开洞对大跨度预应力梁性能的影响

发布时间：2018-08-27 09:56

【摘要】：高层、超高层大跨度预应力混凝土结构建筑随着经济的发展而不断增多。梁上开洞能够节省辅助设施,增大建筑物的空间,降低自重,具有较高的应用价值。然而梁上开洞破坏了结构的整体性和连续性,会直接影响结构的安全性,因此有必要对预应力混凝土开洞特性进行进一步研究,以指导工程实践。本文采用有限元软件对预应力开洞梁进行模拟,研究不同开洞形状、大小及孔间距对应开洞特性,分析其应力、挠度和极限承载力。对比不同模型,研究模拟工况下预应力开洞梁超过《混凝土结构构造手册》对于开洞梁要求的最大开孔尺寸和最小孔间距,主要研究工作和相关结论如下:(1)通过文献调查大跨度预应力混凝土结构和开洞梁的研究现状和发展概况,分析预应力混凝土结构力学模型和本构关系,为预应力开洞梁模拟与分析提供基础。(2)利用PKPM和力学计算对工况进行拟定和计算,为后面5个分析组做基础。分析预应力混凝土梁、普通混凝土开洞梁和预应力开洞梁三种不同模型应力和挠度变化规律,得出梁上开洞的主要影响范围为开洞周边,预应力筋能够改善梁的受力性能及变形,相对普通混凝土开洞梁其应力和挠度分别减小83%、50%。(3)分别以开洞尺寸和孔间距为变量,模拟预应力混凝土圆形开洞梁。结果随着开洞尺寸增大或孔间距减小,梁的应力和挠度增大,极限承载力减小。保证结构安全的最大开洞尺寸可超构造手册规定41.67%,最小孔间距较构造手册规定值减小56.25%。(4)分别以开洞尺寸和孔间距为变量,模拟预应力混凝土矩形开洞梁。结果随着开洞尺寸增大或孔间距减小,梁的应力和挠度增大,极限承载力减小。保证结构安全的最大开洞尺寸可超构造手册规定33.33%,最小孔间距较构造手册规定值减小56.25%。(5)孔间距相对开洞尺寸对预应力混凝土梁上开洞的影响要小,预应力混凝土梁上开圆形孔洞要优于矩形孔洞,在保证结构安全性和功能要求的基础上建议优先考虑选择圆形开洞方法。
[Abstract]:High-rise, super-high-rise prestressed concrete structure buildings are increasing with the development of economy. The opening of beam can save auxiliary facilities, increase the space of buildings and reduce the weight of buildings, so it has high application value. However, the structure integrity and continuity are destroyed by the opening of the beam, which will directly affect the safety of the structure. Therefore, it is necessary to further study the opening characteristics of prestressed concrete in order to guide the engineering practice. In this paper, the finite element software is used to simulate the prestressed beam with open hole. The characteristics of different hole shape, size and hole spacing are studied, and the stress, deflection and ultimate bearing capacity of the beam are analyzed. Compared with different models, the maximum opening size and minimum hole spacing required by prestressed open-hole beam are studied under simulated conditions, which exceed the "manual of construction of concrete structure". The main research work and related conclusions are as follows: (1) by investigating the present situation and development of long-span prestressed concrete structures and open-hole beams, the mechanical model and constitutive relationship of prestressed concrete structures are analyzed. It provides the foundation for the simulation and analysis of prestressed open-hole beam. (2) the working conditions are drawn up and calculated by PKPM and mechanical calculation, and the foundation is provided for the latter five analysis groups. This paper analyzes the stress and deflection variation of prestressed concrete beam, common concrete open hole beam and prestressed open hole beam, and draws the conclusion that the main influence range of the opening on the beam is around the opening. Prestressed tendons can improve the mechanical behavior and deformation of the beams, and the stress and deflection of the beams are reduced by 833% and 50%, respectively. (3) taking the size of the holes and the spacing of holes as the variables, the prestressed concrete beams with circular openings are simulated. Results with the increase of hole size or the decrease of hole spacing, the stress and deflection of the beam increase and the ultimate bearing capacity decreases. The maximum hole size to ensure the safety of the structure can exceed that stipulated in the construction manual 41.67, and the minimum hole spacing is 56.25 smaller than the specified value of the construction manual. (4) taking the opening size and the hole spacing as variables, the prestressed concrete rectangular hole opening beam is simulated. Results with the increase of hole size or the decrease of hole spacing, the stress and deflection of the beam increase and the ultimate bearing capacity decreases. The maximum hole size to ensure the safety of the structure can exceed that stipulated in the structural manual 33.33, and the minimum hole spacing is 56.25 less than the specified value of the construction manual. (5) the influence of the hole spacing relative to the opening size of the hole on the opening of the prestressed concrete beam is small. The circular hole in prestressed concrete beam is better than the rectangular one. On the basis of ensuring the safety and function of the structure, it is suggested that priority should be given to the circular opening method.
【学位授予单位】：西安工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU973.12

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