【作者】 边江；

【导师】 肖明葵；

【作者基本信息】 重庆大学 ， 防灾减灾及防护工程， 2010， 硕士

【摘要】 基于位移的抗震设计非常重视建筑结构在强烈地面运动作用下的最大位移反应,需要结构具有足够的延性。而为了保证结构的弹塑性变形能力,我国抗震规范规定按照不同的抗震等级对梁和柱进行加固(如对结构构件端部的箍筋加密等)。但经研究发现规范用层间位移角达到或超过2%的限值来判断结构整体失效的标准并不能反应地面运动持续时间引起结构累积破坏的影响。而基于能量概念设计方法能够很好的反映结构地震动的持时、强度和频谱特性。尤其能够反应强震持续时间对结构的累积损伤破坏的影响。其概念十分明确、形式又非常简单。因此,基于能量概念设计方法越来越受到国内外地震工程研究界的重视。为了减小柱发生破坏的可能性,降低结构发生整体倒塌的概率,人们通常采取强柱弱梁的结构抗震设计,使梁端先于柱端出铰,以滞回耗能的形式耗散掉地震波输入给结构的总能量。然而,人们往往把塑性铰看作一个截面,忽视了塑性铰长度对结构能量耗散的影响。因为考虑塑性铰长度与不考虑塑性铰长度计算出的滞回耗能有可能不同,所以对同一个结构而言,考虑塑性铰长度与不考虑塑性铰长度得出的结论可能相差甚远。因此,了解塑性铰长度对结构的滞回耗能影响是非常有必要的。本文主要从位移和滞回耗能两个方面对两种情况作了对比研究。研究内容主要做了如下工作:①本文按照中国抗震规范8度设防烈度设计了7个3跨框架结构,分别为4层、5层、7层、9层、11层、13层和15层,采用大型商业有限元软件ABAQUS分别对以上7个平面框架进行建模和弹塑性分析,求出相应的能量和位移的地震反应和相应的时程曲线。而且采用的恢复力模型与以往的不同,不是将梁柱看做一个单元的构件恢复力模型,将质量全部集中在梁或柱的两端,而是从结构材料的本构关系出发,采用材料恢复力模型,将梁柱进行划分为若干单元,采用一致质量矩阵和刚度矩阵,这样就可以避免由于过多的假设所导致误差增加。②在综合考虑地震动因素和结构自身动力特性的情况下,分析不考虑塑性铰长度和考虑三种不同的塑性铰长度模型时平面框架结构总输入能及总输入能分配的变化规律,重点求出由于不考虑塑性铰长度与考虑不同塑性铰长度时对计算总输入能及总输入能的耗散所带来的差异,初步定性和定量地得出了这些差异的规律。③采用不考虑塑性铰长度和考虑塑性铰长度模型,在综合考虑地震动因素和结构自身动力特性情况下,平面框架结构在梁柱之间滞回耗能的分配规律,求出由于选取不同的塑性铰长度模型对计算梁柱的滞回耗能在总滞回耗能的比例所带来的差异,初步定性和定量地得出了这些差异的规律。④过去对塑性铰长度的研究是基于试验的构件层面的研究,并没有从结构整体方面去考虑塑性铰长度的影响。本文与以往从构件的层面出发对塑性铰进行分析研究不同,从结构整体角度出发,在地震动作用下分别计算不考虑塑性铰长度、考虑选取的塑性铰长度模型和梁实际塑性铰长度三种情况对单根梁滞回耗能的差异影响。⑤通过以上研究分析给出适合用于平面框架结构滞回耗能量反应分析的塑性铰长度模型的建议。更多还原

【Abstract】 The displacement-based seismic design highly regards maximum displacement response of structures under strong ground motion, it requires that the structure has enough ductility.For guaranteeing the elastic-plastic deformation capacity of structure, Chinese Code for Seismic Design of Buildings orders that the beam and column must be reinforced according to different seismic grade (such as stirrup densification at the ends of members of structure). Although the research shows that the establishment of the allowed storye-drift-angle which is 2% is used to judge structure failure, it can’t reflect the structural cumulative damage failure caused by the duration of strong earthquake. The analysis and design methods based on energy not only is clear in concept and simple in form, but also better reflects the the duration、intensity of ground motion and spectral characteristics, particularly structural cumulative damage failure caused by the duration of strong earthquake. Therefore, seismic response analysis based on energy has been increasingly paid concern by domestic and international earthquake engineering research community. To reduce the possibility of failure of column and the probability of collapse of overall structure,strong column-weak beam seismic design of structures is adopted so that the plastic hinge of the beam-end appers before column-end. Hysteretic energy dissipates the total energy of structure input by seismic waves. However, plastic hinge is often seen as a section and neglected the impact of the plastic hinge length. For the difference of the hysterectic energy between considering the plastic hinge length or not, the analysis on the same structure using different plastic hinge lenth model may be very different in conclusion. Therefore understanding the influence of the hysterectic energy of the plastic hinge length is very necessary.In this paper, Mainly compared with the displacement and hysteretic energy between the two conditings, this article has done the following work:①In accordance with Chinese Code for Seismic Design of Building, seven three-bay reinforced concrete plane frame of 4 layers, 5 layers, 7 layers, 9 layers, 11 layers, 13 layers and 15 layers are designed. And then these frames are modeled and analyzed using large commercial finite element software ABAQUS. The energy dissipation and relative displacement response is calculated. Different from the previous energy-based analysis in which the beam and column are regarded as an element and the mass of a beam and a column is set at the two ends of the beam and column, this paper apply material restoring force model based material constitutive model, divide elements and use consistent mass matrix and consistent stiffness matrix, avoiding increasing errors due to too many hypothesis.②Considering changes of ground motion factors and structural dynamic properties, changing law of total input energy and its distribution of plane frame structure for using different plastic hinge length model is analyzed, and then it is obtained that the difference of the total input energy and its distribution as a result of different plastic hinge length model selection, reaching a preliminary understanding of these quantitative and qualitative differences in the law.③Considering changes of ground motion factors and structural dynamic properties, changing law of distribution of hysteretic energy and damping energy of beams and columns for adopting different plastic hinge length model or not is analyzed, and then it is obtained that the difference between beam and column distributions of hysteretic energy as a result of considering plastic hinge length model or not, getting a preliminary understanding of these quantitative and qualitative differences in the law.④The previous researchs of plastic hinge are based on structural members by test. They can’t reflect the impact of the structure to plastic hinge length. Different from the previous researchs of plastic hinge on structural members, this paper analyzes the plastic hinge length through the plan frame. It analyzes the different impact of hysteretic energy of single beam considering plastic hinge, plastic hinge length model selected and the actual plastic hinge length .⑤This paper gives a suggestion on the selection of plastic hinge length model for the energy-based analysis by the above analysis.更多还原