108281). This paper conducted a sixsimply supported steel-concrete composite beams‘static load model test.Thesteel-concrete composite beams have been designed with different span/radius ofcurvature ratios and and diaphragm plate number. The finite element analysis ofsteel-concrete composite beams is conducted using the software of ANSYS, andusing M/R method and the load decomposition method to studied the compositebeams torsional effects, The major conclusions are as follows:(1)With the span ratio increases,the curve composite beam stiffness degradation,bearing capacity reduced, failure pattern by bending failure gradually transition tobend torsion. The more higher of the span ratio the curve composite beam‘s bendingtorsional damage characteristics more obvious. Diaphragm plate has little influenceon integral forced performance of curve composite beams.(2)Tangential strain curve of composite beams along the vertical cross sectionbasically identical with flane section assumption; Tangential strain and radial strainincreases with the increase of the ratio of span, Along the transverse cross-section, inthe section of diaphragm,they are small in the inner side of the curves,but they are bigin the other side, otherwise,in the secetion of without diaphragm,they are big in theinner side of the curves,but they are small in the other side.(3)The tangential slip and radial slip of curve composite beam increased with theincrease of span ratio, diaphragm plate has little influence to it. The distribution of thetangential sliding and vertical shear along the beam axis is same. Radial slip value is very small, in the position of diaphragm has a mutation.(4)Warping stress of rigid torsion,distortion warping stress,rigid torsion angle,ditortion angle and warpage increased with span ratio increases,but decreases with thedegree of shear connection increases. Diaphragm has little effect to warping stress ofrigid torsion and rigid torsion angle. Along the transverse cross-section,in thediaphragm section distortion warping stress has the opposite distribution with thesection of without diaphragm. Ditortion angle significantly reduced in the diaphragmsection.