The Experimental Research and Theoretical Analysis of Unbonded Prestressed Concrete Flat Beams at High Temperature
The experiments of 26 unbonded prestressed concrete flat beams under fire with elevating the temperature according to the ISO time-temperature standard curve were accomplished in the large structures electrical heating furnace that was manufactured independently. The macroscopical phenomena of water penetration, the lube flowing, the spalling of concrete and the corlor change of aspect were observed. The laws of behaviors such as temperature distribution on section,the deformation characteristic and stress varieties of prestressed tendons were investigated through the tests. The experiments indicated that temperature distribution was not uniform, the dynamic continuous deformation and the complicated varieties of prestressed stress occurred at high temperature. Based on the increment temperature-stress coupling constitutive models and chief deformation compatibility of the unboded prestressed tendons, the nonlinear finite element calculation formula took the unknown nodes displacements and the tensile forces in the unbonded tendons as unsolved column matrix simultaneously. The Increment format of nonlinear finite element method and calculation model for whole process analysis of unbonded prestressed concrete flexural members at high temperature were presented. The solution of nonlinear equilibrium equations for unboded prestressed concrete flexural members at high tempure was proposed, and a FORTRAN program named NAUPCLF was developed also and the results were in good agreement. The conclusions can supply the way and basis for further fire-resistant design and analysis of prestressed concrete structures.
Guangfan Li, Yong Huang and Chaohe Chen
Z. Q. Wang and Z. W. Yu, "The Experimental Research and Theoretical Analysis of Unbonded Prestressed Concrete Flat Beams at High Temperature", Advanced Materials Research, Vols. 250-253, pp. 2242-2252, 2011