Applied Mechanics and Materials Vols. 361-363

Abstract: From the aspect of accumulated construction error of the bridge, the inaccuracy analysis method was put forward. Considering the two kinds of construction error case in construction stage, the inaccuracy response numerical model was built. The error effect to the bridge was researched quantitatively and qualitatively. The results demonstrate that more attention should be paid to the effects of two kinds of construction error on the stress and deformation of bridge. The study of sensitivity analysis of structural damage cases should also be engaged in the design and construction stage for the optimal reliability.

Abstract: A new type of preflex I-girder with corrugated steel web has been proposed to provide better solution for urban elevated bridge. The purpose of this study is to explore shear stress distribution and deflection of such preflex I-girder. Shear stress distribution in section of steel-concrete composite girder was analyzed by shearing stress integral equation and piecewise function, and a quarter-scale preflex I-girder with corrugated steel web was fabricated and tested. Experimental and analytical results show that the shear stiffness is only depends on corrugated steel web, and the shear stress is uniformly distributed along the height of corrugated web. It is found that the proposed shear stress equation is consistent with the experimental result and the deflection integral equation is agreed well with the FEA result. The result suggests that the shear deflection is as larger as 25.8% of the total deflection, and should take shearing deflection into consideration.

Abstract: Combining with specific engineering example, we used the finite element calculation software and analyzed the lateral deformation and stress of variable cross-section curved continuous rigid frame bridge during cantilever construction. Their some change rules are obtained. They accumulate during cantilever construction, and system transformation influences them greatly. We also put forward some understanding and advice about design and construction.

Abstract: Using Midas/Civil, a nonlinear finite element software, to establish solid element, analyse the process of the construction of a prestressed concrete simply supported box girder which length 32m, this box girder is located on the Shijiazhuang-Wuhan Passenger Dedicated Line, gained the maximum stress and displacement at the control section. Comparative analysis of the simulation results with the monitoring data which gained at the construction site, The results of both are substantially the same, achieve the purpose of assessing the safety of the construction process and the reasonableness of the structure model about the box girder.

Abstract: According to vibration problem of the footbridge, the dynamic characteristics and dynamic responses of the footbridge were analyzed under pedestrian load. Based on one 22m×10 straight line footbridge, this paper established the spatial finite element model to analyze its natural vibration characteristics and discuss the effects on the natural vibration characteristics induced by both connection factors of beam ends and pedestrians weight. And then the dynamic responses of the footbridge caused by pedestrian dynamic load were calculated to analyze the structure stress. In addition, to analyze the calculation result of displacement responses so as to evaluate the comfort of pedestrians. The results show that the natural frequency is lower, and it will probably induce the resonance and larger dynamic response value under pedestrian load although the footbridge structure is safe. Moreover, reducing vibration methods and treatment measures to the footbridge were introduced, and the effective measure was suggested to reduce vibration amplitude at last.

Abstract: The present study employs an electrical resistance method for fatigue crack detection in steel deck. The detection influential factors are analyzed via the finite element analysis under different electrode space and deck width. As a result, the electrode space influenced on detecting precision, and the smaller the better. The resistance measurement method is presented, and the formula of fracture damage ratio and the equivalent crack depth are established. It is proved by fatigue crack detection experiment of U-rib specimen, which shows that using electrical resistance method to detect fatigue crack is feasible.

Abstract: Effective vibration control technology for stay cables is extremely critical to safe operations of cable-stayed bridges. For super-long cables, passive linear damper cannot provide sufficient damping since it can be only optimum for a given mode of cable, while a long cable may vibrate with several modes. This paper focuses on multi-mode vibration control of stay cables with passive magnetorheological (MR) dampers. Firstly, a 21.6m-long model cable was designed and established in the laboratory.Then, control performance of the cable with a passive MR damper was tested. The test results show that modal damping ratios of the cable in the first four modes can be improved significantly with the MR damper. It is further demonstrated that optimal tuned passively operated MR damper can outperform the passive viscous damper.

Abstract: In order to understand the form of deformation and stress characteristics of the integral abutment bridge structures under the loads, this paper bases on Fuyu industrial park crossing bridge, through test vehicle load simulating design load, does a static load test for the bridge, and with the aid of theoretical method to simulate the interaction of pile and soil, builds finite element model, compares between measured and theoretical values of deflection and stress, gets that, the bridge bearing capacity and stiffness is bigger, with sufficient safety reserves.

Abstract: In order to investigate the aerodynamic interference effects between parallel bridges, the aerodynamic interference effects on aerostatic coefficients of double thin-walled hollow pier in the parallel continuous rigid frame bridges with high-pier and long-span were investigated in details by means of wind tunnel test. The tandem interval and side-by-side interval between the two piers and wind direction angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin piers. The test got aerostatic coefficients of 10 conditions. The research results have shown that the aerodynamic interference effects on aerostatic coefficients of double thin-walled hollow pier in parallel bridges can not be ignored. The tandem interval and side-by-side interval between the two piers and wind direction angles are important factors affecting interference effects. The drag coefficient, lateral force coefficient and torque coefficient are affected by these factors.

Abstract: This paper conducts an analytical research on the use of bridges, and discusses how the vibration of bridges is affected by the healthiness of piers. Meanwhile, Impact Vibration Test Method is introduced, by which the modal parameter of bridges can be tested. A lot of dynamic tests of piers are conducted by using this method. By analyzing data and identifying modal information of piers, this paper made a conclusion on the general law of the impact each parameter has on characteristic frequency of the piers. The bridge finite-elemental model is constructed according to the actual structure of piers, the impact vibration test load stimulated, then computed and analyzed with the dynamic time-history method. Bases on the comparison between test result and frequency of Time-domain transverse velocity received the results of the analyses identify the frequency spectrums, the validity of the Impact Vibration Test Method is verified.