Backward Finite Element Analysis of the Existing Prestress of PC Beam

• Main Authors: Ping-Liang Chi, 紀秉良
• Other Authors: Chung-Yue Wang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/xsy6da

碩士 === 國立中央大學 === 土木工程學系 === 106 === This thesis aims at studying the deflection behavior of post-tensioning prestressed concrete beam with single tendon and using the structural deflection to calculate the existing pre-forced.The finite element program which coded by the object-oriented language C++ and named it PCBAP (Prestressed Concrete Beam Analysis Program).Structural deflection analysis is divided into two phases: the preload phase and the service phase. The preload phase simulates the arching behavior of the structure after the prestressing force is applied. The calculation process can be divided into three parts : the first part, the friction loss and the anchor slip loss are calculated and then initial prestressing force value of any section is obtained. In the second part, the internal force of the tendon at the position of the beam element’s node is converted into the equivalent nodal force and loaded onto the structure. The third part performs finite element calculations to solve the displacement of element nodes. The service phase is to simulate the bearing performance of the PC structure. The calculation process can be divided into two parts: the first part considers the PC beam strengthened by the equivalent bending rigidity formula of Kim. The second part applies an external load to the finite element model to solve the displacement of the element nodes. The full text is closely linked to the two-stage analysis concept, and the calculation of the existing pre-forced is completed by repeating the positive calculation steps. The simulation result of the existing pre-forced is closest to the result of the experimental deflection. This research is devoted to the design of the object-oriented program. The PCBAP program focus on the high-expansion of the goal and then the PC beam structure analysis software is born. In the chapter 3, the frame of the program and the abstraction of the object are discussed in detail. The functions of the PCBAP program include: the initial pre-force distribution calculation after friction loss and the anchor slip loss, deflection analysis of the rod structure, deflection analysis of the PC beam, and existing pre-force calculation of the PC beam. These functions will be verified in each chapter and the simulation is compared with the results of SAP2000 and the static load test of the simple supported PC beam. During the simulation of experiment, it is found that the calculation deflection can be in good accordance with the experimental measurement results, but the inverse-calculation existing pre-forced is not ideal. This is attributed to the fact that the scale of the deflection is smaller than the scale of the pre-forced. That is, the sensitivity of the deflection to the pre-forced physical quantity is very low, which is also the main reason for the inaccuracy of the inverse-calculation.