地铁车站平面模型研究综述

地下结构抗震研究是当今地震工程领域重要的研究方向之一.迄今为止,国内外学者在地铁车站结构地震响应研究中采取了原型观测、实验研究、理论分析等方法.随着计算机技术的长足发展,实验研究中的数值模拟方法为越来越多的学者所采用.为提高计算效率,通常简化计算模型,采用平面模型模拟地下车站结构.对二维模型和三维模型的计算结果差异目前...     

基于易损性的基础隔震结构地震动选取方法研究

对基础隔震结构进行动力弹塑性时程分析时,地震记录的选择是关键.提出基于基础隔震结构弹塑性动力放大系数谱进行地震记录选取的方法:首先采用动力弹塑性时程分析方法对基础隔震结构的两自由度简化模型进行分析,得到结构的动力放大系数谱;然后采用谱匹配的方法选取地震记录,对一8层混凝土框架结构的基础隔震结构进行增量动力分析、地震易损...     

多点激励下拱桥竖向地震反应的简化计算方法

以某大跨公路拱桥为例,通过对拱桥在三种行波输入模式下地震反应的对比计算,提出了拱脚行波输入的简化输入方式;利用拱桥结构的对称性特点,提出了多点输入下半拱叠加的简化计算方法。经验证,这一计算方法具有良好的计算精度,可将较为复杂的拱桥多点输入地震反应计算问题,转化为工程技术人员熟悉的一致输入下地震反应计算问题。     

新型型钢-混凝土组合柱恢复力模型研究

提出一种新型型钢-混凝土组合柱,并对其进行数值模拟分析,研究翼缘厚度、钢管径厚比、轴压比、混凝土强度等参数对该组合柱抗震性能的影响。将新型型钢-混凝土组合柱截面进行合理简化,基于平截面假定建立组合柱正截面承载力计算公式,通过对比试验与模拟数据,发现公式计算结果具有较高精度。进一步提出组合柱截面屈服点、峰值点、破坏点、加载刚度、卸载刚度等特征参数的计算方法,确定恢复力模型的滞回规则,最终建立基于退化三线型模型的新型型钢-混凝土组合柱恢复力模型。将公式计算得到的滞回曲线与试验得到的滞回曲线进行对比,发现二者吻合较好。     

Influence of soil to structure stiffness on the accuracy of the pushover method for underground structures

The pushover method for underground structures is a seismic analysis method featured by high calculation accuracy and a simple implementation process. The method has been widely used in seismic design and other related scientific research; however, the influence of different soil-structure flexibility ratios on the accuracy of this method is still not well understood. In this study, we select the cross-section structures beneath the Daikai subway station as the research object and establish 12 finite element analysis models with different soil-structure flexibility ratios using ABAQUS. All models are computed by the dynamic time-history method or the pushover method. Furthermore, the dynamic time-history solution result is taken as the standard solution, and the precision and application of the pushover analysis method are discussed based on the parameters of peak interlayer displacement and peak internal force of the middle column section. The results show that the soil-structure flexibility ratio has a significant influence on the calculation accuracy of the pushover method, and the calculation accuracy of this method is the most ideal when the soil-structure flexibility is equal to 1. The research results can provide significant references for the seismic design of underground structures or the improvement of simplified seismic analysis methods.     

埋深对地铁车站地震反应的影响分析

关于埋深对地下结构地震反应的影响的研究对象多见于地下隧道,对地铁车站地震反应受埋深影响变化规律缺乏深入研究。本文基于ANSYS有限元软件,采用改进的简化方法建立三种不同埋深的地铁车站结构有限元模型,以两种基岩波的水平向和竖向地震动作为激励,求解各模型中地铁车站结构重要部位的地震反应。分析不同埋深时地铁车站结构惯性作用、侧面土体和上部土体三个因素对地铁车站地震反应的影响情况。分析结果表明:在双向地震作用下,地铁车站侧壁弯矩、剪力、轴力和中柱轴力随埋深的增加而增加,中柱剪力和弯矩随埋深增加而减少。埋深越深,侧面土体对地铁车站地震反应影响越大;上部土体使中柱轴力不断增加;结构自身的惯性作用对其地震反应的贡献逐渐减小。     

四种地下结构抗震设计简化分析方法对比

在地下结构抗震设计简化分析方法中,强制反应位移法将土层变形施加在有限元模型侧边界模拟地震作用,反应加速度法将土层加速度施加到整个有限元模型上模拟地震作用,此外还有仅将土层加速度施加到土层模型上模拟地震作用的方法。上述方法均规避了反应位移法中关于弹簧刚度的取值问题,提高了计算效率。本文以1个双跨箱形结构为例,用动力时程分析的计算结果作为校核,分析了强制反应位移法、反应加速度法和仅将土层加速度施加到土体中的简化分析方法在不同侧边距条件下的计算精度,再结合常用的反应位移法,对比分析了4种简化分析方法的误差。分析结果表明:使用强制反应位移法时,侧边距取为1倍结构宽度导致的误差最小,反应加速度法和仅在土体施加加速度的简化方法对侧边距取值不敏感,反应位移法在角点造成的误差最大。     

地下结构抗震理论分析与试验研究的发展展望

目前我国在地下结构抗震分析与破坏灾变机理研究中尚存在诸多问题需要解决,在分析总结我国地下结构抗震理论与试验研究的基础上,重点阐述了需要进一步深入研究的六个关键问题:地下结构振动模型试验研究技术,土体非线性动力本构模型,高轴压的地下结构承重构件地震破坏机理,非一致波动输入及非一致波动输入下地下结构的地震反应,饱和砂土液化大变形理论及本构模型,大型三维非线性土-结构动力相互作用分析模型。这些问题的研究和解决对于完善地下结构抗震理论分析方法与试验研究技术,获得大型地下结构在地震作用下的反应规律与破坏灾变机理具有重要的科学意义和工程应用价值。     

水下长大沉管隧道抗震性能及减震措施研究进展

沉管隧道抗震性能研究是目前地下工程防灾减灾领域重要的研究方向之一,同时也是该领域亟需解决的难题。在总结了隧道震害特点的基础上,全面系统地阐述了原型观测、模型试验、理论分析三种沉管隧道地震响应计算的分析方法及最新研究进展。基于这些方法,进一步介绍了质点-弹簧模型、梁-弹簧模型、多体动力学模型三种水下长大沉管隧道纵向抗震简化模型,并分析模型对应的特点及力学原理,最后简要地总结了沉管隧道的减震措施。一定程度上可以反映出国内外沉管隧道地震响应分析以及减震控制研究目前的发展阶段,并通过这些最新的研究成果提出了进一步的展望。     

Assessment of the vertical distribution on seismic ground motion

It is very important for the facilities such as nuclear power plants to infer seismic force loading on the earthquake stability assessment of the building foundation and the surrounding slope. The purpose of this paper was to propose a method to evaluate underground seismic coefficients, taking into account dynamic response along the depth in horizontally multi-layered ground. The dynamic property of the seismic coefficient was analyzed on the basis of earthquake records observed at hard and soft rock sites mostly found in Tertiary deposits and sedimentary ground sites of the Pleistocene and Holocene epoch. The evaluation methods of a vertical distribution on underground seismic coefficients were proposed for a few calculation methods on the classified layered ground. Extended evaluation for underground seismic coefficients was confirmed with respect to some multi-layered ground during strong motion.     

黄土地区地铁地下结构抗震研究综述

介绍了地铁地下结构抗震研究的发展历史、研究现状及黄土地区地铁地下结构抗震的相关研究,总结归纳出地震作用下地铁地下结构的地震破坏形式与地震反应特征;对地铁地下结构的不同抗震研究方法进行对比研究,指出各种研究方法的优缺点与适用情况。针对我国黄土地区地铁地下结构抗震分析理论研究不足,基础资料积累欠缺,抗震设计尚无可靠依据的实际情况,探讨了黄土动力本构模型、黄土与结构动力相互作用、离心机振动台试验研究及抗震分析方法等因素对黄土地区地铁地下结构抗震研究可靠性的影响,提出黄土地区地铁地下结构地震动力反应分析、地震破坏机理分析、抗震性能分析及抗震设计中需要深入研究的关键问题。     

地下结构地震反应规范计算方法的对比分析

随着地下空间大规模开发利用,地震灾害对其造成的潜在威胁不容忽视。基于《城市轨道交通结构抗震设计规范(GB50909-2014)》和《地下铁道建筑结构抗震设计规范(DG/TJ08-2064-2009)》建议的分析方法,选取惯性力法、反应位移法(国家规范法、上海规范法)、动力时程方法(线弹性方法、等效线性化方法)三类共5种计算方法,以典型两层双柱三跨地铁车站结构为分析对象进行地震反应的对比验算,对上述计算方法的适应性进行评价。分析结果表明,与动力时程方法相比较,惯性力法计算得到的侧墙剪力值偏大,中柱结果较为接近;对于反应位移法,国家规范方法和上海规范方法的计算模型略有不同,但两者计算结果基本相近,其中土体强制位移、集中地基弹簧、土体动剪切模量等参数取值对计算结果影响显著;对于动力时程方法,线弹性方法和等效线性化方法的结果较为接近,且变化趋势相同。     

An improved pseudo-static method for seismic resistant design of underground structures

This paper describes a commonly used pseudo-static method in seismic resistant design of the cross section of underground structures. Based on dynamic theory and the vibration characteristics of underground structures, the sources of errors when using this method are analyzed. The traditional seismic motion loading approach is replaced by a method in which a one-dimensional soil layer response stress is differentiated and then converted into seismic live loads. To validate the improved method, a comparison of analytical results is conducted for internal forces under earthquake shaking of a typical shallow embedded box-shaped subway station structure using four methods： the response displacement method, finite element response acceleration method, the finite element dynamic analysis method and the improved pseudo-static calculation method. It is shown that the improved finite element pseudo-static method proposed in this paper provides an effective tool for the seismic design of underground structures. The evaluation yields results close to those obtained by the finite element dynamic analysis method, and shows that the improved finite element pseudo-static method provides a higher degree of precision.     

考虑结构-土-结构相互作用的区域建筑群震害评估

建筑群震害评估计算对城市区域地震损失评估和震后快速援助救灾有着重要意义。考虑到地震中建筑物相互作用对震害的影响,进行考虑结构间相互作用的区域建筑群震害评估计算。在已有的基于结构—土—结构动力相互作用(SSSI)分析的简化离散模型基础上,扣除基础转动对输出响应的影响,引入基础上部建筑结构非线性多自由度模型,得到考虑SSSI的简化的非线性多自由度离散模型,建立考虑SSSI的区域建筑群震害评估方法。以四川大学望江校区的建筑群在汶川地震中的震害评估为例,采用该方法对该校区建筑群在汶川地震中的震害进行评估计算。同时,也对未考虑SSSI情况下的该校区建筑群震害进行计算。运用HAZUS对建筑群在汶川地震中的震害进行计算。通过对比分析实际震害调查数据、HAZUS震害计算结果和本文建筑群震害计算结果可知,相比HAZUS震害计算结果,本文建筑群震害计算结果更接近实际震害调查数据;与未考虑SSSI的建筑群震害计算结果相比,考虑SSSI的建筑群震害计算结果精确度更高,更能反映建筑群的实际震害情况。     

火灾下约束钢柱临界温度的简化计算方法

在火灾条件下,约束钢柱轴力由于升温而增加,会导致在较低的温度下发生屈曲;但屈曲后,钢柱的轴向温度膨胀得到释放,轴力下降,因此屈曲后钢柱仍能继续承栽。本文通过计算长度系数将转动约束钢柱转换为铰支钢柱,给出了一种轴向约束钢柱在火灾升温条件下的临界温度的简化计算方法——轴力放大系数设计方法。此法通过轴力放大系数将轴向约束钢柱转化为无约束钢柱,再按无约束钢柱计算得到钢柱的临界温度。用验证过的有限元模型对简化计算方法进行了验证,计算结果表明简化方法吻合较好。     

A comparative analysis of seismic response of shallow buried underground structure under incident P,SV and Rayleigh waves

In this study, A time-domain seismic response analysis method and a calculation model of the underground structure that can realize the input of seismic P, SV and Rayleigh waves are established, based on the viscoelastic artificial boundary elements and the boundary substructure method for seismic wave input. After verifying the calculation accuracy, a comparative study on seismic response of a shallow-buried, double-deck, double-span subway station structure under incident P, SV and Rayleigh waves is conducted. The research results show that there are certain differences in the cross-sectional internal force distribution characteristics of underground structures under different types of seismic waves. The research results show that there are certain differences in the internal force distribution characteristics of underground structures under different types of seismic waves. At the bottom of the side wall, the top and bottom of the center pillar of the underground structure, the section bending moments of the underground structure under the incidences of SV wave and Rayleigh wave are relatively close, and are significantly larger than the calculation result under the incidence of P wave. At the center of the side wall and the top floor of the structure, the peak value of the cross-sectional internal force under the incident Rayleigh wave is larger than the calculation result under SV wave. In addition, the floor of the underground structure under Rayleigh waves vibrates in both the horizontal and vertical directions, and the magnification effect in the vertical direction is more significant. Considering that the current seismic research of underground structures mainly considers the effect of body waves such as the shear waves, sufficient attention should be paid to the incidence of Rayleigh waves in the future seismic design of shallow underground structures.     

地下结构强制反应位移法和反应加速度法的对比分析

首先基于地震作用下地下结构的变形受周围地基土变形控制这一相互作用特征,在反应位移法的基础上讨论两种简化分析方法:一种是将土层变形施加在模型边界模拟地震作用;另一种是将土层加速度施加到整个模型上模拟地震作用。这两种简化分析方法都避免了反应位移法中弹簧刚度的取值问题,提高了计算效率。其次分析不同地震动强度、不同侧边距的计算结果,并用动力时程分析的计算结果校核,分析两种简化计算方法的精度。结果表明:随着地震动强度的增加两种简化分析方法的计算结果都令人满意,使用强制反应位移法时建议侧边距取两倍结构宽度,使用反应加速度法时建议侧边距取三倍以上结构宽度。     

A centrifuge study of the influence of site response,relative stiffness,and kinematic constraints on the seismic performance of buried reservoir structures

The seismic performance of underground reservoir structures depends on the properties of the structure, soil, and ground motion as well as the kinematic constraints imposed on the structure. A series of four centrifuge experiments were performed to evaluate the influence of site response, structural stiffness, base fixity, and excitation frequency on the performance of relatively stiff reservoir structures buried in dry, medium-dense sand. The magnitude of seismic thrust increased and the distribution of seismic earth pressures changed from approximately triangular to parabolic with increasing structural stiffness. Heavier and stiffer structures also experienced increased rocking and reduced flexural deflection. Fixing the base of the structure amplified the magnitude of acceleration, seismic earth pressure, and bending strain compared to tests where the structure was free to translate laterally, settle, or rotate atop a soil layer. The frequency content of transient tilt, acceleration, dynamic thrust, and bending strain measured on the structure was strongly influenced by that of the base motion and site response, but was unaffected by the fundamental frequency of the buried structure (f_structure). None of the available simplified procedures could capture the distribution and magnitude of seismic earth pressures experienced by this class of underground structures. The insight from this experimental study is aimed to help validate analytical and numerical methods used in the seismic design of reservoir structures.     

Cyclic Displacement Model for Reinforced Concrete Columns

Reinforced concrete (RC) structures in low to moderate seismic regions and many older RC structures in high seismic regions include columns with steel reinforcement details not meeting the requirements of modern seismic design codes. These columns typically fail in shear or in a brittle manner and their behavior must be accurately captured when RC structures are modeled and analyzed. The total lateral displacement of a low ductility or shear critical RC column can be represented as the sum of three displacement components: (1) flexural displacement, (2) displacement due to slippage of the reinforcing bars at column ends, and (3) shear displacement. In this study, these three displacement components are separately modeled and then combined together following a proposed procedure based on the expected overall behavior of the column and its failure mechanism. A simplified slip model is proposed. The main objective of this research is to develop an easy-to-apply method to model and capture the cyclic behavior of RC columns considering the shear failure mechanism. The proposed model is validated using the available data from RC column and frame experiments.     

扭转不规则结构水平侧向力分布模式与pushover分析

水平侧向力分布模式的施加问题是合理进行pushover分析的关键环节。对于可以简化为平面模型的结构,传统的水平侧向力分布模式表现出较好的适用性,但对于因扭转不规则而导致必须采用空间模型的结构则并不适用。为此,针对扭转不规则结构的水平侧向力分布模式问题,并基于该类结构的地震响应特征,通过引入水平侧向力调整系数和水平侧向力分配系数,提出了扭转不规则结构改进的水平侧向力分布模式。对一具有典型扭转不规则特性的空间钢框架结构分别进行改进分布模式下的pushover分析和IV类场地典型地震动作用下的弹塑性时程分析,计算结果显示:改进分布模式下的pushover分析体现出扭转效应对结构反应的影响,并在一定程度上反映出更多的结构抗震信息,验证了所提出模式的可行性,说明pushover分析法也同样适用于扭转不规则结构。