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Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured pipeline

Mahdi IZADI, Khosrow BARGI

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1105-1119 doi: 10.1007/s11709-019-0539-1

摘要： The present study investigates the mechanical behavior of a new generation of buried pipelines, dubbed the textured pipeline, which is subjected to strike-slip faulting. In conventional cylindrical pipelines, the axial and bending stresses brought about in their walls as a result of fault movement, lead to local buckling, which is construed as one of the major reasons contributing to pipeline failure. The present study has assessed 3-D numerical models of two kinds of buried textured pipelines, with 6 and 12 peripheral triangular facets, subjected to a strike-slip faulting normal to the axis of the pipelines, with and without internal pressure, with the two kinds of X65 and X80 steel, and with different diameter-to-thickness ratios. The results indicate that, because of specific geometry of this pipeline shell which is characterized by having lower axial stiffness and higher bending stiffness, compared to conventional cylindrical pipeline, they are considerably resistant to local buckling. The results of this study can be conceived of as a first step toward comprehensive seismic studies on this generation of pipelines which aim at replacing the conventional cylindrical pipelines with textured ones in areas subjected to fault movement.

关键词： buried pipeline     textured pipeline     local buckling    

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Cyclic responses of three 2-story seismic concentrically braced frames

Ching-Yi TSAI, Keh-Chyuan TSAI, Chih-Han LIN, Chih-Yu WEI, Kung-Juin WANG, Yi-Jer YU, An-Chien WU,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 287-301 doi: 10.1007/s11709-010-0087-1

摘要： Three full scale two-story steel concentrically braced frames (CBFs) were tested at the National Center for Research on Earthquake Engineering (NCREE) in Taipei. The specimen is a single bay with the braces arranged in a two-story X-brace configuration. The main differences among the three tests are the brace types (hollow structural or wide-flange section) and the design criteria adopted for the gusset plate connections. Results of these three tests confirm that the two-story X-shape steel CBFs all have rather good energy dissipation characteristics up to a story drift of about 0.03 radians under the cyclically increasing lateral displacements. Severe brace local buckling and out-of-plane displacements were observed during each test. Tests confirm that both the 2-linear and 8-elliptical designs of the gusset plate connection provide satisfactory ductility for the steel CBF. Hollow structural section (HSS) braces fractured at a story drift smaller than that found using wide flange sections. The nonlinear fine element method (FEM) program ABAQUS was used to simulate the responses of the specimen. The base shear versus the story drift relationships obtained from the tests and the FEM analytical results are quite agreeable in various levels of lateral frame displacement. The analytical results confirm that the severe out-of-plane buckling of the braces can be accurately simulated. FEM analyses also illustrate that the steel moment resisting frame takes about 40% story shear when the inter-story drift is greater than 0.02 radians.

关键词： concentrically braced frame (CBF)     full-scale test     finite element (FE) analysis     flexural buckling     local buckling    

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Thermal buckling behavior of laminated composite plates: a finite-element study

Houdayfa OUNIS,Abdelouahab TATI,Adel BENCHABANE

《机械工程前沿（英文）》 2014年 第9卷 第1期   页码 41-49 doi: 10.1007/s11465-014-0284-z

摘要：

In this paper, the thermal buckling behavior of composite laminated plates under a uniform temperature distribution is studied. A finite element of four nodes and 32 degrees of freedom (DOF), previously developed for the bending and mechanical buckling of laminated composite plates, is extended to investigate the thermal buckling behavior of laminated composite plates. Based upon the classical plate theory, the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element. The numerical implementation of the present finite element allowed the comparison of the numerical obtained results with results obtained from the literature: 1) with element of the same order, 2) the first order shear deformation theory, 3) the high order shear deformation theory and 4) the three-dimensional solution. It was found that the obtained results were very close to the reference results and the proposed element offers a good convergence speed. Furthermore, a parametrical study was also conducted to investigate the effect of the anisotropy of composite materials on the critical buckling temperature of laminated plates. The study showed that: 1) the critical buckling temperature generally decreases with the increasing of the modulus ratio EL/ET and thermal expansion ratio αT/αL, and 2) the boundary conditions and the orientation angles significantly affect the critical buckling temperature of laminated plates.

关键词： thermal buckling     laminated composite plates     anisotropy     critical buckling temperature     finite-element method     high precision rectangular Hermitian element    

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Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 335-343 doi: 10.1007/s11709-011-0121-y

摘要： In this paper, a practical test and finite element analysis has been undertaken to further investigate the effects of contact buckling. A test rig was designed and constructed to record vertical and transverse deflections of compressively loaded steel skin plates. The boundary conditions were modeled as fully fixed. A finite element analysis was also undertaken using the software package Strand7. Results from both analyses have been examined and compared to data established from previous studies on contact buckling. Both the finite element analysis and practical results correlate well with this data. The result of the investigation has confirmed contact buckling theories and has foreshadowed the onset of the newly observed phenomenon of secondary contact buckling.

关键词： compressive     buckling     thin steel skins     unilateral contact     rigid constraints    

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基于高等分析的钢结构设计——材料建模与应变极限 Research Article

Leroy Gardner, Xiang Yun, Andreas Fieber, Lorenzo Macorini

《工程（英文）》 2019年 第5卷 第2期   页码 243-249 doi: 10.1016/j.eng.2018.11.026

摘要：

我们对于钢框架的结构分析通常通过梁单元来进行。然而，由于该类单元无法确切地捕捉钢材截面的局部屈曲行为，因此，传统的钢结构设计规范采用截面分类的概念来确定截面强度以及变形能力受材料局部屈曲影响的程度。而塑性设计方法的使用仅限于 1 级截面，其具有足够的转动能力以形成塑性铰并引发倒塌机制。在更高级截面中，局部屈曲阻止了具有这种转动能力的塑性铰的形成，除非出于计算需求而使用壳单元，否则我们需要对材料进行弹性分析。然而，本文证明了通过将连续强度法（CSM）及其应变极限纳入分析，可以在梁单元中有效地模拟局部屈曲。此外，通过进行几何非线性和材料非线性的高等分析，可确保无需进行额外的设计检查。如果采用适当而精确的应力 - 应变关系，我们在较粗截面中观察到的应变硬化所带来的积极影响亦可以得到有效应用；为此，我们在文详尽地描述了一个用于热轧钢的四元线性材料模型。对于一致的高等分析框架中任意细长比截面的分析问题， CSM 应变极限分析法均适用，同时还可以从荷载重新分配水平的优化中受益。本文所提出的方法可用于单个构件、连续梁单元及相关框架结构，并且在精度与一致性等方面与当前钢结构设计规范相比，本方法具有显著优势。

关键词： 高等分析     连续强度法     局部屈曲     材料建模     应变极限    

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Finding buckling points for nonlinear structures by dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Hossein ESTIRI

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 23-61 doi: 10.1007/s11709-019-0549-z

摘要： Dynamic Relaxation Method (DRM) is an explicit approach for solving the simultaneous systems of equations. In this tactic, the fictitious mass and damping are added to the static governing equations, and an artificial dynamic system is constructed. By using DRM for nonlinear analysis, the structural static equilibrium path is obtained. This outcome is extremely valuable, since it leads to the behavior of structures. Among the finding related to the structural static path are the critical and buckling points for nonlinear structures. In this paper, a new way for calculating the load factor is proposed by setting the external work zero. Mixing the dynamic relaxation scheme with external work technique has not been formulated so far. In all incremental-iterative methods, the load factor increment sign should be determinated by extra calculations. This sign leads to increase or decrease of the load increment. It is worth emphasizing that sign of the load factor increment changes at the load limit points. Therefore, the sign determinations are required in the common work control methods. These disadvantages are eliminated in the proposed algorithm. In fact, the suggested load factor depends only on the Dynamic Relaxation (DR) fictitious parameters. Besides, all DR calculations are performed via vector operation. Moreover, the load factor is calculated only by one formula, and it has the same relation in the all solution processes. In contrast to the arc length techniques, which requires the sign determined, the proposed scheme does not need any sign finding. It is shown that author’s technique is quicker than the other dynamic relaxation strategies. To prove the capability and efficiency of the presented scheme, several numerical tests are performed. The results indicate that the suggested approach can trace the complex structural static paths, even in the snap-back and snap-through parts.

关键词： load factor     external work     dynamic relaxation     static equilibrium path     large displacement    

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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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Flexural-torsional buckling behavior of aluminum alloy beams

Xiaonong GUO,Zhe XIONG,Zuyan SHEN

《结构与土木工程前沿（英文）》 2015年 第9卷 第2期   页码 163-175 doi: 10.1007/s11709-014-0272-8

摘要： This paper presents an investigation on the flexural-torsional buckling behavior of aluminum alloy beams (AAB). First, based on the tests of 14 aluminum alloy beams under concentrated loads, the failure pattern, load-deformation curves, bearing capacity and flexural-torsional buckling factor are studied. It is found that all the beam specimens collapsed in the flexural-torsional buckling with excessive deformation pattern. Moreover, the span, loading location and slenderness ratio influence the flexural-torsional buckling capacity of beams significantly. Secondly, besides the experiments, a finite element method (FEM) analysis on the flexural-torsional buckling behavior of AAB is also conducted. The main parameters in the FEM analysis are initial imperfection, material property, cross-section and loading scheme. According to the analytical results, it is indicated that the FEM is reasonable to capture mechanical behavior of AAB. Finally, on the basis of the experimental and analytical results, theoretical formulae to estimate the flexural-torsional buckling capacity of AAB are proposed, which could improve the application of present codes for AAB.

关键词： flexural-torsional buckling     aluminum alloy beams (AAB)     finite element method (FEM)     theoretical formula    

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Probabilistic stability of uncertain composite plates and stochastic irregularity in their buckling mode

《结构与土木工程前沿（英文）》   页码 179-190 doi: 10.1007/s11709-022-0888-z

摘要： In this study, the mechanical properties of the composite plate were considered Gaussian random fields and their effects on the buckling load and corresponding mode shapes were studied by developing a semi-analytical non-intrusive approach. The random fields were decomposed by the Karhunen−Loève method. The strains were defined based on the assumptions of the first-order and higher-order shear-deformation theories. Stochastic equations of motion were extracted using Euler–Lagrange equations. The probabilistic response space was obtained by employing the non-intrusive polynomial chaos method. Finally, the effect of spatially varying stochastic properties on the critical load of the plate and the irregularity of buckling mode shapes and their sequences were studied for the first time. Our findings showed that different shear deformation plate theories could significantly influence the reliability of thicker plates under compressive loading. It is suggested that a linear relationship exists between the mechanical properties’ variation coefficient and critical loads’ variation coefficient. Also, in modeling the plate properties as random fields, a significant stochastic irregularity is obtained in buckling mode shapes, which is crucial in practical applications.

关键词： uncertain composite plate     stochastic assume mode method     Karhunen−Loève theorem     polynomial chaos approach     plate buckling     irregularity in buckling mode shapes    

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Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

《机械工程前沿（英文）》 2013年 第8卷 第3期   页码 291-297 doi: 10.1007/s11465-013-0255-9

摘要：

This work presents the existence of buckling mode switching with respect to the radius of concentric rigid ring support. The buckling mode may not be axisymmetric as previously assumed. In general, the plate may buckle in an axisymmetric mode but when the radius of the ring support becomes small, the plate may buckle in an asymmetric mode. The optimum radius of the concentric rigid ring support for maximum buckling load is also determined. Introducing internal rigid ring support, when placed at an optimal position increases the elastic buckling load capacity by 149.39 percent. The numerical results obtained are in good agreement with the previously published data.

关键词： buckling     circular plate     elastically restrained edge     rigid ring support     mode switching    

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Experimental study on slender buckling-restrained knee braces with round steel bar cores

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 99-121 doi: 10.1007/s11709-022-0875-4

摘要： This study aimed to investigate a novel slender buckling-restrained knee brace damper (BRKB) for welded and weld-free steel framing systems. The proposed BRKB adopts steel bar cores connected by a central coupler and restrained by tube buckling restrainers with a cover tube supporter. The advantages of the proposed damper include easy assembly compared to conventional buckling restrained braces, and high architectural flexibility for the retrofitting of large-span weld-free or welded steel moment-resisting systems. Specifically, by increasing the number of contraction allowances, undesirable failure mechanisms that are global instability and local buckling of the restrainer ends can be effectively suppressed because the more uniform plastic deformation of the core bar can be achieved longitudinally. In this study, displacement-controlled compression and cyclic loading tests were carried out to investigate the deformation capacities of the proposed BRKBs. Structural performance metrics associated with both loading tests, such as strength capacities, strains at the cover tubes and buckling restrainers, and hysteretic behaviors of the proposed damper under cyclic loads, were measured and discussed. Test results revealed that the geometrical characteristics of the cover tubes and adopted contraction allowances at the dampers play essential roles in their load-bearing capacities.

关键词： weld-free beam-to-column connections     moment-resisting frame     cyclic and compression loading tests     buckling-restrained knee brace     cover tube    

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High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 406-416 doi: 10.1007/s11709-018-0475-5

摘要： We approximate the fracture surface energy functional based on phase-field method with smooth local maximum entropy (LME) and second-order maximum entropy (SME) approximants. The higher-order continuity of the meshfree methods such as LME and SME approximants allows to directly solve the fourth-order phase-field equations without splitting the fourth-order differential equation into two second-order differential equations. We will first show that the crack surface functional can be captured more accurately in the fourth-order model with smooth approximants such as LME, SME and B-spline. Furthermore, smaller length scale parameter is needed for the fourth-order model to approximate the energy functional. We also study SME approximants and drive the formulations. The proposed meshfree fourth-order phase-field formulation show more stable results for SME compared to LME meshfree methods.

关键词： second-order maximum entropy     local maximum entropy     second- and fourth-order phase-field models     B-spline    

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Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

《信息与电子工程前沿（英文）》 2016年 第17卷 第3期   页码 212-223 doi: 10.1631/FITEE.1500255

摘要： The feature extraction algorithm plays an important role in face recognition. However, the extracted features also have overlapping discriminant information. A property of the statistical uncorrelated criterion is that it eliminates the redundancy among the extracted discriminant features, while many algorithms generally ignore this property. In this paper, we introduce a novel feature extraction method called local uncorrelated local discriminant embedding (LULDE). The proposed approach can be seen as an extension of a local discriminant embedding (LDE) framework in three ways. First, a new local statistical uncorrelated criterion is proposed, which effectively captures the local information of interclass and intraclass. Second, we reconstruct the affinity matrices of an intrinsic graph and a penalty graph, which are mentioned in LDE to enhance the discriminant property. Finally, it overcomes the small-sample-size problem without using principal component analysis to preprocess the original data, which avoids losing some discriminant information. Experimental results on Yale, ORL, Extended Yale B, and FERET databases demonstrate that LULDE outperforms LDE and other representative uncorrelated feature extraction methods.

关键词： Feature extraction     Local discriminant embedding     Local uncorrelated criterion     Face recognition    

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Lateral-torsional buckling capacity assessment of web opening steel girders by artificial neural networks

Yasser SHARIFI,Sajjad TOHIDI

《结构与土木工程前沿（英文）》 2014年 第8卷 第2期   页码 167-177 doi: 10.1007/s11709-014-0236-z

摘要： Bridge girders exposed to aggressive environmental conditions are subject to time-variant changes in resistance. There is therefore a need for evaluation procedures that produce accurate predictions of the load-carrying capacity and reliability of bridge structures to allow rational decisions to be made about repair, rehabilitation and expected life-cycle costs. This study deals with the stability of damaged steel I-beams with web opening subjected to bending loads. A three-dimensional (3D) finite element (FE) model using ABAQUS for the elastic flexural torsional analysis of I-beams has been used to assess the effect of web opening on the lateral buckling moment capacity. Artificial neural network (ANN) approach has been also employed to derive empirical formulae for predicting the lateral-torsional buckling moment capacity of deteriorated steel I-beams with different sizes of rectangular web opening using obtained FE results. It is found out that the proposed formulae can accurately predict residual lateral buckling capacities of doubly-symmetric steel I-beams with rectangular web opening. Hence, the results of this study can be used for better prediction of buckling life of web opening of steel beams by practice engineers.

关键词： steel I-beams     lateral-torsional buckling     finite element (FE) method     artificial neural network (ANN) approach    

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Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

《环境科学与工程前沿（英文）》 2007年 第1卷 第4期   页码 418-433 doi: 10.1007/s11783-007-0068-3

摘要： The challenge of making central requirements work at local levels is a common problem for environmental governance throughout the world. Countries can learn from one another s approaches, but must understand the local context in w
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标题 作者 时间 类型 操作

Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured pipeline

Mahdi IZADI, Khosrow BARGI

期刊论文

Cyclic responses of three 2-story seismic concentrically braced frames

Ching-Yi TSAI, Keh-Chyuan TSAI, Chih-Han LIN, Chih-Yu WEI, Kung-Juin WANG, Yi-Jer YU, An-Chien WU,

期刊论文

Thermal buckling behavior of laminated composite plates: a finite-element study

Houdayfa OUNIS,Abdelouahab TATI,Adel BENCHABANE

期刊论文

Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

期刊论文

基于高等分析的钢结构设计——材料建模与应变极限

Leroy Gardner, Xiang Yun, Andreas Fieber, Lorenzo Macorini

期刊论文

Finding buckling points for nonlinear structures by dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Hossein ESTIRI

期刊论文

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

期刊论文

Flexural-torsional buckling behavior of aluminum alloy beams

Xiaonong GUO,Zhe XIONG,Zuyan SHEN

期刊论文

Probabilistic stability of uncertain composite plates and stochastic irregularity in their buckling mode

期刊论文

Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

期刊论文

Experimental study on slender buckling-restrained knee braces with round steel bar cores

期刊论文

High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

期刊论文

Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

期刊论文

Lateral-torsional buckling capacity assessment of web opening steel girders by artificial neural networks

Yasser SHARIFI,Sajjad TOHIDI

期刊论文

Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

期刊论文