【作者】 刘佩玺；

【导师】 刘福胜；

【作者基本信息】 山东农业大学 ， 水利水电工程， 2007， 硕士

【摘要】 叠合梁是建筑工程中常见的一种结构形式,它将预制与现浇工艺相结合,与现浇梁相比,具有施工方便、节约模板、缩短工期、降低造价等优点,与预制装配式梁相比,具有整体性好、抗震性能好等优点。其效益已为众多工程实践所证实,大力发展和研究这种结构是符合我国工程建设需要的。本文在无粘结部分预应力混凝土叠合梁的受力性能试验研究的基础上,利用有限元分析软件ANSYS对试验全过程进行了仿真模拟。本文总结了近年来国内外无粘结部分预应力混凝土叠合结构方面的研究现状,系统归纳了钢筋混凝土非线性有限元法作为设计理论的优点和意义,以及存在的问题。系统整理了20根无粘结部分预应力混凝土叠合梁(其中2根为对比梁)受力性能的试验研究,在试验结果和理论分析的基础上,总结出了无粘结部分预应力混凝土叠合梁的承载力、变形和裂缝特性,以及“荷载预应力”、“应力超前”、“压应变滞后”的产生机理。系统阐述了混凝土非线性理论,包括破坏准则(单轴和多轴)、本构模型(Ottosen非线性弹性全量模型和弹塑性本构模型)和钢筋混凝土非线性有限元模型(整体式、分离式和组合式模型)。对本次模拟中两种主要单元Solid65和Pipe20的特性和应用条件进行了详细的阐述,对软件中混凝土的屈服准则、裂缝模式、压碎处理进行了系统的论述。考虑到钢筋和混凝土的联合作用,采用分离式模型,裂缝采用片状裂缝模式,不考虑混凝土的压碎,根据本次试验的特点,利用ANSYS中单元生死功能和重起动技术来解决试验梁二次浇筑和二次受力特性。本文在已有的混凝土叠合结构研究成果基础上,考虑其自身受力的特点,用有限元软件ANSYS建立了无粘结部分预应力混凝土叠合梁的力学模型,分析了在二次荷载作用下从加载到破坏的全过程,得到了试验梁的承载力和变形,以及应变和应力的全过程变化曲线,对“荷载预应力”、“应力超前”和“应变滞后”这些叠合结构的典型特征进行了详细的分析,并间接得到了试验梁裂缝宽度值。经过对比分析,数值模拟值与实测值吻合良好,证明用ANSYS来分析无粘结部分预应力混凝土叠合结构是可行的,数值模拟结果是可靠的。在国内外叠合面试验研究的基础上,建立了叠合面剪切滑移数值模型,分析了叠合梁在试验荷载作用下叠合面的抗剪性能,与试验内容和数据相近的山东建筑科学研究院和原武汉水利电力大学研究成果对比分析,得出本次试验叠合梁不会发生叠合面剪切破坏而引起的构件破坏,即叠合面能保证整个梁的正常工作状态。以上研究结果可为无粘结部分预应力混凝土叠合梁的工程应用和进一步研究提供参考。最后,对本文研究进行全面总结,并就该课题的进一步深化提出建议更多还原

【Abstract】 Composite beam is a familiar structure form in construction engineering, and combines together with prefabrication and concreting in spot technics. Compared with concreting beam,it has such merits as convenient construction, saving moulding board, shortening time limit for a project, reducing cost, etc; and compared with prefabricating beam, it has such merits as good whole and good resist-shaking. Its benefit has been approved by many projects, and it will accord with project building need of our country to develop and study this structure at full steam.On the basis of experimental study of mechanics characteristic about unbonded and partially prestressed concrete composite beams in this paper, numerical simulation about the whole process of experiment was done by finite element software-ANSYS.It was summarized about study actualities recent inside and outside our country for unbonded and partially prestressed concrete composite beams in this paper, and it was concluded systemically about merits, significance and existent questions of RC nonlinear finite element law as design theory. It was neatened systemically about experimental study of mechanics characteristic for 20 pieces of unbonded and partially prestressed concrete composite beams (2 pieces as contrasted beams in 20 pieces). On the basis of experimental results and theoretic analysis, it was summarized about properties of ultimate bearing force, crack width and deformation, and being mechanism about“load-prestress”,“stress-exceeding”and press strain-lagging”for composite beams.It was expatiated on nonlinear theory of concrete, including failure rule (uniaxial and multiaxial relations), constitutive model (ottosen model and elastic-plastic model) and RC nonlinear finite element model(overall, discrete and complex model).It was expatiated in detail on properties and application conditions of two main elements, Solid65 and Pipe20 in this simulation, and discussed systemically about yield rule, crack mode and crush disposing of concrete in the software. Considering the combination of rebar and concrete, discrete model, smeared cracking model was adopted, and crush in concrete was not considered. From the point of this experiment, two stages property of concreting and bearing loads was solved by the birth and death function of element and the restarting technology in ANSYS.In this paper, on the basis of study fruits about concrete composite structure, considering itself point of loading, it was established about mechanics model of unbonded and partially prestressed concrete composite beams in ANSYS, and the whole process from loading to failure was analyzed under twice loads, and ultimate bearing force, deformation and curve of strain-stress in whole process were attained. As representative characters of composite structure, it were analyzed in detail about“load-prestress”,“stress-exceeding”and press strain-lagging”, and crack width values of experimental beams were indirect attained. By contrast analysis, numerical simulation values tally with measurable value in fact, and it was proved that ANSYS was feasible to analyse unbonded and partially prestressed concrete composite structures, and numerical simulation results were reliable.On the basis of experimental study about composite plane inside and outside our country, shear-slip numerical model of composite plane was established, and shear-resist capability of composite plane was analyzed under the action of experimental loads. By contrast with study fruits that have similar experimental contents and datas by ShanDong Construction Science Academe and WuHan Water Conservancy and Electric Power university, it was gained about the conclusion that composite beams were not destroyed by the failure of composite plane, and namely composite plane can assure normal work condition of whole beams.The study results from above can provide reference for engineering application and further study of unbonded and partially prestressed concrete composite beams. Finally, whole summarization about the study in this paper was done, and advice about furthering the task was brought forward.更多还原