| In recent years, through and half through arch bridges had become one of top-priority bridge type in the city bridge design scheme because of its graceful mode, comprehensive apply occasion as well as favorable economic indicator and other factors. According to related documents and materials, there have been more than 300 through and half through arch bridges built in our country, which develop in the direction of larger span and scale, and the area of use is expanding gradually. Since the characters of through and half through arch bridges are having more composed members and complicated construction craft, in company with its continually enlarged span, the difficulty of construction increased correspondingly, and the importance of construction technique as well as construction security gradually extruded. According to related documents and materials, more than 90% arch bridge security accidents occurred in the construction stage, so the construction control of through and half through tied arch bridge should be studied. In recent years, owing to the requirement of bridge construction , bridge construction control technique had already aroused many bridge staff unlimited interest, and this dissertation is written and developed in this background.The main bridge of second bridge of Zhanhe in Kaifa road of Pingdingshan city is a reinforced concrete through tied arch bridge with 120 meters span, and it adopted the disposal form of stiff arch ribs as well as stiff tied beams but flexible suspenders, with reinforced concrete box shaped cross section of arch ribs and tied beams. Its two arch ribs inclined 10 degrees to the hub of bridge, and utilizing six I-shaped cross sectional reinforced concrete transverse bracing in the crown zone of arch, they connected as a whole, and composed "X-shaped" arch structure. There were 32 suspenders with symmetrically disposed in the bridge, and the suspenders were within the plane of arch rib. The bridge deck system and arch rib of this arch bridge were adopted the construction style of full framing brackets laying. In this dissertation, the arch bridge was discretized by the FEM according to its structural characteristics with the spatial beam element simulating the tied beams, end floor beams, middle floor beams, arch ribs and the like and with the spatial link element simulating the suspenders to erect the bridge's spatial mechanical computational finite element model. Finite element common software ANSYS was applied for analysis of this arch bridge's mechanical properties of the static state, dynamic characteristics and stability in the initial balanced state. Meanwhile, the design of this arch bridge was checked up in its completed stage, and the difference in stability aspect between this "X-shaped" arch bridge and parallel ribbed arch bridge was discussed. At last, combined with the project of construction control of the second bridge of Zhanhe, this dissertation proceeded detailed study of the theory and method in bridge construction control, and utilized Finite element common software Midas/civil to simulate the construction process of this bridge, and introduced the construction control work of the second bridge of Zhanhe concretely. Synthesized above work, this dissertation achieved following conclusion:1. The ribs of this bridge was chiefly undergone compression and its bending moments was smaller; although the tied beams was members undergone tension and bending, but they were in full cross-section compressing because of having disposed more tendons; the distribution of tension of suspenders were comparatively even, and the controlling action of suspenders' tension to the line shape of bridge deck system was comparatively conspicuous; both the deformation and the internal force state of each members of this bridge were within the specialized range of bridge design norms, so that the stress state of this bridge structure was rational.2. The bridge's vibrations mainly involve three types of vibrations, the arch ribs' vibrations out of plane, the vertical vibrations of the whole bridge and torsional vibrations. The bridge arch ribs had a smaller stiffness out of plane, so the first vibration of this bridge was the arch ribs' vibrations out of plane; each vibration of this three types accounted for one-third in the first 15 sets of modes of vibration, and that was different from common through and half through parallel ribbed arch bridge.3. The unstability characteristic of this bridge mostly behave as the unstability of arch ribs out of plane, same as the common through and half through arch bridge, but owing to the existence of arch ribs' obliquities, the transverse stability of this bridge was conspicuously excel parallel ribbed arch bridges, and the stability factors of this "X-shaped" arch bridge was apparently higher than that of parallel ribbed arch bridge in two cases.4. According to this bridge's structural characteristics and construction craft, the detailed construction control scheme was made, and utilizing the idea of the engineering cybernetics, calculated the tensioning procedure of suspenders and tendons of bridge deck system, the internal force and displacement during the arch ribs' laying and the centering unloading of arch ribs' bracket, and the parameter identification was proceeded with least square method.5. The construction supervision was proceeded according to the construction control scheme, and the result indicated that the fore-and-aft elevation change of tied beams and arch ribs dovetailed well with the calculation, and the value was within the rational range; actual measurement line shape of bridge deck system and arch ribs approached comparatively the design line shape.6. The mensuration value of suspenders dovetailed well with the calculation in the general situation, and the minima of the two was 0.17%, the maxima was 15.44% , the average error was 3.89%, meanwhile, the error of each suspender tension acted like discreteness. The distribution of all the suspenders' tension values was relatively even, but the mensuration value of serial number in the headwaters of K 2 ^ 5 ^ 11 and the serial number in the tail waters of K 5^ 12 were comparatively small than calculation, so that these suspenders should be adjusted for the second jacking to guarantee the mensuration value approached calculation and tension value distribution was even.7. By the practice of bridge construction control, the importance and necessity of construction control for large span through and half through arch bridges were approved. The internal force and line shape of through reinforced concrete "X-shaped" arch bridge changedfrequently during the construction stage due to its structural characteristics, especially, in the each construction stage and completed state, the tensioning procedure and value of suspenders and prestress affected bridge structure state remarkably; since the bridge deck system and arch ribs were adopted the construction style of full framing brackets irrigating, their elevation were hard to adjust after centering unloading, so ascertaining the reasonable forming elevation was very important to the control of the line shape of whole bridge; the strength and stability of brackets during the construction, reasonable laying and centering unloading scheme of arch ribs were all the important factors to affect the quality and security of the bridge construction.The computation and analysis of this dissertation had applied to the practice of design and construction of second bridge of Zhanhe in Kaifa road of Pingdingshan city, and obtained preferable effect. This bridge had achieved the scheduled target of construction control from the practice. The computational data and conclusion could also supply basic data for the healthy detection and maintenance during the transport operation stage, as well as for the design and construction of homogeneous bridge, so this dissertation has prodigious engineering practical value. |
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