Verification and Improvement of the Effectiveness of Seismic Capacity Design Measures of Shear Wall

In order to investigate the effective seismic capacity design measures of shear wall and to realize expected failure modes under strong earthquake,the existing problems in current seismic capacity design measures are pointed out through theoretical analysis.The effectiveness of the measures of Chinese seismic design code is verified by fine finite element dynamic time-history analysis of examples.Improving measures are then put forward and are verified through example analysis.It is shown the bending ductile demand of bottom section of shear wall increases too much based on moment capacity design measures of Chinese seismic design code 2001 in the rigid foundation assumption under rare earthquake action,and its bearing capacity for vertical axis force loses;the shear capacity design measures of current seismic design code would lead to shear failure in the stores above the bottom ductility strengthening area.Some improved bending and shear seismic capacity design measures of shear wall are proposed and are verified to be effective.     

复合土钉支护转角有利影响范围

基坑复合土钉墙转角处有明显的空间效应，受力变形较小，对支护结构有利，但不清楚转角定量的有利影响范围，目前设计中仍按照与基坑中部一样保守设计，为在此范围内降低土钉用量，避免保守设计，对水泥土搅拌桩复合土钉支护结构建立了全尺寸整体三维有限元模型，这种模型包含基坑的转角，能考虑基坑的空间效应，通过建立接触面单元，能考虑土体和搅拌桩、土体和土钉的相互作用，量化分析了基坑转角对支护结构受力和变形的有利影响范围，计算结果表明，基坑转角对开挖面水平位移、地表沉降、坑底隆起、土钉轴力的有利影响范围分别约为1.3、1、1、1.2倍的开挖深度。经与实际工程现场实测值对比，验证了该模型分析结果的可靠性，同时分析结果优于平面二维和局部三维有限元模型，结论为复合土钉支护结构的优化设计和安全施工提供了理论依据和研究方法。     

流固耦合的多元结构深厚覆盖层透水地基的力学特性

深厚覆盖层多元结构坝基在渗流过程中各土层力学差异明显，分析时关注的具体问题也不尽相同，需要深入研究。基于比奥固结理论，考虑土体的非线性流变以及土体固结变形过程中孔隙度、渗透系数、弹性模量及泊松比的变化；借助ADINA流固耦合模块来模拟西藏达嘎水电站坝基渗流场与应力场耦合过程，分析各层力学特性及相互作用。研究表明，透水性较强的表层土体是渗流主要通道，也是渗流进出区和沉降变形体现区，应在上游采取措施提高其压缩模量，下游区域增设反滤层和排水设施；坝基中的粉细砂层是坝基沉降的主要原因，对坝基沉降起主导作用，同时应注意其液化特性对坝基的不利影响；坝基中的承压含水土层对下游上部结构产生向上顶托力，若位置较深，则破坏性较小；坝基深部土层对整个坝基的渗流破坏影响较小，但对沉降和渗流量的影响不可忽视；表层砂卵砾石层和粉细砂层的渗透系数相差较小时，土层间不会发生接触冲刷。此外，还发现坝基孔隙水压力在快速衰减阶段被消散，期间土体固结较快。垂直防渗墙能有效降低渗透坡降和渗流量，将坝基沉降变形控制在防渗墙上游区域，但上游坝基变形对防渗墙产生较大的水平推力，应加大防渗墙尺寸或者采用辅助渗控措施。     

Mechanism Analysis of Wall Crack and Method of Reinforcement on Isolated Foundation House

The machanism analysis for production of wall crack about a masonry construction building, based on the wall's stress alternation is given and is verified by the numerical method.Then,a method of reinforcing foundation and wall is introduced.     

Experimental Research of Vertically-Loaded RC Joint of Local Transfer from Inclined Column with Different Angle to Beeline-Shaped Short Shear Wall

According to test results of two different angle specimens of local transfer RC joint from inclined column to Beeline-shaped short shear wall under vertical static loads and results of corresponding finite element analysis(ANSYS), fundamental behaviors of the joint are achieved for the change of the angle.The result indicates that there is much difference in the stress distributions of the transfer beam and short shear wall for different angles of inclined column, which shows that the larger angle, the more great tensile force and the earlier crack in the transfer beam and the lower capacity. Otherwise, the angle is smaller, the evener stress distributions in short shear wall, the later crack, the worse degenerate in the transfer beam and the higher capacity.Furthermore, the mechanical behaviors of the joint obviously followed the characteristics of a truss model.     

Yield Displacement Calculation Method of High-Strength Concrete Shear Wall

It is assumed that concrete compressive stress of the cross-section compression zone is linear distribution when the cross-section of high-strength concrete shear wall reaches yield situation. Based on the plane section assumption, the yield curvature formula of shear wall section is obtained by using moment - curvature analysis method. The parameters affecting yield curvature of high-strength concrete shear wall are studied by using the yield curvature formula. The results show that longitudinal reinforcement yield strain is the most vital factor of the yield curvature in addition to axial load ratio. When axial load ratio is larger, both wing walls of shear wall section have larger impact. The yield curvature formula is presented, considering the impact of axial load ratio, boundary reinforcement yield stress and both ends of wing walls of shear wall section based on the regression analysis of calculation results. On this basis, the vertex yield displacement formula of high-strength concrete shear wall is proposed, and the calculation results of formula correspond well to the vertex yield displacement experimental values of the 12 high-strength concrete cantilever wall. The formula is also suited for the vertex yield displacement of comment concrete shear wall.     

Influence of Pile-soil Dynamic Interaction for the Structure Elastio-plastic Deformation

It is necessary to analysis the structure elastoplastic deformation subjected to rare seismic action and the present methods are mostly based on the rigid foundation assumption, which give rise to the method considering the soilstructure dynamic interaction. Adopting the plan pile-soil-structure elastoplastic finite element models, the influence of soil- structure interaction for the structure elastoplastic deformation in the horizontal earthquake has been analyzed. Through analysing we found, considering interaction, the muhilayer-frame elastoplastic displacement was discounted, elastic displacement was minished in the weakness layer and the possibility of break was reduced. The elastoplastic deformation computed by the Code is conservative.     

Earthquake Response Properties of the Support Structure of Large Cross Section Tunnel

The response properties of displacement and stress of tunnel support structure are discussed in detail under the action of horizontal earthquake acceleration(Ya),longitudinal earthquake acceleration(Za) and horizontal-longitudinal earthquake acceleration(YZa).This discussion is based on an analysis of the surrounding rock-support structure-earthquake interaction,adoption of an ADINA nonlinear finite element and construction mechanics,and transient dynamic time domain analysis of a large cross section tunnel.Results of analysis show that:(1) Horizontal earthquake acceleration has important influence on horizontal displacement,maximum principal stress,acceleration and velocity.(2) Longitudinal earthquake acceleration has important influence on longitudinal displacement,effective stress,maximum and minimum principal stress,maximum shear stress,acceleration and velocity.(3) When Ya=0.191g and 0.440g or Za=0.141g and their combined action,the initial support of tunnel would be damaged and the local lining would have partial damage.(4) When Ya=0.440g or Za=0.326g and their combined action,the lining of tunnel would be damaged.(5) When Ya=0.880g or l Za=0.652g,the support structure of tunnel would have severe damage.     

多点锚固预应力CFRP带加固T梁的有限元分析

采用非线性有限元分析程序ABAQUS对无粘结体外预应力CFRP片材加固简支钢筋混凝土T形梁后进行数值模拟，该模拟梁共4根分别为3根梁侧对称加固，1根为梁底加固均为四点波形齿锚固预应力CFRP带。对比结果显示，数据模拟与试验结果在构件屈服以前的承载力、变形以及极限承载力吻合程度较好，构件屈服以后的变形差别较大，因此，可在一定程度上有效替代试验分析方法。依据吻合程度最好的TL3参数设计了“两点锚固”和“四点锚固”的模型进行模拟分析。通过对锚固点数及加固量改变的对比分析可知，依据加固构件的弯矩改变各段加固量及布置锚固点数的方法既可以保证加固效果不降低，又可以节约CFRP材料。     

Effect of Shear Lag on Structural Behaviours in Indeterminate Box Girders

A finite element method considering interaction betwee bending and shear lag deformation was proposed and the finite element formulations including the effect of shear lag was deduced. The effect of shear lag on structural behaviours in indeterminate box girders was studied in detail based on the proposed method. Firstly, the shear lag effects on deflection and the shear lag coefficients were analyzed for both determinate and indeterminate beams. The results obtained by using the proposed method were compared with those by using the analytical method. Finally, the effect of shear lag on redistribution of internal forces including shear force, bending moment, and additional bending moment due to shear lag in indeterminate box girder bridges was studied. It is found that the effects of shear lag on deflection and stresses at a cross section are obvious for both determinate and indeterminate beams, while the effect of shear lag on internal forces in indeterminate box girder bridges is small and may be neglected.     

Theoretical Analysis and Finite Element Computing for Rectangular Plates Bucking under Shear Load

By adopting the energy and finite-element methods with analysis software MATLAB and ANSYS,a detailed and complete solution process for bucking of simply supported rectangular elastic plates is provided.By increasing the triangular series for the deflection function,the amendments have been made to the K values given in references.Through finite element analysis,the expression of K value is fitted out.It is ascertained that the shear stress,taken as a critical shear stress,is reasonable according to the small deflection theory under limited plate deflection.The results of two analytical methods show that the fitting curve of K values used by finite element analysis has more comprehensive practical significance.     

Analysis on Deformation Characteristics of CFG Piles-Gravel Cushion Composite Foundation of the Deep Embedded Secret Passage

In order to investigate the issue in the field of the application of CFG pile application of CFG pile composite foundation technology in deep embedded secret passage of such special structure ground treatment, the settlement deformation of CFG pile composite foundation according to deep are studied and detailed analysis are given in the field test and indoor model test of the gravel cushion with different thickness. Moreover it points out that the cushion compressive deformation must be taken into account, and that the settlement deformation calculation cannot simply consider the amendments of composite foundation. The amendments of cushion deformation must be considered. The effect of the different thickness of cushion on pile-soil stress ratio, total settlement of composite foundation, cushion compression and axial stress of pile body were analysed by using ABAQUS finite element method. Through the analysis of the field test, indoor model test and the numerical simulation of CFG piles-gravel cushion composite foundation of the deep embedded secret passage, a settlement deformation monitoring method has been described and the selection principle of the cushion has determined so as to provide the cushion design basis in the process of composite foundation design.     

红层泥岩桩岩接触面本构模型试验及数值模拟

桩-岩（土）接触面力学特性的研究是桩基承载机理研究的基础。通过红层泥岩桩岩接触面大型直剪试验，研究了红层泥岩桩岩接触面的力学特性，结果表明：接触面剪应力先随剪切位移增大而增大，在达到峰值后，剪应力随着剪切位移增大而降低，并最终趋于稳定值，应力应变曲线呈现出应变软化的特征。根据剪切试验结果，推导出桩岩接触面应变软化本构方程。利用fish语言对FLAC^3D中自带的理想弹塑性接触单元进行二次开发，并应用开发的模型对桩岩接触面直剪试验进行了数值模拟，分析剪应力与剪切位移之间的关系，证明了该本构能够较好地模拟接触面间的应变软化特性。     

Effects of different constitutive models on the calculation of stress of diaphragm wall

Stress of diaphragm wall is analyzed by plane finite element method for high earth-rockfill dams built on deep soil foundation. The differences of stress are studied with two kinds of different constitutive models, i.e. elastic model and nonlinear elastic model, and meanwhile, the influences of the height of dam and diaphragm wall for this two constitutive models are also compared. The results show that, the variation laws of the stress of diaphragm wall are similar for both of the models. But, the stress computed by nonlinear elastic model is much smaller than elastic model does. Under the condition of low stress, the results are similar for the two models, but have big differences for high stress. In addition, for this two models, with the increasing of height of dam and diaphragm wall, the maximal values of the stress are increasing constantly, and relative error of the maximal value of the stress as well, which have the linear relation with the height of dam and diaphragm wall. So, for the conditions of high dams or deep soil foundations, nonlinear elastic model is the right one to use because of the high stress of diaphragm wall.     

Primary Study of Applicability of Plane-section Assumption of Shaped RC Columns

Adopting the element SOLID65 and LINK8 in the general finite element analysis software ANSYS and fiber model beam-column element based on finite element flexibility method respectively, the comparative analysis of the cross, L and T-shaped RC columns under compression, bending, shear and torsion with flange width-thickness ratio of 4:1 is carried out. The applicability of plane section assumption in the nonlinear analysis is discussed primarily, which shows that it is feasible on the whole for shaped RC columns with flange width-thickness ratio equal to or smaller than 4:1.     

Earthquake of Steel Frames-the Seismic Performance of Composite Structural Systems of Concrete Core wall

The steel fame-concrete core wall combination of structural system is outside the framework with steel inner cylinder with concrete shear wall, steel frame-concrete inside the tube system. In this paper ,the finite element software ANSYS earthquake seismic response analysis and stability analysis, the 25-story steel frame-concrete core wall combination of structural system data results show that the structural system performance than the purity steel framework structure is superior.     

Numerical simulation analysis on small clear spacing crossing viaduct pile foundation of shielded subway tunnels

Aimed at the problem of the in partial section of the Nanjing Metro Line 3, the three-dimensional pattern of tunnel, segment and pile foundation was established after appropriate simplification. The simulation results showed that, the Overpass pile foundation of Shield Tunneling to Adjacent Metro Shield Tunnel will have effect on the force and deformation of the earth's surface and pile foundation, the maximum deformation value of the earth's surface is larger than that of the pile foundation top, stress concentration appeared in right working slope lower side segment of tunnel. Through the comparison with field monitoring results, the field dates is consistent with the Numerical Simulation Results, the execution parameters are advised to be well controlled in the further construction, in the same time strengthing the track monitoring, tracking grouting reinforcement should be carried when necessary. The research results could provide reference for the smooth going of the project.     

Experimental Analysis on Shear Strengthening Capacity of Secondary Dapped end Beams

Because section steel can only be extended to the edge of the support, when a simple support RC beam is reinforced by bonded section steel, a notch comes into being at the end of the beam which is called a secondary dapped end beam, making the stress state of the beam more complex. Through experimental analysis on 21 dapped end beam specimens shear reinforced by steel plate bonded, the deformation process, performing characteristics and failure mechanism of the specimens were investigated. The result shows that two steel bonded forms, including horizontal steel plate and oblique steel plate with angle 45° bonded, delay the appearance of cracks significantly and improve the maximum bearing capacity by 102% and 93%. Due to the impact of stress concentration at the notch, the main modes of damage include concrete tensile or shear failure with the result of bonding failure of a steel plate. By changing the width of steel plates and analyzing different reinforcement effects, formula of bearing capacity of shear reinforcement was proposed based on the method of truss analogue, which provides a reference for engineering application.     

G324牵引车车架弯曲工况强度分析及改进

为了对G324牵引车的车架进行强度分析及改进,根据牵引车的实际工况,选择对车架影响较大的弯扭工况进行分析,利用HyperMesh有限元软件建立了某牵引车车架结构有限元分析计算模型。通过计算得出该车架在这两种工况下的应力分布云图,对车架进行改进并分析增加L板和将鞍座瓦轮板改为平板以及取消加强板3种模型的实际情况,得出满足车架强度要求的具体模型,为牵引车车架的设计及改进提供参考依据。     

Finite Element Analysis and Experimental Research on Pedestal of PC Beam for Light Railcar

In design of light railcar used freely supported beam, the cast steel pedestals will bear complex loads, which include weight, acceleration and wind, etc. Because of pedestals' peculiarity and complexity, the strength of the pedestals play an important role in safety of light railcar. So it's necessary to analyze their stress and deformation in order to insure safety of light railcar. Up to now, finite element analysis is still the most effective means. By studying cast steel pedestal with finite element method, 3-D finite element models of fixed and kinetic pedestals were built, and the loads and boundary condition of pedestals were analyzed. By means of finite element analysis software, the contact and von mises stresses were obtained and deformation were resolved. As a result of analysis, the tow of pedestal can fulfill requirement of use in light railcar, the contact stress and von mises stress are not exceeded limit stress strength of materials. There is enough static strength for the structures of pedestals. For verifying theoretical analysis result, the fatigue test was carried out, with examining the testing points locating on the pedestals, the stress and deformation data were measured. By comparing between theoretical analysis and test data, the experimental results show calculated and testing results can meet the case well which assure the reliability of finite element analysis. But in the result, there are differences in deformations of them. The reason may be that boundary conditions and loads are not same between analysis and experiment.