Abstract: The calculation formulas for concrete and steel utilization rate of reinforcing layer have been deduced, in view of the underutilization of reinforcing layer material by composite main arch circle method. The calculation formulas is defined as load bearing capacity of reinforcing layer divided by the ultimate bearing capacity of reinforcing layer, combined with initial strain of main arch ring before reinforcement and reinforcing layer section edge strain, take compression zone partial of reinforcing layer subjected to tension and compression as example. The calculation formulas for concrete utilization rate of reinforcing layer is divided into 2 types according to the height of compression zone and on the edge of compressive strain in the reinforcing layer, the calculation formulas for steel utilization rate of reinforcing layer is divided into 1 types according to tension strain of the steel. The results show that controlling the stress and strain of stone arch bridge before reinforcement can make full use of compression resistance on main arch ring, strength of materials and reduce the waste of materials relying on engineering example. The calculation formulas provide the theoretical basis for calculation and design of the similar reinforcement structure.
Abstract: Due to the limit of complicated landform in western China, a typical continuous rigid-frame bridge could be easy to be built, especially for asymmetric spans. Based on the engineering background of Sinan Yantou river Bridge in Guizhou province, dynamic characteristics of the type of bridge are studied in this paper. Firstly, by using Midas/Civil, 6 different models are established and their modal analysis could be done while it is considered that the beam of left T-shaped is gradually decreasing under the same height of piers. Then, all seismic responses are calculated by using response spectra method. Finally, the computational results are discussed and some key features are summarized. Our investigation will have some valuable references for seismic analysis of the same style bridge.
Abstract: Taking the four-span 40m simply supported multi-box steel-concrete composite girder bridge in the ProjectⅡ of Qiushi Expressway in Hangzhou as the background, this paper analyzed the static and dynamic behaviour of the bridge by FEM, then finished a field test study for the bridge. Finally, comparing the test values with the results obtained from FEM analysis, it was verified that the rigidity transverse beam method with infinte stiffness is also adaptive to caculating and predicting the load transverse distribution of the multi-box steel-concrete composite bridge. Steel diaphragm and stiffening rib of the multi-box steel- concrete composite bridge can improve the flexural capacity of bridge to some extent, so these contributions should be reasonably considered during the design stage in order to reduce the engineering cost. The measured modes agree well with the results from FEM.
Abstract: Based on the characteristics of low tower and few cables in extradosed Cable-Stayed bridges, simulation models are established for investigations of structural dynamic characteristics under different design parameters, which is related to the practical engineering of Longjing Bridge. As the design radius and pier beam connection form are chosen for the variable, the paper is focus on the influence of dynamic characteristics under the two parameters in extradosed cable-stayed curved bridges. Since the earthquake response spectrum data from National seismic code in 2008 and with the CQC vibration mode combination method, the diversified models are built by Midas/civil so as to explore the earthquake response mechanism under different design parameters. The result show that these two design parameters have some great impacts on dynamic characteristics of extradosed cable-stayed curved bridges, which has direct effect on the bridge seismic performance. The conclusion is the important reference for practical engineering and providing basis for seismic design parameters, but also for seismic design and construction in extradosed cable-stayed curved bridges.
Abstract: A mathematical model of vehicle-bridge coupled oscillations for a simple-supported bridge beam subjected to speed-varied moving loads was established according to TFDVM and model superposition method. This model can consider the pitching and vertical movements of a vehicle. By contrast to a vehicle-bridge oscillation coupled model based on one-freedom-degree Mass-Spring-Mass vehicle model (OFDMSMVD), the mathematical model of vehicle-bridge coupled vibrations based on TFDVM can more accurately reflect the dynamic behaviors of vehicle-bridge coupled vibrations .The maximum middle-span deflections of bridges under speed-varied cases are not linearly proportional to the entrance speeds of moving loads, and they happen at a number of entrance speed points of moving loads. The influence of acceleration and deceleration of moving loads on the dynamic deflections of bridges is dependent on the entrance speeds of moving loads.
Abstract: A simplified seismic evaluation method for steel members with thin-walled stiffened box sections is developed. First, a finite element model based on the shell element was carried out and its effectiveness was validated by comparison with the experiment. Twelve numerical cases were then simulated by the shell model and the fiber model, respectively, and their accuracies were discussed. Numerical results showed that the proposed method using the fiber model, employing the bilinear kinematic hardening relation, is of good accuracy. If the maximum strength is taken as the ultimate point, the bilinear stress-strain relation, replacing the yield point by the buckling stress, was recommended. If a point corresponding to 95% of the maximum strength after the peak is regarded as the ultimate point, the elastic-perfectly plastic stress-strain relation was suggested.
Abstract: When designing under-supported bar-tied arch bridge, the type of bar-tied usually is straight. But sometimes based on design or the needs of some aspects, curved bar-tied is often used. Taking the main bridge of XinZhang highway bridge as the background, this paper, by using general finite-element software to set up calculation model, studies and analyzes the effects of different types of bar-tied on the arch bridge’s structural performance. Through the analysis, we know that it is not suitable to choose curved bar-tied for under-supported bar-tied arch bridge when designing and constructing.
Abstract: Considering the characteristics of high-speed railway settlement requirement, i.e. high precision and strict control after construction, the subgrade settlement of the Wuhan-Guangzhou high-speed rail on the red clay area is calculated by ES method, e-lgp method, triaxial stress method, secant modulus method and field test method. In this essay, the accuracy of various calculation methods has been compared and corrected with the values from loading test. In this process, correction coefficients for various calculation methods have been obtained.
Abstract: 4 RC round-ended piers with HRBF 500 steel bars are analyzed by finite element package ABAQUS under low reversed cyclic loading. In order to check the validity of the FEM analysis，the numerical analyses results of RC round-ended piers with HRBF 500 steel bars are compared with the previous experimental results. It indicates that the analytical results calculated by ABAQUS agree well with the test results. The paper mainly researches the seismic performance, including component ductility, strength and hysteresis dissipation characteristics, of HRBF 500 steel bars applied in High-speed railway piers. The effects of strength of longitudinal reinforcement, axial compression ratio, hoop reinforcement ratio on the seismic behaviors of piers are analyzed. The research results will provide the important datas for HRBF 500 steel bars used in bridge pier of high speed railway.
Abstract: A lot of existing reinforced concrete girder bridges appeared cracks in the service phase. Because of the beam's cracks existing, the sectional bending stiffness of the beam decreased. It would reduce the structure's bearing capacity, so the bridges' structure performance urgently needs to be assessed by effective methods, so as to study further measures. In this paper, based on the indoor model test results of four pieces of model beams, regression analysis of the crack characteristics parameters and test's load-displacement curves has been carried out. The relationship between crack characteristics parameters and girder bridge's bending stiffness has been established. The qualitative assessment of structure crack's appearance inspection is transmitted to quantitative assessment, so it will make the assessment more objective and scientific.