Research On Construction Control Of Curved Continuous Steel Concrete Composite Beam Bridge

Steel-concrete composite beam is widely used in highway,urban overpass and ramp bridge because of its light weight,high stiffness,high bearing capacity and can maximize the material properties of steel and concrete.However,in the application process of the composite continuous beam bridge,there is an unfavorable stress state that the steel beam is compressed and the bridge deck concrete is stretched in the negative moment area,and the cracking of the bridge deck concrete hinders the development of the composite beam.In order to overcome the large negative bending moment near the middle support in the continuous structure,the traditional method is to use the Jack to lift only the steel beam at the middle support,and then pour the bridge deck concrete to reach the strength and then fall back to the support position.Because only the middle support is lifted,the tensile stress of bridge deck concrete is not suitable to be controlled.In addition,the lifting height,falling sequence and falling height of the bearing directly affect the pouring length of concrete and the compressive stress value of concrete in the negative moment area,as well as the durability of the service stage.For this reason,based on the engineering background of a curved steelconcrete composite continuous beam bridge,this paper studies the construction technology of curved continuous steel-concrete composite beam bridge,and puts forward a new construction technology pre-lifting and falling method.The main research contents are as follows:(1)The study on the reasonable segment position of steel-concrete composite continuous beam.The sectional hoisting construction of steel-concrete composite continuous beam is usually adopted,and the setting of segmental point is particularly important,so based on the differential equation of beam deflection curve,the expressions of deflection and rotation angle at pier top and primary bridge are derived.The deflection difference between segmented hoisting and primary bridge is analyzed,and the influence of different span and section stiffness of steel-concrete composite continuous beam on weld width at segmented position is analyzed.As a result,the rationality of the segment position is verified,and the corresponding suggestions are put forward.(2)On the basis of the traditional support lifting and falling method,the bearing pre-lifting and falling method is put forward-all the supports are pre-raised first,and then for the steel-concrete composite beam bridges with different spans,through numerical analysis,the corresponding falling sequence and falling height are put forward.in order to obtain the expected stress control value to improve the tensile stress of concrete in the negative moment area,the formula for calculating the maximum and minimum pre-lifting height of steel beam is derived based on the force method.And the calculation formula of the falling height of the bearing,the falling sequence and the pouring length of the bridge deck concrete after the bridge deck concrete pouring,carries on the parametric analysis to the falling height combined with the calculation formula,and gives the error limit of the bearing falling height.(3)Aiming at the curved steel-concrete composite continuous beam bridge with small curve radius,in order to improve the tensile stress of the bridge deck concrete in the negative moment area,the formula for calculating the bearing falling height of the curved steel-concrete composite continuous beam bridge is derived based on the displacement method.Based on an engineering example,a finite element model is established,and the correctness of the formula is verified by comparison with the finite element model.On this basis,the calculation formula can be applied to practical engineering,and the bearing falling height of steel-concrete composite continuous beam bridge with small curve radius,such as 50 m,100m,150 m,200m,300 m and so on,can be calculated.