具有两个附着点的塔机结构二阶效应分析

对具有两个附着点的塔机结构二阶效应分析提出了相应的简化计算模型,对该简化模型进行了弹性二阶效应分析并与ANSYS有限元软件分析计算的结果进行了比较。最后对FZQ2000Z型自升式塔机实际结构进行了有限元分析计算,与相应简化模型分析结果进行了对比分析。     

某高层结构抗震超限分析与设计

本文对某高层结构进行了抗震超限分析与设计,针对建筑的不规则情况,采取了相应的抗震计算加强措施。采用振型分解反应谱法对结构进行了分析,用2个软件进行了对比分析,应用弹性动力时程进行了补充校核。针对项目的平面不规则情况,进行了楼板应力分析。     

具有两个附着点的塔机结构二阶效应分析

对具有两个附着点的塔机结构二阶效应分析提出了相应的简化计算模型,对该简化模型进行了弹性二阶效应分析并与ANSYS有限元软件分析计算的结果进行了比较.最后对FZQ2000Z型自升式塔机实际结构进行了有限元分析计算,与相应简化模型分析结果进行了对比分析.     

基于ANSYS的深水桥墩流固耦合分析方法

针对深水桥墩耦合分析的难题,解说了ANSYS中进行耦合分析的基本理论,并结合工程实例,应用命令流方式对耦合分析的过程进行了阐述,该方法为一线技术人员应用ANSYS进行耦合分析提供了技术支持。     

电子设备电磁屏蔽的结构设计

文章首先分析了电子设备屏蔽设计标准,其次,对缝隙电磁屏蔽设计进行了分析,紧接着分析了孔洞的电磁屏蔽设计,最后,对电磁屏蔽仿真技术在机箱结构设计中的应用进行了分析。     

塔式起重机金属结构整体有限元分析

对塔式起重机整体有限元结构分析与评定方法进行了研究,给出了总体分析思路和主要步骤。探讨了有限元模型建立中结构简化、离散及边界条件的施加方法,建立了参数化分析系统,对各功能模块的实现细节进行了讨论。使用建立的分析系统对某塔机进行整体有限元分析,对起重臂的初步设计结构进行了评定。     

探讨建筑门窗气密性能检测技术

本文主要对建筑门窗气密性能检测技术进行了分析,主要分析了气密性能检测的定义、概念及以及相关的分析方式进行了分析。     

武汉市某体育馆钢牛腿的稳定性及应力分析

采用规范法对牛腿的稳定性进行了分析;并用有限元软件对构件进行了应力分析,与实测结果进行了对比。根据分析结果得到了相关结论,可为类似结构的设计提供借鉴。     

ABAQUS在土木工程中的数值分析

介绍了大型有限元软件ABAQUS中钢筋混凝土的本构关系、破坏准则,并对非线性求解过程中影响精度的因素进行了分析。最后,对一钢筋混凝土简支梁进行有限元分析,并将ABAQUS分析值与材料力学计算值进行比较,结果表明利用ABAQUS进行钢筋混凝土结构分析的完全可行。     

桥梁结构分析中的不确定性问题及其研究方法

针对桥梁结构分析中的各种不确定性问题,对其进行了归类分析,给出了目前不确定性分析中的三种方法——随机分析方法、模糊分析方法和区间分析方法;对三种不确定性分析方法在桥梁结构分析中的应用领域进行了综述,并对三种方法的适用情况进行了分析说明。     

Seismic analysis incorporating detailed structure–abutment–foundation interaction for quasi-isolated highway bridges

The Illinois Department of Transportation has adopted an economical and pragmatic methodology for designing earthquake-resistant highway bridges in the Midwestern United States. These so-called quasi-isolated bridges employ low-cost non-seismically designed bearing components as sacrificial structural fuses. During seismic events, fusing actions of these components and subsequent sliding of superstructures on substructures are intended to achieve response characteristics similar to those of conventionally isolated bridges that employ specially designed isolators. This study explores seismic structure-abutment-foundation interaction for quasi-isolated bridges in Illinois, employing a detailed yet efficient non-linear finite-element model for seat-type bridge abutments. The abutment model incorporates many structural components and geotechnical mechanisms that are critical to seismic response of the structure-abutment-foundation (SAF) system. Through non-linear static analyses performed on a complete bridge model, the force-transfer mechanisms, component fusing performance, and potential failure modes of the SAF system were explored. Using earthquake ground motions, non-linear dynamic analyses were conducted to evaluate seismic characteristics of the quasi-isolated bridge, sequences of critical limit state occurrences, and effects of abutment attributes on bridge seismic performance. The influence of abutment model sophistication on simulated bridge response was also highlighted by direct comparison of simulation results obtained from different models.     

斜拉桥动力反应桩基础影响分析

介绍了大跨度斜拉桥动力反应分析时计算模型的建立过程及模拟桩—土相互作用的弹簧刚度的确定方法,结合工程实例对斜拉桥的动力反应中桩基础的影响作了进一步的分析。     

Advanced dynamic finite element analysis of a skew steel railway bridge

The aim of this paper is to present advanced modelling techniques for dynamic analysis of steel railway bridges. Finite element analyses of a case study skew bridge are carried out and the results are compared with available field measurements. Initially, eigenvalue analyses of different models are carried out in order to obtain the fundamental mode shapes and bridge frequencies and to assess the capability of each model to capture the dynamic behaviour of the bridge. Single-span, three-span and full bridge models are investigated with different elements such as shell, beam and combinations of these. A very good agreement between the fundamental dynamic properties of the bridge and empirical results is found. Following the eigenvalue analyses, time history dynamic analyses are carried out using the full bridge model. The analyses are carried out for different train speeds and the strain histories are compared with available field measurements. In terms of fatigue assessment, the mean stress range values obtained from the strain histories at selected locations on the bridge members are also compared to each other. The results show that a full bridge model using a combination of beam and shell elements is a reasonably accurate and computationally efficient way of capturing the dynamic behaviour of a bridge and estimating the mean stress range for fatigue damage calculations.     

Determination of the critical loading conditions for bridges under crossing trains

A procedure based on experimental and theoretical analyses to identify critical loading conditions on existing metallic railway bridges is presented. This method requires knowledge of the principal modal frequencies, and for this reason, a consolidated and simple procedure to study the bridge dynamics is herein explained. This consists of: preliminary studies; material and dynamic tests; and identification techniques to identify modal parameters and eventual non-linear behaviours. Generally the information collected can be used both to calibrate the bridge model and to obtain the refined frequency response function. In order to avoid high computational effort due to long time-history dynamic analyses by using the bridge model subjected to a series of train crossings, a new frequency domain approach for the identification of critical loading conditions is proposed. Evidence of the influence of the axle spacing and velocity of the vehicle on the dynamic magnification due to the train crossing is shown. The method is based on the construction of an excitation spectrum related to the train axle spacing and the velocity, given the weight of the vehicle. Comparison of the excitation spectrum with the frequency response function allows identification of the load patterns that bring the bridge to resonance conditions and might threaten bridge stability, bearing in mind continual changes in train technology.     

斜铁路钢桥的高等动力有限元分析

介绍斜铁路钢桥动态分析的模型。给出一个有限元分析的案例及其与实际测量结果的对比。首先,通过不同模型的特征值分析,得到基础模型选型和桥梁频率,以及评估每个模型分析桥梁动态性能的能力。通过壳单元、梁单元以及组合单元对单跨、三跨和全比例桥梁建模。结果显示,桥梁基本动态特征数值分析结果与试验结果吻合。全比例桥梁模型用于分析特征值和动力时程分析。对不同列车时速和应变记录的分析与实际测量进行比较。疲劳评估通过选取桥梁某一位置的平均应力值也进行了比较研究。结果表明,采用梁单元和壳单元的组合单元的全比例尺模型,可以高效准确地预测桥梁的动力性能和疲劳破坏的平均应力值的范围。     

Influential fluid–structure interaction modelling parameters on the response of bridges vulnerable to coastal storms

Analysis of coastal bridges under hurricane-induced wave and surge loads is essential for safety and performance assessment of water crossing bridge inventories. A reliable numerical model that can be employed to study the behaviour of bridges in hurricane events is beneficial because it reduces the cost and effort required for experimental models. Furthermore, it is important to identify modelling parameters that have a significant effect on the simulated response in order to guide uncertainty treatment for future bridge reliability studies. To address these needs, a high fidelity numerical model for simulation of coastal bridges is utilised that takes into account the fluid–structure interaction and includes contact surfaces that permit deck shifting and unseating during surge and wave passage. After validation of the model with experimental test data, it is implemented to examine the response of a typical water crossing bridge in the Houston area, revealing the values of wave and surge loads and also the potential of deck unseating under extreme wave and surge conditions. A sensitivity study is conducted to determine the uncertain structural modelling parameters that significantly affect the bridge response when subjected to surge and wave. Concrete strength and density, coefficient of friction between super- and substructure and soil shear strength are found to influence the bridge response and should be considered in probabilistic analyses and reliability assessments of coastal bridges.     

悬链线无铰肋拱桥的抗震性能分析

分析各向地震激励作用下无铰石肋拱桥的动力特性,通过工程实例,给出了地震位移响应谱表达式的适用形式,并利用大型通用有限元程序建立了三维空间有限元模型,应用现有的抗震理论,分析了这种情况下的各向地震激励对结构的影响。     

调谐质量阻尼器(TMD)在大跨斜拉桥减震控制中的应用

将调谐质量阻尼器(TMD)运用于润扬北汊斜拉桥地震反应控制。给出了TMD的减震机理及其力学分析模型,建立了TMD-斜拉桥地震反应控制系统的有限元模型,并进行了TMD对斜拉桥减震效果分析。分析发现,TMD使斜拉桥结构的阻尼耗能减少了30%,主梁跨中和端部的横向位移减少了12%,竖向位移减少了24%。结果表明,调谐质量阻尼器能有效的控制大跨斜拉桥在地震作用下的振动。     

Dynamic test and finite element model updating of bridge structures based on ambient vibration

The dynamic characteristics of bridge structures are the basis of structural dynamic response and seismic analysis, and are also an important target of health condition monitoring. In this paper, a three-dimensional finite-element model is first established for a highway bridge over a railroad on No.312 National Highway. Based on design drawings, the dynamic characteristics of the bridge are studied using finite element analysis and ambient vibration measurements. Thus, a set of data is selected based on sensitivity analysis and optimization theory; the finite element model of the bridge is updated. The numerical and experimental results show that the updated method is more simple and effective, the updated finite element model can reflect the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring.     

Finite element model development,validation and probabilistic seismic performance evaluation of Vincent Thomas suspension bridge

Based on recent findings, the main span of the Vincent Thomas suspension bridge crosses directly over the Palos Verdes fault, which has the capacity to produce a devastating earthquake. In spring 2000, the bridge underwent a major retrofit using visco-elastic dampers. This study focuses on seismic vulnerability of the retrofitted bridge. Three-dimensional member-based detailed and panel-based simplified finite element models of the bridge are developed. In order to show the appropriateness of these models, eigenproperties of the bridge are evaluated and compared with the system identification results obtained using ambient vibration data. In addition, a model validation is performed by simulating the dynamic response during the 1994 Northridge earthquake and comparing with the measured response. Finally, considering a set of strong ground motions in the Los Angeles area, nonlinear time history analyses are performed and the ductility demands of critical sections are presented in terms of fragility curves. The study shows that a ground motion with peak ground acceleration of 0.9 g or greater will result in plastic hinge formation at one or more locations with a probability of exceedance of 50%. Also, it is found that the effect of dampers is minimal for low to moderate earthquakes and high for strong earthquakes.