Experimental Research On Bending-tortional Behavior Of Negative Moment Zone In Curve Composite Beams

The regional curved composite beams in the intermediate supports is complex status when it under the action of negative bending momentan and torque, But at present the research on flexural torsional behavior of the steel – concrete curved composite beam is mainly aimed at common action of positive moment and torque. This paper is based on national natural science foundation of china Research on bending-torsion coupling mechanism and diaphragm effect of curved composite bridges stiffened by diaphragm(51108281). The steel-concrete composite beams have been designed with different span/radius of curvature ratios, This paper conducted a two simply supported steel-concrete curved composite beams’ static load model test, And the test beam was analyzed by numerical simulation and parameters with ANSYS software. The major conclusions are as follows:(1)With the span ratio increases, the steel-concrete curved composite beams under the action of negative bending moment and torque, the action of negative bending moment is enhanced, its bending stiffness and torsional stiffness degradation, bearing capacity reduced;(2)The steel-concrete curved composite beams under the action of negative bending moment and torque, before loading to 0.8Pu, is consistent with the assumption of plane cross-section, The radial strain and tangential strain in the floor of steel girder of the steel-concrete curved composite beams, along the transverse cross-section, in the secetion of without diaphragm, they are big in the inner side of the curves, but they are small in the other side, otherwise, in the section of diaphragm, they are small in the inner side of the curves, but they are big in the other side; the tangential slip by the effect of diaphragm is very small;(3) The steel-concrete curved composite beams under the action of negative bending moment and torque, the tangential slip and radial slip decrease with the span ratio decrease, the tangential slip by the effect of diaphragm is very small, but the radial slip subject to greater impact in diaphragm and compared to the tangential slip is small;(4) The steel-concrete curved composite beams under the action of negative bending moment and torque, the concrete plate at about 0.15 Pu has beencracking, the crack is tilted because of the existence of torque; the crack spacing affected transverse reinforcement spacing; the formula about crack spacing and modified formula for calculating crack width which is proposed by the paper can be used for the steel-concrete curved composite beams negative moment zone;(5) The steel-concrete curved composite beam’s limit torque increased, because of the existence of negative bending moment, but limit negative bending moment by the effect of torque is very small; when 1.0≤T/Tu≤2.0 and 0≤M/Mu≤0.8, The steel-concrete curved composite beam’s limit torque and limit negative bending moment is mutually reinforcing when 0≤T/Tu≤2.0 and 0.8≤M/Mu≤1.0 The steel-concrete curved composite beam’s limit torque and limit negative bending moment is mutually weakened.