预应力钢筒混凝土管弯矩重分布问题的探讨

Study on moment redistribution for prestressed concrete cylinder pipe

预应力钢筒混凝土管(PCCP)在安装及运行过程中,将承受外荷载(土荷载、附加荷载、瞬时荷载及施工荷载)、管子重量、流体重量和内水压力的共同作用。由于这些荷载的作用,使得PCCP管壁的弯矩和轴力发生变化,管壁可能发生弯矩重分布现象。国内外现行规范针对工作、弹性和强度在内的三种极限状态的设计准则,给出了相应的计算方法和公式,但对于出现弯矩重分布时,规范中却未给出明确的计算方法和公式,给工程应用带来极大不便。本文依据极限状态设计理论,研究了嵌置式PCCP(ECP)管体不同工况下的应力状态,推导出弯矩重分布的计算公式,并以ANSI/AWWAC304-2007规范中的例题对公式进行了验证,证明了计算公式的正确性和可靠性。

During installation and operation,the Prestressed Concrete Cylinder Pipe（PCCP）will be subjected to combined loading condition under the external loads（soil pressure,additional load,transient load and construction load）,self weight,water weight and internal water pressure.These loads can result in the changes of the moment and axial force of the pipe wall,thus leading to the moment redistribution.For the design criteria of the three limit states of serviceablity,elasticity and ultimate strength,corresponding calculation methods and formulas are given in current domestic and foreign standards.However,there is no specific calculating method or formula specified for the condition of moment redistribution.On the basis of limit state design theory,stress analyse of Embedded-Cylinder Pipes in different working conditions are studied,and the formulas for PCCP under the condition of moment redistribution are introduced in this paper.These formulas are verified through the examples in ANSI/AWWA C304-2007,and proved to be valid and reliable.