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Improved prediction of pile bending moment and deflection due to adjacent braced excavation

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0961-2

摘要： Deep excavations in dense urban areas have caused damage to nearby existing structures in numerous past construction cases. Proper assessment is crucial in the initial design stages. This study develops equations to predict the existing pile bending moment and deflection produced by adjacent braced excavations. Influential parameters (i.e., the excavation geometry, diaphragm wall thickness, pile geometry, strength and small-strain stiffness of the soil, and soft clay thickness) were considered and employed in the developed equations. It is practically unfeasible to obtain measurement data; hence, artificial data for the bending moment and deflection of existing piles were produced from well-calibrated numerical analyses of hypothetical cases, using the three-dimensional finite element method. The developed equations were established through a multiple linear regression analysis of the artificial data, using the transformation technique. In addition, the three-dimensional nature of the excavation work was characterized by considering the excavation corner effect, using the plane strain ratio parameter. The estimation results of the developed equations can provide satisfactory pile bending moment and deflection data and are more accurate than those found in previous studies.

关键词： pile responses     excavation     prediction     deflection     bending moments    

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Damage propagation and strength prediction of a single-lap interference-fit laminate structure

Peng ZOU, Xiangming CHEN, Hao CHEN, Guanhua XU

《机械工程前沿（英文）》 2020年 第15卷 第4期   页码 558-570 doi: 10.1007/s11465-020-0591-5

摘要： Experimental and finite element research was conducted on the bolted interference fit of a single-lap laminated structure to reveal the damage propagation mechanism and strength change law. A typical single-lap statically loading experiment was performed, and a finite element damage prediction model was built based on intralaminar progress damage theory. The model was programmed with a user subroutine and an interlaminar cohesive zone method. The deformation and damage propagation of the specimen were analyzed, and the failure mechanism of intralaminar and interlaminar damage during loading was discussed. The effect of secondary bending moment on load translation and damage distribution was revealed. The experimental and simulated load–displacement curves were compared to validate the developed model’s reliability, and the ultimate bearing strengths under different fit percentages were predicted. An optimal percentage was also recommended.

关键词： single-lap     interference fit     secondary bending moment     damage mechanism     bearing strength    

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Field validation of UHPC layer in negative moment region of steel-concrete composite continuous girder

Minghong QIU; Xudong SHAO; Weiye HU; Yanping ZHU; Husam H. HUSSEIN; Yaobei HE; Qiongwei LIU

《结构与土木工程前沿（英文）》 2022年 第16卷 第6期   页码 744-761 doi: 10.1007/s11709-022-0843-z

摘要： Improving the cracking resistance of steel-normal concrete (NC) composite beams in the negative moment region is one of the main tasks in designing continuous composite beam (CCB) bridges due to the low tensile strength of the NC deck at pier supports. This study proposed an innovative structural configuration for the negative bending moment region in a steel-concrete CCB bridge with the aid of ultrahigh performance concrete (UHPC) layer. In order to investigate the feasibility and effectiveness of this new UHPC jointed structure in the negative bending moment region, field load testing was conducted on a newly built full-scale bridge. The newly designed structural configuration was described in detail regarding the structural characteristics (cracking resistance, economy, durability, and constructability). In the field investigation, strains on the surface of the concrete bridge deck, rebar, and steel beam in the negative bending moment region, as well as mid-span deflection, were measured under different load cases. Also, a finite element model for the four-span superstructure of the full-scale bridge was established and validated by the field test results. The simulated results in terms of strains and mid-span deflection showed moderate consistency with the test results. This field test and the finite element model results demonstrated that the new configuration with the UHPC layer provided an effective alternative for the negative bending moment region of the composite beam.

关键词： field test     steel-concrete composite beam     continuous girder bridge     negative bending moment region     ultrahigh performance concrete    

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Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 412-423 doi: 10.1007/s11709-017-0416-8

摘要： Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.

关键词： instantaneous deflection     light-weight concrete     expanded polystyrene     effective moment of inertia     cracking moment     moment capacity     service moment    

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深层搅拌桩墙围护结构裂缝成因探讨

高文华,王祥秋,陈秋南,张志敏

《中国工程科学》 2005年 第7卷 第12期   页码 88-91

摘要：

针对基坑支护中深层搅拌桩墙围护结构出现的开裂，采用Mindlin厚板理论对其受力与变形性状进行弹塑性分析，建立了墙体的厚板力学模型和三维有限元分析模型，并编制了有限元分析程序；基于墙体受到纵向弯矩、横向弯矩和扭矩的综合作用，提出采用等效弯矩法评价墙体的综合抗弯性能；利用所编制的程序，获得了某基坑深层搅拌桩墙围护结构墙体水平位移和等效弯矩的空间分布规律；计算结果表明，墙体东侧环球广场横向支撑附加力的作用是使墙体形成破裂面的主要原因。

关键词： 裂缝     深层搅拌桩墙     厚板     等效弯矩     三维有限元    

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Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 926-936 doi: 10.1007/s11709-019-0527-5

摘要： In this paper, an empirical model based on self-evolving neural network is proposed for predicting the flexural behavior of ferrocement elements. The model is meant to serve as a simple but reliable tool for estimating the moment capacity of ferrocement members. The proposed model is trained and validated using experimental data obtained from the literature. The data consists of information regarding flexural tests on ferrocement specimens which include moment capacity and cross-sectional dimensions of specimens, concrete cube compressive strength, tensile strength and volume fraction of wire mesh. Comparisons of predictions of the proposed models with experimental data indicated that the models are capable of accurately estimating the moment capacity of ferrocement members. The proposed models also make better predictions compared to methods such as the plastic analysis method and the mechanism approach. Further comparisons with other data mining techniques including the back-propagation network, the adaptive spline, and the Kriging regression models indicated that the proposed models are superior in terms prediction accuracy despite being much simpler models. The performance of the proposed models was also found to be comparable to the GEP-based surrogate model.

关键词： ferrocement     moment capacity     self-evolving neural network    

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Shaking-moment balancing of mechanisms with principal vectors and momentum

V. van der WIJK

《机械工程前沿（英文）》 2013年 第8卷 第1期   页码 10-16 doi: 10.1007/s11465-013-0359-2

摘要：

The design of shaking-moment-balanced linkages still is challenging. Considering moment balance in the very beginning of the design process of mechanisms is important for finding applicable solutions. For this purpose, the method of principal vectors is investigated, showing a compact notation of the angular momentum with respect to the center of mass. The moment balance conditions are derived for three elements in series from which balance solutions are synthesized and illustrated. From the application for moment balancing of a 4R four-bar linkage it is shown that the moment balancing of closed kinematic chains remains challenging.

关键词： shaking-moment balancing     principal vector linkage     angular momentum    

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Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 345-351 doi: 10.1007/s11709-009-0054-x

摘要： In beam-to-column joint with bolted end-plate connection, the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed. The joint is divided into some basic components, and the initial stiffness of each component is obtained. Especially, the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis. The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component. The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method, and the design moment resistances of other components are deduced based on present codes. The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components. By comparison with the results of finite element calculation, it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.

关键词： steel structure     end-plate connection     backing plate     supplementary web plate     initial stiffness     moment resistance    

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A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

《结构与土木工程前沿（英文）》 2022年 第16卷 第1期   页码 75-85 doi: 10.1007/s11709-021-0798-5

摘要： An efficient and meshfree approach is proposed for the bending analysis of thin plates. The approach is based on the choice of a set of interior points, for each of which a basis function can be defined. Plate deflection is then approximated as the linear combination of those basis functions. Unlike traditional meshless methods, present basis functions are defined in the whole domain and satisfy the governing differential equation for plate. Therefore, no domain integration is needed, while the unknown coefficients of deflection expression could be determined through boundary conditions by using a collocation point method. Both efficiency and accuracy of the approach are shown through numerical results of plates with arbitrary shapes and boundary conditions under various loads.

关键词： plate     bending     meshless method     collocation    

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Rare-earth separation based on the differences of ionic magnetic moment via quasi-liquid strategy

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1584-1594 doi: 10.1007/s11705-022-2189-4

摘要： The separation of rare earth elements is particularly difficult due to their similar physicochemical properties. Based on the tiny differences of ionic radius, solvent extraction has been developed as the “mass method” in industry with hundreds of stages, extremely intensive chemical consumption and large capital investments. The differences of the ionic magnetic moment among rare earths are greater than that of ionic radius. Herein, a novel method based on the large ionic magnetic moment differences of rare earth elements was proposed to promote the separation efficiency. Rare earths were firstly dissolved in the ionic liquid, then the ordering degree of them was improved with the Z-bond effect, and finally the magnetic moment differences between paramagnetic and diamagnetic rare earths in quasi-liquid system were enhanced. Taking the separation of Er/Y, Ho/Y and Er/Ho as examples, the results showed that Er(III) and Ho(III) containing ionic liquids had obvious magnetic response, while ionic liquids containing Y(III) had no response. The separation factors of Er/Y and Ho/Y were achieved at 9.0 and 28.82, respectively. Magnetic separation via quasi-liquid system strategy provides a possibility of the novel, green, and efficient method for rare earth separation.

关键词： rare earth element     different magnetic moment     magnetic separation     ionic liquid    

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High-order moment methods for LRFD including random variables with unknown probability distributions

Zhao-Hui LU, Yan-Gang ZHAO, Zhi-Wu YU

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 288-295 doi: 10.1007/s11709-013-0210-1

摘要： The reliability-based load and resistance factors design (LRFD) has been widely used in the structural design codes. In almost all of the current reliability methods for the determination of the load and resistance factors, the basic random variables are assumed to have known probability distributions. However, in reality, the probability distributions of some of the basic random variables are often unknown due to the lack of statistical data. In this paper, the high-order moment methods for LRFD including random variables with unknown probability distributions are proposed. From the investigation of the present paper, it can be concluded that: 1) The load and resistance factors can be determined even when the probability distributions of the basic random variables are unknown; 2) The present method is convenient and more effective in estimating the load and resistance factors in practical engineering since it needs neither the iterative computation of derivatives nor any design points; 3) In the applicable range of the high-order moment method, although the load and resistance factors obtained by the proposed method may be different from those obtained by first order reliability method (FORM), the target mean resistances obtained by both methods are essentially the same.

关键词： high-order moment methods     applicable range     load and resistance factors     target mean resistance    

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Damage identification in connections of moment frames using time domain responses and an optimization

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 851-866 doi: 10.1007/s11709-021-0739-3

摘要： Damage is defined as changes to the material and/or geometric properties of a structural system, comprising changes to the boundary conditions and system connectivity, adversely affecting the system’s performance. Inspecting the elements of structures, particularly critical components, is vital to evaluate the structural lifespan and safety. In this study, an optimization-based method for joint damage identification of moment frames using the time-domain responses is introduced. The beam-to-column connection in a metallic moment frame structure is modeled by a zero-length rotational spring at both ends of the beam element. For each connection, an end-fixity factor is specified, which changes between 0 and 1. Then, the problem of joint damage identification is converted to a standard optimization problem. An objective function is defined using the nodal point accelerations extracted from the damaged structure and an analytical model of the structure in which the nodal accelerations are obtained using the Newmark procedure. The optimization problem is solved by an improved differential evolution algorithm (IDEA) for identifying the location and severity of the damage. To assess the capability of the proposed method, two numerical examples via different damage scenarios are considered. Then, a comparison between the proposed method and the existing damage identification method is provided. The outcomes reveal the high efficiency of the proposed method for finding the severity and location of joint damage considering noise effects.

关键词： damage identification     beam-to-column connection     time-domain response     optimization    

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growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and bending

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 905-913 doi: 10.1007/s11709-021-0683-2

摘要： In a nuclear powerplant, the rotary equipment, such as a pump directly fitted with hanger in the piping system, experiences torsional and bending loads. Higher crack growth rate occurs because of this torsional load in addition to the bending load. Hence, it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and bending load. In this study, experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 mm. The experimental crack depth was measured using alternating current potential drop technique. The fatigue life of the stainless steel straight pipe was predicted using experiments, Delale and Erdogan method, and area-averaged root mean square–stress intensity factor approach at the deepest and surface points of the notch. Afterward, the fatigue crack growth and crack pattern were discussed. As a result, fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

关键词： fatigue life     Delale and Erdogan method     RMS–SIF approach     stainless steel     torsion and bending load     fatigue crack growth    

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A novel structural modification to eliminate the early coupling between bending and torsional mode shapes

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 131-142 doi: 10.1007/s11709-016-0376-4

摘要： In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词： aeroelastic instability     structural damping     flutter wind speed     bending stiffness     torsional stiffness    

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Estimation of load and resistance factors using the third-moment method based on the 3P-lognormal distribution

Yan-Gang ZHAO, Zhao-Hui LU

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 315-322 doi: 10.1007/s11709-011-0117-7

摘要： Load and resistance factors are generally obtained using the first order reliability method (FORM) in which the design point should be determined and derivative-based iterations used. In this article, the third-moment reliability index, based on the three-parameter lognormal (3P-lognormal) distribution, is investigated. A simple method based on the third-moment method for estimating load and resistance factors is then proposed, and a simple formula for the target mean resistance is also presented to avoid iterative computations. Unlike the currently used method, the proposed method can be used to determine load and resistance factors, even when the probability density functions (PDFs) of the basic random variables are not available. Moreover, the proposed method does not require the iterative computation of derivatives or any design points. Thus, the method provides a more convenient and effective way to estimate load and resistance factors in practical engineering applications. Numerical examples are presented to demonstrate the advantages of the proposed third moment method for determining load and resistance factors.

关键词： load and resistance factors     third-moment method     three-parameter lognormal (3P-lognormal) distribution     target mean resistance     simple formula    

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标题 作者 时间 类型 操作

Improved prediction of pile bending moment and deflection due to adjacent braced excavation

期刊论文

Damage propagation and strength prediction of a single-lap interference-fit laminate structure

Peng ZOU, Xiangming CHEN, Hao CHEN, Guanhua XU

期刊论文

Field validation of UHPC layer in negative moment region of steel-concrete composite continuous girder

Minghong QIU; Xudong SHAO; Weiye HU; Yanping ZHU; Husam H. HUSSEIN; Yaobei HE; Qiongwei LIU

期刊论文

Instantaneous deflection of light-weight concrete slabs

Behnam VAKHSHOURI, Shami NEJADI

期刊论文

深层搅拌桩墙围护结构裂缝成因探讨

高文华,王祥秋,陈秋南,张志敏

期刊论文

Estimating moment capacity of ferrocement members using self-evolving network

Abdussamad ISMAIL

期刊论文

Shaking-moment balancing of mechanisms with principal vectors and momentum

V. van der WIJK

期刊论文

Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

期刊论文

A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

期刊论文

Rare-earth separation based on the differences of ionic magnetic moment via quasi-liquid strategy

期刊论文

High-order moment methods for LRFD including random variables with unknown probability distributions

Zhao-Hui LU, Yan-Gang ZHAO, Zhi-Wu YU

期刊论文

Damage identification in connections of moment frames using time domain responses and an optimization

期刊论文

growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and bending

期刊论文

A novel structural modification to eliminate the early coupling between bending and torsional mode shapes

Nazim Abdul NARIMAN

期刊论文

Estimation of load and resistance factors using the third-moment method based on the 3P-lognormal distribution

Yan-Gang ZHAO, Zhao-Hui LU

期刊论文