Current Issue : July-September Volume : 2023 Issue Number : 3 Articles : 5 Articles
The hydrodynamic problems associated with the construction of the sea-crossing bridge were proposed. The deep-water approach bridge on both sides of the main bridge of Fuzhou Xiamen high-speed railway adopts the bearingless prestressed concrete integral rigid frame bridge for the first time in the domestic railway bridge design. The rigid frame bridge applies the hanging basket cantilever construction, and there are several options for closure. Because the bridge structure system changes before and after closure, which will cause the redistribution of bridge internal force, the results of internal force redistribution will be different with the sequence and position of closure, and sometimes, there will be great changes. In order to select the optimal closure scheme, this article establishes the finite element model of the whole bridge and analyzes the whole construction process according to the working conditions and the mechanical state of the bridge before closure is obtained. Based on this state, eight closure schemes are analyzed and studied, which provides a sufficient mechanical basis for the determination of the final closure construction scheme....
Bridges are strategic infrastructures which are subject to degradation during their lifetime. Therefore, structural health monitoring is becoming an essential tool in this field to drive maintenance activities. Conventional vibration monitoring systems relying on wired sensors present several limitations for continuous monitoring projects on a huge number of structures. In this work, a smart wireless monitoring system is developed for bridge modal identification with the aim of providing an alternative tool to wired sensors in this field. The main peculiarities of the designed wireless accelerometers are the low cost, the ease of installation on the structure, and the long-term autonomy granted by the use of energy harvesting techniques. To assess their measurement performance, some prototypes were installed for a field test on a railway bridge and significant data were acquired. Through the processing of the collected data, bridge main natural frequencies were estimated, and their values were in good agreement with the reference ones obtained with a conventional system. The assessment of the developed solution paves the way to the instrumentation of many bridges with the aim of performing continuous monitoring activities using simple diagnostic indicators, such as the variation of frequencies in time....
In order to study the dynamic response of parallel mountain tunnels under the oblique incidence of seismic waves, based on the display finite element method and using viscoelastic artificial boundary, the oblique incidence of three-way seismic waves was realized by angular incident mode. The displacement and stress distribution characteristics of the tunnel lining under different propagation angles and vibration angles of SV waves were studied. The results show that the oblique incidence of SV wave has a certain effect on the displacement of the double tunnel, the forces in the tunnel are symmetrical and the axis displacement increases with the increase of incident angle, and the vertical displacement changes greatly. The stress of the tunnel lining under the oblique incidence of the SV wave is elliptical. Thepeak value of the maximum principal stress appears at the maximum span on both sides, and the maximum principal stress decreases with the increase of the vibration angle. The maximum principal stress of the right tunnel is flat. The minimum principal stress of the left and right holes decreases with the increase of vibration angle, and the minimum principal stress of the left hole is 90°270°. The distribution of the minimum principal stress in the range is large. Mises stress increases with the increase of the incidence angle of seismic waves....
Under the action of vertical pressure, the variation of pile spacing affects the bearing performance of concrete expanded-plate (CEP) double pile and the damaged state of soil around the pile. In this study, finite element simulation analysis is performed by ANSYS software, and six sets of semisectional double pile models with different pile spacings and one set of semisectional monopile models with the same specifications are established after applying the vertical pressure to the model pile. The mapping method is used for the pile-soil model meshing, the model adopts the contact type of rigid and flexible bodies, and the simulation analysis adopts the way of applying surface load and loading step-by-step. The displacement distribution, load-displacement curve, stress cloud, and shear stress curve are collated to obtain the displacement and stress change law of pile-soil under different pile spacings and then determine the effect of the changes in pile spacing on the CEP double pile. Meanwhile, the CEP double pile model is compared with the monopile model to determine their similarities and differences. Finally, a reasonable range of pile spacing for CEP double piles is provided. It further improves the research theory of CEP group pile compressive load-bearing capacity and provides the theoretical basis for its design and application in practical engineering....
The rainfall often causes changes in the physical performance of the embankment, which leads to disasters such as embankment collapse and road surface settlement and cracking. Past research has tended to be limited to traditional embankment seepage models and is mostly based on the assumption that surface precipitation is uniform and rainfall intensity is constant. To adapt to the changes and development of the times, based on the water leakage mode of the flexibly assembled highway embankment, a new rainfall calculation model of the reinforced soil embankment is constructed and combined with the solid-fluid coupling physics theory, the sedimentation amount and slope stability of the embankment are analyzed at multiple levels, the mechanical properties of the new embankment under rainfall conditions are summarized, the factors affecting the settlement of the embankment and the stability of the slope are explored, and the reference model is provided for the construction of the new embankment, and the existing construction process is improved through multilevel cause analysis. We improve and develop the existing theoretical system to reduce the probability of road diseases, improve the efficiency of road construction, and reduce the cost of road maintenance....
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