Current Issue : April - June Volume : 2021 Issue Number : 2 Articles : 5 Articles
In the asphalt pavement structure design method, the structural analysis and design are generally performed in the form of point values. However, determining the point value form of design parameters based on the statistical analysis theory cannot fully reflect the complex properties such as variability and uncertainty of parameters. In order to further improve the reliability and practicability of pavement design parameters, in this article, we have introduced the interval number representation that can better reflect the complex nature of parameters; but the interval number algorithm is too complicated and common calculation tools and software are difficult to adopt, which limit the wide application of interval analysis to some extent. The article analyzes the algorithm of interval numbers, focusing on the analysis of interval numbers of unary and binary functions. In this way, the point number operation can be used to obtain the interval number result of the function consistent with the interval number algorithm, which avoids the complicated interval number operation process and the interval expansion. The point numerical function algorithm of interval numbers is verified by design parameters and the calculation of asphalt pavement structure such as axle load conversion, cumulative equivalent axis calculation, calculation of foundation layer tensile stress of each structure layer, calculation of mixture penetration strength, fatigue cracking check of asphalt mixture layer, permanent deformation check, and vertical pressure strain test of roadbed top surface. In conclusion, this research provides a simple and easy way to implement the application of mathematical tools for interval analysis, which is suitable for direct use for existing point numerical calculation tools and software....
To reduce the vibration of a cantilever steel plate in high-temperature environments (25°C–500°C), a new composite structure with entangled metallic wire material (EMWM) core was proposed. The damping performance of the EMWM under different temperatures was investigated. The results show that when the temperature does not exceed 260°C, the damping property of the EMWMis not affected by temperature. When the temperature exceeds 260°C, the damping property of theEMWMdecreases with the increase of temperature. A thermal-vibration joint test system was set up to verify the energy dissipation mechanism of the composite structure with EMWM core and to research the effect of vibration reduction under different temperatures. The displacement deviation between the baseplate (steel plate) and constraining plate was sufficient to cause frictional energy dissipation of the EMWM core. The thermal-vibration joint test results indicated that the EMWM core had a positive impact on the damping properties of the cantilever structure. Adding EMWM core and constraining plate can significantly increase the damping ratio and reduces the vibration of the cantilever structures under different temperatures. This research is helpful to control the structural vibrations of cantilever structures in high-temperature environments....
The Senegalese road network is strongly influenced in the long term by seasonal variations in climate and weather conditions. Indeed, much of the damage is due to these environmental factors. The objective of this paper is to study the behaviour of bituminous structures under the effect of high temperatures. Material samples were taken for a physico-mechanical characterization of the coated components. The results show that Marshall creep (2.87, 3.39, 5, 5.5 mm) and the bitumen penetrability increase with the increasing of temperatures respectively from 34˚C to 45˚C and from 20˚C to 50˚C. Marshall Stability drops from 15.81 kN to 11.31 kN for temperatures between 34˚C and 45˚C. The simulation carried out on Alize-LCPC shows an increase in distortions of traction at the basis of the rolling layer and at the top of the platform if temperatures vary between 34˚C and 45˚C. This work makes it possible to conform that the bituminous concrete is thermally sensitive and the hypothesis of fixing the constant modulus of the bituminous layers in Senegal for all projects remains unsuitable for a good dimensioning of sustainable road structures. The knowledge of the equivalent regional temperature will make it possible to produce quality pavements with a long lifespan....
Structure material properties are heterogeneous in nature and would be characterized with different statistics at different length scales due to the spatially averaging effects. This work develops a framework for the modal analysis of beam structures with random field models at multiple scales. In this framework, the random field theory is adopted to model heterogeneous material properties, and the cross-correlations between material properties are explicitly considered. The modal parameters of a structure are then evaluated using the finite element (FE) method with the simulated heterogeneous material properties taken as input. With the aid of Monte Carlo simulation, the modal parameters are analyzed in a probabilistic manner. In addition, to accommodate the necessity of different mesh sizes in FE models, an approach of evaluating random field parameters and generating random field material properties at different length scales is developed. The performance of the proposed framework is demonstrated through the modal analysis of a simply supported beam, where the formulation of the multiscale random field approach is validated and the effects of heterogeneous material properties on modal parameters are analyzed. Parametric studies on the random field parameters, including the coefficient of variation and the scale of fluctuation, are also conducted to further investigate the relations between the random field parameters at different scales....
It is still a challenge to accurately evaluate the structural safety of tunnel during the process of construction. To address this issue, a safety evaluation approach of tunnel based on the monitoring data during construction is proposed in this study. Firstly, the detailed description of modelling the tunnel excavation, releasing the load acting on the tunnel, and selecting the constitutive relationship of surrounding rock of tunnel is introduced. Secondly, aiming at an actual shallow-buried tunnel with underground excavation, utilizing the analytical results of deformation of tunnel, the structural safety of tunnel is evaluated by using a reliability- based method. Finally, the effectiveness of the proposed method is demonstrated by using the dynamic monitoring data obtained during the construction of an actual tunnel....
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