基于多尺度混合有限元模型的钢框架地震时程分析

为了研究建筑结构在强震作用下的微观破坏机理以及提高建筑结构地震反应分析的精确性和可靠性,将多尺度有限元分析方法引入抗震混合试验中。根据经验将复杂结构在地震作用下表现出来的特性划分为线性,非线性以及强非线性部分,形成由宏观有限元模型模拟线性部位,微观有限元模型模拟非线性部位以及试验单元模拟用有限元单元难以模拟的强非线性部位的多尺度混合有限元模型。本文基于3层4跨Benchmark钢框架模型建立多尺度混合有限元模型进行地震反应分析。通过多尺度混合有限元模型与相应普通有限元模型之间的地震时程对比分析,验证了多尺度模型在抗震混合模拟试验中与普通有限元模型相比具有耗时相对较小同时能够得到较高精度的优越性。     

基于ABAQUS高层剪力墙结构的有限元建模及其振动台试验验证

采用ABAQUS建立12层剪力墙结构的有限元模型,利用该结构1/5缩尺模型振动台试验时预留试块的材性试验结果及相似关系,确定相应原型结构材料的性能参数,将试验参数和我国混凝土结构设计规范给出的混凝土单轴受拉/压应力-应变关系曲线相结合,确定ABAQUS模型中混凝土损伤塑性模型所需的应力-应变参数;将试验参数和张劲公式法相结合,确定ABAQUS模型中混凝土损伤塑性模型所需的损伤因子参数。对比有限元分析结果和振动台试验结果,验证参数设置的有效性。ABAQUS有限元分析和振动台试验所得原型结构前三阶振型和自振周期相差很小,说明ABAQUS模型和参数设置能够反映并用于计算实际结构的弹性响应。ABAQUS有限元分析得到的结构损伤情况与试验模型的损伤情况基本一致;结构的顶点加速度曲线和滞回曲线等响应的有限元分析结果与试验结果在多遇地震作用下基本吻合,但由于振动台试验累积损伤的影响,两者的差异随着地震波幅值的增大而逐渐增大;ABAQUS有限元分析得到的位移包络曲线与剪力墙结构弯曲变形的特点相符。以上弹塑性分析结果进一步表明了ABAQUS模型和参数设置能够很好地模拟结构在地震作用下的响应。     

板柱节点在剪力和反复荷载作用下的非线性有限元分析

本文对板采用四结点分层板弯曲单元,对柱采用八结六面体等参单元,建立了钢筋混凝土板柱节点有限元非线性计算模型,编制了反复荷载下钢筋混凝土非线性有限元计算程序。文中介绍了作者进行的板柱节点在反复荷载作用下的试验结果,用试验数据合流验证了所建立的有限元程序的可靠性。文反柱中节点和边节 竖向剪力和低周反复水平茶叶工共同作用下的受力性能进行了全过程计算分析。     

渭惠渠跨越管道地震动响应分析

主要利用ANSYS有限元分析软件，建立了跨越管道有限元数值分析模型，对其动特性进行了分析，得到了其振型和频率。通过输入地震波，对不同场地不同地震烈度下的地震响应进行了有限元数值仿真计算，得到了在不同地震作用下管道的地震动响应，为管道的抗震设计提供理论依据。     

跨断层水泥管试验的有限元分析

在考虑管道的材料非线性和几何非线性、管土相互作用的非线性和管道接口非线性的基础上,建立了由管体梁单元、三向土弹簧单元和接口单元组成的埋地非连续管道在断层位移作用下的有限元模型,并以美国密歇根大学Junhee等(2010)所做的跨断层水泥管试验为原型进行了模拟分析。有限元结果给出的水泥管最终变形、接口转角、接口位移与实验结果基本一致,表明本文提出的跨断层埋地非连续管道抗震计算的有限元分析方法具有一定的合理性。有限元结果和试验结果都表明,在逆冲断层作用下,水泥管的破坏主要是因为在管道接口处的轴向压力和弯矩的耦合作用,在断层附近的管道接口承受了较大的转动和压缩位移。本文所提出的分析方法可推广到埋地非连续管道在其它永久地面变形作用下的有限元分析。     

钢筋混凝土筒体的非线性有限元分析模型

本文提出了一种反复荷载下混凝土材料的本构模型，该模型采用平面应力状态下的弥散正交裂缝假设，钢筋采用弥散假设，并考虑了屈服、应变硬化、循环卸载与再加载规则等因素。该本构模型与其他模型相比，具有简便有效的优点。在此基础上，本文采用八结点平面应力单元建立了钢筋混凝土核心筒体非线性有限元分析模型，并对试验模型进行了非线性分析，计算结果与试验结果吻合较好。     

混凝土小型空心砌块组合墙抗侧力试验研究

扼要介绍了纵、横向混凝土小型空心砌块组合墙在竖向菏载和往复侧推力共同作用下的受力机理、变形特征和破坏形态；在试验研究和有限元计算分析的基础上，提出砌块组合墙抗侧刚度和抗侧承载力的简化计算公式，可供工程设计参考。     

受火钢筋混凝土柱三维温度场的数值模拟

受火构件内部温度场随时间和空间的变化规律对结构和构件的高温响应和抗火性能是至关重要的。应用通用有限元分析程序ABAQUS,对火灾下钢筋混凝土柱的二维温度场和三维温度场进行了有限元分析计算。所得计算结果与相关试验数据吻合,证明了通过通用有限元软件对钢筋混凝土结构进行三维温度场分析的可行性,也为混凝土结构在高温下以及高温后的三维响应分析提供了理论依据。     

空间钢网架结构力学性能的试验研究

当前有关空间钢网架结构安全性能的检测试验资料明显不足。文中以某实际空间钢网架结构为研究对象,对其进行了较系统的静动力试验和有限元分析。试验测试时将网架区划为9个带状单元,在每个单元的最大挠度位置进行了逐级加载的静力试验和0 kN、40kN两种配重条件下网架整体结构的振动测试,获得了表征网架变形性能的刚度值和网架前三阶竖向弯曲振动频率,依据试验结果对该网架的力学特点进行了分析。由于理论简化与实际工程的差别,导致有限元分析结果与实测结果误差较大,但有限元分析结果可用于试验模态的辅助判断。文中对网架试验的单元区划、数据采集方法和试验数据的处理过程均作了详细说明,可为网架结构检测试验法的深入研究提供参考。     

夹层橡胶支座轴压承载力的非线性有限元分析

本文建立了夹层橡胶支座在轴压下有限元计算的简化模型，并进行了非线性有限元分析，研究了夹层钢板的应力重分布规律和轴压破坏机理，轴压承载力计算结果同已有的轴压承载力试验结果符合较好。     

An explicit finite element－finite difference method for analyzing the effect of visco－elastic local topography on the earthquake motion

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考虑土-结构相互作用的大跨度斜拉桥非线性地震反应分析

运用大型有限元通用软件ANSYS/LS-DYNA及其并行运算功能,进行了考虑土-结构相互作用的大跨度斜拉桥地震反应分析。考虑混凝土、土介质和悬索材料的非线性与考虑材料线弹性的计算结果比较表明,考虑材料非线性情况时,由于进入塑性阶段后的能量耗散,内力比考虑线性情况时小;而进入塑性阶段后,结构刚度变小,运动量要比考虑线性情况时大。     

弹性波传播数值模拟的区域分裂法

本文针对弹性波波场传播的数学模型,提出了一种基于有限元和有限差分耦合的区域分裂方法．它有灵活的网格剖分,克服了单纯用差分方法对区域的依赖性,可以适用于曲边地表;达到同样精度所需的计算量比有限元方法小;并易于实现并行计算．数值实验表明了算法的有效性．     

Coupling multiscale finite element method for consolidation analysis of heterogeneous saturated porous media

The multiscale finite element method is developed for solving the coupling problems of consolidation of heterogeneous saturated porous media under external loading conditions. Two sets of multiscale base functions are constructed, respectively, for the pressure field of fluid flow and the displacement field of solid skeleton. The coupling problems are then solved with a multiscale numerical procedure in space and time domain. The heterogeneities induced by permeabilities and mechanical parameters of the saturated porous media are both taken into account. Numerical experiments are carried out for different cases in comparison with the standard finite element method. The numerical results show that the coupling multiscale finite element method can be successfully used for solving the complicated coupling problems. It reduces greatly the computing effort in both memory and time for transient problems.     

Finite element simulation of steady state SH wave motion

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Direct finite element method for nonlinear analysis of semi‐unbounded dam–water–foundation rock systems

A direct finite element method is presented for nonlinear earthquake analysis of interacting dam–water–foundation rock systems. The analysis procedure applies viscous damper absorbing boundaries to truncate the semi‐unbounded fluid and foundation‐rock domains and specifies at these boundaries effective earthquake forces determined from the design ground motion defined at a control point on the free surface. The analysis procedure is validated numerically by computing the frequency response functions and transient response of an idealized dam–water–foundation rock system and comparing with results from the substructure method. Because the analysis procedure is applicable to nonlinear systems, it allows for modeling of concrete cracking, as well as sliding and separation at construction joints, lift joints, and at concrete–rock interfaces. Implementation of the procedure is facilitated by commercial finite element software with nonlinear material models that permit modeling of viscous damper boundaries and specification of effective earthquake forces at these boundaries. Copyright © 2017 John Wiley & Sons, Ltd.     

保温夹心节能墙体抗震性能分析

本文采用三维有限元方法对夹心墙体进行抗震性能分析，通过计算结果与实验结果对比，确定合理的计算模型，对夹心墙体进行数值模拟计算、分析了墙体抗震性能、内外叶墙体参与工作情况及应力分布，研究了拉接筋的拉接率对墙体影响．     

Parallel finite element modeling of earthquake ground response and liquefaction

Parallel computing is a promising approach to alleviate the computational demand in conducting large-scale finite element analyses. This paper presents a numerical modeling approach for earthquake ground response and liquefaction using the parallel nonlinear finite element program, ParCYCLIC, designed for distributed-memory message-passing parallel computer systems. In ParCYCL1C, finite elements are employed within an incremental plasticity, coupled solid-fluid formulation. A constitutive model calibrated by physical tests represents the salient characteristics of sand liquefaction and associated accumulation of shear deformations. Key elements of the computational strategy employed in ParCYCL1C include the development of a parallel sparse direct solver, the deployment of an automatic domain decomposer, and the use of the Multilevel Nested Dissection algorithm for ordering of the finite element nodes. Simulation results of centrifuge test models using ParCYCLIC are presented. Performance results from grid models and geotechnical simulations show that ParCYCLIC is efficiently scalable to a large number of processors.     

Direct differentiation method for response sensitivity analysis of a bounding surface plasticity soil model

Finite element (FE) response sensitivity analysis is an important component in gradient-based structural optimization, reliability analysis, system identification, and FE model updating. In this paper, the FE response sensitivity analysis methodology based on the direct differentiation method (DDM) is applied to a bounding surface plasticity material model that has been widely used to simulate nonlinear soil behavior under static and dynamic loading conditions. The DDM-based algorithm is derived and implemented in the general-purpose nonlinear finite element analysis program OpenSees. The algorithm is validated through simulation of the nonlinear cyclic response of a soil element and a liquefiable soil site at Port Island, Japan, under earthquake loading. The response sensitivity results are compared and validated with those obtained from Forward Finite Difference (FFD) analysis. Furthermore, the results are used to determine the relative importance of various soil constitutive parameters to the dynamic response of the system. The DDM-based algorithm is demonstrated to be accurate and efficient in computing the FE response sensitivities, and has great potential in the sensitivity analysis of nonlinear dynamic soil-structure systems.     

Coupling of finite element and optimization methods for the management of groundwater systems

The paper describes an optimization method for the solution of groundwater management problems. The method consists of a combination of the computation of horizontal plane groundwater flow with a free surface (finite element method) and a linear optimization procedure (simplex algorithm). Considering the special structure of data which result form computing the groundwater flow with the finite element method, and modifying the simplex algorithm, the solution of management problems with complex groundwater flow is realized without any difficulties. Compared to a flow computation alone the additional effort of the optimization (computer time and scope for data storage) is only small.