高层中间层隔震结构的非线性动力分析

采用时程分析方法,分析高层隔震结构在罕遇地震作用下的响应.主要包括结构的塑性变形和塑性发展情况,结构的层问位移及楼层加速度响应.结果表明,在罕遇地震作用下,隔震结构进入塑性的程度较轻,震后稍加修复即可继续使用.塑性铰最先出现在结构底部,逐渐向上层开展.塑性铰均产生在梁端,柱端始终未出铰.楼层位移主要集中在隔震曾层,但上...     

大型全回转浮式起重机平衡系统优化数学模型

针对大型全回转浮式起重机的结构和工况特点,在满足抗倾覆稳定性要求下,将浮式起重机自重产生的不平衡力矩与起升货物产生的不平衡力矩之和的均方根力矩作为目标函数值,建立以平衡系统主要构件强度、刚度、结构尺寸和回转轮压合理性为约束条件的多目标设计优化数学模型,运用遗传算法优化浮式起重机平衡系统,最终得出优化数据.该数学模型在具体优化过程中取得较为满意的优化结果,为大型全回转浮式起重机的设计优化提供有效方法.     

双单体组合隔震结构振动随机最优控制

用作动器将相距很近的两结构连为一体,并对其中一个结构施加隔震,形成一种新的结构体系—组合隔震结构体系.推导了其振动及控制方程,假定地震动输入为白噪声,运用随机最优控制原理,分析研究了组合结构振动控制性能及隔震度、阻尼及场地等参数的影响.研究结果表明:经过优化控制参数,组合隔震结构振动控制体系能对结构地震响应进行有效控制,并且控制成本降低.     

基于性能需求的基础隔震结构附加调谐惯容阻尼器的优化设计研究

为了克服调谐质量阻尼器(Tuned Mass Damper,TMD)质量过大的缺陷,用惯容器(Inerter)代替TMD中的质量块,形成调谐惯容阻尼器(Tuned Inerter Damper,TID).将TID附加在基础隔震结构的隔震层,对TID进行优化设计研究.以两自由度基础隔震结构体系的简化模型为研究对象,以白噪声激励下的振动响应为指标对TID进行参数研究,确定了一种以隔震层水平位移控制为约束、以最小上部结构绝对加速度为优化目标的优化问题,在两种控制准则下对TID进行优化设计,与仅附加线性粘滞阻尼器(Linear Viscous Damper,LVD)的基础隔震结构进行比较,最终发现TID对基础隔震结构的性能控制有着良好的效果,能同时降低隔震层水平位移和上部结构绝对加速度,并且效果优于LVD.     

风载下高压直流巡检机器人磁力矩平衡方法

针对高压直流巡检机器人在高空作业过程中易受风载影响,导致机身稳定性差和作业安全性低的难题,提出了一种基于高压直流磁场的磁力矩平衡方法:利用载流线圈在高压直流磁场中产生的安培力力矩与风载荷力矩的抵消实现动态平衡.根据机器人结构和高压直流输电线路周围的磁场特性,建立了磁力矩装置的物理模型,对磁力矩进行了理论计算并分析了风载下机器人所受风力及其影响;基于ANSYS Workbench平台,在风场环境下对机器人所受风力矩进行仿真计算;利用COMSOL软件对磁力矩模型进行仿真分析.通过对两次仿真结果及理论计算值的比较分析,表明模型在设定参数下能产生符合要求的磁力矩.     

智能隔震结构序列最优控制Simulink仿真分析

介绍了现有经典控制算法特点及Simulink S-函数实现主动控制仿真的方法。针对地震引发结构受迫振动最优控制问题,借鉴离散系统最优控制Bellman最优法则,提出了基于全状态反馈的主动序列最优控制律。与现有经典控制算法相比,序列最优控制算法增益矩阵具有时变的特点。通过对五层基础隔震结构地震反应控制仿真分析表明,经典最优控制算法和序列最优控制算法都能有效地减少地震反应,但序列最优控制算法具有较强的抗噪声能力且具有良好的鲁棒性能。     

分离式三维隔震结构与非隔震结构振动台试验对比研究

提出了一种分离式三维隔震结构设计方法,将竖向隔震层和水平隔震层分开布置,实现它们的解耦,进行设计计算时更加方便快捷.根据这种方法制作了一个2层钢框架模型,与非隔震结构模型一同进行振动台试验,对试验结果进行对比分析,试验结果表明分离式三维隔震结构模型加速度反应和层剪力均小于传统结构模型,三维隔震效果良好.     

沉入式大直径圆筒结构倾覆转动点数值分析

针对各种关于沉入式大直径圆筒结构稳定性计算方法的基本假设、分析思路、参数取值和计算结果等存在较大差异的情况,通过ABAQUS模拟其在竖向载荷和水平载荷作用下的倾覆. 该方法由位移变化寻找其倾覆转动点,分析其倾覆转动点随参数变化的规律.数值模拟结果与解析计算结果虽然存在约±20%的误差,但是数值解与解析解关于转动点位移随圆筒各参数变化的规律表现一致,有助于沉入式大直径圆筒结构的倾覆稳定性分析.     

工业机器人联合式支承回转装置的结构及设计

本文论述用于工业机器人的支承回转装置的联合式结构及计算方法。这种结构的特点是既保障了静态时的支承精度,又能承受得住动态时的倾覆弯曲力矩和轴向力,并且还具有一定的经济性。这为高速重负载的工业机器人的支承回转装置提供了一种新的结构形式。     

震后火灾下钢筋混凝土结构性能的研究进展

地震引发的火灾对于建筑结构是一种极大的危害,那是因为结构会在地震中受到损伤,而这种损伤将会改变结构原有的抗火性能,这要比没有损伤的结构更容易受到火灾的威胁,一旦火灾次生极可能导致受损结构的迅速倒塌,后果将不堪设想。然而在建筑结构的设计中还没有充分考虑这一点,因此,对震后损伤下的钢筋混土结构进行分析并研究其抗火性能是很有必要的。将对国内外研究钢筋混凝土结构在震后火灾下的文献进行分析与归纳,总结地震对哪些结构构件的损伤较大及其损伤程度;火灾对这些构件产生哪些影响,分析最易失效的构件。为今后能够提高结构在震后受损情况下的抗火时间做铺垫,从而延长逃生和救援的宝贵时间。     

An image-based seismic damage assessment system

Surveillance systems are commonly used by command centers to monitor and assess seismic damage inside buildings, such as schools, shopping malls, office buildings and skyscrapers. It is expected that checking camera images manually on monitors can be a very time-consuming and inefficient process, especially for a large surveillance system. One of the alternative ways is to first deploy sensors to monitor objects inside buildings, such as tables, cabinets, bookcases and so on, and, after fusing sensor data, to assess damage. However, deploying sensors can be impractical and costly when there are too many objects needed to be monitored. In this paper, we present IDEAS, an image-based disaster damage assessment system, to evaluate seismic damage inside buildings. IDEAS first compares images taken inside a building before and after an earthquake, it then maps the damage to a Mercalli intensity scale. In order to investigate the effectiveness and accuracy of IDEAS, we collect over forty pairs of closed-circuit television (CCTV) images from Youtube website. Each pair of images represents a real scenario of an earthquake inside a building. Our results show that IDEAS performs better than existing methods and can achieve an average accuracy of 97.6 % in mapping Mercalli intensity scale.     

A spatial panel approach to the statistical assessment of seismic impacts and building damages: Case study of Taichung,Taiwan

A set of seismic-related statistical models is developed, using pseudo-data generated by an earthquake-engineering simulation model. The Peak Ground Acceleration (PGA) is the principal measure of seismic hazard, the Peak Ground Displacement (PGD) represents secondary impacts, and land-use patterns characterize urban vulnerability. A PGA model based on earthquake magnitude, epicenter-to-site distances, and source depth is formulated as a spatial lag panel (SLP) model to account for PGA spatial interactions (neighborhood effects). A PGD spatial lag panel model is also specified to account for soil liquefaction effects. Finally, a model of seismic damages to buildings is formulated, relating monetary damages (loss in property values) to seismic hazards (PGA and PGD) and urban vulnerabilities (residential, commercial, industrial, and facility building stocks). Pseudo-data are generated under 22 simulated historical seismic events for the city of Taichung, Taiwan. These data are then used for model estimation. By combining the three models, monetary damages can be estimated as a function of land-use patterns, PGA, PGD, their neighborhood effects, and other seismic characteristics. These models can therefore provide seismic information for policy making and help in allocating land to new activities while minimizing potential seismic damages.     

Supervised fuzzy logic modeling for building earthquake hazard assessment

Building hazard assessment prior to earthquake occurrence exposes interesting problems especially in earthquake prone areas. Such an assessment provides an early warning system for building owners as well as the local and central administrators about the possible hazards that may occur in the next scenario earthquake event, and hence pre- and post-earthquake preparedness can be arranged according to a systematic program. For such an achievement, it is necessary to have efficient models for the prediction of hazard scale of each building within the study area. Although there are subjective intensity index methods for such evaluations, the objective of this paper is to propose a useful tool through fuzzy logic (FL) to classify the buildings that would be vulnerable to earthquake hazard. The FL is a soft computing intelligent reasoning methodology, which is rapid, simple and easily applicable with logical and rational association between the building-hazard categories and the most effective factors. In this paper, among the most important factors are the story number (building height), story height ratio, cantilever extension ratio, moment of inertia (stiffness), number of frames, column and shear wall area percentages. Their relationships with the five hazard categories are presented through a supervised hazard center classification method. These five categories are “none”, “slight”, “moderate”, “extensive”, and “complete” hazard classes. A new supervised FL classification methodology is proposed similar to the classical fuzzy c-means procedure for the allocation of hazard categories to individual buildings. The application of the methodology is presented for Zeytinburnu quarter of Istanbul City, Turkey. It is observed that out of 747 inventoried buildings 7.6%, 50.0%, 14.6%, 20.1%, and 7.7% are subject to expected earthquake with “none”, “slight”, “moderate”, “extensive”, and “complete” hazard classes, respectively.     

梁柱半刚性连接对钢结构整体抗震性能的影响研究

本文研究空间钢结构力学模型中,梁柱之间纯刚性连接和不同程度的半刚性连接对整体结构抗震性能的影响.以一阶横向振动周期、结构梁柱轴力比和层间位移限角为评价指标,在实测地震波的激励下,采用ANSYS软件分析横向弯曲和轴向扭转刚度对塔形钢结构整体抗震性能的影响.仿真分析表明,横向弯曲刚度对结构抗震性能的影响显著,从而为钢结构建筑的设计和分析提供参考.     

Photo-realistic visualization of seismic dynamic responses of urban building clusters based on oblique aerial photography

Highly realistic visualizations of seismic dynamic responses of building clusters are critical for earthquake safety education. To this end, a photo-realistic visualization method of the seismic dynamic responses of urban building clusters is proposed based on oblique aerial photography. Specifically, a sparsification algorithm of aerial photograph footprints and the model optimization solutions are designed to reduce the size of a city model reconstructed by oblique aerial photography. A building segmentation algorithm based on Boolean operations and building footprints is designed to separate buildings from a reconstructed three-dimensional city model. A visualization algorithm for the seismic dynamic responses of building clusters is designed based on the Callback mechanism, by which the shaking process of building clusters can be realistically displayed according to the results of a city-scale nonlinear time-history analysis. New Beichuan City in China is adopted as a case study to visualize seismic dynamic response. The visualization produced by the proposed method is more realistic than that of the finite element method and can support decision making on earthquake safety actions. The outcome of this study provides well-founded and photo-realistic scenes of the seismic dynamic response of building clusters and has promising application prospects for earthquake safety education.     

Numerical and experimental evaluation of seismic capacity of high-rise steel buildings subjected to long duration earthquakes

Occurrences of large earthquakes having a magnitude larger than eight along subduction zones have been reported worldwide. Due to large number of load reversals the effect of cumulative damage on structural components due to deterioration becomes critical for steel buildings of old construction but may also become critical for buildings designed based on current seismic provisions. A state-of-the-art analytical model that simulates component deterioration and fracture due to low cycle fatigue has been developed and implemented in the OpenSees computational framework. The model serves for seismic evaluation of steel moment frame structures subjected to long duration records. The effectiveness of the numerical model in quantification of the seismic capacity of high rise steel structures is demonstrated through validation with a full scale shaking table test of a high-rise steel building subjected to a long duration record at the world’s largest shaking table facility (E-Defense). Limitations of the proposed numerical model are also discussed.     

Modified-modal-pushover-based seismic optimum design for steel structures considering life-cycle cost

A modified-modal-pushover-based optimization technique is presented to design steel moment resisting frame buildings for minimizing the life-cycle cost based on the framework of performance based earthquake engineering. Modified modal pushover analysis (MMPA) procedure capturing the higher mode effect well is utilized to analyze the inelastic seismic demands of the structures subjected to the considered design earthquakes in terms of the Chinese seismic code for buildings, especially for the medium- to high-rise buildings. Furthermore, the life-cycle cost is formulated as the summation of the initial material cost and the future expected damage loss, which can be stated as a function of seismic performance levels and their corresponding failure probability by means of a statistical model. Meanwhile, the damage loss is explicitly and continuously expressed by the defined interstory drift index using the fuzzy-decision theory. Moreover, the powerful adaptive simulated annealing algorithm is applied to solve the discrete optimization problem due to the discreteness of standard steel sections. Finally, a 9-story planar steel frame is provided to illustrate the effectiveness of the proposed optimization design technique, which achieves not only more cost-effective design but greatly improves the robustness of the optimum design as well.     

Seismic loss assessment for buildings with various-LOD BIM data

Earthquake-induced loss of buildings is a fundamental concern for earthquake-resilient cities. The FEMA P-58 method is a state-of-the-art seismic loss assessment method for buildings. Nevertheless, because the FEMA P-58 method is a refined component-level loss assessment method, it requires highly detailed data as the input. Consequently, the knowledge of building details will affect the seismic loss assessment. In this study, a seismic loss assessment method for buildings combining building information modeling (BIM) with the FEMA P-58 method is proposed. The detailed building data are automatically obtained from the building information model in which the building components may have different levels of development (LODs). The determination of component type and the development of the component vulnerability function when the information is incomplete are proposed. The modeling rules and the information extraction from BIM through the Autodesk Revit application programming interface (API) are also proposed. Finally, to demonstrate the rationality of the proposed method, an office building that is available online is selected, and the seismic loss assessments with various-LOD BIM data are performed as case studies. The results show that, on the one hand, even if the available building information is limited, the proposed method can still produce an acceptable loss assessment; on the other hand, given more information, the accuracy of the assessment can be improved and the uncertainty can be reduced using the proposed method. Consequently, this study provides a useful reference for the automation of the refined seismic loss assessment of buildings.     

Numerical calibration of an easy method for seismic behaviour assessment on large scale of masonry building aggregates

The paper deals with the numerical calibration of a speedy procedure for large scale seismic vulnerability assessment of masonry building aggregates, which are typical building compounds diffused within historical centres of many Italian towns. First of all, based on several numerical analyses developed with the 3MURI calculation program, this simplified assessment procedure has been implemented, it being derived from the well known vulnerability form for masonry buildings integrated by five parameters accounting for the aggregate conditions among adjacent units. Later on, the set-up procedure has been validated through an application to a single building aggregate in the Vesuvius area. Since the results previously achieved have been again confirmed, subsequently the procedure has been used to investigate a wide area of the historical centre of Torre del Greco, allowing for the knowledge of the buildings most at risk under earthquake.Finally, the methodology has been applied to the historical centre of Poggio Picenze (AQ), damaged by the recent Italian earthquake (2009), in order to prove its effectiveness to foresee the damage level experienced by other types of masonry aggregates under seismic actions.