【作者】 潘峰；

【导师】 王正霖；

【作者基本信息】 重庆大学 ， 结构工程， 2004， 硕士

【摘要】 预应力混凝土技术已经在我国土木工程领域得到了广泛的运用. 而预应力超静定结构更是以其优越的结构性能备受设计人员的青睐 .多年来. 国内外预应力界的专家学者对预应力超静定结构进行了不懈的研究和探讨. 对于预应力超静定结构的受力性能和内力重分布的特性有了一定的认识和共识. 为工程设计提供了依据 .但由于预应力结构自身的特点. 经常被运用于底部大开间或转换层中. 框架梁跨度加大. 单柱负荷面积大. 上部层数多. 必将导致框架柱中的轴压比较大有必要考虑其对弯矩重分布的影响. 但现有文献资料多数仅考虑了框架柱轴压比对结构延性的影响. 而对结构内力及内力重分布的影响均未加讨论 .重庆大学土木工程学院本着客观 .严谨的态度 .进行了两榀足尺单层双跨预应力框架的试验本文针对两榀不同轴压比下施加不对称荷载的预应力框架. 对其加载过程中的裂缝发展规律. 结构的塑性弯矩重分布进行了探讨和研究. 并得到以下主要认识和结论.(1) 单跨和双跨预应力框架中. 轴压比变化引起的二阶效应对结构荷载内力的影响始终存在 .但即使在影响最大的柱底截面变化幅度也在 1 左右. 故而可以忽略不计.(2) 对于同榀框架中各框架柱轴向变形不等的框架. 轴压比的变化将影响结构内力. 且这种影响的大小取决于柱顶轴力与跨间荷载的比例. 柱顶轴力相对于跨间荷载越大. 其影响亦越大. 并且在某种极端情况下. 边柱柱底弯矩将超过边柱顶弯矩. 最终可能导致结构边柱底出现塑性铰.(3) 预应力框架中轴压比的变化将影响框架柱的延性 .为实现. 大震不倒 的目标。 有必要规定预应力框架柱的轴压比限值 .但这一限值并不是一个固定的数值 应根据具体情况适当增减.(4) 轴压比对预应力框架的极限荷载影响不大. 可认为框架柱轴压比仅影响框架梁内力重分布的过程而不影响弯矩调幅的最终结果.更多还原

【Abstract】 The technique of prestressed concrete is already to get in our civil engineeringrealm more and more extensive application. For the statically indeterminate structure ofprestressed concrete,it is especially have the favor of the designers by its superiority.These year, internal and foreign specialists in the prestressed concrete field dedicatethemselves into the study on statically indeterminate structures of prestressed concreteand get some cognitions of their mechanice characteristics and specialities of internalforce redistribution. These study results offer the engineering realm good references.Because of the characteristics of itself, prestressed concrete structures are often used tobottom wide bays or transform-floors. For these structures, the span of frame beamsincrease, the load-supported areas of single column increase,the number of upside-layesis more, So the axial compress ratio of frames is relatively big and it is necessary for usto consider its effect to moment redistribution. But most references in existence onlyconsider the effects of axial compress ratio to structure ductility and donot discuss theeffects of axial compress ratio to structure internal forces and internal forcesredistribution. With the impersonal and precise attitude, the civil engineering college ofchongqing university has finished the experimentation of two full-scale. One layer anddouble-span prestressed concrete frames. In allusion to the two prestressed frames of different axial compress ratiosupporting non-symmetrical loads, this paper discusses crack develop-rules andstructural plastic moment redistributions of the loading process. The main conclusionsof the paper are below: (1) For single-span and double-span prestrssed frames, the second-order effectbrought by the change of axial compress ratio always effects structural internal forces,but the effect extent is only about 1% at the column-bottom sections which are effectedmost markediy. So it can be ignored. (2) For the frames of which only partial frame-columns exist axial compress ratioor which the axial deformations of frame columns are different, changes of axialcompress ratio will bring changes of structural internal forces, and the changes will bemore obvions with the decreases of the ratio of beam rigidity to column. When axialcompress ratio increases to a certain degree, the column-bottom moment of the span ofside-column which exists axial compress ratio will exceed the moment of the II<WP=6>corresponding beam-border’s bearing, the structures maybe destroy at the form ofcolumn-hinge mechanismfinally. (3) For prestressed frames, the change of axial compress ratio will effect theductility of frame column. To realize the aim of “experted rare earthquakes, nocollapse”, it is necessary to regulate the limit axial compress ratio of prestressedconcrete frame column which is not a fixed value but should be adjusted by realconditions. (4) axial compress ratio effects the limit loads of prestressed frames so little thatwe can conclude axial compress ratio effects only the internal force redistribution butnot the last moment mondulation results of prestressed concrete frames.更多还原