Applied Mechanics and Materials Vols. 178-181

Abstract: Based on the model of discrete-time linear systems, the paper builds up the state space model of cantilever assembly method by studying the stream of variation theory. To address the problem of evaluation in alignment error, the evolution index of comprehensive stability is presented after comparing the advantage and disadvantage of evaluation index of point stability and evaluation index of slope stability. The method of evolution index of comprehensive stability is demonstrated by evaluating the alignment error of a long-span cable-stayed bridge, and it can accurately evaluate the error of assembly process.

Abstract: Computation of the energy release rate, based on the FEA software ANSYS, with the virtual crack close technique, is studied. To reduce post-processing workload, the spring element is imposed at the cracktip. In practical applications, COMBIN14 spring elements are adopted to set up the finite element model. Then, the numerical analysis method is applied in interface crack. But the calculaed strain energy release rates are pseudo values, and only the total strain energy release rate convergences. At last, two numerical experiments are presented to validate this method. The results show that the calculated values of the total strain energy release rate are well with the theoretical values. This numerical analysis method is an efficient and accurate numerical analysis method.

Abstract: The dynamic temperature field of a concrete pier is actively studied in this study with the aiding of the commercial package ANSYS. Thermal boundary conditions are utilized to obtain the temperature distribution of the concrete bridge pier. The surface temperature of the pier is measured by using a thermal infrared imager at different time instant. The ambient temperature and wind velocity are also collected at the same time. The made observations demonstrate that the simulated temperature variation of the concrete pier agrees well with measurement results. The thermal gradient of the concrete in the thickness direction is a little large. It is seen that the numerical models can successfully predict the structural temperature field at different time. The methodology employed in the paper can be applied to other concrete bridges as well.

Abstract: According to the coordination equation of displacement between two system, spatial finite element model of curved continuous rigid frame bridge built by grillage method and whole vehicle model of 7 DOF, spatial numerical resolution of vehicle-bridge coupling was achieved. Then response curves of vehicle-bridge coupled vibration under different eccentric loads were obtained and dynamic coefficients of each web were solved. Compared with beam model, the results indicate that dynamic coefficients curves of each web under eccentric loads can be well simulated by grillage method and their differences also be reflected. So this method is universal and can be referenced by coupled vibration analysis of other complicated bridges.

Abstract: Taking Beijiang Bridge as an example, using 3D finite element method, influence of side stringer to deck deformation of four-lines high-speed railway cable-stayed bridge with double cable planes is studied. The results show that the stiffness of the side stringer hardly influence the long wave of bridge deformation and the ratio of deflection to span, but significantly affects the short wave and transversal wave of the bridge deformation. The location of the side stringer influences the long wave slightly, but influences the short wave and transversal wave significantly. If the distance between the side stringer and the center of the main trusses changed, the long wave changes slightly, while the maximum short wave and transversal wave change a lot. The larger the distance, the less the transversal span of the deck and panel beams are, and the less the short wave and transversal wave are. The influence of the axial stiffness of horizontal K-shaped brace to the bridge deformation is small.

Abstract: Taking a low-pylon cable-stayed bridge as engineering background, control indexes in design of bridge were studied[1]. Designers often complete prestressing tendon adjustments based on the existing experience，which can only finish design conservatively rather than get correct results. In order to obtain relative accurate results, this article conduct relative reserch. Overall force calculation and later checking research is analysed by the finite element analysis software MIDAS Civil. Calculation and checking of the cable-stayed locks, prestressing tendon and other control indicators are in accordance with the relevant norms, and reasonable results can be obtained, which can provide a basis for similar bridges.

Abstract: Cable wire is characterized by light weight and high strength and is widely applied in long span bridges. However, steel cable wire is vulnerable to fatigue and corrosion, which has been proved to be true through collapses of several bridges because of cable failure. This paper will the following 4 types of the fractures of steel wire: cone-shaped fracture, serrated fracture, cup-shaped fracture and step-like fracture to explore failure cause of cable wire. This paper also illustrates the fracture feature respectively and failure causes considering environmental and loading condition of cable.

Abstract: Considering that the health monitoring system and construction monitoring system are not combined flexibly, the whole life monitoring model is conceived. That method is based on data dependence analysis of pre-buried and table-posted sensor, at the same time, correction of monitoring data is also taken into consideration. All the works focus on the research about collaborative work mode of monitoring data from pre-buried and table-posted sensor. This achievement brings so many benefits, firstly, it makes dead loads and living loads are considered together. Secondly, it brings new ideas to guarantee the safety of large bridges in construction or operation. Thirdly, the research results are embodied fully in the engineering practice of Nujiang Bridge.

Abstract: This paper aims to analyze the statistic rules of the live load effect and the degradation effect and propose some ideas on the bridge structural safety assessment on the condition that both effects closely relate to bridges’ structural performance. Besides, the technology of bridge structural safety assessment based on statistic analysis is also supported by a EWMA controlling Figure with double control limits suitable for bridge structures. After the application in the Ma Sang Xi Yangtze River Bridge project, the technology is proved as reliable, visualized, and perspective in application.

Abstract: In the earthquakes, the skew bridge is subjected to bending shear and torsion at the same time, and at present, the studies on it are inadequate at home and abroad. In this paper, the numerical analysis model of the skew bridge was simplified, the effects what the three parameters (including stiffness ratio, skew angle, and eccentricity) make on the dynamic characteristics of skew bridge were obtained by the eigenvalue analysis, and especially, the effects on the translation-torsion coupling vibration of skew bridge and its mechanism were focused on. The results show that the three parameters have effects on the translation-torsion coupling of the skew bridge.