Weiwei Han

Numerical Simulation on Cross-Tensioned Prestressed Concrete Pavement

Cross-tensioned prestressed concrete pavement (CTCP) could eliminate transverse joints and cracks. Prestressing should increase load-carrying capacity of the pavement and lower the maintenance cost. It is applicable to all levels of road surface layer, composite pavement, heavy traffic road, and the toll plaza. A calculation formula for the average compressive stress caused by prestressing was deduced first, the finite model of cross-tensioned prestressed concrete pavement was built based on finite element method, the pavement slab stress distribution caused by prestressing was analyzed, and the results are consistent with full-scale model test results. The influence of strand acting position, the angle and distance of strand, and diameter on the slab stress distribution were analyzed. The results show that it is reasonable to place the strand below the mid-depth of the slab; the compressive stress of the slab bottom is larger than that of the slab top; the strand angle of 25° to 45° is recommended; undersize layout spacing for strand is not recommended; the minimum spacing should be 50cm considering economy and the space needed for strand extension; and the oversize layout spacing is not recommended either, otherwise the slab bottom transverse tensile stress appears, causing uneven stress distribution. In the event that the calculated prestressed tendon layout spacing or the angle is undersize, diameter can be adjusted to increase road slab compressive stress.

Research on the Design Method of Diagonal Post-Tensioned Prestressed Jointless Cement Concrete Pavement

Diagonal post-tensioned pre-stressed jointless cement concrete pavement is a new form of road building. There are double diagonal prestressed steel strands in the cement concrete pavement which exert force on the prestress in the horizontal and vertical direction of the road, so that transverse joints are not needed in the slab. Through analysis of the load characteristics of the pavement, the basic design principles of the pre-stressed pavement, and established calculation models of the traffic load fatigue stress, temperature stress and subgrade friction stress etc., a value of prestress was determined. Through analysis of the pre-stress distribution characteristics, the angle between diagonal prestressed steel strands and the longitudinal direction of the slab, key design parameters such as the arrangement and spacing of diagonal prestressed steel strands are determined; through the study on the stress characteristics of the compressive region and partial positions such as End-board, the design methods in local areas is proposed. Finally, a recommended design procedure for diagonal post-tensioned, pre-stressed, jointless cement concrete pavements is proposed.