低周往复荷载作用下生态复合墙体抗震性能研究

通过对2榀1/2比例生态复合墙体(施工工艺:装配式、现砌式)模型在水平低周反复荷载作用下的抗震性能试验,研究复合墙体在低周反复荷载作用下的受力特点和破坏机制,对比分析其承载力、滞回特性、延性、刚度退化、耗能等抗震性能.试验结果表明:不同施工工艺下生态复合墙体破坏模式均为“砌块-(框格)-边框”,实现结构具有多道抗震防线的设计概念;2榀墙体从屈服到破坏,等效黏滞阻尼系数均有较明显的增大,都具有较强的耗能能力.抗倒塌能力较强,可根据不同地区差异选取适当的工艺来满足实际应用的需求.     

边坡动力响应的非线性特征分析

以节理岩质边坡作为研究对象,采用离散单元法,分析了边坡在地震作用下的变形特征,根据边坡演化过程中所表现出的非线性特征,应用相空间重构理论证明边坡的演化过程是混沌序列,边坡动力失稳过程包含2次分岔,边坡失稳的本质是分岔.     

RC剪力墙结构小震与中震设计对比及其抗震性能研究

近年来,国内学者强调对于复杂和超限结构需进行中震性能设计,即在小震弹性设计后进行中震下的承载力复核及调整,然而中震设计能否提高结构整体抗震性能仍存在争议.为探究中震设计与小震设计方法的差异,本文依据现行规范,以设防烈度、结构高度和场地类别为变化参数,建立了48个典型RC剪力墙模型,并分别以"小震"、"高规中震"、"广东...     

竖向地震荷载下人字批顶结构石窟的稳定性分析

我国部分石窟的空间建造采用了人字批顶形式,体现了中国传统建筑形式与佛教石窟建造形式上的融合.选取莫高窟典型的人字批顶结构的254号石窟作为研究对象,建立了三维的石窟计算模型,考虑了竖向地震荷载作用,通过输入不同地震加速度时程,计算了4种模型情况下石窟岩体的拉应力分布情况.结果表明,石窟的人字批顶处易形成较大拉应力区,易遭受地震破坏;石窟中心塔柱可以有效地提高所在石窟岩体的抗震能力,但对下部窟体的上部岩体会产生应力集中,是窟体防护加固的重点部位.同时,对于洞窟密集而又分上下几层的石窟群,在抗震防护中应充分考虑竖向地震荷载的作用.     

Nonlinear response of single piles under lateral inertial and seismic loads

A macroscopic model that consists of distributed hysteretic springs and frequency dependent -pots is utilized to model the lateral soil reaction and a practical method based on one-dimensional finite element formulation is developed to compute the nonlinear response of single piles under dynamic lateral loads. The model is physically motivated, adequate for cohesive and cohesionless soils, and involves standard geotechnical parameters. Only two parameters have to be calibrated by fitting experimental data. Hysteretic and radiation damping are modeled realistically within the practical range of amplitudes and frequencies. The model is calibrated and validated against five well instrumented full-scale experiments and typical values for the range of the model-parameters are provided. Subsequently, the developed model is utilized to study the nonlinear seismic response of single piles. Finally, the developed method and the calibrated model are used to predict the inertial and seismic response of one of the piles used in the foundation of the Ohba bridge near Tokyo, Japan.     

地震荷载作用下黄土地基震陷研究

在某大型企业的地震安全性评价工作中,采用随机地震荷载输入动三轴进行了黄土震陷试验,探讨了该场地黄土在不同动荷载作用下的震陷特性。并对该场地地基未来可能发生的震陷灾害进行了评价,为工程地基抗震处理提供了依据。     

Modelling of shear keys in bridge structures under seismic loads

Shear keys are used in the bridge abutments and piers to provide transverse restraints for bridge superstructures. Owing to the relatively small dimensions compared to the main bridge components (girders, piers, abutments, piles), shear keys are normally regarded as secondary component of a bridge structure, and their influences on bridge seismic responses are normally neglected. In reality, shear keys are designed to restrain the lateral displacements of bridge girders, which will affect the transverse response of the bridge deck, thus influence the overall structural responses. To study the influences of shear keys on bridge responses to seismic ground excitations, this paper performs numerical simulations of the seismic responses of a two-span simply-supported bridge model without or with shear keys in the abutments and the central pier. A detailed 3D finite element (FE) model is developed by using the explicit FE code LS-DYNA. The bridge components including bridge girders, piers, abutments, bearings, shear keys and reinforcement bars are included in the model. The non-linear material behaviour including the strain rate effects of concrete and steel rebar are considered. The seismic responses of bridge structures without and with shear keys subjected to bi-axial spatially varying horizontal ground motions are calculated and compared. The failure mode and damage mechanism of shear keys are discussed in detail. Numerical results show that shear keys restrain transverse movements of bridge decks, which influence the torsional–lateral responses of the decks under bi-axial spatially varying ground excitations; neglecting shear keys in bridge response analysis may lead to inaccurate predictions of seismic responses of bridge structures.     

夯土墙在单调和反复水平荷载下的试验研究

通过对不同类型的夯土墙在单调荷载和反复荷载作用下的试验研究,分析了不同添加材料对夯土墙抗剪性能、抗震性能的影响,得到了夯土墙的裂缝开展规律、破坏特征、承载能力、延性及滞回性能。借用砌体结构的抗震承载力计算公式,给出了夯土墙抗剪、抗震计算的简化公式。     

钢-混凝土组合剪力墙抗震研究与发展

剪力墙是高层建筑抗震的主要抗侧力体系,随着大型复杂高层建筑的快速发展,对剪力墙抗震性能的要求也越来越高,钢-混凝土组合剪力墙就是一种抗震性能好的剪力墙。国内外在钢-混凝土组合剪力墙抗震研究方面,从抗震性能到设计方法和工程应用都取得了较快的发展。本文介绍了国内外有关钢-混凝土组合剪力墙抗震研究的部分成果,同时介绍了笔者提出的钢-混凝土多重组合剪力墙及其抗震研究情况,包括工程应用情况。已有研究表明:钢-混凝土组合剪力墙特别是钢-混凝土多重组合剪力墙,具有良好的抗震屈服机制和多道抗震防线,抗震耗能能力强,工程应用价值较大。     

水平荷载作用下密肋复合墙结构的变形计算

密肋复合墙结构是近年来应用在住宅领域中的一种新型建筑结构体系,目前关于地震作用下密肋复合墙结构的变形计算方法尚不完善,采用等效剪力墙结构模型不能同时考虑密肋墙的有效弹性模量和有效面内剪切模量,导致等效模型在水平荷载作用下的变形与实际结构存在一定误差.在试验研究基础上,依据铁木辛柯剪切梁理论并考虑密肋墙体弹性常数取值和构造特点,建立了包含剪切变形在内的密肋复合墙侧移曲线方程;同匀质混凝土墙侧移方程相比,密肋墙侧移方程中的弹性常数是与墙体构造有关的变参数表达式.算例分析表明,等效混凝土墙结构模型的侧移变形计算结果较实际结构偏小,在中高层结构中表现尤为明显,可能引起不可忽略的误差而导致结构存在安全隐患;建议对等效混凝土墙模型的侧移变形结果进行修正,给出了初步的修正系数供工程设计参考.     

Topology optimization of shear wall structures under seismic loading

A topology optimization formulation is developed to find the stiffest structure with desirable material distribution subjected to seismic loads. Finite element models of the structures are generated and the optimality criteria method is modified using a simple penalty approach and introducing fictitious strain energy to simultaneously consider both material volume and displacement constraints. Different types of shear walls with/without opening are investigated. Additionally, the effects of shear wall-frame interaction for single and coupled shear walls are studied. Gravity and seismic loads are applied to the shear walls so that the definitions provide a practical approach for locating the critical parts of these structures. The results suggest new viewpoints for architectural and structural engineering for placement of openings.     

石材幕墙结构抗震性能试验研究

为研究石材幕墙的抗震性能和破坏特征,以阿尔及利亚大清真寺南区石材幕墙工程为背景,设计了两组1:1振动台试验模型,通过振动台试验研究总结出了石材幕墙结构的地震响应特性,在此基础上,给出了石材幕墙结构动力特性简化模型,并通过引入相应的质量修正系数,得到震损石材幕墙结构自振频率计算公式。研究表明:结构自振频率在挂件和石材出现松动与损伤后逐渐降低;石材加速度响应受挂件位置和尺寸影响较大;石材与挂件之间的间隙增大了石材的加速度响应,但同时也减小了挂件的内力需求。     

On time-domain uncoupled analyses for offshore wind turbines under seismic loads

For seismic assessment of wind turbines in seismically-active areas, International Standards and Guidelines allow the combination of two uncoupled analyses under environmental and earthquake loads, respectively. The separate earthquake response is generally computed including an additional aerodynamic damping in the structural model. Although some work has been done to estimate the effectiveness of uncoupled analyses for land-based wind turbines, and determine appropriate levels of aerodynamic damping, to date no similar studies have been carried out for offshore wind turbines. This paper assesses the accuracy of different time-domain implementations of uncoupled analyses for offshore wind turbines, and investigates pertinent levels of aerodynamic damping. The case study is a 5-MW wind turbine, resting on a tripod in intermediate waters.     

Earthquake damage potential and critical scour depth of bridges exposed to flood and seismic hazards under lateral seismic loads

Many bridges located in seismic hazard regions suffer from serious foundation exposure caused by riverbed scour. Loss of surrounding soil significantly reduces the lateral strength of pile foundations. When the scour depth exceeds a critical level, the strength of the foundation is insufficient to withstand the imposed seismic demand, which induces the potential for unacceptable damage to the piles during an earthquake. This paper presents an analytical approach to assess the earthquake damage potential of bridges with foundation exposure and identify the critical scour depth that causes the seismic performance of a bridge to differ from the original design. The approach employs the well-accepted response spectrum analysis method to determine the maximum seismic response of a bridge. The damage potential of a bridge is assessed by comparing the imposed seismic demand with the strengths of the column and the foundation. The versatility of the analytical approach is illustrated with a numerical example and verified by the nonlinear finite element analysis. The analytical approach is also demonstrated to successfully determine the critical scour depth. Results highlight that relatively shallow scour depths can cause foundation damage during an earthquake, even for bridges designed to provide satisfactory seismic performance.     

改善钢筋混凝土低矮剪力墙抗震性能的研究

普通钢筋混凝土低矮剪力墙抗震性能较差，其抗震性能的改善一直受到工程界的关注。总结了一些改善低矮剪力墙抗震性能的国内外研究成果，包括：开缝低矮剪力墙、带暗支撑低矮剪力墙、设耗能装置的低矮剪力墙和低矮组合剪力墙等。在此基础上，提出了一种新型耗能剪力墙，并进行了初步的试验研究。     

Response of reinforced mortar-less interlocking brick wall under seismic loading

Bulletin of Earthquake Engineering - Mortar-less construction with interlocking bricks has many advantages, such as improved construction efficiency and relatively low requirements on labour...     

钢筋混凝土短肢剪力墙抗震性能试验研究

通过6片1：2单层短肢墙试体的低周反复荷戴试验,研究了在低周反复荷载作用下钢筋混凝土短肢剪力墙的整体工作性能、破坏形态及滞回特性。结果表明：试件的最终破坏均是由连梁失效引起的,连梁是短肢剪力墙结构的薄弱环节,因此,连梁的混凝土强度不应低于墙肢的混凝土强度,以免连梁出现粘结破坏;有翼墙的短肢剪力墙试体其延性系数都达到了3．5以上．其耗能能力较无翼墙短肢墙好。     

钢筋混凝土核心筒性态水平及性能指标限值研究

结合国内外对钢筋混凝土结构性能水平的划分标准并根据核心筒结构破坏特征及抗震性能要求,文中在现行规范基础上进一步细分,将钢筋混凝土核心筒结构的性能水准划分为良好使用、暂时使用、生命安全和接近倒塌4个水平;基于混凝土连梁及剪力墙构件的受力、变形及破坏特点,分别提出了连梁及剪力墙构件对应于4个性能水平的失效判别标准和变形限值...     

强震作用下框架支撑结构的破坏机构及其极限荷载

针对单层框－桁结构体系,运用结构塑性极限分析原理给出了在罕遇地震作用下可能出现的破坏机构及相应的极限荷载半解析解。通过比较分析,得出最可能出现的几种破坏机构,从而可求出最小的破坏地震作用。     

Seismic performance of eccentrically-compressed steel pier under multi-directional earthquake loads

In this article, the seismic performance of box-shaped steel piers embedded with energy-dissipating shells under a multi-directional seismic load is investigated. A finite element(FE) model was accurately established and verified by the quasi-static test results. A parametric analysis of the hysteretic behaviour of a novel box-shaped steel pier under eccentric pressure was carried out on this basis. We discussed the influence of the eccentricity, axial compression ratio, thickness of embedded shell, ratio of slenderness, spacing of transverse stiffening ribs on the embedded shell, and width-to-thickness ratio of wallboard on the anti-seismic performance of a novel box-shaped steel bridge pier. The results revealed that the load carrying capacity and ductility coefficient of the specimen are substantially influenced by the eccentricity, variation in the axial compression ratio, and slenderness ratio. The specimen′s plastic energy dissipation capacity can be effectively improved by increasing the thickness of the embedded shell. The spacing of the transverse stiffening ribs only marginally affects seismic performance. In addition, the width-to-thickness ratio of the wallboard exerts a more considerable influence on the deformability of the square-section specimen. Finally, a formula for calculating the bearing capacity of the novel box-shaped steel piers under cyclic loading is proposed.