Zhao Xi

Bio: Zhao Xi is an academic researcher from Beijing University of Technology. The author has contributed to research in topics: Moving load & Asphalt concrete. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Response Analysis of Saturated Asphalt Pavement under Action of Moving Load

Abstract: Asphalt concrete pavement structure is used widely in highway of china.The using performance of concrete pavement is not only related to the materials and structure,but also impacted by the external environment such as temperature,water,etc.Based on the theory of porous media,this article simulates the dynamic response of asphalt pavement under moving load by using finite element analysis software ABAQUS and analyzes variation discipline of the pavement structure stress,strain and pore pressure under different speeds and loads.The results show that as the speed of motor vehicle increases,the inner stress of pavement structure decreases gradually,pore pressure grows rapidly,which will gradually increase the adverse effects to asphalt pavement;the inner stress of pavement structure and pore pressure show a linear growth as the load increases.The study can provide theoretical guidance for understanding water damage and the prevention of water damage in asphalt pavement.

Effect of Clogging on the Permeability of Porous Asphalt Pavement

Abstract: The purpose of this paper is to report on the drainage of porous asphalt pavement evaluation method suited for use in analyzing clogging effect. To preliminarily reveal the decrease in permeability caused by clogging of permeable asphalt pavement, an innovative device was proposed to evaluate the anisotropy of permeability influenced by clogging, and the maximum drainage capacity without surface ponding can be obtained when the supplied water was controlled. Then, finite element models for asphalt pavements with hydromechanical coupling were proposed based on porous media theory and Biot’s theory. The variation in pore water pressure was simulated by considering the decrease in voids and the increase in clogging grains. The results indicate that the internally retained water should not be ignored because the semiconnected voids were filled with water rapidly at the beginning of permeability tests. To avoid surface ponding, the drainage capacity coefficient (DCC) can be used to evaluate the maximum drainage capacity (MDC) influenced by clogging. Moreover, the pore water pressure increased due to the reduction in voids and a high level of clogging. In addition, the peak value of pore water pressure is also affected by the upper-layer height of the pavement. Under the action of clogging and driving load, a reasonable thickness of the upper layer and a drainage evaluation should be considered to improve road safety.

Improved algorithms applying the numerical Laplace method for response analyses of Timoshenko beam subjected to typical external loads

Abstract: This study develops Su and Ma’s theory regarding the stationary load case by considering the structural damping (which can be arbitrarily proportional or non-proportional) and various boundary constraints. Original derivations are presented based on Timoshenko’s beam model and the Kelvin–Voigt damping model. Numerical Laplace inversion, i.e., the Durbin method, is applied to obtain the time-domain solutions. Further, an extension to the general moving load case is performed by means of the finite element method, and an algorithm by virtue of mathematical fast transformation is exploited to improve the computational efficiency. The normal mode superposition method is introduced to validate the numerical solutions. In case studies, the accuracy of the Laplace method is first verified through contrastive studies. Based on that analysis, numerical experiments regarding the moving load case are conducted while considering the implications of moving velocities and non-proportional damping. The results demonstrate that the numerical method is effective and efficient for typical boundary conditions, although this approach suffers from certain algorithm-based instabilities. The load velocity and the structural damping are fundamental influential factors on the dynamical performance, in which even divergence appears in a damped system, and regular piecewise-linear rules are concluded in non-proportional damping variations. Since damping is a fundamental parameter for structural dynamics and the stationary and moving loads consist of the basic excitations, the Laplace method has a strong application prospect.

Fundamental solution and its validation by numerical inverse Laplace transformation and FEM for a damped Timoshenko beam subjected to impact and moving loads

Abstract: This paper, taking the clamped boundary condition as an example, develops Su and Ma's fundamental solutions of the dynamic responses of a Timoshenko beam subjected to impact load. Based on that, a ...

Identification of Moving Load Characteristic on Pavement Using F-P Cavity Fiber Optical Technology

Abstract: The weigh-in-motion (WIM) system is a necessary piece of equipment for an intelligent road. It can provide real-time vehicle weight and lateral distribution data on wheel load to effectively support pavement structure design and service life analysis for autonomous driving. This paper proposed an enhanced weigh-in-motion sensors system using Fabry–Pérot (F-P) cavity fiber optical technology. Laboratory testing was performed to evaluate the feasibility of the proposed system and field application was conducted as well. The laboratory results show that the traffic loads could be obtained by measuring the center wavelength changes in the embedded F-P Cavity tunable filter. The laboratory results also show that the vehicle load and the number of vehicle axles can be estimated based on the system transfer function between the dynamic loading and the wavelength variation. The field application indicates that the weighting accuracy of the proposed system could reach 94.46% for moving vehicles, and the vehicle passing speed is the potentially relevant factor. The proposed system also has the ability to estimate the number of vehicle axles and the loading position, and the precision could reach 97.1% and 300 mm, respectively.