根据“欧洲规范3”对由背板加强的T型螺栓连接的分析

通过背板加强的连接，成本较低且容易施工，其性能与位于拉力区的加劲肋性能一致。目前，在欧洲规范3中，这种加固方式仅用于抵御受力。首先分析了在有限元建模中无钢筋状态下的T型连接，其为弯曲作用下螺栓连接的主要方式。然后，利用多种几何形状的背板对T型连接进行加强，旨在更好地理解背板在性能和机械作用方面对连接件刚度和抗力的贡献。     

Explicit Pseudodynamic Algorithm with Unconditional Stability

An unconditionally stable explicit pseudodynamic algorithm is proposed herein. This pseudodynamic algorithm can be implemented as simply as the very commonly used explicit pseudodynamic algorithms, such as the central difference method and the Newmark explicit method as reported in 1959. Thus, it can be used to perform pseudodynamic tests without using any iterative scheme or extra hardware that is generally needed by the currently available implicit pseudodynamic algorithms. This integration method is second-order accurate and the most promising property of this explicit pseudodynamic algorithm is its unconditional stability. In addition, it possesses much better error propagation properties when compared to the Newmark explicit method and the central difference method.     

Compound-element modeling accounting for semi-rigid connections and member plasticity

A general model of a compound element is proposed in this article to consider the combined influence of semi-rigid connections and plasticity on the non-linear responses of steel frameworks. The stiffness degradation of semi-rigid connections is modeled by a moment–rotation relationship with four parameters, while the plasticity formation of a member end from initial yield to full yield is modeled by an elliptic moment–rotation relationship. The compound element resulting from the combined influence of member plasticity and semi-rigid connection behaviour is used to facilitate the derivation of member stiffness coefficients where the effects of geometrical non-linearity and member shear deformation are also included for the progressive-failure analysis. On the basis of member plasticity behaviour, the categories of semi-rigid connections are investigated. Three semi-rigid steel frameworks are analysed to illustrate the proposed analysis method, and the results are compared with those obtained from experiments and the application of other methods.     

正压冲固海洋平台的地震分析

对正压冲固平台这一新型的浅海海洋平台进行地震计算。将正压冲固基础简化为动刚度一阻尼系统,采用振型叠加和响应谱分析法,并根据《海上固定平台入级与建造规范(1992)》,计算了结构的最大可能位移响应;同时计算了延长六倍桩径后底端固支的模型。计算结果表明,后者由于没有考虑基础的刚度和阻尼特性,偏于保守。     

非线性排气系统波纹管修正模型的模态分析

应用hypermesh建立双层无加强型波纹管非线性接触有限元模型进行静力学分析。试验应力验证了该非线性模型基本可行,但比较仿真刚度与试验刚度、经验公式计算刚度时显示轴向刚度误差较大,主要原因是由于波纹管加工成型后管壁变薄引起的。参考经验公式中修正壁厚的方法,对轴向刚度仿真结果及非线性有限元模型参数进行修正,修正后的仿真结果均满足工程要求。最后应用修正后的波纹管非线性有限元模型进行动态特性分析,结果表明该波纹管怠速工况下不会共振。     

数显式上销簧弹性测量仪设计

目前,机械式弹簧拉压试验机仅能测试上销簧某一点的压力值,无法检测上销簧的弹性系数。为了对上销簧的刚度曲线和阻尼比进行测试,从而对上销簧的技术参数进行改进以获得较好的抗应力松弛特性,研制了数显式上销簧弹性测量仪。介绍了测量仪的机械结构和测控系统,采用Lab VIEW软件,通过计算机对电动位移台进行控制,使用数据采集卡采集上销簧的压缩量和所受力的关系曲线。通过对圆柱螺旋压缩弹簧的检测,验证了本测量仪的准确性和可靠性。利用该测量仪对一组上销簧进行测试,实现了上销簧刚度曲线和阻尼比的检测,取得满意效果,为产品开发人员优化上销簧的设计参数提供科学数据,并能根据需要对系统进行二次开发。     

Fatigue performance of lightweight steel-concrete-steel sandwich systems

This paper investigates the static and fatigue strength behavior of a composite sandwich system, which consists of a lightweight concrete core sandwiched in between two steel plates and interconnected by J-hook connectors. For this purpose, fibre-reinforced lightweight concrete, of density less than 1450 kg/m³, and novel J-hook connectors that are capable of resisting tension and shear have been developed. Fatigue tests were carried out to study the fatigue behaviour of sandwich beams by varying the maximum applied load and load range. It is found that maximum applied load and load range affect fatigue performance independently. The maximum applied load has a significant effect on fatigue performance when the difference between it and the load range is large. Test evidence shows that considering only the load range, without taking into account the maximum applied load, may over-predict the fatigue life of the sandwich structural system. Finally, a three-parameter fatigue design equation, taking into account both the load range and maximum applied load, is proposed based on regression analysis of test data.     

Berechnung einer Kombinierten Pfahl‐Plattengründung am Beispiel des Hochhauses “Skyper” in Frankfurt/Main

Am Bespiel des Hochhauses “Skyper” wurden durch den Unterausschuss “Kombinierte Pfahl‐Platten‐ und Pfahlgruppengründungen” des DIN verschiedene Berechnungsverfahren zur Berechnung einer Kombinierten Pfahl‐Plattengründung angewendet. Die Ergebnisse werden verglichen und diskutiert, wobei sich für den vorliegenden Fall herausstellte, dass sowohl numerische Verfahren als auch vereinfachte Verfahren, die auf der Halbraumtheorie basieren, akzeptable Ergebnisse liefern. Für eine Auswahl der geotechnischen Berechnungsverfahren wurden Federmodelle für die Abbildung der Reaktion der Baugrundoberfläche und der Pfähle abgeleitet und mit Ansatz dieser Federmodelle die Fundamentplatte bemessen. Auf dieser Grundlage gibt der Unterausschuss eine Empfehlung zur Anwendung von Berechnungsverfahren. Calculation of a piled raft foundation as a case study for the high rise building “Skyper” in Frankfurt/Main. Various calculation methods were applied on the piled raft foundation of the high rise building ”Skyper“. The results are compared and discussed. Numerical methods as well as simplified methods based on the elastic half space theory lead in the actual case to reasonable results. With the derived subgrade reaction modulus and pile stiffness the raft reinforcement was computed. A recommendation for the application of numerical and simplified methods is given.     

势能法计算剥落故障齿轮时变啮合刚度

剥落故障发生时,齿轮啮合刚度变化引起的振动响应特征是实现齿轮故障诊断的重要依据。针对剥落故障对轮齿时变啮合刚度的影响,提出将势能法应用于计算剥落故障齿轮时变啮合刚度的模型。分析了故障长宽厚参数对其时变啮合刚度的影响,得出沿轴向的宽度参数对啮合刚度下降影响最为明显,厚度参数影响最小;通过势能法中5要素对比,分析出赫兹刚度和基体柔性变形刚度是影响剥落故障时变啮合刚度的关键因素,为快速求解故障刚度提供新途径。     

水润滑轴承刚度测试中磁力加载激振技术研究

针对水润滑径向轴承刚度测试中加载力和激励力的实现问题,研制了一套电磁径向加载激振装置,并在大长径比水润滑橡胶轴承刚度测试中得到应用。设计并制造了一个八极式电磁加载装置,构成四组电磁铁,通过PID技术实现装置的静态加载、正弦及冲击动态激励功能,并能对转轴实现小角度角位移控制;开发了一套磁力监测软件,试验验证了电磁加载装置的各项功能,将该加载装置安装在单轴承支承的正置式试验台中,识别的水润滑橡胶轴承的刚度值数量级为107N·m-1。结果表明:该磁力装置可实现静态加载以及谐波动态激振功能,此技术可用于水润滑径向轴承刚度测试。