考虑附加质量的旋转柔性梁的随机动力学分析

摘要：研究了带有附加质量的中心刚体-柔性悬臂梁系统在参数具有随机性时作大范围运动的动力响应问题。基于假设模态法和Lagrange方程建立了带有附加质量的中心刚体-柔性悬臂梁系统的一次近似耦合随机动力学方程,利用混沌多项式结合高效回归法将其转化为完全隐式纯微分方程,求解方程得到柔性悬臂梁变形位移响应的数字特征。最后,通过数值仿真对物理参数和几何参数具有随机性的系统进行动力特性研究。仿真结果表明：利用随机参数的动力学模型能客观地反映出系统的动力学行为;部分随机参数的分散性对柔性体动力响应的影响不可忽视。     

随机刚架结构在平稳随机激励下的动力响应分析

文中研究了随机刚架结构的平稳随机响应问题。考虑结构物理参数的随机性，导出了结构在平稳随机激励下位移响应均方值和应力响应均方值的均值、方差和变异系数的计算表达式。通过算例考察了结构物理参数的随机性对结构动力响应均方值随机性的影响，并获得了若干有意义的结论。     

钢筋砼结构非线性随机地震响应分析

考虑地震作用和结构参数的随机性,建立了钢筋砼结构药非线性随机动力学模型。文中导出了随机结构动力分析的非线性随机有限元法的增量列式,并据此对多层钢筋砼结构进行了弹塑性随机地震响应分析。计算结果与该建筑物的实际震害作了对比,效果良好。还讨论了动力模型中随机变量对响应量的影响。     

考虑附加质量的旋转柔性梁的随机动力学分析EI北大核心CSCD

研究了带有附加质量的旋转柔性梁系统在参数具有随机性时的动力响应问题。基于假设模态法和Lagrange方程建立了带有附加质量的柔性悬臂梁系统的一次近似耦合随机动力学方程,利用混沌多项式结合高效回归法将其转化为完全隐式纯微分方程,求解方程得到柔性悬臂梁变形响应的数字特征。最后,通过数值仿真对物理参数和几何参数具有随机性的系统进行动力特性研究。仿真结果表明:利用随机参数的动力学模型能客观地反映出系统的动力学行为;部分随机参数的分散性对柔性体动力响应的影响不可忽视。     

平稳随机激励下线性随机桁架结构动力响应分析

考虑桁架结构的物理参数、几何尺寸的随机性，利用求解随机变量函数矩的方法和求解随机变量数字特征的代数综合法，从结构平稳随机响应在频域上的表达式出发，导出了随机桁架结构在平稳随机激励下位移响应均方值和应力响应均方值的均值、方差和变异系数的计算表达式。通过算例考察了结构物理参数和几何尺寸的随机性对结构位移响应均方值和应力响应均方值随机变量随机性的影响，并获得了一些有意义的结论。     

强风下导线的等效随机静风荷载概率模型

输/配电线路是典型的风振敏感结构，而且导线风荷载往往大于杆塔自身风荷载。结构风荷载常呈现强随机性，合理地考虑这种随机性是输/配电线路抗风设计与风险评估的基础。该文以气弹模型风洞试验为依据，结合随机风振反应基本理论，获得导线等效静风荷载的计算方法；引入强风风场特性参数的随机性，推导并拟合得到导线的等效随机静风荷载概率模型；将建立的随机风荷载概率模型应用于配网结构的可靠度分析中，评估现有配网结构规范设计的可靠度水准。分析结果表明，导线风荷载效应占比大于5%时，按现有配网线路规范设计的构件可靠度指标低于构件呈现二级延性破坏所对应的目标可靠度水平。该文建立的随机风荷载概率模型，考虑了平均风荷载的随机性、脉动风荷载的随机过程性及其对结构的随机动力效应，同时引入了描述脉动风随机过程特性参数的随机性，可应用于强风下输/配电网的抗风设计和风险评估。     

板壳结构的随机有限元分析

本文利用随机有限元法对板壳结构进行弹性静力分析，分析中计及材料性能和几何尺寸的随机性，随机性的表述是利用等参局平均模型，研制了三角形板壳单元的计算机程序，算例显示本文的方法和程序是有效的。     

不确定结构非线性动力分析的增量随机有限元法

针对不确定性结构能力分析中采用线弹性假设的不足。本文提出了预测具有随机参数的非线性结构动力响应的一种数值方法－增量随机有限元方法，可以同时考虑结构参数的随机性和材料非线民生，算例表明，增量随机有限元法可以较地预测随机结构的非线性动力行为。     

基于改进点估计法的随机车桥竖向振动分析

铁路混凝土桥梁在施工制造过程中不可避免会造成结构参数的随机性(如混凝土弹性模量、密度等),列车在运营过程由于旅客及货物的随机性会造成列车车体质量的随机性,这些随机性在列车桥梁随机振动中不可忽略。建立了竖向车桥耦合振动模型,利用基于自适应降阶的改进点估计法及Newmark-β积分法编制了随机车桥竖向振动程序,分析了考虑列车车体质量与桥梁结构参数随机的列车、桥梁随机响应的前四阶中心矩,与Monte Carlo法对比结果表明,改进点估计法能够高效精确地计算车桥耦合随机响应,效率提高了2~3个数量级。在得到相应的前四阶中心矩后,通过立方正态变换技术拟合出响应的概率密度函数,该方法可为列车-桥梁极限状态设计提供参考。     

基于完全概率的随机桁架固有频率的可靠性分析

对随机桁架固有频率的概率密度函数提出了一种求解方法。考虑结构物理参数和几何参数的随机性，通过构建随机参数桁架结构的有限元模型，利用瑞利商公式获得了结构固有频率随机函数的计算表达式，应用随机函数的概率分布函数表达式，通过确定积分区间、变量替换、积分顺序变换等一系列数学上的处理，获得结构固有频率的概率密度函数，进而实现对结构固有频率可靠度的精确计算。箅例的结果与Monte-Carlo模拟法结果比较，表明该方法的正确性和有效性。     

Forensic analysis of buildings affected by mining subsidence

This work presents a forensic analysis of ground subsidence occurred in Lo Tacón industrial area, which is located at the outskirts of La Unión (Murcia, SE Spain). Subsidence was triggered by the collapse of abandoned underground mining labours occurred in 1998. Coinciding in time with this event, it was detected a seismic movement, whose epicentre was located close to the study area.In the first part the affected area is analysed and delimited, as well as the spatial and temporal evolution of the damages attributed to the collapse of 1998. Then the causes of ground failure are also determined, as well as their possible temporal and spatial relationship with the seismic movement detected. Through this analysis it is presented a methodology to determine the effects of this phenomenon. It consists on extending field work radially to all existing buildings within the affected area, considering the centre around the zone where the greatest damage was produced. Finally it is analysed the temporal and spatial evolution of the cracks inventoried in buildings to determine active areas where certain subsidence persists. According to the results presented in this work, it may be concluded that damages are the consequence of buildings constructed in a potentially dangerous area where ground settlement occurs due to mining subsidence.     

抚顺发电厂地面变形现状与预测研究

抚顺发电厂位于抚顺西露天矿北帮、西露天矿北帮地面变形监测网范围内，且为监测的主要部位，该厂的原有历史监测资料，对西露天矿北帮的地面变形预测具有很好的参考价值。本文针对抚顺发电厂的地面变形现状，分析了影响地面变形的因素，并进行数值计算分析及综合研究。厂区的移动与变形受断层的影响与控制，预测厂区未来的最大沉降为1012mm，主厂房的影响最大沉降为413．9mm。并得出预测在近5年内的地面变形要达到最大值的1／2，根据西露天矿的开采计划，预计最终沉降在今后约10年内完成。     

Mechanical failure mechanisms and forms of normal and deformed coal combination containing gas: Model development and analysis

In coal mining, coal seams often contain several normal coal layers and deformed coal layers in the same region. However, the existence of deformed coal may promote the occurrence of coal and gas outbursts. To analyze the role of failure of different combinations of deformed coal on coal and gas outbursts, force analysis of normal and deformed coal combinations containing gas was carried out, and the expressions of interfacial stress induced by uncoordinated horizontal deformation were first derived in this paper. The results showed that the additional interfacial stresses are affected by the external stresses, internal gas pressure, gas sorption-induced swelling deformation and mechanical parameters of coal and that the additional interfacial stresses on the normal coal and deformed coal are equal and opposite. Then, based on the Mohr-Coulomb criterion and uncoordinated deformation, the mechanical failure mechanisms and forms of combinations containing gas under ideal conditions were analyzed. We found that there are seven failure forms for the combination containing gas, and in most cases, the destruction of the combination is caused by the structural failure of deformed coal. Finally, the failure mechanisms of the combination due to mining were discussed using the parameters from the Qinshui Basin. The results showed that failure is more probable at the interface between the deformed coal and normal coal bodies and that the existence of deformed coal can promote the damage of normal coal. These research results can help us to better understand the role of mechanical failure in coal and gas outbursts within combinations, and provide a theoretical basis for the control of coal and gas outbursts.     

Flexural analysis of cross-ply laminated plates subjected to nonlinear thermal and mechanical loadings

The objective of this paper is to present an equivalent single-layer shear deformation theory for evaluation of displacements and stresses of cross-ply laminated plates subjected to uniformly distributed nonlinear thermo-mechanical load. A trigonometric shear deformation theory is used. The in-plane displacement field uses a sinusoidal function in terms of the thickness coordinate to include the shear deformation effect. The theory satisfies the shear stress free boundary conditions on the top and bottom surfaces of the plate. The present theory obviates the need of a shear correction factor. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. Stresses and displacements for orthotropic, two-layer antisymmetric, and three-layer symmetric square cross-ply laminated plates subjected to uniformly distributed nonlinear thermo-mechanical load are obtained. Numerical results of the present theory for displacement and thermal stresses are compared with those of classical, first-order and higher-order shear deformation plate theories.     

隔膜压缩机膜片破裂理论分析

隔膜压缩机膜片裂纹通常产生在支板最外圈环槽边沿及中间处,且裂纹呈周向分布,因此径向应力过大是导致膜片破裂的主要原因。隔膜压缩机中柱塞泵不稳定工作会导致油缸内油量不足,在此情况下当活塞运动到下止点时膜片会紧贴支板,环槽处膜片承受贴合支板引起的大挠度变形径向应力及环槽处附加变形引起的小挠度变形径向应力。该文利用薄板大挠度及小挠度理论对两种应力进行了求解,计算结果表明:当进气压力为1.7MPa,最外圈环槽两边沿处及中间处膜片总径向应力为272.6MPa、275.7MPa、220.4MPa,大于膜片许用径向应力170MPa,其中小挠度变形径向应力为140.1MPa、138.2MPa、107.4MPa,因此附加变形对膜片寿命影响很大。     

Joint Bearing Mechanism of Coal Pillar and Backfilling Body in Roadway Backfilling Mining Technology

In the traditional mining technology, the coal resources trapped beneath surface buildings, railways, and water bodies cannot be mined massively, thereby causing the lower coal recovery and dynamic disasters. In order to solve the aforementioned problems, the roadway backfilling mining technology is developed and the joint bearing mechanism of coal pillar and backfilling body is presented in this paper. The mechanical model of bearing system of coal pillar and backfilling body is established, by analyzing the basic characteristics of overlying strata deformation in roadway backfilling mining technology. According to the Ritz method in energy variation principle, the elastic solution expression of coal pillar deformation is deduced in roadway backfilling mining technology. Based on elastic-viscoelastic correspondence principle, combining with the burgers rheological constitutive model and Laplace transform theory, the viscoelastic solution expression of coal pillar deformation is obtained in roadway backfilling mining technology. By analyzing the compressive mechanical property of backfilling body, the time formula required for coal pillar and backfilling body to play the joint bearing function in roadway backfilling mining technology is obtained. The example analysis indicates that the time is 140 days. The results can be treated as an important basis for theoretical research and process design in roadway backfilling mining technology.     

“Unexpected” failure patterns and dynamic collective behaviour of an assembly of buildings subjected to horizontal impact

Based on a fully-coupled rigorous mathematical approach, we analyse the anti-plane collective behaviour of a group of identical buildings that stand at regular spatial intervals on a linear elastic half-space and are subjected to dynamic horizontal impact load. Each building in this “town” is assumed to consist of an elastic spring that connects a concentrated mass at the top and the rigid foundation at the bottom. We show that, due to the multiple interactions between the buildings through (the waves in) the ground, the eigenfrequencies of the structural group (town) become lower than the resonant frequency of a single building. This shift of eigenfrequencies may be called the “town (or city) effect,” and may give rise to “unexpected” dynamic structural failure patterns at lower frequencies. We summarise some quantitative information about this town effect and suggest its significance by investigating the actual structural failure patterns found on the occasions of the 1976 Friuli, Italy, and 2007 Noto Peninsula, Japan, earthquakes. The elastodynamic collective failure analysis here is different from the conventional ones in engineering seismology where each individual structure is handled separately. The frequency shifts and “unexpected” structural behaviour may be recognised if the mechanical movement of the structural group is analysed jointly. The town effect may be induced by dynamic structural impact in general (e.g., blasting, aircraft impact), and therefore, the simple analytical model handled here may contain the essential features that will be of crucial importance in evaluating more general dynamic performance and safety of structural groups in urban environments.     

适用于城市高层建筑群的震害预测模型研究

高层建筑是城市建筑的重要组成部分,现有建筑震害预测模型难以满足城市区域高层建筑群震害分析的要求。该文提出了一套非线性多自由度弯剪耦合模型（NMFS）以及其参数标定方法。该模型:1）能模拟高层建筑显著的弯剪耦合变形行为。与传统的剪切层模型对比,该模型能准确的模拟高层建筑的层间位移角包络,其结果与精细有限元模型的结果非常接近;2）具有非常高的计算效率。与精细有限元模型对比,该模型的计算加速比超过60000倍;3）参数标定简单。仅需要借助于少量的建筑属性信息（结构高度、建设年代、设计信息和结构类型）就能生成整个模型的弹塑性参数;4）能输出各层时程响应以及层间位移角情况,使未来基于工程需求参数（EDP）的区域高层建筑经济损失预测成为了可能。论文针对一栋典型高层结构详细展示了模型的建立与标定流程,并对标定参数的准确性进行了校验。最后对北京CBD地区高层建筑群进行了震害模拟,验证了该方法在城市区域中应用的可行性。该文的成果期望为未来区域高层建筑的地震损失预测提供参考。     

Effects of adding illegal storeys to structural systems

Earthquakes in Turkey are frequently occurring disasters, causing much loss of life and property. It is tragic indeed that earthquakes should share the agenda with amnesty laws for illegal buildings. Illegal buildings are those constructed without authorization, legal bureaucratic sanction and, in most cases, without normal engineering control and checks. Buildings may become illegal for a variety of reasons. The very prospect of a waiver bill for illegal buildings spurs further illegal construction. The status of illegal buildings may legally change in time. What is an illegal building today may well be legal tomorrow under these circumstances. The present study deals with two different kinds of building: one is the framed building and the other has shear-wall frame. The capacity ratios, storey drifts and natural periods for the legally approved buildings and the effects of illegal or legal additional floors on these values are compared. It is determined that these buildings with illegal storeys should be strengthened and retrofitted by providing cast in-situ reinforced concrete shear walls.     

Mechanical behaviour analysis of buried pressure pipeline crossing ground settlement zone

Numerical simulation model of buried pipeline crossing ground settlement zone was established considering pipeline–soil interaction. Mechanical behaviour of the buried pipeline was investigated, and effects of ground settlement, pipeline parameters and surrounding soil parameters on mechanical behaviour of the buried pipeline were discussed. These results show that there are two high stress areas on both sides of the dividing plane. High stress areas are oval on the top and bottom of the pipeline. Z-shape bending deformation appears under the action of ground settlement. In ground settlement zone, axial strain on the top of the pipeline is compression strain, and axial strain on the bottom of the pipeline is tension strain. On the contrary, they are tension strain and compression strain respectively in no settlement zone. Bending deformation, axial strain and plastic strain of the buried pipeline increase with the increase in ground settlement. Von Mises stress, high stress area, axial strain and plastic strain of the buried pipeline increase with the increasing diameter-thick ratio and internal pressure, but they decrease with the increase in buried depth. Diameter-thick ratio and internal pressure have a small effect on the bending deformation of the buried pipeline. Bending deformation decreases with the increase in buried depth in ground settlement zone. Von Mises stress and high stress area increase with the increasing surrounding soil’s elasticity modulus and cohesion, but they increase first and then decrease with the increase in Poisson’s ratio. Bending deformation of the pipeline in no settlement zone increases with the increase in elasticity modulus and Poisson’s ratio, but it is affected little by the cohesion. Axial strain and plastic strain have a bigger relationship with the elasticity modulus and Poisson’s ratio. Axial strain and plastic strain of the buried pipeline increase with the increase in cohesion, and the change rates increase with the increase in ground settlement.