Natural frequency sensitivity analysis of a road model based on the finite element method

Abstract

The vibration caused by moving loads gradually destroys the road, negatively affecting the performance of the road structure. Therefore, a study on the natural frequency of a road structure is necessary for a dynamic analysis of the road. In this study, the natural frequency of an expressway was calculated based on the finite element method with the help of the ABAQUS software. Results indicated that the natural frequencies of the first to the fifth orders of the road were 4.016, 4.271, 4.361, 4.431 and 4.956 Hz, respectively. Further study indicated that natural frequency was sensitive to model size, such that the former decreased when the latter increased. The result of natural frequency was highly sensitive to length (along the driving direction) and thickness. A suitable model size should be selected to ensure a reliable and accurate calculation result of natural frequency. The suitable model size should be 3.75 m wide (one lane), 30 m long (along the drive direction), and 10 m thick. The calculation result of natural frequency was also highly sensitive to boundary conditions. Therefore, rational boundary constraints should be determined to obtain accurate results. The calculation results of natural frequency differed slightly with the variations in contact conditions between layers. Fully continuous contact conditions between layers should be selected for the road model. The natural frequency was not sensitive to the horizontal alignment parameter of the road, remaining constant when the horizontal radius changed from ∞ to 1000 m. Thus, the effect of the horizontal alignment parameter on the natural frequency can be ignored. Furthermore, the natural frequency was not sensitive to the material density of the road except that of the sub-grade material. No obvious change was observed from the calculation result of natural frequency when the material Poisson's ratio varied. © 2014 Kavala Institute of Technology.