Applied Mechanics and Materials Vols. 638-640

Abstract: This paper introduces the concept of jointless bridge, classification, characteristics and use of the existing problems, and seamless bridge between home and abroad in the course of development and the current situation, Summary analysis of its technical difficulties and influencing factors.

Abstract: Bridge piers generate local destruction at impact point after suffering medium and low speed impact, and then their bearing capacities decrease a lot. In order to analyze the reliability of piers with damage, based on the formula in code, this thesis used ANSYS to analyze surplus normal section load-carrying capacity of reinforced concrete bridge piers with notches in different sizes. The relation curve between axial bearing capacity of piers and scaling area of concrete was obtained. After comparing with formula in code, a new formula was obtained, which can be used in calculating surplus normal section load-carrying capacity of chipped bridge piers.

Abstract: This paper selected one bonded prestressed concrete box beam which was No.33-2 in the left picture of shahe bridge of one highway project as a test beam. We tested the deformation (deflection, residual deformation), strain(stress), cracking condition and cracking width under three cycles loading at the middle of span through the static load test. We compared and analyzed the tested values with the theoretical calculating values, then we get the security of the bonded prestressed concrete box beam can be guaranteed.

Abstract: Based on a 125 - days natural environment temperature changing observation of one cable-stayed bridge in zhejiang province and the reasonable simplification of the thermal field and stress distribution of concrete bridge tower, the bridge tower thermal stress finite element analysis is done through the first kind boundary condition and the third kind boundary condition. It is confirmed that the deviation of thermal stress between the first kind boundary condition and the third kind boundary condition is below 6% because the outside temperature change range is limited in the practical engineering case. Using the first kind boundary condition can meet the accuracy requirement of the project at the same time greatly simplify the calculation process.

Abstract: This paper analyzes the vortex induced vibration (VIV) phenomena of twin box bridge girders by means of 2D computational fluid dynamics (CFD) models. The modeling of turbulence follows a methodology known as large eddy simulation (LES) in which the large scales of turbulence are resolved, while the small ones are modeled by means of sub-grid-models. The dynamic response of structure in relation to the fluid is solved by embedding the code of Newmark-β method in user defined functions of Fluent. The time history of girder’s vibration displacement is obtained successfully, which agrees well with the experiment results of wind tunnel tests. “Lock-in”, “beat” phenomena and the displacement “detuning” phenomena in the locked field are also gained.

Abstract: Pasco-Kennewick (PK) section girder is widely used in the concrete cable stayed bridges with double cable planes, because of its excellent mechanical properties. By created the double girder finite element model, this paper analyzed the dynamic response of one concrete cable stayed bridges with PK section and the dynamic response of the diaphragms. According to the results of the analysis, the diaphragms which near the auxiliaries’ pier s and pylons generated large seismic internal force under the seismic load, and it is account for large proportion when compared with the static load. So, single-girder model can not satisfy the requests for the dynamic analysis of the girder. Due to the cross beams generated large positive, negative bending moment when seismic load impact, we must take notice of strengthening reinforcement in diaphragms. Especially the reinforcement for the negative bending moment, so as to meet the requests for the anti-seismic.

Abstract: Wuhan Tianxingzhou Yangtze River Rail-cum-Road Bridge is the first four line rail cable-stayed bridge in china, with three-truss cross section. The new structure presents complex load performance, especially the spatial mechanical characteristics, because the bridge supports six lanes and four railway load, inevitably the main truss will produce a great torque, leading to three-truss cross section distortion and warping deformation. Analysis of the whole bridge spatial structures is carried out. The space shear flexible beam grillage model is used for bridge structure simulation, the upper and lower vertical member and the horizontal link simulated with beam element, while the pylon with space beam element, the cable with cable element. Though the calculation of the cable force and stress, the main girders stress, the pylon stress, the displacement of the main girder and the pylon, it can be shown that the space force and displacement keep within the standard requirement.

Abstract: By investigating and examining one 40 years old girder arch bridge, this paper gets the current situation of the bridge. On account of these data, the reliability analysis and safety evaluation have been done, the reliability index was calculated, the dynamic reliability of the bridge was analyzed, and the disciplinarian of bearing capacity change with the deck pavement thickness and vehicle load level increasing was discuss. Moreover, the treatment project and strengthening measures was put forward.

Abstract: The problem of high temperature closure of concrete arch bridge using cable-stayed buckle and cantilever method was resolved by pre-jacking force and counterweight in the arch rib closure port. The arch closure status effect of temperature difference was error array, the unit pre-jacking force and unit counterweight were impact parameter array. The impact matrix was the arch closure status effect of unit pre-jacking force or unit counterweight. The matrix equation was established on the error and the impact of parameters. Then, the pre-jacking force and additional counterweight value were solved by the least square method. Finally, the control method was verified by the calculation and analysis of Mupeng bridge. It was applied to achieve the closure of arch bridge using cable-stayed buckle and cantilever in any high temperature conditions.

Abstract: Based on the concrete carbonization theory, we analyze the time when prestressed steel strands begin to corrode, and put forward the degradation time-dependent model for cross-sectional area of a corroding steel strand; with the comparison of existing research results, we propose the degradation time-dependent model for mechanical properties of corroded steel strands, including the nominal ultimate strength and nominal elastic modulus. We deduce a time-dependent model for the prestressing loss due to steel strand corrosion. Taking a prestressed concrete hollow slab bridge as an example, we analyze the time-dependent effect of the corroded strands on the concrete stress at serviceability limit state and flexural bearing capacity at ultimate limit state. Research shows that the bottom edge stress and flexural bearing capacity at mid-span of the beams will reduce sharply if the prestressed strands corrode, even corrosion can damage the safety of bridge in just a few years. These results can be for information of further experiments and researches.