## 6 Conclusions  
In this paper, a method is proposed to compute the dynamic response of JPCPs under the moving axle load, considering the combined effects of the pavement surface roughness, the dynamic load parameters, and the pavement structure parameters. The dynamic axle load is generated based on the quarter-car model, running through three successive slabs of which the surface roughness level is determined by the power spectral density function, and the critical locations in slabs where the largest tensile stresses occur are identified.  
As the pavement roughness deteriorates from level A to level D, both the tensile stress and the dynamic factor of JPCP are significantly increased. Under conditions of deteriorated pavement surface roughness, increasing vehicle speed also increases the tensile stress and the dynamic factor. For the roughness level D, the tensile stress reaches a maximum value of 3.13 MPa, and the dynamic factor reaches a maximum value of 2.46, which is much larger than the dynamic factor of 1.15 or 1.2 currently used in design guidebooks [3; 4]. Although the generated maximum tensile stress is less than the tensile strength of concrete, it is greater than the fatigue tensile strength of 2.25 MPa [12], which means that fatigue failure is to be expected under repeated vehicle loads.  
Increasing the thicknesses of pavement slab or the subbase layer is an effective way to reduce tensile stress in JPCP, while increasing the thickness of base layer is not effective. Considering that the construction cost will be tremendously increased by thicker slab or subbase layer, it is suggested to improve the surface roughness as the primary preventive maintenance method to reduce tensile stress and consequently to improve the service life of JPCP. Overloading should be avoided as well, due to the greater dynamic factor under the coupled effect from heavy wheel load and the deteriorated surface roughness.  
The results of this study can benefit future pavement design and pavement performance evaluation by providing the tensile stress and useful dynamic factor values for various conditions of field pavements. A greater dynamic factor should be included in the PCC pavement design guide to reflect the actual dynamic behavior under moving vehicle loads. Moreover, preventive maintenance, particularly the improvement of pavement surface roughness, can be planned by referring to the results of this study to avoid generation of high tensile stress in JPCPs. Typical methods include void repairment by polymer grouting, pothole repairment by epoxy resin, crack repair by cement concrete cover, and so on. For flexible pavement, it is also necessary to analyze its dynamic response under different roughness conditions and vehicle loads. It should be noted that the effects of temperature curling and moisture warping of JPCPs are not considered in this study, and are certainly worthy of further investigation. Also, axle load spectra from the LTPP database or other sources can be considered in the future to further verify the methodology proposed in this paper.  
Conceptualization, Y.W.; methodology, C.Y.; formal analysis, C.Y.; investigation, Y.W. and C.Y.; writing--original draft preparation, C.Y.; writing--review and editing, Y.W.; supervision, Y.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Key Research and Development Program of China, grant number 2021 YFB3202901.  
Not applicable.  
**Data Availability Statement:** All data are contained within the article.  
**Acknowledgments:** The authors are grateful for the support from National Key Research and Development Program of China, grant number 2021 YFB3202901.  
**Conflicts of Interest:** The authors declare no conflict of interest.