IDA方法在无粘结预应力混凝土框架结构地震易损性分析中的应用

发布时间：2018-02-10 10:44

本文关键词： 无粘结预应力混凝土框架预应力度抗震性能增量动力分析地震易损性　出处：《合肥工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：无粘结预应力混凝土作为混凝土领域里的一门新兴技术,不仅能加快施工进度、减轻结构自重、节约钢材,而且还能提高其综合效益,是当前建筑结构发展的一种趋势。近些年,虽然对无粘结预应力混凝土结构抗震性能的研究也取得不错成果,但该类结构在抗震设防地区的应用很少,对于其基于性能的抗震研究也很少。为了有效改善无粘结预应力混凝土结构的抗震性能,推广此类结构在抗震设防地区的应用,本文采用增量动力分析方法对无粘结预应力混凝土框架结构进行了基于性能的抗震研究,结合地震易损性分析对结构的抗倒塌能力以及地震经济损失进行了评估。施加在无粘结预应力混凝土结构中的预应力大小可以用预应力度来表示,能够直接影响结构的抗震性能。为此,本文考虑了预应力度的影响,以某五层两跨无粘结预应力混凝土框架为研究对象,利用MIDAS/gen有限元软件分别对预应力度为0.4、0.6、0.8和1.0的结构模型进行增量动力分析,以谱加速度1(,3%)aS T以及最大层间位移角max?分别作为地震动强度指标和结构损伤指标来建立IDA曲线,对多条IDA曲线汇总统计,研究了结构的抗震性能,研究结果表明:在弹性阶段,随着预应力度的增大,无粘结预应力混凝土框架结构的强度和刚度有所增大,结构的抗震性能也有所改善;在结构进入弹塑性阶段后,结构达到CP极限状态时,预应力度为0.6结构的谱加速度1(,3%)aS T最大,并且随着谱加速度1(,3%)aS T的增大结构的强度和刚度退化较为缓慢,具有良好的抗震性能,适合在抗震地区应用。本文采用地震易损性理论,总结了无粘结预应力混凝土框架结构基于IDA分析结果的结构地震易损性分析流程,分析不同预应力度结构在不同性能水准下的易损性曲线,并对其抗倒塌能力以及地震经济损失进行评估。研究结果表明:结构在IO和LS极限状态的易损性曲线不随预应力度的改变而产生较大变化。对于结构在CP极限状态的易损性曲线,预应力度为0.6时,结构易损性曲线最为平缓,在相同水平罕遇地震作用下超越CP极限状态的概率较小,说明在进入弹塑性阶段以后,结构表现出较好的塑性变形能力以及良好的延性耗能性能。从结构的抗倒塌储备系数可以看出,预应力度为0.6的结构抗倒塌储备系数最高,说明无粘结预应力混凝土结构在中等预应力度下,结构抗倒塌能力较强,具有较高的安全储备,而且在遭受一次确定性年频率地震时,造成结构的直接经济损失最小,有利于结构在抗震地区的应用。
[Abstract]:As a new technology in the field of concrete, unbonded prestressed concrete can not only accelerate construction progress, reduce structural weight, save steel, but also improve its comprehensive benefit. In recent years, although the research on the seismic behavior of unbonded prestressed concrete structures has also achieved good results, the application of this kind of structures in seismic fortification areas is rare. In order to effectively improve the seismic performance of unbonded prestressed concrete structures, the application of such structures in seismic fortification areas is extended. In this paper, an incremental dynamic analysis method is used to study the aseismic behavior of unbonded prestressed concrete frame structures. Combined with seismic vulnerability analysis, the anti-collapse ability and seismic economic loss of structures are evaluated. The size of prestress applied to unbonded prestressed concrete structures can be expressed by the degree of prestress. Therefore, the influence of prestress degree is considered in this paper, and a five-story two-span unbonded prestressed concrete frame is taken as the research object. The increment dynamic analysis of the structural models with prestressing degree of 0.4U 0.60.8,1.0 is carried out by using the MIDAS/gen finite element software, respectively. The spectral acceleration is 1 / 3AS-T and the maximum interstory displacement angle is max.? The IDA curve is established as the strength index of ground motion and the damage index of the structure respectively. The seismic performance of the structure is studied by collecting and statistics of many IDA curves. The results show that in the elastic stage, with the increase of the degree of prestress, the seismic behavior of the structure is studied. The strength and stiffness of unbonded prestressed concrete frame structure are increased, the seismic behavior of the structure is improved, and when the structure enters the elastic-plastic stage, the structure reaches the limit state of CP. The spectral acceleration of 0.6 structure is the largest, and with the increase of spectral acceleration, the degradation of strength and stiffness of the structure is slow, and the structure has good seismic performance. The theory of seismic vulnerability is used to summarize the flow of seismic vulnerability analysis of unbonded prestressed concrete frame structures based on the results of IDA analysis. The vulnerability curves of structures with different prestressing degrees under different performance levels are analyzed. The results show that the vulnerability curve of the structure in IO and LS limit state does not change with the change of prestress degree, and for the structure in the CP limit state, the damage curve of the structure is not changed with the change of the degree of prestress. The vulnerability curve of the state, When the degree of prestress is 0.6, the vulnerability curve of the structure is the most gentle, and the probability of exceeding the limit state of CP under the action of rare earthquakes at the same level is relatively small, which indicates that after entering the elastic-plastic stage, The structure shows good plastic deformation ability and good ductility energy dissipation performance. It can be seen from the collapse resistance reserve coefficient of the structure that the prestressing degree of 0.6 is the highest. The results show that the unbonded prestressed concrete structure has strong collapsing resistance and high safety reserve under the condition of moderate prestress, and the direct economic loss of the structure is minimal when it is subjected to a deterministic annual frequency earthquake. It is beneficial to the application of structure in seismic area.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU378.4

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