Analysis Model And Program Of Elastic-plastic Behavior Of The Prestressed Concrete Frame Beam

With the widely use of prestressed concrete (PC) structures in seismic areas, the seismic behavior of the PC structure has been attracting more attention to the engineering society. Combining the Project Seismic Analysis Program of Prestressed Concrete Frame supported by the Natural Science Foundation of Jiang-Su Province for the scholars return from abroad, this dissertation choosing the PC frame beam as the research objects to carry out a detailed investigation to the elastic-plastic deformation characteristics of the PC structure. Based on the research results of low-cyclic reversed loading tests which our group did early, this investigation established corresponding mechanical analysis models and computer program. The investigation mainly focuses on the following research task:1. According to the theory of strain-coordination and principle of force-balance, considering the effects of hoop ratio on the concrete stress-strain curves and the compendious characteristics of stress-strain graph on the compression zone of cross-section, give a new method to calculate the entire moment-curvature skeleton curve of PC member cross-section. Reference to the experimental data, setup the rational model parameters and develop an analysis program FMPHIP to calculate the entire moment-curvature skeleton curve of PC member.2. Refered to the results of research on the length of plastic-hinge zones of PC beams and reinforced concrete beams obtained from the correlative literatures and reports, and compared the test data of PC cantalever beams with the analysis values simulated by the program FMPHIP, study the relationship between the plastic-hinge length, prestress degree, hoop ratio and the effective height of the cross section of the PC beam under the ultimate state. A simplified formula for calculating the length of plastic-hinge zone of PC beam has been suggested, which will provide an effective reference for the structure ductile design and plastic hinge layout in test.3. Based on the low-cyclic reversed loading tests of PC cantalever beams which our group did early, study the relationship between the moment-curvature hysteretic curve and load-displacement hysteretic curve, give a practical method to perfect the moment-curvature hysteretic curve with the known load-displacement hysteretic curve. Which will setup a data base for the analysis model of damage characteristic evaluation of PC member that with the basic parameters of moment-curvature hysteretic curve.4. With the moment-curvature hysteretic curve of PC member, carry out mathematical induction to the stiffness degradation law of the member under the cyclic loading, and study the relationship between the stiffness degradation, prestress degree and load history based on the fitting of the test results, finally bring out a stiffness degradation model of the PC member under different loading history. Based on above research, while refere to the programming concept of program SARCF (Seismic Analysis of Reinforced Concrete Frame), a subroutine SLOPE for hysteretic characteristic analysis of the PC frame beam is compiled, which will provide a contributive support for the development of the SAPCF (Seismic Analysis of Pre-stressed Concrete Frame).