Study On Model Test And Engineering Application Of Masonry Arch-bridge Reinforced With Composite Arch Circle

Masonry arch bridge reinforced by composite arch circle can increase the integrity,durability, strength, stiffness and bearing capacity of the reinforcment structure, meanwhile,this reinforcement method has the advantage of convenient construction and low cost, so ithas a broad application prospect in our country. However, for reinforcement theory of amasonry arch bridge, its theoretical study is seldom carried out so far both at home and abroad.So the study on this reinforcement technology as for masonry arch bridge is ofgreat theoretical significance and engineering applications’value.In the engineering background of a some masonry arch bridge reinforced by compositearch circle method, this paper gives a research on reinforced arch segment by combination oftheoretical analysis, numerical simulation and model test. According to the stresscharacteristics of a reinforced arch segment, the research is carried out for the theoreticalanalysis method, bearing capacity, failure mode, stress-strain curve, eccentric compressionconstitutive relation of composite arch circle and the formulas of reinforcement normalsection bearing capacity. Finally, main contents in our study are applied to a design exampleof masonry arch bridge reinforced by composite arch circle, which promotes the applicationof research results to engineering practice. The principal results are as follows:1. Nine typical reinforced columns and two columns without reinforcement have beendesigned, produced and carried out periodical experimental design. The complete test plan hasbeen made, the test content and test purpose has been definited, and the static test loadingscheme of uniaxial compressive failure has been determined. The above work is theprecondition of fulfilment of strengthening test, which is directly related to the success orfailure of whole experiment, and provides the analysis foundation and calculation for masonryarch bridge reinforced by composite arch circle.2. Eleven speciments has been tested by2000kN jack in the testing laboratory. Duringthe test, the failure process of specimens were observed, the bearing capacity and load-straincurves of these were collected. The analysis of various factors which have influence onultimate bearing capacity of specimens has been carried out, such as the depth of compression,the fracture height of original arch ring, the width of reinforcing layer and the initial stress. It has been found that the whole test values of the load-strain curves are almost close to thepartial test values at the test section of each specimens, thus the accuracy of experimental datais verified. According to measurement data, the analysis shows that the section’s straindistribution of masonry and concrete is failed to meet plane section assumption at an initialstages of loading. Along with increase of loading, the composite section stress will beredistributed, the masonry and concrete will be coordination deformed and costressing. Whenloading is up to0.9Pu, the strain distribution of section will be approximately to meet planesection assumption. Therefore, the deformation of a composite section is able to approximatlymeet plane section assumption.3. According to assumed conditions that a composite arch circle meets the plane sectionassumption, four kinds of the composite material constitutive relations are deducedrespectively by four different kinds of concrete’s constitutive relation and one kind ofmasonry’s constitutive relation. The four kinds of the composite material constitutive relationsare used for finite element simulation model of specimens, the finite element numerical andthe measured value are compaMPared, the result shows that the finite element numerical ofultimate bearing capacity is close to the measured value by using the composites materialconstitutive relations of the concrete Rüsch model of quadratic parabola plus horizontal line.The distribution of stress and strain are analyzed by taking that the composite materialconstitutive relations as a research object, it is found that theoretical failure process is close tothe practical failure process, numerical and curves of theoretical load-strain is derived, incompaMParison with numerical vale and curves of practical load-strain, we can see thattheoretical value by load-strain curves of masonry and concrete under eccentric compressionLoading agree with practical value. It shows that the composite material constitutive relationsof the concrete Rüsch model of quadratic parabola plus horizontal line is compaMParativelycomformable to actual conditions, thus providing a simplified way to numerical analysis ofmasonry arch bridge reinforced by composite arch circle.4. In considerations of the initial stress of unreinforced original arch ring and theconstitutive relations between masonry, concrete and steel, according to judgement whetherthe masonry arch bridge has horizontal crack or not, the formulas of normal section flexuralload-bearing capacity of masonry arch bridge reinforced by composite arch circle are deduced with a masonry arched bridge reinforced ribbed section as example. The bearingcapacity of every section can be calculated fastly by means of a mapple software which iseasy to be adopted by engineers. A numerical example shows that an error between calculatedvalues by fomula measured values by test is within9%. This provides a theoretical support forpractical engineering application of that derivation formulas, and shows that the derivationformulas are coMParatively comformable to practical engineering application. The derivationformulas are suitable to big and small excursion compressive members, so that these formulasare of high suitability.5. This paper in detail puts forward a reinforcement design process from section designto section check on the basis of a plane section assumption, composite material constitutiverelation and formulas of normal section flexural load-bearing capacity of masonry arch bridgereinforced by composite arch circle. It is proved that the deductive composite materialconstitutive relation and formulas of normal section flexural load-bearing capacity in thepaper can be safely applied to the calculation of normal section flexural load-bearing capacityof a masonry arch bridge reinforced by composite arch circle through a complete designexample of masonry arch bridge reinforced by composite arch circle. The combination oftheoretical analysis with project practice can help the promotion of the result to theengineering project.In a word, three innovative points of this paper are summed up:1. Plane section assumption of reinforced section from loading to failure is certified onthe basis of analysis of experimental data. Section’s strain distribution isn’t able to meet planesection assumption in initial stages of loading due to deformation asynchrony of masonry andconcrete. Along with the increase of loading, the composite section stress will be redistributed,masonry and concrete will be coordinately deformed and costressing. While loading is up to0.9Pu, the strain distribution of section is able to approximatly meet plane section assumption.Therefore, it can be seen that the deformation of composite section is able to approximatlymeet the plane section assumption.2. According to the assumed conditions that a composite arch circle meet the planesection assumption, four kinds of the composites material constitutive relations are deducedrespectively by four different kinds of concrete’s constitutive relation and one kind of masonry’s constitutive relation. When the four kinds of the composites material constitutiverelations are used for finite element simulation model of specimens, and the finite elementnumerical value is compared with the measured value, the result shows that the finite elementnumerical of ultimate bearing capacity is close to the measured value by using the compositesmaterial constitutive relations of the concrete Rüsch model of quadratic parabola plushorizontal line. If this composite material constitutive relation is applied to finite elementanalysis on engineering example, ultimate bearing capacity can be accurately calculatedconsidering both simplify finite element model and calculation work.3. In combination of the initial stress of reinforcement structure with the reinforcedmaterials nonlinear, and based on an judgement whether the masonry arch bridge withoutreinforcement has horizontal crack or not, the formulas of normal section flexuralload-bearing capacity are deduced and verified by test. The result shows that an error betweencalculated values by fomula and measured values is within9%, load-bearing capacity of everysection is accurate and can be rapid calculated. When the formulas of normal section flexuralload-bearing capacity are applied to engineering example, finite element calculation is thesame as that of formulas, the result shows that derivation formulas is coMParativelycomformable to practical engineering application.