【作者】 齐志刚；

【导师】 张希黔；

【作者基本信息】 重庆大学 ， 土木工程， 2008， 博士

【摘要】 双曲混凝土扭壳是薄壳混凝土结构中比较简单同时也是比较优秀的结构型式,它具有优美的曲面外型、施工支模容易、造价经济、结构工作效率高等优点。而双曲混凝土组合扭壳不仅能够提供更大的跨度和建筑空间,而且能产生更为丰富的建筑艺术造型,因而当建筑美学的需要超过经济要求时,选用双曲混凝土组合扭壳结构较为合适。本文通过对大跨度双曲混凝土扭壳屋盖结构的结构设计与优化分析、双曲混凝土组合扭壳屋盖结构施工以及工程实例应用,掌握了双曲混凝土组合扭壳屋盖结构的基本结构性能、结构设计与施工方法,为将来大跨度双曲混凝土组合扭壳屋盖结构的应用提供了较好的参照。在大跨度双曲混凝土扭壳屋盖结构的结构设计与优化分析中,详细阐述大跨度双曲混凝土组合扭壳屋盖结构设计和优化分析方法,当采用有限元和数值模拟分析时应该合理的采用有限单元和合适的求解方法,并指出结构设计方法要点,这对于同类结构的设计具有较好的指导作用。利用数值模拟技术,对大跨度双曲混凝土组合扭壳屋盖结构从尺寸角度进行了优化设计分析,包括重量优化和矢跨比优化分析,得到最优矢跨比的分布范围及相应的平缓度。通过矢跨比对结构最大位移、滑动支座位移、屋盖水平推力、应力分布等方面的影响分析,得到矢跨比和混凝土组合扭壳平缓度的合理取值范围取值,分析表明:通过重量优化,可以使屋盖重量减少19.8%。通过矢跨比对结构最大位移、滑动支座位移、屋盖水平推力、应力分布等方面的影响分析,得到当矢跨比取值在0.15~0.2时,其对应的扁平度取值在0.74~1.31时,壳体内力分布较为合理,且能够很好的发挥其索拱机制。优化分析结论能够为类似的双曲混凝土组合扭壳屋盖结构设计提供较好的参考,这是论文的第一个创新点(论文第3.6节)。考虑到大跨度双曲混凝土组合扭壳结构的空间曲面复杂性,采用常规传统的测量方法不能快捷、准确地完成空间测量定位。本文采用简化的方法,对华南理工大学体育馆双曲混凝土组合扭壳屋盖进行了空间精确测量定位,即利用扭壳直纹特点,先进行二维平面的定位测量,将组合扭壳由三维空间投影至水平面,转化为二维平面,在此基础上在水平面内找寻第三维的变化规律,进行高程放样实现空间坐标精确定位,并通过利用壳面角点的关键控制点,确定控制坐标。并且运用高精度测量准确地完成了空间定位和消除了系统误差。这种方法快速、准确解决了双曲混凝土组合扭壳结构的空间精确定位问题,为模板支撑以及后续的施工奠定了良好的基础,同时也为空间曲面的平滑度提供了必要的保证,这是论文的第二个创新点(论文第4章)。大跨度双曲混凝土组合扭壳外形生动、美观,壳体由两个方向的直纹组成,支模、扎筋和预应力筋铺设等都很方便,与斜柱人字架组合后采用现代预应力技术,跨度达到100m,而且壳体的厚度达到130mm,无论是跨度还是厚度都较以往有所突破,这是论文的第三个创新点(论文第6章)。大跨度双曲混凝土组合扭壳屋盖混凝土结构施工完毕后,模板拆除顺序的不同,对强度还未达到最大的扭壳结构影响很大,本文采用有限元方法,对其施工拆模进行了考虑多种拆模方式的优化分析,通过优化拆模方式和拆模顺序,分析了不同拆模顺序的内力分布,并通过对比分析,得到其最优拆模方式和拆模顺序。在双曲混凝土组合扭壳屋盖结构施工部分中,以华工扭壳为基本算例,重点讨论双曲混凝土组合扭壳屋盖结构临时支撑体系拆模顺序的优化,对双曲混凝土组合扭壳屋盖结构满堂脚手架施工拆模顺序进行了全面的优化分析,将混凝土组合扭壳的主拉应力控制作为其不利受力状态的标准,并以此来确定合理的临时支撑体系拆模顺序。分析之前,考虑了多种拆除方式,并通过对比分析得出当立杆间距为1.2m时,按照2.5m2/单元左右进行拆除时,屋盖结构受力较为合理,即按照环状分割的拆除方式,每次拆两排立杆支撑较为合理。通过实际施工拆模顺序的计算和实测分析,得出壳体最大拉应力和各方向最大位移的变化情况,进一步掌握大跨度混凝土组合扭壳屋盖结构的受力变化和安全储备,为施工拆模期间的安全提供了理论上的保障,分析结论为今后类似的工程施工提供了理论基础,这是论文的第四个创新点(第7章)。更多还原

【Abstract】 Hyperbolic paraboloidal(H.P.) shell has some own virtue such as graceful curved surface, easy to support formwork, inexpensive cost. H.P. shell can be seen as surface action system. Arch mechanism and append mechanism are working together, and they restrict each other, so the structure can work high efficiency, which superiority than other kind of shell. While H.P. combined shell has mentioned above advantage, and can design longer span and space. Therefore, it is appropriate to utilize H.P. combined shell when economical consideration more than architecture aesthetics request.Theory analysis, structure design, structure construction and its project application of H.P. concrete combined torsion shell with parallelogram bottom surface projection were discussed in this paper, which make us grasp the basic performance, methods of structure design and construction of H.P. combined torsion shell, so the reference was offered for a similar project application in the future.In the structure design of the H.P. combined torsion shell, keypoints were pointed out. In the optimization analysis, the method of structure optimization analysis of long-span H.P. concrete combined torsion shell roof with parallelogram bottom surface projection was particularly expatiated. During the structure design, analysis of wind load, seismic effect, and structure bulking stability were done. Weight and rise-span ratio optimization were analyzed by numerical simulation technology and self-design programme, and obtained the distribution of optimizational rise-span ratio and corresponding gentle degree. The reasonable elements and analysis method were adopted, and essentials were pointed out about structure design, which guide the similar project in the future. The optimization analysis shows that Weight optimization made the weight less 19.8 percent and the cable-arch mechanism play better role when the distribution range of rise-span ratio is from 0.15 to 0.2 through the keypoint such as most displacement of structure, glide seat displacement, horizontal force of shell roof and stress distribution. The result of optimization analysis of this paper can provide better preference for the similar structure design.construction include key construction technology of spatial exact precision location, design and installation of high scaffold, concrete cast, prestressed construction, vacuum aided grouting, supprot system removal, construction measurement and so on. The construction model test of shell roof was made before construction. The practise show that the safty of shell structure is better,meanwhile construction quality and the operation after completion is well.Considering the complicated dimensional curve surface of H.P. combined torsion shell with parallelogram bottom surface projection, traditional measurements cannot rapidly and accurately complete the spatial measurement location. In this paper, the simplified method was adopted, which made spatial accurate measurement location to H.P. concrete combined torsion shell of Huanan Technology university in Guangzhou university city. First of all, using straight line characteristics, plane measurement location was carried through, which the dimensional points were projected into plane, and then to find the rule of the third dimension and realized the accurate spatial measurement location, meanwhile, controlling points were confirmed by using keypoints in shell corner and avoid system error. The problem of spatial coordinate accurate measurement location of combined shell was solved, which establish well basis for the formwork supporting and subsequent construction, and assure the smoothness of spatial curve surface.Long-span prestress reinforced concrete H.P. combined torsion shell with parallelogram bottom surface projection has vivid and beautyful style, which have two direction straight line, so the formwork supporting and steel bar construction was very convenient. Because using modern pre-stressed technology, the span and thichness are all get high level and make proper internal force distribution and construction sequence by prestressing on the shell roof, meanwhile ensure the safty of shell roof.After finished cast concrete of shell roof, different formwork removal methods have much influence on shell because of its inadequate strengthen. For the sake of safty during construction period, the dissertation use FEM program to optimize formwork removal sequence of H.P. combined shell roof with parallelogram bottom surface projection for the example of Huanan Technology University Gymnasium in Guangzhou university city. The main tension stress controll as its standard, and then determine the proper sequence of formwork removal. Several method of formwork removal were considered, by comparsion, the way of annular segmentation is proper for formwork removal. the variation most tension stress and displacement were obtained through the computaion and measurement, and obtained internal force distribution of different sequence, furthermore got optimal formwork removal sequence, and providing basis of theory for construction, and then making for guiding similar project construction.更多还原