Research On The Key Design Technologies And Model Test Of Curved Bridge

Due to its good linear adaptability,curved beam bridge is widely used in highway and urban road construction.However,due to its complex spatial mechanical characteristics and the lack of targeted design guidelines,on the one hand,it leads to the careful application of the bridge type in practical engineering,on the other hand,it also leads to the occurrence of some diseases of curved beam bridges.With the development of national economy and traffic construction level,in order to make the curved beam bridge more widely used,so as to better serve the needs of national traffic construction,it is necessary to carry out a more in-depth study of the bridge type to supplement and improve the design theory of the bridge type.In this paper,through model test,theoretical derivation and numerical analysis,the design method,spatial mechanical characteristics and restraint system of curved beam bridge are studied.The main research contents are as follows:1.The mechanical behavior and deformation characteristics of continuous concrete curved beam bridge under static loading are studied by using a large-scale laboratory test model of the same material and loading blocks which can simulate the real load distribution.According to the test results,the variation rules of bearing reaction force and mid span deflection of curved beam bridge under static loading are summarized,and the influence of middle diaphragm on the mechanical performance and deformation law of curved beam bridge is summarized.The influence of temperature on the mechanical performance of continuous concrete curved beam bridge is experimentally studied.The results of the whole model test can provide detailed test data and basis for the design and application of this structure.2.Based on the results of static loading test of curved bean model test,three key technologies in the design of curved beam bridge are studied through numerical analysis.The stress distribution and torsional distortion effect of curved box beam bridge is analyzed.The influence of curve radius,the number of intermediate diaphragms on distortion and warpage is studied,and the reasonable layout method of middle diaphragm is considered.In view of the problem that the main tensile stress in the outer web and bottom plate of curved beam bridge is too large due to the large torsional shear stress,a new arrangement of transverse prestressed reinforcement of concrete box beam is proposed,which can significantly improve the crack resistance performance of curved beam bridge.In addition,a calculation method of the additional uniform torque caused by the weight difference between the inside and outside of the curved beam bridge is also proposed.This method can supplement and perfect the calculation method of the single beam model.3.Based on the model test results of the influence of temperature change on the curved beam,the influence law of temperature and horizontal constraint stiffness on the stress and deformation of curved beam bridge is analyzed by numerical model,and the reasonable constraint system of curved beam bridge is studied.The research focuses on the establishment of reasonable horizontal restraint system of curved beam bridge,and puts forward the pin shaft type horizontal restraint system.This kind of horizontal restraint system can release the corner constraint at the fulcrum,allow the middle beam to produce radial displacement,adapt to the curvature change under the temperature change,reduce the secondary internal force influence of the temperature effect on the beam body,significantly reduce the stress load of the horizontal limit device,and effectively alleviate and prevent the occurrence of "creeping".4.On the basis of the theoretical research of pin type horizontal restraint system,the engineering application of the system is further studied.Taking a curved beam bridge with"creeping" disease as the engineering background,the causes of "creeping" is analyzed,and the "pin type" horizontal restraint system which can better adapt to the deformation characteristics of the bridge is reestablished.The establishment of the new restraint system effectively reduces the influence of temperature effect on the stress and deformation of the structure,and improves the stress state of the whole bridge structure.The repair work of the bridge starts from the cause to solve the disease,which provides a good reference and reference value for solving similar engineering problems in the future.In addition,the application of "pin type" restraint system in a new concrete continuous curved beam bridge is also carried out.The research results provide a new idea for the design of horizontal constraint of curved beam bridge.5.Based on pure torsion theory,the mechanical method is used to study the difference of straight bending analysis of simply supported concrete curved beam bridge under the action of self weight.The relative error formula of mid span bending moment and fulcrum reaction force in straight bending analysis of curved beam bridge under dead weight is derived,and the curve of relative error changing with various structural parameters is drawn.On this basis,the influence law of various structural parameters on relative error is studied.The correctness of the formula of relative error between mid span bending moment and fulcrum reaction is verified by numerical model,which proves that the research results are suitable for engineering analysis.6.According to the current bridge design code for vehicle load,the difference of mechanical performance of simply supported concrete curved beam bridge under vehicle load is studied by straight bending analysis.The relative error formula between the mid span bending moment and the fulcrum reaction force in straight bending analysis of simply supported curved beam bridge under automobile load is derived.By setting the relative error limit,the limit of straight bending analysis based on structural parameters is put forward,which makes the applicability of the design method of replacing bending with straight in engineering.Based on the research results of the difference in straight bending analysis of simply supported concrete curved beam bridges,the amplification factor of mid span moment and the adjustment coefficient of supporting reaction force are introduced,thus expanding the application scope of the design method of replacing curve with straight in the design of curved beam bridge.