【作者】 张俊；

【导师】 王金昌；

【作者基本信息】 浙江大学 ， 工程硕士（专业学位）， 2017， 硕士

【摘要】 在高层和超高层建筑项目设计中,梁板混凝土强度和竖向构件的混凝土强度等级常常不同,在高层项目中,往往粱板混凝土强度比竖向构件混凝土强度低4～5个个级别差。当竖向构件与水平构件出现混凝土等级差时,对结构设计是要求分开浇筑,尤其是节点区。目前设计上,多数设计院采用常规做法:45度放坡并附加钢丝网片来浇注节点或者当节点区竖向构件和梁板构件混凝土等级差控制在2级时,允许节点区按照低标号混凝土浇注。但现在很多图审单位以根据规范认定此方法存在两大问题:(1)在梁端支座负弯矩最大处会出现不易处理的施工缝,进而使得塑性铰提早出现并对强度有较大的影响;(2)人工控制的泵送混凝土初凝时间不易控制,浇筑和振捣质量也存在较大的偶然性。因此项目相关结构设计人员需重新制定节点区域不同混凝土强度的浇注方案,但目前规范或其他相对较权威的技术手册没有明确的方案可做参考。对于所有节点区不做抗震等级、设防烈度、结构功能性要求的区分而均统一按照有2级混凝土级别差时来控制节点区可以随梁板构件的低标号混凝土一起浇注则显得较为笼统,同时在实际工程中易出现施工浇筑质量事故,对结构安全性产生影响。此研究课题目前并无较为深入的研究,当在实际工程中出现节点区被低标号混凝土误浇筑的情况出现时,结构设计人员没有很好的加固处理办法,所以本课题研究成果能在实际工程中有较好的应用,能为设计方提供一个技术参考。本文第一步工作在文献阅读的基础上,了解目前国内外对框架梁柱节点区的试验研究现状以及根据不同国家的结构设计规范对梁柱节点区设计上的不同构造要求进行了分析归纳,并进一步提出个人意见。第二步工作,对梁柱节点区和梁柱节点核心区两者做了区分,且阐述了两者各自的破坏机理。通过引述文献中具体算例对两者分别在水平和竖向荷载作用力下的受力情况进行分析,验证了梁柱节点区主控受力为剪切力,且此结论符合规范中对节点区的设计计算假定。第三步工作,通过实际工程中出现的具体事故案例,分析出现浇筑事故的原因,根据加固规范提出加固思路。第四步工作,通过工程有限元软件的使用,对规范规定的几种加固方法进行复核验算,而后对此做出各自优缺点的总结析。最后根据工程实际要求,结合目前常规加固方法的优点提出新的加固思路和手段,并用工程有限元软件复核验证,同时对规范中节点抗剪验算公式中进一步完善,提出自己的补充公式。第五步工作,通过有限元软件对比该加固节点与原始样本节点区的受力变形特性,来验证真对本工程此节点加固的方法以及所提出的外加箍筋作用计算公式的可行性。最后,提出对框架梁柱节点区采用低标号混凝土浇筑方式的结论和展望。更多还原

【Abstract】 In high-rise and super high-rise buildings designing,concrete strength grade of beam-slab and vertical members is usually different.There are always 4 to 5 grade differences of concrete strength.When there is a concrete strength grade difference between vertical members and horizontal members,concrete needs to be poured separately during construction,especially in joint region.While during designing,most design institutes pour concrete in usual way,which is,45 degree slope settling design added with wire mesh on joint.Or there is another way.It is allowed to pour with low-grade concreteon joint region when the strength grade is grade 2 between vertical members and beam-slab.However,based on "Structure Design of the 2009 National Civil Building Engineering Technical Measures(Concrete Structure)",many drawing-censoring institutes consider that this will cause two problems.First,high-slump commercial concrete makes form work very difficult on joints.Meanwhile,impertinent vibration on joint regions will causes widespread high strength concrete.As the joint region is the biggest cogging moment,it will properly occur plastic hinge earlier than expecting.Second,concrete is usually poured by constructor.So part of drawing-censoring institutes consider the common practice unreasonable.Those two problems demand the structural designers to make a new pouring plan for the different concrete strength grade on joint region.However,there is no specific plans can be referred so far.While it is too general that using second strength grade difference in all joint regions to control if joint region is poured with beam and slab.There is no intensive study before this research subject.Structure designers have no way to reinforce when there is a pouring mistake with low-grade concrete during construction project.Therefore,this research subject is really meaningful to actual operating,which can provide a technical reference.This paper clearly points out the difference frame beam-column core region and node core region,as first step.Second,through the analysis of stress condition of frame beam-column in both vertical and horizontal stress,the paper confirms that it is horizontal stress which mainly controls the frame beam-column.Third,through the stress analysis of node core region as rigid,putting forward that the main deformation of rigid node core is shear deformation.Fourth,concluding through the analysis and research of destruction characteristic and mechanism in node core region,while knowing the principle of structure design in beam-column joints in technical specification of different countries.Besides,through the segmentation of buildings in different using function,the paper presents the advice in concrete strength grade of beam-column joints.At last,this paper puts forward the conclusion and expect of research of frame beam-column node region.更多还原