BRB框架结构罕遇、极罕遇地震下倒塌性能研究

发布时间：2018-06-04 22:47

  本文选题：钢筋混凝土框架结构 + 屈曲约束支撑(BRB)　； 参考：《中国建筑科学研究院》2017年硕士论文

【摘要】：普通支撑受压会产生屈曲现象,当支撑受压屈曲后,刚度和承载力急剧降低。当支撑由压曲状态逐渐变至受拉状态时,支撑的内力以及刚度接近为零。因而普通支撑在反复荷载作用下滞回性能较差。屈曲约束支撑又称防屈曲支撑或BRB(Buckling restrained brace)是新型的耗能支撑,与传统支撑最大的区别是BRB的主要耗能构件,即内核单元外围有约束单元的限制,使其在轴向压力的作用下,发生全截面屈服之前不会发生屈曲,从而避免了传统支撑受压时容易失稳的问题。BRB有良好的延性和滞回性能,在弹性阶段工作时,就如同普通支撑可为结构提供很大的抗侧刚度,可用于抵抗小震以及风荷载的作用。在弹塑性阶段工作时,变形能力强、滞回性能好,就如同一个性能优良的耗能阻尼器,可用于结构抵御强烈地震作用,提高结构的抗倒塌性能。安装屈曲约束支撑(BRB)的框架结构(以下简称BRB框架结构)可以减少设计配筋,那么按多遇地震设计后能否满足“大震不倒”的抗震设防要求自然成为研究者关注的一个问题。本文用数值模拟的方法分析不同构件尺寸,不同高度,不同空间布置(包括按6度、7度、8度、9度分别设计的三层框架、五层框架结构以及按所在烈度设计的其余四个框架结构)的框架结构和BRB框架结构在罕遇地震、极罕遇地震下的抗震性能,具体体现在结构的层间变形,基底剪力,塑性铰数量和发育情况以及竖向构件耗能等。通过比较BRB框架结构和框架结构的有限元计算结果,本文认为:(1)得益于BRB卓越的耗能能力,BRB框架结构在罕遇地震和极罕遇地震作用下,结构地震反应减弱,结构完全可以满足“大震不倒”的抗震设防要求。(2)框架结构和BRB框架结构在罕遇地震作用下层间位移角均满足规范要求。极罕遇地震作用下,框架结构6度时位移角最大值均小于1/50,7度时位移角最大值已十分接近1/50(部分地震波计算层间位移角最大值大于1/50),8度、9度时部分结构位移角最大值已大于1/50;各烈度BRB框架结构层间位移角均满足规范1/50限值要求。BRB框架结构有较高的安全储备,可预防突发性超强烈地震作用下结构的倒塌破坏。美国学者在上世纪90年代初率先提出了基于性能的抗震设计思想。在这一思想的指导下,许多学者提出了他们基于位移的抗震设计方法。本文在他们研究的基础上,由相关基本假定和一些既定的理论研究结果推导出配箍特征值的理论计算公式。将有限元软件模拟得到的不同BRB框架结构的最大层间位移角均值带入配箍特征值公式,从而得到BRB框架结构的配箍特征值建议值。
[Abstract]:The buckling of common braces is induced by compression, and the stiffness and bearing capacity decrease sharply after buckling. The internal force and stiffness of the bracing are close to zero when the buckling state is gradually changed to the tensile state. Therefore, the hysteretic behavior of common braces under repeated load is poor. Buckling restrained braces, also called buckling braces or BRB(Buckling restrained brace, are a new type of energy dissipation support. The biggest difference from traditional braces is that the main energy dissipation components of BRB, that is, the core element is limited by the constraint element, make it under the action of axial pressure. There will be no buckling before the full section yield occurs, thus avoiding the problem of instability of traditional braces under compression. BRB has good ductility and hysteretic performance. Just as ordinary braces can provide large lateral stiffness for structures, they can be used to resist small earthquakes and wind loads. In the elastic-plastic stage, the deformation ability is strong, the hysteretic performance is good, just like a good energy dissipation damper, it can be used to resist the strong earthquake action of the structure and improve the collapse resistance of the structure. The frame structure with buckling constraint bracing (hereinafter referred to as BRB frame structure) can reduce the design reinforcement, so whether or not the seismic fortification requirement of "big earthquake can not collapse" can be satisfied after frequent earthquake design has become a problem that researchers pay attention to naturally. In this paper, the numerical simulation method is used to analyze the three story frames with different dimensions, different heights and different spatial arrangements (including three layers designed according to 6 degrees, 7 degrees, 8 degrees and 9 degrees, respectively). The seismic behavior of the five-story frame structure and the other four frame structures designed according to the intensity of the structure) and the BRB frame structure under rare and extremely rare earthquakes are embodied in the interstory deformation of the structure and the shear force of the base. The number and development of plastic hinges and the energy consumption of vertical components. By comparing the finite element results of BRB frame structure with that of frame structure, it is concluded in this paper that the structural seismic response of BRB frame structure is weakened under rare and extremely rare earthquake due to the excellent energy dissipation capacity of BRB. The structure can completely meet the requirements of seismic fortification of "strong earthquake not collapsing". 2) frame structure and BRB frame structure can meet the requirements of code for displacement angle between the lower layer of rare earthquake action. Under the action of extremely rare earthquakes, When the maximum displacement angle of frame structure is less than 1 / 50 / 7 degree, the maximum displacement angle of frame structure is very close to 1 / 50 (the maximum displacement angle of partial seismic wave is greater than 1 / 50 / 9 degree and the maximum value of displacement angle of partial seismic wave is more than 1 / 50 when the maximum value of displacement angle is more than 1 / 50). The inter-story displacement angle of BRB frame structure meets the limit value of 1 / 50 of code. BRB frame structure has a high safety reserve. It can prevent the structure from collapsing and destroying under the action of sudden super strong earthquake. American scholars first put forward the idea of performance-based seismic design in the early 1990s. Under the guidance of this idea, many scholars put forward their displacement-based seismic design methods. On the basis of their research, this paper deduces the theoretical calculation formula of the eigenvalue of collars based on the relevant basic assumptions and some established theoretical results. The maximum interstory displacement angle of different BRB frame structures is introduced into the hoop eigenvalue formula by finite element simulation, and the suggested hoop eigenvalue of BRB frame structure is obtained.
【学位授予单位】：中国建筑科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU352.11
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本文编号：1979161