Theoretical And Experimental Research On Performance Of Nonlinear Behavior Of Self-anchored Suspension Bridge Of Large Span From Geometry

In recent years, with the span of self-anchored suspension increasing, and in theconstruction, geometric nonlinear characteristics become more prominent, resulting in asystem conversion. Structural characteristics of the force and displacement variation isalso very complex, and the current domestic engineering studies for this is less. there isno experience to learn, therefore, study self-anchored suspension span geometricnonlinear characteristics is essential.On self-anchored suspension bridge simulationanalysis, there is a certain degree of simplification (especially boundary conditions),there are some errors cause analysis results, and thus the bridge’s geometric nonlinearitycan not be ensured.Using full-bridge model test, although this bridge geometricnonlinearity can not be directly analyzed based on test data, but can be indirectly fromthe experimental results and theoretical calculations to verify the degree of fit theory tocalculate the geometric accuracy of the nonlinear characteristics.Therefore, the use offull-bridge model tests to explore this large span self-anchored geometric nonlinearity isnecessary.Based on the above considerations, this paper is based on the ministry oftransportation scientific and technological project "large full-span self-anchoredsuspension bridge model test" to study the geometry nonlinear behavior characteristicsof the Yellow River Bridge taohuayu, and to analyze the mechanical properties and themain cable slings displacement law in its construction process based on the test data.The main contents are as follows:1、To introduce the Yellow River Bridge taohuayu full bridge model test similarityrelation, reduced scale than choosing, the model structure of the various parts of thedesign, structural design parameters, structural design checking parameters,counterweight (dead load compensation) status. The main cable and sling tensiondesigned, force measurement system design and displacement measurement systemdesign are elaborated, and the measuring points and analog construction conditions aredescribed.2、Based on the experimental data, to analyze the main cable position in theconstruction of a typical vertical displacement and longitudinal displacementcharacteristics by comparing the actual conversion value of theoretical and experimentalbridge bridge theoretical calculations. The results showed that: in construction, the maincable of different cable grips cumulative displacement variations are not the same; in the same conditions, and side spans across the bridge tower on the symmetry of thecable grips midspan displacement magnitude is always greater than the side spans; theside span main cable cumulative vertical displacement and vertical displacement anddeformation accumulated value is basically the same and the main cable across thevertical cumulative displacement and longitudinal displacement and deformation valuesaccumulated from the bridge tower to the span, the difference becomes larger;conversion architecture has significant effects on the vertical cumulative displacementof the main cable and to the longitudinal cumulative displacement is weak, and in themid-span1/4most significant, from the mid-span to span across1/4, the impactgradually increased; cross from1/4to the bridge tower place, gradually weakened,almost no effect on the side span.3、Based on the experimental data, to analyze the the typical hanging cable tensionvariation in construction by comparing the actual conversion value of theoretical andexperimental bridge bridge theoretical calculations. The results showed that: inconstruction, the side span and slings force variation is different; due to side across thesling tension obtained through the cable force, without affecting the adjacent tensioningrope, slings of the other longer force becomes larger sling, and sling system powerconversion does not change after completion of the process; the experienced acrosssling tension due to cable forces obtained by adjacent sling tension effect is small; theimpact of longer other sling force gradually becomes larger; system conversion iscompleted sling force changed little process.4. Based on the test data, the comparison of actual bridge theory conversion valueand test bridge theory calculation value, analyzed the typical sling in ratio, the cableforce growth under different working conditions and the final cable force results showthat: the sling side span suspenders eventually cable force mainly comes from othersling tension generated by the cumulative effect of growth; the sling eventually cableforce mainly comes from the adjacent sling other sling tension generated by the slingcumulative growth effect.5.Effect of structural system change on typical cable force is analyzed based on testdata and the comparison between theoretical bridge calculated value and experimentalbridge calculated value. The results show that: the sling force increase with the tensionof the slings before the girder off the frame; the sling force decrease gradually with thetension of the slings when the stiffening girders are partly off the frame; the sling forcehardly change with the tension of the slings when the stiffening girders are completely off the frame.6.Using actual bridge’s theoretical calculated value, the rules of adjacent cables’effects on each other under construction is analyzed. The results show that: adjacentcables’ forces decrease sharply when a cable is being tensioned, other cables don’tsuffer this effect; both the slings(excluding adjacent slings) in side span and the midspan are basically suffer the same effect from the cable tension; as the constructionprogresses, the effect the adjacent slings in side span suffered increase gradually and theeffect the effect the adjacent slings in mid-span suffered reduce then increase.7. A method of analyzing geometry nonlinear characteristics of self-anchoredsuspension bridge is proposed: following the principle that force does not change anddisplacement, there is a change in the same condition, the same position and under thesame system of sling tension average is divided into two parts, with the node load (force)simulation, the tensioning position role in two consecutive times, compare the maincable displacement increment of each node. If same increment, structure is linear; Ifincrement is different, the structure is nonlinear. And points out this method thoughunable to explain the Taohuayu Yellow River bridge, the geometrical non-linearity ofthe overall structure strength, but can explain the working condition of the bridge acrossthe geometric nonlinear characteristics, and can analyze the geometric nonlinearcharacteristics changing with the working condition. Reason this way although slightlyclumsy, but feasible.8. Using the method proposed by the author, the over all geometry nonlinearcharacteristics of vertical displacement and longitudinal displacement of the main cableunder construction stage and operation stage are analyzed. The results show that: themain cable displacement under construction has experienced all the cable clip pointlinearization characteristic obviously, not tension sling corresponding pinch nonlinearfeature enhancement, not tension sling corresponding weakening pinch nonlinearcharacteristics, has been tensioned cable corresponding to pinch nonlinear featureenhancement, has tension sling corresponding cable clip again some nonlinearcharacteristics weakened, and all the cable clamp is obvious trait of linearizationprocess; after construction, the main cable displacement is completely linearized andthere is no geometric nonlinear characteristics any more.9. Using the method proposed by the author, the part geometry nonlinearcharacteristics of vertical displacement and longitudinal displacement of the main cableunder construction stage and operation stage are analyzed. The results show that: main cable displacement changes appeared inflection point it is actually the main cabledisplacement influence line of zero, it often shows a geometric nonlinear characteristicsthan other position is more obvious; Structural system transformation characteristics ofmain cable displacement suffer a geometric nonlinear effect: before the systemtransformation, the main cable displacement geometric nonlinear characteristicsgradually enhanced; Upon the completion of the system transformation, structureweight transfer to the main cable, the gravity stiffness is heavy, main cabledisplacement geometric nonlinear characteristics gradually blurred, linear features tendto be more obvious.