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Dynamic in-plane transversal normal stresses in the concrete face of CFRD

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 135-148 doi: 10.1007/s11709-018-0481-7

摘要： Severe earthquakes can induce damages to Concrete Face Rockfill Dams (CFRDs) such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses develop. Although these damages rarely jeopardize the dam safety, they cause large water reservoir leakages that hinder the dam functioning. This issue can be addressed using well know numerical methods; however, given the wide range of parameters involved, it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD’s overall behavior. Accordingly, once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the dam. To this end an easy-to-use procedure that accounts for the dam height effects, valley narrowness, valley slopes, width of concrete slabs and seismic excitation characteristics was developed. The procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD’s due to dam reservoir filling [ ]. Using these two procedures in a sequential manner, it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross river. Both procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD’s. Then, the results were interpreted with the Buckingham Pi theorem and various relationships were developed. In the above reference, the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was reported. In this paper, the seismic procedure is first developed and then through an example the whole method (dam construction, reservoir filling plus seismic loading) of analysis is assessed.

关键词： CFR dams dynamic analysis in-plane normal stresses concrete face

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In-plane transversal normal stresses in the concrete face of CFRD induced by the first-dam reservoir

Neftalí SARMIENTO-SOLANO, Miguel P. ROMO

《结构与土木工程前沿（英文）》 2018年第12卷第1期页码 81-91 doi: 10.1007/s11709-016-0378-2

摘要： To evaluate the effects of dam height, valley narrowness and width of concrete slabs on the first-dam reservoir filling in-plane transversal normal stresses in the concrete face of CFRD´s, 3D finite difference analyses were carried out. Behavior of rockfill dams considered in this study was defined from the monitoring of a number of 3D sets of pressure cells and extensometers installed in three large dams in Mexico. The 3D analyses results show that high in-plane transversal compressive stresses develop within the concrete panels located in the central concrete face zone upon dam reservoir filling loading. Likewise, in-plane induced tensile transversal stresses in the zones near the abutments increase the potential of slabs cracking and damaging the waterstops in-between the vertical and perimetral joints. From the results of the 3D finite difference analyses, a simple method to estimate in-plane normal stresses in the concrete face is advanced and through comparisons with the results of a 3D case numerical study, its accuracy assessed.

关键词： concrete face CFR dams reservoir filling slab in-plane stresses

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Seismic response of precast reinforced concrete wall subjected to cyclic in-plane and constant out-of-plane

《结构与土木工程前沿（英文）》 2021年第15卷第5期页码 1128-1143 doi: 10.1007/s11709-021-0753-5

摘要： This paper provides insight into the seismic behavior of a full-scale precast reinforced concrete wall under in-plane cyclic loading combined with out-of-plane loading replicated by sand backfill to simulate the actual condition of basement walls. The tested wall exhibited flexural cracks, owing to the high aspect ratio and considerable out-of-plane movement due to lateral pressure from the backfill. The wall performed satisfactorily by exhibiting competent seismic parameters and deformation characteristics governed by its ductile response in the nonlinear phase during the test with smaller residual drift. Numerical analysis was conducted to validate experimental findings, which complied with each other. The numerical model was used to conduct parametric studies to study the effect of backfill density and aspect ratio on seismic response of the proposed precast wall system. The in-plane capacity of walls reduced, while deformation characteristics were unaffected by the increase in backfill density. An increase in aspect ratio leads to a reduction in in-plane capacity and an increase in drift. Curves between the ratio of in-plane yield capacity and design shear load of walls are proposed for the backfill density, which may be adopted to determine the in-plane yield capacity of the basement walls based on their design shear.

关键词： precast wall basement wall out-of-plane response quasi-static test sand backfill seismic parameters

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Seismic safety evaluation methodology for masonry building and retrofitting using splint and bandage technique with wire mesh

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

《结构与土木工程前沿（英文）》 2022年第16卷第4期页码 478-505 doi: 10.1007/s11709-022-0817-1

摘要： The paper presents a seismic safety assessment of unreinforced masonry (URM) building using two approaches. The first approach uses the ‘Pier Analysis’ method, based on the concept of equivalent lateral stiffness, where in-plane and out-of-plane actions are considered independently. The second approach is developed with the program SAP2000, where the linear response is evaluated using continuum ‘finite element modelling’ (FEM). Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces. The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension. It is also observed that the pier analysis method is conservative compared to FEM, but can be used as a simplified and quick tool in design offices for safety assessment, with reasonable accuracy. To safeguard the URM wall piers under lateral loads, a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages, respectively, using welded wire mesh (WWM) reinforcement. The study using the ‘Pier Analysis’ shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique. Further, the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.

关键词： unreinforced masonry seismic in-plane and out-of-plane forces pier analysis finite element modelling splint and bandage technique with wire mesh

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(011)取向单晶衬底上生长的非晶Sm-Co薄膜的面内各向异性调控 Article

梁文会, 周厚博, 熊杰夫, 胡凤霞, 李佳, 张健, 王晶, 孙继荣, 沈保根

《工程（英文）》 2020年第6卷第2期页码 158-163 doi: 10.1016/j.eng.2019.11.010

摘要：

具有单轴面内各向异性的非晶Sm-Co薄膜在信息存储和自旋电子学领域中都具有广阔的应用前景。产生单轴面内各向异性的最有效方法是在薄膜沉积过程中施加面内磁场。然而，这种方法通常需要复杂的设备。本文中，我们报道了一种产生单轴面内各向异性的新方法，只需要将非晶Sm-Co薄膜生长在(011)取向的单晶衬底上，薄膜生长过程中不需要施加任何外部磁场。薄膜的各向异性常数k_A随衬底晶格常数的变化而变化。生长在LaAlO₃ (011)衬底上的非晶Sm-Co薄膜的各向异性常数k_A高达3.3×10⁴ J·m⁻³。详细分析表明，衬底各向异性应变引起的铁磁畴的择优生长，以及薄膜中Sm-Co、Co-Co取向对的有序化，在非晶Sm-Co薄膜单轴面内各向异性的产生上起到了重要作用。这项工作为在非晶Sm-Co薄膜中获得单轴面内各向异性提供了一种新方法。

关键词：非晶Sm-Co膜，面内单轴各向异性，磁控溅射

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全尺寸复合楼板的试验 Article

Dennis Lam, Xianghe Dai, Therese Sheehan

《工程（英文）》 2019年第5卷第2期页码 223-233 doi: 10.1016/j.eng.2018.11.021

摘要：

为了研究楼板在复合梁的格栅中的弯曲性能以及面内效应，我们对一种全尺寸复合楼板进行了试验，以降低混凝土板沿主梁线纵向开裂的趋势。在钢板定向平行于梁却不并排放置的情况下，这样的改变非常重要。在这种情况下，重要的是证明从剪切连接件中传递的局部力，以及与欧洲规范4 相比，其所需的横向钢筋量有所减少。研究机制涉及混凝土板产生的面内压缩力，这是由于楼板受到外围的复合梁支撑产生了约束作用；而次梁作为横向纽带用于抵抗楼板中的作用力，否则会导致混凝土板沿主梁线分裂。我们对主梁中心线及外围梁的开裂趋势进行了精密测试，这是自20世纪90年代初卡丁顿试验以来，在实验室条件下进行的第一次大型楼板试验，虽说卡丁顿试验并没有失败。这次楼板试验的目的是即使主梁传递的纵向力相对较高（即设计为全剪切连接件），但混凝土面层中钢筋最小配筋率仅为0.2%。该试验证实，尽管在钢板不连续，以及使用欧洲规范4中规定的横向分布钢筋最小配筋率的情况下，主梁仍然达到了其塑性抗弯性能。在此基础上，我们提出了无 U 形钢筋（U-bars）的边梁剪切连接件的折减系数。

关键词：楼板试验复合梁边梁欧洲规范4 面内效应柱移除坚固性

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Single-chip 3D electric field microsensor

Biyun LING, Yu WANG, Chunrong PENG, Bing LI, Zhaozhi CHU, Bin LI, Shanhong XIA

《机械工程前沿（英文）》 2017年第12卷第4期页码 581-590 doi: 10.1007/s11465-017-0454-x

摘要：

This paper presents a single-chip 3D electric field microsensor, in which a sensing element is set at the center to detect the Z-axis component of an electrostatic field. Two pairs of sensing elements with the same structure are arranged in a cross-like configuration to measure the X- and Y-axis electrostatic field components. An in-plane rotary mechanism is used in the microsensor to detect the X-, Y-, and Z-axis electrostatic field components simultaneously. The proposed microsensor is compact and presents high integration. The microsensor is fabricated through a MetalMUMPS process. Experimental results show that in the range of 0–50 kV/m, the linearity errors of the microsensor are within 5.5%, and the total measurement errors of the three electrostatic field components are less than 14.04%.

关键词： electric field microsensor three-dimensional single-chip in-plane rotation

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Finite element analysis of creep for plane steel frames in fire

Hui ZHU, Yuching WU

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 297-307 doi: 10.1007/s11709-012-0162-x

摘要： Steel is widely used for the construction of bridges, buildings, towers, and other structures because of its great strength, light weight, ductility, and ease of fabrication, but the cost of fireproofing is a major disadvantage. Therefore, the resistance of a steel structure to fire is a significant subject for modern society. In the past, for simplification, creep behavior was not taken into account in research on the resistance of a steel structure to fire. However, it was demonstrated that the effect of creep is considerable at temperatures that commonly reach 600°C and should not be neglected in this context. In this paper, a co-rotational total Lagrangian finite element formulation is derived, and the corresponding numerical model is developed to study the creep behavior of plane steel frames in fire conditions. The geometric nonlinearity, material nonlinearity, high temperature creep, and temperature rate of change are taken into account. To verify the accuracy and efficiency of the numerical model, four prototypical numerical examples are analyzed using this model, and the results show very good agreement with the solutions in the literature. Next, the numerical model is used to analyze the creep behavior of the plane steel frames under decreasing temperatures. The results indicate that the effect of creep is negligible at temperatures lower than 500°C and is considerable at temperatures higher than 500°C. In addition, the heating rate is a critical factor in the failure point of the steel frames. Furthermore, it is demonstrated that the deflection at the midpoint of the steel beam, considering creep behavior, is approximately 13% larger than for the situation in which creep is ignored. At temperatures higher than 500°C, the deformed steel member may recover approximately 20% of the total deflection. The application of the numerical model proposed in this paper is greatly beneficial to the steel industry for creep analysis, and the numerical results make a significant contribution to the understanding of resistance and protection for steel structures against disastrous fires.

关键词： creep plane steel frame fire finite element method geometric nonlinearity

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Genomic variations in the counterpart normal controls of lung squamous cell carcinomas

null

《医学前沿（英文）》 2018年第12卷第3期页码 280-288 doi: 10.1007/s11684-017-0580-1

摘要：

Lung squamous cell carcinoma (LUSC) causes approximately 400 000 deaths each year worldwide. The occurrence of LUSC is attributed to exposure to cigarette smoke, which induces the development of numerous genomic abnormalities. However, few studies have investigated the genomic variations that occur only in normal tissues that have been similarly exposed to tobacco smoke as tumor tissues. In this study, we sequenced the whole genomes of three normal lung tissue samples and their paired adjacent squamous cell carcinomas. We then called genomic variations specific to the normal lung tissues through filtering the genomic sequence of the normal lung tissues against that of the paired tumors, the reference human genome, the dbSNP138 common germline variants, and the variations derived from sequencing artifacts. To expand these observations, the whole exome sequences of 478 counterpart normal controls (CNCs) and paired LUSCs of The Cancer Genome Atlas (TCGA) dataset were analyzed. Sixteen genomic variations were called in the three normal lung tissues. These variations were confirmed by Sanger capillary sequencing. A mean of 0.5661 exonic variations/Mb and 7.7887 altered genes per sample were identified in the CNC genome sequences of TCGA. In these CNCs, C:G→T:A transitions, which are the genomic signatures of tobacco carcinogen N-methyl-N-nitro-N-nitrosoguanidine, were the predominant nucleotide changes. Twenty five genes in CNCs had a variation rate that exceeded 2%, including ARSD (18.62%), MUC4 (8.79%), and RBMX (7.11%). CNC variations in CTAGE5 and USP17L7 were associated with the poor prognosis of patients with LUSC. Our results uncovered previously unreported genomic variations in CNCs, rather than LUSCs, that may be involved in the development of LUSC.

关键词： lung cancer counterpart normal control genomic variations

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Thermally developing forced convection and the corresponding thermal stresses in a porous plate channel

YANG Xiao, LIU Xuemei

《机械工程前沿（英文）》 2007年第2卷第1期页码 57-61 doi: 10.1007/s11465-007-0009-7

摘要： Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection of the local thermal equilibrium and the corresponding thermal stresses in a semi-infinite saturated porous plate channel are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the P晱let number () and Brinkman number () on temperature, Nusselt number () and thermal stress are revealed numerically.

关键词： semi-infinite saturated direction interaction skeleton thermal equilibrium

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Feedback linearization based control for weak grid connected PV system under normal and abnormal conditions

Rahul SHARMA,Sathans SUHAG

《能源前沿（英文）》 2020年第14卷第2期页码 400-409 doi: 10.1007/s11708-017-0459-5

摘要： This paper proposes a control strategy for interface of distributed energy sources into the weak grid system with a focus on the energy and ancillary services. A novel controller has been designed and implemented to tackle the challenges of coupling terms in the LCL filter, the transient behavior under sudden changes, and the voltage support under fault condition using the feedback linearization technique. The controller proposed has been implemented on the PV system connected with the weak grid using the LCL filter and the performance of the controller has been verified using Matlab/Simulink through simulation under different conditions. The results of the controller proposed have been compared with the conventional PI dual loop controller. The simulation results obtained demonstrate the effectiveness and simplicity of the controller design strategy.

关键词： PV system grid interface feedback linearization inverter LCL filter

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Residual stresses in coating-based systems, part II: Optimal designing methodologies

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年第2卷第2期页码 125-136 doi: 10.1007/s11465-007-0022-x

摘要： In this part of the work, different cases are studied to illustrate the implementation of the analytical models that have been developed in Part I [Front. Mech. Eng. China, 2007, 2(1): 1 12]. Different topics are involved in the optimal design of coating-based systems. Some essential relations among material properties and dimensions of the coating and substrate and the residual stress variations are reflected. For the multilayered coating-based systems, some optimal design methodologies are proposed, such as the decrease in stress discontinuity at the interface between the adjacent layers, the curvature as a function of the coating thickness, the effect of the interlayer on the residual stress redistribution, and so on. For the single-layered coating-based systems, some typical approximations that are often used to predict the residual stresses in the coating-based system or bilayer structure are corrected. A simplified model for predicting the quenching stress in a coating is also developed.

关键词： function different substrate interlayer implementation

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Out-of-plane elastic buckling load and strength design of space truss arch with a rectangular section

Senping WANG; Xiaolong LIU; Bo YUAN; Minjie SHI; Yanhui WEI

《结构与土木工程前沿（英文）》 2022年第16卷第9期页码 1141-1152 doi: 10.1007/s11709-022-0866-5

摘要： The out-of-plane stability of the two-hinged space truss circular arch with a rectangular section is theoretically and numerically investigated in this paper. Firstly, the flexural stiffness and torsional stiffness of space truss arches are deduced. The calculation formula of out-of-plane elastic buckling loads of the space truss arch is derived based on the classical solution of out-of-plane flexural-torsional buckling loads of the solid web arch. However, since the classical solution cannot be used for the calculation of the arch with a small rise-span ratio, the formula for out-of-plane elastic buckling loads of space truss arches subjected to end bending moments is modified. Numerical research of the out-of-plane stability of space truss arches under different load cases shows that the theoretical formula proposed in this paper has good accuracy. Secondly, the design formulas to predict the out-of-plane elastoplastic stability strength of space truss arches subjected to the end bending moment and radial uniform load are presented through introducing a normalized slenderness ratio. By assuming that all components of space truss circular arches bear only axial force, the design formulas to prevent the local buckling of chord and transverse tubes are deduced. Finally, the bearing capacity design equations of space truss arches are proposed under vertical uniform load.

关键词： torsional stiffness strength design elastic buckling space truss arches out-of-plane

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Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年第2卷第1期页码 1-12 doi: 10.1007/s11465-007-0001-2

摘要： Thin films and multi-layered coatings comprised of different classes of materials are often used for various functional devices. The thermo-mechanical integrity of these systems is becoming a major concern and is strongly related to the residual stresses because of the fabrication processes. In this paper, the sources of the residual stresses in the coating-based systems and the concept of misfit strain were briefly reviewed. Analytical models were developed to predict the residual stresses in multi-layered film structures or coating-based systems using the force and moment balances. In addition, the residual stress distributions in the func tionally and compositionally graded coatings were also analyzed.

关键词： briefly different thermo-mechanical integrity addition residual

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论正态云模型的普适性

李德毅,刘常昱

《中国工程科学》 2004年第6卷第8期页码 28-34

摘要：

分布函数是分析随机现象的重要工具，正态分布是最重要的概率分布，在自然科学和社会科学中应用广泛；隶属函数是模糊集合的基石，正态隶属函数也有广泛的应用。但是，精确确定一个模糊概念的隶属函数已经成为模糊学应用的瓶颈。云模型把随机性和模糊性结合起来，用数字特征熵，揭示随机性与模糊性的关联性，并用来表示一个定性概念的粒度。正态云模型通过期望、熵和超熵构成的特定结构发生器，生成定性概念的定量转换值，体现概念的不确定性。这种特定结构不但放宽了形成正态分布的前提条件，而且把精确确定隶属函数放宽到构造正态隶属度分布的期望函数，因而更具有普遍适用性，更简单、直接地完成了定性与定量之间的相互转换过程。

关键词：正态分布函数隶属度正态云模型概念粒度普适性