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Parametric analysis and design equation of ultimate capacity for unstiffened overlapped CHS K-joints

CHEN Yu, ZHAO Xianzhong, CHEN Yiyi

《结构与土木工程前沿(英文)》 2008年 第2卷 第2期   页码 107-115 doi: 10.1007/s11709-008-0014-x

摘要: A finite element model simulating an experiment on unstiffened, overlapped circular hollow structure (CHS) K-joints was generated and validated by comparing the ultimate capacities, deformation processes and failure modes of the experimental results. Using this model, the stress distribution, propagation of plasticity and the failure modes of overlapped joints with through-brace-in-compression and welded hidden seams were analyzed. The effect of geometric parameters, with or without hidden welds, and the loading hierarchy reversal of braces on the ultimate capacity of the joints were also studied. The results of finite element parametric analysis indicate that the brace-to-chord thickness ratio has relatively large effects on the failure mechanism and ultimate capacity of overlapped joints. It was also found that the absence of hidden welds has less significance on the ultimate capacity of through-brace-in-compression joints than through-brace-in tension joints. Finally, based on the design equation of gap joints, a formula predicting the ultimate capacity of overlapped CHS K-joints was derived by applying multivariate regression analysis. Results from the proposed design equation are consistent with experimental results.

关键词: regression analysis     consistent     unstiffened     plasticity     overlapped    

The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 456-461 doi: 10.1007/s11709-016-0334-1

摘要: The relationship between the convexity on the ultimate bearing surface of a structure and the second-order effects of loads is discussed. All of generalized non-overload forces acted on a structure forms a convex set when ignoring the second-order effects (coupling effects between the generalized forces). It is true also when the Hessian matrix composed of the second-order partial derivatives on the hypersurface about the ultimate bearing of the structure is negative definite. The outward convexity is kept when the surface is expressed by certain dimensionless parameters. A series of properties based on the convexity are pointed out. Some applications in the analysis of bearing capacity of structures were illustrated with examples. The study shows that an evaluation about the bearing capacity state of a complex structure can be made on the basis of several points on the surface of the ultimate bearing of the structure.

关键词: service     limit load     ultimate bearing surface     convexity     generalized force     generalized displacement     frame structure    

Stability analysis of large diameter thin-walled tube beam-columns

PAN Hanming, GUO Yanlin, LIANG Shuo, PEI Shengxing, LIANG Weisheng, WANG Lewen

《结构与土木工程前沿(英文)》 2008年 第2卷 第2期   页码 123-132 doi: 10.1007/s11709-008-0017-7

摘要: Based on a blind spot in the current design standard of steel structures, the large diameter thin-walled tube beam-columns are analyzed using nonlinear finite element method in this paper. The influence of several factors on stability capacity of the large diameter thin-walled tube beam-columns is taken into account. Thus, according to the correlative design standard of steel structures, and on the basis of the numerical analytical results by the finite element methods, the calculation formulas of the stability bearing capacity are presented for beam-column members of the large diameter thin-walled tubes. Three tests of thin-walled steel tube beam-columns were reported. Test results for deformations and ultimate strength are found to be in a good agreement with the corresponding values predicted by the calculation formulas, and the proposed methods can be used in design practice.

关键词: ultimate strength     nonlinear     numerical analytical     diameter thin-walled     practice    

DX旋挖挤扩灌注桩群桩数值分析研究

万飞,张德华

《中国工程科学》 2012年 第14卷 第1期   页码 46-50

摘要:

通过数值计算软件FLAC3D对DX旋挖挤扩灌注桩(简称DX桩)群桩的承载性状和桩周土体的沉降规律进行了研究。分析了桩间距、承力盘布置对群桩极限承载力和沉降控制能力的影响,并比较了6根基桩的DX群桩和8根基桩的直桩群桩的极限承载力。研究结果表明:DX群桩的基桩具有DX单桩的受力性状。承力盘下方土体位移大于承力盘上方土体位移,盘腔上部出现临空面。3D(D为盘径)桩间距的承载力和沉降控制能力最佳。同一地层内,承力盘布置方式(平行、错开布置)对DX群桩的承载力影响甚微。6根基桩的DX群桩的极限承载力是8根基桩的直

关键词: 桩基础     极限承载力     数值计算     DX群桩    

Higher heating value prediction of torrefaction char produced from non-woody biomass

Nitipong SOPONPONGPIPAT,Dussadeeporn SITTIKUL,Unchana SAE-UENG

《能源前沿(英文)》 2015年 第9卷 第4期   页码 461-471 doi: 10.1007/s11708-015-0377-3

摘要: The higher heating value of five types of non-woody biomass and their torrefaction char was predicted and compared with the experimental data obtained in this paper. The correlation proposed in this paper and the ones suggested by previous researches were used for prediction. For prediction using proximate analysis data, the mass fraction of fixed carbon and volatile matter had a strong effect on the higher heating value prediction of torrefaction char of non-woody biomass. The high ash fraction found in torrefied char resulted in a decrease in prediction accuracy. However, the prediction could be improved by taking into account the effect of ash fraction. The correlation developed in this paper gave a better prediction than the ones suggested by previous researches, and had an absolute average error (AAE) of 2.74% and an absolute bias error (ABE) of 0.52%. For prediction using elemental analysis data, the mass fraction of carbon, hydrogen, and oxygen had a strong effect on the higher heating value, while no relationship between the higher heating value and mass fractions of nitrogen and sulfur was discovered. The best correlation gave an AAE of 2.28% and an ABE of 1.36%.

关键词: higher heating value     correlation     biomass     proximate analysis     ultimate analysis    

The influence of hand hole on the ultimate strength and crack pattern of shield tunnel segment joints

Shaochun WANG, Xi JIANG, Yun BAI

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1200-1213 doi: 10.1007/s11709-019-0546-2

摘要: With the shield tunnel going deeper and deeper, the circumferential axial force becomes the governing factor rather than the bending moment. The hand hole acts as a weak point and initial damage in the segment joint especially when the circumferential axial force is extremely high. Despite the wide application of steel fiber or synthetic fiber in the tunneling, limited researches focus on the structural responses of segment joint with macro structural synthetic fiber (MSSF). In this paper, a 1:2 reduced-scale experiment was conducted to study the structural performance of the segment joint with different types of hand holes under ultra-high axial force. Special attention is paid to failure mode and structural performance (bearing capacity, deformation, cracking, and toughness). Moreover, segment joints with MSSF are also tested to evaluate the effects of MSSF on the failure mode and structural performance of the segment joints. The experiment results show that the hand hole becomes the weakest point of the segment joint under ultra-high axial force. A \ /-type crack pattern is always observed before the final failure of the segment joints. Different types and sizes of the hand hole have different degree of influences on the structural behavior of segment joints. The segment joint with MSSF shows higher ultimate bearing capacity and toughness compared to segment joint with common concrete. Besides, the MSSF improves the initial cracking load and anti-spallling resistance of the segment joint.

关键词: shield tunneling     structural synthetic fiber concrete     hand hole     segment joint     ultimate bearing capacity     crack pattern    

Ultimate load analysis of pretensioned inverted T-beams with circular web openings

Hock Tian CHENG , Bashar S. MOHAMMED , Kamal Nasharuddin MUSTAPHA ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 262-271 doi: 10.1007/s11709-009-0031-4

摘要: The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. In this paper, ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented. Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized. An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web openings. It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.

关键词: pretensioned inverted T-beam     web opening    

Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

《结构与土木工程前沿(英文)》 2014年 第8卷 第2期   页码 194-200 doi: 10.1007/s11709-014-0251-0

摘要: The paper presents a numerical study on the undrained lateral response of a single, free-head, reinforced concrete pile in soft clays. Soil conditions simulating normally consolidated clays are examined—undrained shear strength increasing with depth—and the pile-soil interaction under static lateral loading is analyzed. The nonlinear ? curves proposed in literature for soft clays are imported into a beam-on-nonlinear-Winkler-foundation simulation in order to predict the pile head lateral load—displacement curve and the distribution of the horizontal displacement and bending moment along the pile. The striking differences among these methods require further investigation via 3D finite element analyses. The determination of the ultimate soil resistance from the results of the finite element analyses aims at providing the estimation of a range of values for the ultimate soil resistance coefficient with depth and the comparison of the derived values to the corresponding ones proposed by existing methodologies.

关键词: laterally loaded     pile     soft clay     p?y curves     finite element method (FEM)    

Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1016-1024 doi: 10.1007/s11709-021-0751-7

摘要: This study investigated the use of recycled tire-derived aggregate (TDA) mixed with kaolin as a method of increasing the ultimate bearing capacity ( UBC) of a strip footing. Thirteen 1g physical modeling tests were prepared in a rigid box of 0.6 m × 0.9 m in plan and 0.6 m in height. During sample preparation, 0%, 20%, 40%, or 60% (by weight) of powdery, shredded, small-sized granular (G 1–4 mm) or large-sized granular (G 5–8 mm) TDA was mixed with the kaolin. A strip footing was then placed on the stabilized kaolin and was caused to fail under stress-controlled conditions to determine the UBC. A rigorous 3D finite element analysis was developed in Optum G-3 to determine the UBC values based on the experimental test results. The experimental results showed that, except for the 20% powdery TDA, the TDA showed an increase in the UBC of the strip footing. When kaolin mixed with 20% G (5–8 mm), the UBC showed a threefold increase over that for the unreinforced case. The test with 20% G (1–4 mm) recorded the highest subgrade modulus. It was observed that the UBC calculated using finite element modeling overestimated the experimental UBC by an average of 9%.

关键词: kaolin     physical modeling tests     stabilization     numerical modeling    

An experimental study on the flexural behavior of heavily steel reinforced beams with high-strength concrete

Yasser SHARIFI, Ali Akbar MAGHSOUDI

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 46-56 doi: 10.1007/s11709-014-0237-y

摘要: In recent years, an emerging technology termed high-strength concrete (HSC) has become popular in construction industry. Present study describes an experimental research on the behavior of high-strength concrete beams in ultimate and service state. Six simply supported beams were tested, by applying comprising two symmetric concentrated loads. Tests are reported in this study on the flexural behavior of high-strength reinforced concrete (HSRC) beams made with coarse and fine aggregate together with Microsilica. Test parameter considered includes effect of being compressive reinforcement. Based on the obtained results, the behavior of such members is more deeply reviewed. Also a comparison between theoretical and experimental results is reported here. The beams were made from concrete having compressive strength of 66.81–77.72 N/mm and percentage reinforcement ratio ( / ) in the range of 0.56% – 1.20%. The ultimate moment for the tested beams was found to be in a good agreement with that of the predicted ultimate moment based on ACI 318-11, ACI 363 and CSA-04 provisions. The predicted deflection based classical formulation based on code provisions for serviceability requirements is found to underestimate the maximum deflection of HSC reinforced beams at service load.

关键词: high-strength concrete (HSC) members     flexural behavior     reinforced concrete     experimental results     ultimate moment    

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

《中国工程科学》 2007年 第9卷 第6期   页码 64-70

摘要:

对设计强度为10MPa的混凝土立方体试件进行三轴压缩试验,系统研究了等围压条件下混凝土的强 度和变形特性,围压分别为0,4,8,12,16MPa5个量级;同时研究了不等围压条件下混凝土强度变化特性, 试验表明,随着围压增加,混凝土的极限抗压强度有明显增强的趋势;随着小主应力的增加,中主应力的影响 有减弱的趋势;峰值应力处应变随围压增加幅度显著。得出了在不同恒定围压下混凝土的应力应变全过程曲线; 通过与当前文献资料的对比分析,指出了在混凝土结构计算中适用的强度及变形表达式,为工程实践提供了 依据。

关键词: 三向受力状态     不等围压     极限强度     变形     混凝土    

Function and principle innovative design of mechanical products based on TRIZ/FA

YUAN Feng, WANG Tai-yong, NIE Hui-juan

《机械工程前沿(英文)》 2006年 第1卷 第3期   页码 350-355 doi: 10.1007/s11465-006-0031-1

摘要: Function and principle innovation is the ultimate innovation of a product. To achieve Function and principle innovation design of mechanical products, a new process model of function and principle solving is proposed, based on TRI

关键词: TRI     principle solving     product     principle innovation     ultimate innovation    

Evaluation of a novel Asymmetric Genetic Algorithm to optimize the structural design of 3D regular and irregular steel frames

Mohammad Sadegh ES-HAGHI, Aydin SHISHEGARAN, Timon RABCZUK

《结构与土木工程前沿(英文)》 2020年 第14卷 第5期   页码 1110-1130 doi: 10.1007/s11709-020-0643-2

摘要: We propose a new algorithm, named Asymmetric Genetic Algorithm (AGA), for solving optimization problems of steel frames. The AGA consists of a developed penalty function, which helps to find the best generation of the population. The objective function is to minimize the weight of the whole steel structure under the constraint of ultimate loads defined for structural steel buildings by the American Institute of Steel Construction (AISC). Design variables are the cross-sectional areas of elements (beams and columns) that are selected from the sets of side-flange shape steel sections provided by the AISC. The finite element method (FEM) is utilized for analyzing the behavior of steel frames. A 15-storey three-bay steel planar frame is optimized by AGA in this study, which was previously optimized by algorithms such as Particle Swarm Optimization (PSO), Particle Swarm Optimizer with Passive Congregation (PSOPC), Particle Swarm Ant Colony Optimization (HPSACO), Imperialist Competitive Algorithm (ICA), and Charged System Search (CSS). The results of AGA such as total weight of the structure and number of analyses are compared with the results of these algorithms. AGA performs better in comparison to these algorithms with respect to total weight and number of analyses. In addition, five numerical examples are optimized by AGA, Genetic Algorithm (GA), and optimization modules of SAP2000, and the results of them are compared. The results show that AGA can decrease the time of analyses, the number of analyses, and the total weight of the structure. AGA decreases the total weight of regular and irregular steel frame about 11.1% and 26.4% in comparing with the optimized results of SAP2000, respectively.

关键词: optimization     steel frame     Asymmetric Genetic Algorithm     constraints of ultimate load     constraints of serviceability limits     penalty function    

Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial force, traverse speed, and rotational speed

Biranchi PANDA,A. GARG,Zhang JIAN,Akbar HEIDARZADEH,Liang GAO

《机械工程前沿(英文)》 2016年 第11卷 第3期   页码 289-298 doi: 10.1007/s11465-016-0393-y

摘要:

Friction stir welding (FSW) process has gained attention in recent years because of its advantages over the conventional fusion welding process. These advantages include the absence of heat formation in the affected zone and the absence of large distortion, porosity, oxidation, and cracking. Experimental investigations are necessary to understand the physical behavior that causes the high tensile strength of welded joints of different metals and alloys. Existing literature indicates that tensile properties exhibit strong dependence on the rotational speed, traverse speed, and axial force of the tool that was used. Therefore, this study introduces the experimental procedure for measuring tensile properties, namely, ultimate tensile strength (UTS) and tensile elongation of the welded AA 7020 Al alloy. Experimental findings suggest that a welded part with high UTS can be achieved at a lower heat input compared with the high heat input condition. A numerical approach based on genetic programming is employed to produce the functional relationships between tensile properties and the three inputs (rotational speed, traverse speed, and axial force) of the FSW process. The formulated models were validated based on the experimental data, using the statistical metrics. The effect of the three inputs on the tensile properties was investigated using 2D and 3D analyses. A high UTS was achieved, including a rotational speed of 1050 r/min and traverse speed of 95 mm/min. The results also indicate that 8 kN axial force should be set prior to the FSW process.

关键词: tensile properties     ultimate tensile strength     tensile elongation     friction stir welding     tool rotational speed     genetic programming     welding speed    

DX旋挖挤扩灌注桩在LNG储存罐中的应用

贺德新,张成伟,郑建华,贺建彤,张新生

《中国工程科学》 2012年 第14卷 第1期   页码 19-25

摘要:

针对场地上部为吹填海砂、下部为粉砂的特殊地层条件,在储存罐的基础中采用了普通直孔灌注桩和三节DX旋挖挤扩灌注桩;通过现场自平衡载荷试验,判定桩的竖向抗压极限承载力和沉降量,分析桩的载荷传递机理,并对桩侧阻力、桩端阻力的分配和发展规律进行研究;同时通过对两种桩的试验结果进行对比,发现DX挤扩灌注桩的极限承载力、桩身沉降明显优于普通直孔灌注桩,而且DX桩的长度明显小于直孔桩。

关键词: DX旋挖挤扩灌注桩     桩侧阻力     桩端阻力     极限承载力     沉降    

标题 作者 时间 类型 操作

Parametric analysis and design equation of ultimate capacity for unstiffened overlapped CHS K-joints

CHEN Yu, ZHAO Xianzhong, CHEN Yiyi

期刊论文

The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

期刊论文

Stability analysis of large diameter thin-walled tube beam-columns

PAN Hanming, GUO Yanlin, LIANG Shuo, PEI Shengxing, LIANG Weisheng, WANG Lewen

期刊论文

DX旋挖挤扩灌注桩群桩数值分析研究

万飞,张德华

期刊论文

Higher heating value prediction of torrefaction char produced from non-woody biomass

Nitipong SOPONPONGPIPAT,Dussadeeporn SITTIKUL,Unchana SAE-UENG

期刊论文

The influence of hand hole on the ultimate strength and crack pattern of shield tunnel segment joints

Shaochun WANG, Xi JIANG, Yun BAI

期刊论文

Ultimate load analysis of pretensioned inverted T-beams with circular web openings

Hock Tian CHENG , Bashar S. MOHAMMED , Kamal Nasharuddin MUSTAPHA ,

期刊论文

Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

期刊论文

Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

期刊论文

An experimental study on the flexural behavior of heavily steel reinforced beams with high-strength concrete

Yasser SHARIFI, Ali Akbar MAGHSOUDI

期刊论文

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

期刊论文

Function and principle innovative design of mechanical products based on TRIZ/FA

YUAN Feng, WANG Tai-yong, NIE Hui-juan

期刊论文

Evaluation of a novel Asymmetric Genetic Algorithm to optimize the structural design of 3D regular and irregular steel frames

Mohammad Sadegh ES-HAGHI, Aydin SHISHEGARAN, Timon RABCZUK

期刊论文

Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial force, traverse speed, and rotational speed

Biranchi PANDA,A. GARG,Zhang JIAN,Akbar HEIDARZADEH,Liang GAO

期刊论文

DX旋挖挤扩灌注桩在LNG储存罐中的应用

贺德新,张成伟,郑建华,贺建彤,张新生

期刊论文