Construction Monitoring And Analysis Of Steel-concrete Composite Continuous Beam Bridge

The steel-concrete composite bridge structure connects steel beams and concrete decks into a whole through shear connectors,which can give full play to the performance advantages of steel and concrete.Compared with traditional bridge structures,it is economical and environmentally friendly.It has obvious advantages and is widely used in modern bridges.However,the bridge body of the steel-concrete composite continuous beam bridge is subject to a large negative bending moment near the middle pier,and the combined section is in an unfavorable stress state.The concrete deck in the negative bending moment area bears a large tensile stress and is prone to cracking.This leads to corrosion of steel bars and steel beams,which affects the bearing capacity and durability of the structure.In addition,the shrinkage and creep effect of concrete itself will also bring a series of unpredictable adverse effects to the composite structure.In order to solve the above problems,this paper,based on a bridge construction monitoring project in Zhejiang,carries out a numerical simulation study on each construction stage of a steel-concrete composite bridge structure,and compares and analyzes with the measured data on site,considering different lifting heights and different lifting sequences The effect of the middle fulcrum lifting method is studied to effectively reduce the negative bending moment of the steel-concrete composite continuous beam bridge to reduce the risk of concrete slab cracking,and to study the effect of concrete shrinkage and creep on the long-term performance of the steel-concrete continuous beam bridge.The main findings include:(1)The use of mid-support point lifting method to apply prestress can effectively reduce the risk of negative moment concrete cracking in steel-concrete composite continuous beam bridges.And as the amount of lifting increases,the more prestress that can be stored in the negative bending moment zone.(2)The single-sided fulcrum lifting method needs to limit the vertical displacement of the side pier near the lifting end when lifting,and there is a risk of cracking of the roof concrete when the beam is dropped,but this method can reduce the manpower and equipment investment in the construction process.Therefore,it is recommended to use when there is a shortage of manpower and construction equipment.(3)After finite element simulation of 10-year concrete shrinkage and creep effect,it is found that the overall displacement of the bridge is reduced.The vertical displacement at the mid-span of the bridge is reduced from 120 mm to 115 mm.The stress increases.At the middle fulcrum,there is a risk of cracking on the concrete slab and lower flange.The calculation results guide the on-site construction to ensure that the structural force and deformation of the beam bridge during the construction process are always within a safe range,and the bridge is completed The linear shape of the main beam afterwards meets the design requirements,and the internal force state of the structure under constant load is close to the design expectations.(4)Based on this construction monitoring project,starting from the adjustment of engineering materials,structural design and construction measures,the study summarized measures to reduce the adverse effects of the beam bridge due to the shrinkage and creep of the concrete.Numerical simulation and field measurement data can provide references for similar bridge construction and construction monitoring projects in the future.