The cross beam of a long-span bridge will freeze in low temperature. When the temperature rises, the ice on the cross beam will thaw and fall off. If the ice is too heavy, it may cause vehicle damage and casualty. In order to reduce the risk of falling ice, a scale model of the cross beam was taken as an example, and a kind of numerical simulation method is presented to study the icing distribution characteristics on surface of the cross beam. This paper simulates the ice accretions process of the cross beam by Fluent module and FENSAP-ICE module of ANSYS and investigates the influence of wind and temperature in the process. This is a new numerical simulation method for studying ice accretions of buildings. The results indicate that water freezes mainly on the windward surface, and the thicker ice is near the top and bottom edge of windward surface. According to the results of numerical simulation, a measure of ice melting based on electric heating method is proposed in this paper, and the feasibility and effectiveness of this method are verified by numerical simulation. The results show that the icing distribution characteristics are accord with the fact and the ice-melting measure is feasible and effective.
The icing of bridge pylon crossbeams is a problem that could pose a serious threat to traffic during a cold winter. However, little research has been carried out on the problem and few corresponding countermeasures have been provided. This paper aims to propose a novel heating system, and to study the feasibility of beam de-icing and the related de-icing strategies so as to provide a reference scheme for the practical application of beam de-icing. A number of icing and de-icing tests were carried out on a scale model of Wuhan Yangtze River Second Bridge in the cold chamber. The de-icing effects of the beam in different environments and different de-icing methods were compared, and the recommended pre-heating time, applicable environment range, and heating method were given. The results of the model experiments show that pre-heating the heating system can prevent the surface of the beam from freezing and that the anti-icing method is more suitable for beam de-icing than the passive de-icing method. When the pre-heating time exceeds 7 min, the entire anti-icing process can be ice-free. When the wind velocity exceeds 5 m/s, it is safer to shut down the heating system, and using the passive de-icing method at the end of the icing can also eliminate the hidden danger of beam icing.
Dynamic time history analysis is a powerful and effective method to study the seismic response of tunnels, the dynamic time history to analyze the seismic response of the tunnel in the typical subway in this paper. The analysis results show that the overall levelling of the tunnel will not affect the tunnel too much, and the seismic response of the tunnel is mainly related to the relative displacement of the ground around the tunnel. The analysis results show that the internal force of the tunnel and the tunnel inclination have a good linear relationship, and the tunnel inclination can be used to measure the magnitude of the seismic response of the tunnel.
An increasing number of studies have shown that the seismic response of shield tunnels differs from that of aboveground structures. While the seismic response of aboveground structures is mainly influenced by the peak acceleration and frequency of the earthquake, the seismic response of shield tunnels is more influenced by the ground displacement due to the surrounding soil layers. In this study, it is not appropriate to follow the seismic concept of aboveground structures. Dynamic time-history analysis is a powerful and effective method to study the seismic response of tunnels in the typical subway in this paper. The analysis results show that the overall levelling of the tunnel will not affect the tunnel too much, and the seismic response of the tunnel is mainly related to the relative displacement of the ground around the tunnel. The analysis results show that the internal force of the tunnel and the tunnel inclination have a good linear relationship, and the tunnel inclination can be used to measure the magnitude of the seismic response of the tunnel. In the seismic design of shield tunnels, the inclination of the tunnel can be taken into account to evaluate the change in the internal forces of the tunnel during earthquakes, which avoids the need for complex dynamic time-history analysis and greatly improves the efficiency of the seismic design of shield tunnels.
The large-diameter shallow buried tunnel is not advantageous for ground surface deformation control. It's necessary to make study and research on the ground deformation caused by the advance of TBM. In this paper, the ground surface deformation curve is obtained based on the deformation measured data during the excavation of TBM in the soft ground of Shanghai, and the parameters of excavation, including slurry pressure and volume of synchronized grouting that affect the ground deformation are discussed. In addition, a fitting method to estimate the ground loss is put forward, which reduces the experience dependence and enhances the reliability of peck formula. It is also very simple for practical application to estimate the ground deformation.
In this paper, a novel technique for connecting residential shear walls to floor slabs is investigated. Shear wall structures with two different connection methods were established and numerically analyzed using ABAQUS (2024) finite element software. The two structures were connected by sleeve grouted connections (hereinafter referred to as the original structure) and profile + bolted connections (hereinafter referred to as the new structure). Numerical analyses yielded a positive maximum load for the new structure 1.41 times that of the original structure and a negative maximum load 1.12 times that of the original structure. The ratio of the ultimate tensile strength (load value corresponding to the peak point) to the yield strength (load value corresponding to the yield point) of the two structures (strength-to-yield ratio) was in the range of 1.15–1.27. The original structure was 2.62 times more ductile in the negative direction and 2.24 times more ductile in the positive direction than the new structure. The stiffness degradation of the new structure was greater in the later stages of loading, and that of the original structure was greater in the early stages of loading. The original structure had 1.08 times the energy-consuming capacity of the new structure. The cost of labor and materials for the original structure was approximately 1.50 times the cost of the new structure. The results of the data analysis showed that, compared to the original structure, the new structure had comparable performance in terms of strength-to-flexure ratio, ductility, stiffness degradation, and energy dissipation capacity. However, the new structure was more advantageous in terms of load-bearing capacity and required lower construction costs than the original structure. Therefore, the connection nodes designed in this paper are of great significance for engineering practice.