CALCULATION METHODS OF CRACKING MOMENT AND ULTIMATE FAILURE MOMENT OF PRESTRESSED HIGH STRENGTH CONCRETE PIPE PILES

Flexural behavior is one of the most important qualifying index of prestressed high strength concrete (PHC) pipe pile.The calculation methods of cracking moment and ultimate failure moment of PHC pipe piles are based on the approaches in the Code for Design of Concrete Structures (GB 500102002) at present.In fact,the concrete strength grade of PHC pipe piles are beyond the adaptable scope of the GB 500102002 Code.The approaches in the code for estimating the cracking moments and ultimate failure moments of PHC pipe piles can not well match the actual bearing capacities.In this paper,combining with the analysis of the flexural experimental results and the behavior of centrifugal shaped producing method of PHC pipe piles,new approaches for calculating the cracking moment and ultimate failure moment of PHC pipe piles are proposed based on the present methods in the code.Comparing analysis shows that the calculation results by the modified methods are well agreed with the experimental results of PHC pipe piles.The suggested approaches for estimating the flexural capacities of PHC pipe piles are suitable in practice design.