Office
Journal Information
  • 工程力学
    Engineering Mechanics
    (月刊,1984年创刊)
    主管单位:中国科学技术协会
    主办单位:中国力学学会
    主  编:陆新征
    编辑出版:《工程力学》编辑部
    ISSN 1000-4750 CN 11-2595/O3
30 Most Down Articles
Published in last 1 year | In last 2 years| In last 3 years| All| Most Downloaded in Recent Month | Most Downloaded in Recent Year|

All
Please wait a minute...
For Selected: Toggle Thumbnails
The significance, the key technical problems and the mechanical problems of Qinghai-Tibetan Railway
Liang bo;Chen Xingchong
Engineering Mechanics    2004, 21 (S1): 139-149.  
Abstract785)      PDF(pc) (3515KB)(33039)       Save
Considering the highest altitude, the severely natural environment and the complex geological conditions of Qinghai-Tibetan plateau, recalling about the present research on frozen soil and the history of Qinghai-Tibetan Railway, the article explain the specialty, complexity and feasibility of Qinghai-Tibetan Railway as well as its significance in West Development of China. The article discussed the key technical problems of subgrade engineering, bridge engineering and tunnel engineering. Thus gave clearly understanding on the aims and focuses of different tests and researches. These tests and researches provide a foundation for different technology or engineering measure to apply in Qinghai-Tibetan Railway. According to the research task of Lanzhou Jiaotong University, the mechanical character and principle of part of structure shape were discussed under permafrost condition and the difficulty and specialty were compared at the same time. These analyses are useful for further research. In a word, through the operations of Qinghai-Tibetan Highway over past decades and the construction of Qinghai-Tibetan Railway in recent three years. The three key technical problems are mainly concentrated on frozen soil. The real research about frozen soil would be a long and tough process.
Related Articles | Metrics
"TEST STUDY ON HYSTERETIC BEHAVIOR OF PEC COLUMNS (STRONG AXIS) FABRICATED WITH CRIMPING THIN-WALLED BUILT-UP SECTION "
FANG You-zhen,MA Ji,LU Cheng-duo,QU Yan-quan,SHEN Lin
Engineering Mechanics    2013, 30 (3): 181-190.   DOI: 10.6052/j.issn.1000-4750.2011.09.0640
Abstract1140)      PDF(pc) (19321KB)(3772)       Save

In order to alleviate the mechanics defects of PEC columns fabricated with thin-walled built-up sections as the biaxial unequal flexural stiffness and concentration of local buckling in flanges, new PEC columns fabricated with crimping thin-walled built-up sections were put forward. The transverse steel sheet links-spacing was taken as a primary design parameter, 4 specimens were designed and fabricated by full-scale. The tests of specimens were conducted with constant axial compression and low-cycle lateral reversed loading in the column strong axis, the local buckling in the flange of a crimping thin-walled built-up section and the crack forming and crushing of concrete were investigated, the load-displacement hysteretic curves were obtained. Base on the test results, the specimens’ relative performance were analyzed, including the load-carrying capacity, lateral stiffness, the seismic ductility and energy-dissipation capacity, the deformation pattern and failure mode. The conclusion showed that all specimens exhibited soundly deformation and energy-dissipation capacity resulted from the post-buckling performance of crimping flanges were utilized fully; the failure mode is primarily induced by the local buckling region growing in flanges of crimping thin-walled built-up sections with large-area crushing and spalling of concrete at the corner region of a column.

Reference | Related Articles | Metrics
COMPARISON STUDY OF CONSTITUTIVE MODEL OF CONCRETE IN ABAQUS FOR STATIC ANALYSIS OF STRUCTURES
NIE Jian-guo,WANG Yu-hang
Engineering Mechanics    2013, 30 (4): 59-67.   DOI: 10.6052/j.issn.1000-4750.2011.07.0420
Abstract2583)      PDF(pc) (964KB)(2128)       Save

The smeared crack and plasticity damage models in general finite element program ABAQUS were detailed introduced, including the uniaxial stress-strain relationship, crack model, yield criterion, flow rules and hysteretic rules. Then comparison and analysis were made on the key factors of concrete constitutive models that have effect on the static mechanical behavior of structural members. The mechanical behavior of reinforced concrete members and steel-concrete composite members under monotonic and cyclic loadings were simulated using various concrete constitutive models, thusly the suitable model could be chosen when analyzing structural members according to the comparison results.

Reference | Related Articles | Metrics
Engineering Mechanics    1985, 2 (2): 132-137.  
Abstract1093)      PDF(pc) (2438KB)(1863)       Save
Related Articles | Metrics
DEVELOPMENT AND APPLICATION OF STEEL-CONCRETE COMPOSITE FIBER BEAM MODEL IN ABAQUS PLATFORM
NIE Jian-guo;WANG Yu-hang;
Engineering Mechanics    2012, 29 (1): 70-80.   DOI: 10.6052/j.issn.1000-4750.2010.04.0278
Abstract1625)      PDF(pc) (1263KB)(1852)       Save

A steel-concrete composite fiber beam model is developed in this paper, which can divide the composite sections into fibers and the user-defined uniaxial hysteretic material constitutive model can be incorporated in subprogram UMAT provided by ABAQUS. The steel-concrete composite fiber beam model can be used to perform global elasto-plastic analysis of composite frames with full connections subjected to the combined action of gravity and cyclic lateral loads. The model is verified through a number of experiments showing that the composite fiber beam model developed by authors possesses good accuracy and wide applicability compared with the traditional finite element model. Although the fiber beam model neglects the slip between steel beam and concrete slab, the accuracy of global predictions of steel-concrete composite frames is not affected. So the developed steel-concrete fiber beam model possesses modelling simplicity and calculation efficiency, and is suitable for the seismic analysis of steel-concrete composite frames.

Related Articles | Metrics
EXTENDED FINITE ELEMENT METHOD BASED ON ABAQUS
FANG Xiu-jun;JIN Feng
Engineering Mechanics    2007, 24 (7): 0-010.  
Abstract1678)      PDF(pc) (395KB)(1830)       Save
A virtual node method for coupling the eXtended Finite Element Method (XFEM) with commercial finite element software ABAQUS is presented. The relationship between the subdomain integration and the Heaviside function is formulated, and a subtriangle integration algorithm is improved. The brittle fracture process of a 3-point bending beam was simulated. The computational results demonstrate the capacity of the presented method to simulate the moving discontinuities. Crack path is not necessary to coincide with element boundaries in XFEM and re-meshing can be avoided. The coupling with commercial finite element software proposes an efficient way for solving practical complex problem using XFEM.
Related Articles | Metrics
CONSTITUTIVE PARAMETRIC EXPERIMENT OF TIRE RUBBER HYPERELASTIC LAWS WITH APPLICATION
GONG Ke-jia;WEI Yin-tao;YE Jin-xiong
Engineering Mechanics    2009, 26 (6): 193-198.  
Abstract1498)      PDF(pc) (361KB)(1701)       Save
An accurate material parameter of rubber has a key influence in tire FEA. Based on the image analysis, an entire test system was developed and applied to perform a uniaxial tension, biaxial tension and planar tension tests of rubbers usually used by truck tires. The stability, reliability and accuracy of some constitutive laws are researched by the basis of these test results, such as Polynomial, Ogden and Arruda-boyce etc. These results show that the biaxial tension and planar tension test are necessary for the inflation and static loading analysis of a TBR tire. The numerical simulation results prove that the contact pressure and the maximum strain energy density depend on the rubber constitutive parameters seriously and the Polynomial (2 order) and Ogden constitutive laws have better FEA results for tire rubber.
Related Articles | Metrics
EXPERIMENTAL STUDY ON PANCAKE COLLAPSE OF RC SPACIAL SLAB-COLUMN STRUCTURES UNDER EARTHQUAKE
WU Bo,WANG Ming-jun,ZHAO Xin-yu
Engineering Mechanics    2013, 30 (1): 277-287.   DOI: 10.6052/j.issn.1000-4750.2011.06.0411
Abstract485)      PDF(pc) (23808KB)(1659)       Save

Shaking table tests were conducted for two three-story spacial slab-column structure models with weak stories. The El-Centro (NS) earthquake record was used to produce the excitation and its peak acceleration increased gradually until the pancake collapse of the weak story occurred. Horizontal accelerations were recorded for all stories before and after the occurring of pancake collapse. The vertical accelerations induced by the pancake collapse were also recorded for the floor slabs of the weak story and the story just below. Model M-2 had more weight than Model M-1. Test results show that: 1) with the increasing of the seismic damage degree, the models’ torsional responses increased; 2) the fundamental frequencies of Models M-1 and M-2 prior to the occurring of pancake collapse were only 8.9% and 4.7% lower than their initial values respectively, indicating that it may be impractical to use the change of frequency to predict structural collapses; 3) intensive fluctuation occurred in a very short time period for the horizontal acceleration of each story due to the pancake collapse; and the maximum absolute accelerations of Models M-1 and M-2 during the fluctuating period were in a range of 5g~10g, 5~20 times larger of M-1’s and 10~50 times larger of M-2’s maximum absolute accelerations respectively; 4) the vertical accelerations of the weak story floor slab and the floor slab just below the weak story induced by the pancake collapse were in a range of 30g~40g.

Reference | Related Articles | Metrics
APPLICATION OF LACONIC NOTATIONS IN FORMULA DERIVATION AND CALCULATION OF COMPONENTS IN TENSOR ANALYSIS
SHI Jiao;WANG Zheng-zhong;CAI Kun
Engineering Mechanics    2006, 23 (10): 45-48.  
Abstract789)      PDF(pc) (206KB)(1657)       Save
Tensor analysis plays an important role in computational mechanics. Due to its complexity, the theory is hard to be accepted and applied conveniently. To solve this problem, laconic notations for tensors are presented here to simplify formula derivation in tensor analysis. These notations are different from traditional ones of tensors. They are similar to arrays used in Fortran routine or commercial software Matlab. Laconic notations for the operations of tensors such as dyadic product, inner product and transposition etc. are given, respectively. By this method, one can derive formula easily and accurately. Another point in this work is that a simple method of obtaining the components of a fourth-order tensor is presented by introducing the concept of vectorization of matrix. It makes the components of high-order tensors to be visual and straightforward for symbolic operation and numerical calculation. The theory of tensor analysis will be easy to master if one grasps these two points of this article.
Related Articles | Metrics
DUCTILE DAMAGE ANALYSIS FOR FRACTURE IN SHEET METAL FORMING BASED ON GTN MESOSCOPIC DAMAGE MODEL
CHEN Zhi-ying;DONG Xiang-huai
Engineering Mechanics    2009, 26 (7): 238-244.  
Abstract1942)      PDF(pc) (388KB)(1595)       Save
Based on the Gurson-Tvergaard-Needleman (GTN) mesoscopic damage constitutive model, a finite element numerical method is developed to describe the damage and fracture problems in the sheet metal forming. It combines the implicit stress integration method and the explicit finite element solving algorithm. The plastic anisotropic behavior is also considered. The GTN damage models are implemented in the commercial finite element software ABAQUS by using the user material subroutine VUMAT to simulate the damage and failure process in AA5052-O aluminum alloy deep cup drawing. Experiments and numerical analysis of damage and fracture are performed with different sheet diameters. Numerical results show that the GTN damage model can effectively reveal the complicated damage behavior and predict the fracture of the sheet metal forming. The theoretical results of the damage model are in good agreement with the experimental observations. The fracture tendency of the cups increases with the increase of the initial sheet diameter.
Related Articles | Metrics
NONLINEAR FINITE ELEMENT ANALYSIS OF STEEL PLATE-CONCRETE COMPOSITE BEAMS
ZHAO Jie;NIE Jian-guo
Engineering Mechanics    2009, 26 (4): 105-112.  
Abstract1384)      PDF(pc) (388KB)(1416)       Save
Based on the experimental study of eight Steel Plate-Concrete Composite (SPCC) beams, the numerical studies on the entire process of the loading and other structural behaviour in the flexural failure and steel plate bonding failure of SPCC beams are conducted in the platform of ABAQUS. The nonlinear behavior of materials, load-slip behavior and fracture model of studs are taken into account in the analysis. The results of the finite element analysis are found to be in good agreement with the experimental results. The main parameters affecting the behavior of SPCC beams are analyzed, including the thickness and the length of steel plate and the space between studs, etc. The result shows that the ultimate shear strength of studs should be reduced in design in order to make sure SPCC beams fail in flexural failure mode.
Related Articles | Metrics
STUDY ON CONCEPT AND CHARACTERISTICS OF SEISMIC JERK RESPONSE SPECTRA
HE Hao-xiang;YAN Wei-ming;CHEN Yan-jiang
Engineering Mechanics    2011, 28 (11): 124-129.  
Abstract3131)      PDF(pc) (351KB)(1370)       Save
Jerk is the time rate of acceleration, reflecting the variation of structural forces. The study on jerk and its response spectra can enhance the recognitions on the non-stationary of ground motion. The mechanical meaning and research value of jerk is described. The calculating methods for jerk are discussed and their performance and disadvantages are compared. The solution method of elastic and inelastic jerk response spectra under ground motion is established. The characteristics of jerk response spectra are studied according to the influencing factors, such as a site condition, an amplification factor, a ductility factor and a reduction factor. The concept of an impact reduction factor is presented. The analysis results show that jerk influences the building structures with short or middle periods more obviously, and the impact responses can be reduced significantly when the structural ductility is enhanced. The impact reduction factor increases with the incensement of a structural natural period and the influence of jerk on long-period structure can be ignored.
Related Articles | Metrics
ANALYSIS FOR DEVELOPMENT AND UTILIZATION OF UNDERGROUND SPACE IN GUANGZHOU
ZHANG Ji-chao;DING Xiao-min;PANG Yong-shi;LI Wu-ping;TONG Hua-wei;ZHENG Xian-chang;XU Yong
Engineering Mechanics    2009, 26 (增刊Ⅱ): 106-114.  
Abstract1310)      PDF(pc) (4059KB)(1311)       Save
The development and utilization of urban underground space is conducive to improve the urban functions and give full play to the city’s social benefits, environmental benefits and economic benefits. This article introduced the home’s status quo of the development and utilization of urban underground space, and then a new axis of urban underground space as an example. Details of the new technology, investment and financing patterns were also presented, thus a reference was provided for other similar projects.
Related Articles | Metrics
THE EXTENDED FINITE ELEMENT METHOD AND ITS RELATIONS WITH OTHER NUMERICAL METHODS
JIN Feng;FANG Xiu-jun
Engineering Mechanics    2008, 25 (增刊Ⅰ): 0-017.  
Abstract1063)      PDF(pc) (1208KB)(1298)       Save
The development of an extended finite element method (XFEM) is investigated and the relation between XFEM and some other numerical methods is illustrated. First, the backgrounds and the development of meshfree methods are surveyed. Comparative analysis of them is given from the phase of approximation construction. Based on the general form of partition of unity, the characteristics of XFEM and the relations with conventional FE and other meshfree methods are presented. The main research domain about the applications and theory foundation of XFEM are summarized. And the prospect of XFEM is evaluated.
Related Articles | Metrics
Engineering Mechanics    1997, 14 (4): 139-144.  
Abstract529)      PDF(pc) (253KB)(1286)       Save
Related Articles | Metrics
EXPERIMENTAL INVESTIGATIONS OF RELEASABLE ENERGY AND DISSIPATIVE ENERGY WITHIN ROCK
LI Li-yun;;XIE He-ping;;JU Yang;MA Xu;WANG Li
Engineering Mechanics    2011, 28 (3): 35-040.   DOI: 10.6052/j.issn.1000-4750.2009.08.0584
Abstract1435)      PDF(pc) (15244KB)(1278)       Save

The failure of an underground rock structure is a synthetic process of energy dissipation and energy release. The releasable strain energy stored in rock structure and dissipated energy mainly depend on the unloading elastic modulus and Poisson’s ration of rocks in-situ and are related to the loading rate and load level. In this paper, static cyclic loading-unloading uniaxial compression tests under different loading rates are carried out. The variation laws of unloading elastic modulus and Poisson’s ratio, as well as the releasable strain energy and dissipated energy are obtained. The SHPB impact tests are also conducted and the total absorbed energy is measured. The testing analysis results can be used for the calculation of releasable strain energy, dissipated energy in a rock structure and for the prediction of rock structure failure.

Related Articles | Metrics
LOAD SPECTRUM AND FATIGUE LIFE ANALYSIS OF THE BLADE OF HORIZONTAL AXIS WIND TURBINE
LI De-yuan;YE Zhi-quan;CHEN Yan;BAO Neng-sheng
Engineering Mechanics    2004, 21 (6): 118-123.  
Abstract906)      PDF(pc) (373KB)(1254)       Save
This paper presents the load spectrum and an engineering estimating method of the fatigue life of GRP blade of large-scale wind turbine. The distribution of aerodynamic loads which affect the fatigue life of the blade are analyzed using strip theory. The stiffening effects of the rotating blade are discussed, using the multi-body dynamics method. The influence of the dynamic stiffening effect on the blade vibration mode is then analyzed. The dynamic stress response caused by the deterministic dynamic loads such as aerodynamic load, gravitational load and rotating centrifugal load, etc., is calculated using finite element mode superposition method. The fatigue damage performance, fatigue damage rule and fatigue life estimate method of GRP blade are discussed. Based on the Palmgren Miner linear fatigue damage accumulation rule, a safety life estimate method is developed. The fatigue life estimate of the 1.5MW variable speed pitch regulated wind turbine blade shows that the GRP blade fatigue life estimate method is reliable and feasible.
Related Articles | Metrics
A SUMMARY REVIEW AND ADVANTAGES OF VIBRATION-BASED DAMAGE IDENTIFICATION METHODS IN STRUCTURAL HEALTH MONITORING
ZHU Hong-ping;YU Jing;ZHANG Jun-bing;
Engineering Mechanics    2011, 28 (2): 1-011,.   DOI: 10.6052/j.issn.1000-4750.2010.06.ST03
Abstract1538)      PDF(pc) (412KB)(1231)       Save

The vibration-based damage identification method has been rapidly developed in the past few decades. The basic idea behind this technology is that the vibration characteristics (such as frequency, mode shape, modal damping, etc.) are functions of the physical properties of the structure (such as mass, damping and stiffness). Therefore, changes in the physical properties will cause detectable changes in the vibration characteristics. In this paper, the meaning, application status and classification of vibration-based damage identification methods in structural health monitoring are described. The structural damage detection methods based on dynamic characteristics and recognition algorithms are presented, and their advantages and shortcomings are analyzed. Finally, some topics which are worth studying further and the future trends for damage detection of civil engineering structures are proposed.

Related Articles | Metrics
A DRUCKER-PRAGER CONSISTENT RATE-DEPENDENT MODEL
XIAO Shi-Yun;LIN Gao;WANG Zhe
Engineering Mechanics    2003, 20 (4): 147-151.  
Abstract1555)      PDF(pc) (199KB)(1194)       Save
According to viscoplastic consistency model and the dynamic experimental results of concrete, a Drucker-Prager consistent rate-dependent model is set up. It evolves from the classical Drucker-Prager model by incorporating the effect of strain rate on concrete. Compared with experiment results, the model can predict the dynamic behavior of concrete accurately. A plane beam is studied using the model. The results are compared with those of the linear elastic model and rate-independent plastic model. The comparison shows that the dynamic behavior of the beam exhibits significant change when the effect of strain rate is considered.
Related Articles | Metrics
BOND-SLIP CONSTITUTIVE MODEL BETWEEN GFRP/STEEL WIRE COMPOSITE REBARS AND CONCRETE
HAO Qing-duo;WANG Yan-lei;HOU Ji-lin;OU Jin-ping;
Engineering Mechanics    2009, 26 (5): 62-072.  
Abstract1647)      PDF(pc) (469KB)(1182)       Save
The bond behavior is the basis of collaboration between GFRP/steel wire composite rebar and concrete, and the bond-slip constitutive model is the overall reflection of bond behavior of GFRP/steel wire composite rebar embedded in concrete. Thus, the research on the constitutive model of bond-slip relationship between GFRP/steel wire composite rebar and concrete has theoretical and practical value in the performance analysis, design theory and engineering application of concrete structures reinforced with GFRP/steel wire composite rebars. In this study, 180 pull-out specimens were tested to investigate the effect of rebar rib spacing, rebar diameter, embedded length, concrete compressive strength, concrete cover thickness, and concrete cast depth on bond behavior, and the bond-slip curves were obtained for each specimen. Based on the existing bond-slip constitutive models worldwidely, one new bond-slip constitutive model was proposed according to the analysis of bond failure, bond-slip mechanism, and loading process of GFRP/steel wire composite rebar. The newly built bond-slip constitutive model was compared with the test results and existing bond-slip models. It is explicit in physical concept and simple in form, and fits the whole loading process of GFRP ribbed rebar and the test results well.
Related Articles | Metrics
STRUCTURAL HEALTH MONITORING—INTELLIGENT INFORMATION PROCESSING AND APLLICATION
JIANG Shao-fei
Engineering Mechanics    2009, 26 (增刊Ⅱ): 184-212.  
Abstract1934)      PDF(pc) (626KB)(1176)       Save
A number of large-scale complex structures have been built promoted by the development of economy, science and technology. It is an interesting issue how to monitor and manage these large structures so that the alarm will be warned before various accidents occur, thus the disaster loss can be decreased to the minimum. Numerous large long-term structural health monitoring systems have been developed and installed in China. However, another problem arise gradually how to effectively deal with the huge and abundant measured information from a structural health monitoring system, thus to asses structural condition states. In view of this, intelligent information processing, which is a process of transforming the incomplete, imprecise, inconsistent and uncertain information into complete, precise, consistent and certain information, provides an approach and technique assurance to solve the above difficulties. This paper startes from the structural health monitoring and its primary issues, and then presentes a survey and overview of the intelligent information and its application in structural health monitoring and damage diagnosis, including modern signal processing, neural network, fuzzy theory, data/ information fusion, fractal theory, rough set and evolutionary computation. Further research in the future are discussed finally. This study shows that intelligent information processing technique is one of the efficient processing tools and techniques in structural health monitoring and it also represents the effort direction in the future.
Related Articles | Metrics
DESIGN OF FLEXURE HINGES
WU Ying-fei;ZHOU Zhao-ying
Engineering Mechanics    2002, 19 (6): 136-140.  
Abstract868)      PDF(pc) (194KB)(1106)       Save
This paper presents the compliance equations for rectangular single-axis hinges and right circular hinges. The equations are given in closed-form and concise expressions so that they are handy for design. Comparison is made between the present equations and those of widely used J. M. Paros' equations. Results indicate that the present equations are simple and effective, particularly for the right circular hinges. Some suggestions are made in regard to the design of flexure hinges.
Related Articles | Metrics
APPLICATION OF STABILIZATION DIAGRAM FOR MODAL PARAMETER IDENTIFICATION USING STOCHASTIC SUBSPACE METHOD
CHANG Jun;;ZHANG Qi-wei;SUN Li-min
Engineering Mechanics    2007, 24 (2): 0-044.  
Abstract1700)      PDF(pc) (389KB)(1099)       Save
Parameter identification is currently one of the main research topics in the area of structural health monitoring. Stochastic subspace identification is a novel approach developed in recent years. It can identify modal parameters of linear structure from its ambient vibration. The key issue in stochastic subspace identification is to obtain the order of the system. Stabilization diagram is a novel approach to identify the order of the system, but it may yield false modes. An improved stabilization diagram is presented so that false modes can be distinguished and more precise identification results can be obtained. The improvement to stabilization diagram is to distinguish the false modes by using modal assurance criteria. At the same time, because the present damping theory does not accord to actual damping, the identified results are not satisfactory. Therefore, structural damping is eliminated or loosed in stabilization diagram, and more precise results are obtained. Improved stabilization diagram method is evaluated by numerical simulation on a three-span continuous beam.
Related Articles | Metrics
DEVELOPMENT AND PROSPECTS OF HEAT PRESERVING AND ENERGY CONSERVATION WALL SYSTEM IN BUILDINGS
ZHANG Ze-ping;LI Zhu;DONG Yan-li
Engineering Mechanics    2007, 24 (增刊Ⅱ): 0-128.  
Abstract777)      PDF(pc) (391KB)(1093)       Save
With the rapid development of economy, the shortage of energy resources has become a serious problem in China. To meet the requirements of sustainable development, a number of worldwide researchers have been attracted by energy efficiency. By analyzing the importance of thermal-insulating and energy-saving and the policy requirements in buildings, the conclusion is drawn out that energy-saving walls plays a key role in improving building energy efficiency. The national classification of thermal-insulating and energy-saving walls, their characteristics and some construction technique are discussed. Meanwhile, a new environmental friendly material is introduced, named as glazed-hollow bead which could be used in the new thermal-insulating and energy-saving wall system. Finally, combined with the actual state in China, some suggestions are proposed on the further development of thermal-insulating and energy-saving walls in civil engineering.
Related Articles | Metrics
TEST STUDY ON OVERLOAD AND ULTIMATE BEHAVIOR OF OLD REINFORCED CONCRETE BRIDGE THROUGH DESTRUCTIVE TEST OF CORRODED BRIDGE
ZHANG Jian-ren;PENG Hui;ZHANG Ke-bo;HAO Hai-xia
Engineering Mechanics    2009, 26 (增刊Ⅱ): 213-224.  
Abstract1332)      PDF(pc) (3663KB)(1083)       Save
Long time employment and frequent overload will result in structural damage and deterioration of bridges, therefore the overload and ultimate behavior of these bridges and their actual capacity are always important concerns of researchers worldwide. Although the actual bridge destruction tests are the most effective way to research in this field, the limitations of tests opportunities, cost and difficulties makes them seldom be carried out. This paper conducted a destruction test on a forty-three years old reinforced concrete simply supported T-beam bridge in Changsha City Hunan Province, when it was to be torn down for rebuilding. The experiment employed 8-12 hydraulic rams to simulate the over-load of the two-axle and three-axle trucks, to study the overload behavior of the bridge under simulated vehicle loads, and the damage accumulation resulting from the loading cycles was also analyzed. Furthermore, two 500t jacks were used to load the bridge till its destruction, and the mechanical performance of bridge during the whole process and the structure reaction in ultimate conditions were investigated. In this paper, some innovative work was made, which will contribute to the development of the design theory and the rating method of bridges.
Related Articles | Metrics
THE EXTREME WIND SPEED PREDICTING MODEL OF TYPHOON BY USING MONTE-CARLO METHOD
CHEN Zhao-hui;TANG Hai-tao
Engineering Mechanics    2009, 26 (增刊 I): 193-197.  
Abstract1445)      PDF(pc) (287KB)(1071)       Save
Taking Xiamen as an example, based on the assumption of Batts wind field model and numerical simulated wind speed data of typhoon by using Monte-Carlo method, the distribution functions of extreme wind speed were analyzed and the maximum wind speeds in different return periods were predicted. The numerically simulated results of the extreme distribution functions are coincide with those of empirical distribution function. Compared with the analysis results of different extreme distribution functions, such as Gumbel distribution function, Fréchet distribution function, reverse Weibull distribution function, and Generalized Parato distribution function, the reverse Weibull distribution function provides the most reasonable prediction of maximum wind speed in 100 years of return period, while the predicting values of Fréchet distribution function are significantly different from the historical data. In addition, the extreme wind speeds of different return periods in Xiamen were estimated.
Related Articles | Metrics
NUMERICAL WIND TUNNEL TECHNIQUE FOR THE WIND RESISTANCE ANALYSIS OF LONG SPAN SPATIAL STRUCTURES
MA Jun;ZHOU Dai;LI Hua-feng;ZHU Zhong-yi;DONG Shi-lin
Engineering Mechanics    2007, 24 (7): 0-085,.  
Abstract1028)      PDF(pc) (714KB)(1054)       Save
Based on Computational Fluid Dynamics (CFD), the numerical wind tunnel technique (NWTT) is studied, which is effectively applied to the investigation of the wind pressure distribution of complicated structural shapes. The wind fields around and close to structural surface and the wind-load shape coefficients were calculated. Some comparisons between numerical results and wind tunnel model test data were carried out. The changes of the wind-load shape coefficients and wind fields around the structures caused by other structural system were analyzed, and the possible errors and their reasons of the wind tunnel model test were discussed by means of the NWTT. Based on the wind pressure contours or constant value line of wind-load shape coefficients, the sub-areas subjected to different wind actions were plotted and the local wind-load shape coefficients corresponding to these sub-areas were obtained in terms of area weighted average strategy. Additionally, the wind-load shape coefficients under different wind angles were analyzed.
Related Articles | Metrics
RECONSTRUCTED FATIGUE RELIABILITY S-N CURVES OF ZG230-450 CAST STEEL
PENG Yu-ling;ZHAO Yong-xiang;HU Hai-bin
Engineering Mechanics    2007, 24 (10): 0-050.  
Abstract1321)      PDF(pc) (403KB)(1034)       Save
The commonly fatigue reliability curves with few of given reliability levels can do only reliability design and life prediction with the given reliability levels. For the realization of reliability design, fatigue life prediction and reliability assessment at arbitrary reliability level, reconstruction of the fatigue reliability S-N curves is essential in an entire probability sense. The fatigue limits and the S-N data of railway vehicle ZG230-450 wheel cast steel are first re-constructed by a Monte Carlo simulation with an acceptable error range. The basic reliability curves in the mid-and-short life regime are then estimated by the general maximum likelihood method. The reliability S-N curves of the material covering the mid-and-short life regime and the long life regime are finally established by a so-called probabilistic fatigue limit extrapolating method in an entire probabilistic sense. In addition, the reliability curves in terms of ten thousand km unit suitable for vehicle structures are developed of the material. By the present curves, reliability design, fatigue life prediction, and reliability assessment can be realized at arbitrary reliability level.
Related Articles | Metrics
RESEARCH STATUS ON FATIGUE BEHAVIOR OF STEEL-CONCRETE COMPOSITE BEAMS
NIE Jian-guo, WANG Yu-hang
Engineering Mechanics    DOI: 10.6052/j.issn.1000-4750.2010.08.0587
THEORETICAL MODEL ON ELASTIC-PLASTIC GRANULE IMPACT
HE Si-ming;;WU Yong;;LI Xin-po;
Engineering Mechanics    2008, 25 (12): 19-024.  
Abstract1509)      PDF(pc) (523KB)(1021)       Save
Base on the Hertz contact mechanics, assuming the materials as elastic-plastic hardening, and considering the adjustment and release of contact stress on the plastic contact region, a new granule elastic-plastic contact theory has been suggested. Then, the elastic-plastic impact among granules has been investigated under the material’s quasi-static hypothesis. At last a corresponding formula is given and compared with other models. The results have shown that the force-deformation relation locates between the curves following Hertz theory and Thornton theory according to new model. It also clearly shows the curve will approach closer to the Hertz solution when the hardening coefficient becomes higher and to the Thornton solution when hardening coefficient is lower, so the Thornton model is a special case of this model. In fact, the impact pressure predicted with the new model is far smaller than the Hertz elastic solution and more conformable to reality.
Related Articles | Metrics
COMPARISON AMONG IMPLEMENTATIONS OF FREE-SURFACE BOUNDARY IN ELASTIC WAVE SIMULATION USING THE FINITE-DIFFERENCE METHOD
WANG Zhou;LI Zhao-hui;LONG Gui-hua;GAO Qin;ZHAO Jia-fu
Engineering Mechanics    2012, 29 (4): 77-83.  
Abstract1753)      PDF(pc) (465KB)(1020)       Save
Representation of free-surface boundary condition in numerical calculations is an important aspect for seismic wave simulation. The effectiveness of numerical representation directly relates to whether the wave field can represent the true response of free-surface medium characteristics. Five common implementations of free-surface boundary used in the staggered-grid finite-difference method were evaluated, including the direct method, the stress image method, the improved stress image method, the transversely isotropic medium approach and the acoustic-elastic boundary approach, and a comparison with the finite-element method was also conducted. Simulation results of the transversely isotropic medium approach and the finite-element method are consistent best in visual comparison of waveform curve and quantitative comparison of amplitude ratio and correlation coefficient. Further numerical simulation results of elastic wave in layered medium model show that the transversely isotropic medium approach is the most accurate and reliable one which could represent seismic wave propagation in free-surface medium.
Related Articles | Metrics
FINITE ELEMENT ANALYSIS FOR SLIDING ABRASION OF TREAD BLOCKS OF RADIAL TIRE
HE Tao;LI Zi-ran;WANG Yang
Engineering Mechanics    2010, 27 (7): 237-243,.  
Abstract1970)      PDF(pc) (592KB)(1019)       Save
The global finite element model of 205/55R16 radial tire with simple longitudinal and lateral tread patterns is constructed. The free rolling and braking processes are simulated using ABAQUS/Standard commercial code. The distribution of stick and slip areas of contact surface under free rolling and braking conditions is investigated. The numerical results indicate that large contact deformations could occur at the front part of tread blocks along the sliding direction. To obtain more accurate stress field and deformation characteristics, a refined meshed finite element model of local tread block is set up. The boundary conditions of local model are derived from the results of global model. Sliding behavior of the tread block is analyzed using ABAQUS/Explicit incorporating thermo-mechanical coupling. Large contact deformations including curling and self contact are presented. In the end, an abrasion process of tread block during the course of ABS (antilock brake system) braking is simulated and the irregular abrasion character along the circumference of tire is presented.
Related Articles | Metrics
COMPARISON AMONG THREE TRANSFORMATION METHODS FOR STRUCTURAL RELIABILITY ANALYSIS WITH CORRELATED VARIABLES
WU Shuai-bing;;LI Dian-qing;;ZHOU Chuang-bing;
Engineering Mechanics    2011, 28 (5): 41-048,.  
Abstract1549)      PDF(pc) (355KB)(1015)       Save
This paper aims to compare three most representative transformation methods, namely, Orthogonal transformation, Rosenblatt transformation, and Nataf transformation, for structural reliability analysis with correlated variables. Firstly, the above three transformation methods are introduced. Then, the merits and applicable conditions for the considered three methods are compared. Finally, three examples are employed to compare the reliability results using the three transformation methods. The results indicate that the essential difference between the Nataf transformation and the Orthogonal transformation is that the former can take the reduced covariance matrix of correlated standard normal variables into consideration. The difference between the reliability indexes for the Nataf transformation and the Orthogonal transformation depends on the coefficients of variation, correlation coefficients, and distribution types associated with input variables, especially for coefficients of variation of the input variables. For different orderings of input variables, the reliability indexes using the Rosenblatt transformation can differ significantly when FORM is used to calculate the reliability index. After transformed into independent standard normal space using the considered three transformation methods, the performance function becomes highlynonlinear, which further impair the accurate estimation of the reliability index when FORM is used. It is recommended that the Nataf transformation be used for reliability analysis involving correlated input variables due to its accuracy and applicability.
Related Articles | Metrics
INFLUENCES OF SIZE AND ROUGHNESS OF MICROCHANNELS ON FRICTION FACTORS UNDER DIFFERENT PRESSURES
LIU Zhao-miao,PANG Yan
Engineering Mechanics    2012, 29 (5): 200-205.  
Abstract1887)      PDF(pc) (474KB)(1015)       Save
The characteristics of liquid flow in the microchannels with circular and trapezoidal cross-sections were studied by numerical simulation. The friction factor of liquid flow in microchannels was investigated with different pressures, the sizes and roughness of microchannels. The different flow regimes of laminar and turbulence were also analyzed in the microtubes. In addition, the range of a transition Reynolds number can be inferred from the friction factor profiles under different Reynolds numbers. The friction factors in the microchannels decrease with the increasing of Reynolds numbers gradually. The Reynolds number at transition from laminar to turbulent flow changes with the cross-section’s equivalent diameter. At the same Reynolds number, the friction factor increases with the roughness of the inner wall of the microchannel when the flow is turbulent.
Reference | Related Articles | Metrics
A COUPLED POROCHEMOTHERMOELASTIC MODEL FOR A BOREHOLE IN SHALES
SHENG Jin-chang;LIU Ji-shan;XU Xiao-chen;;ZHAN Mei-li
Engineering Mechanics    2009, 26 (12): 240-245.  
Abstract1287)      PDF(pc) (415KB)(1011)       Save
The evolution of borehole stresses and borehole stability in chemically active shales is profoundly affected by their complex physical and chemical interactions with drilling fluids (e.g. hydraulic flow, diffusion of ions, heat transport, thermo-osmosis, electro-osmosis, chemo-osmosis, ion exchange, and changes in swelling pressure). In this paper, a coupled porochemothermoelastic model for chemically active rocks is presented to evaluate these complex intricate links and their impact on the evolution of borehole stresses and pore pressure, which incorporates cross-coupled fluid flow equation, energy conservation equation, ion diffusion equation and mechanical equilibrium equation with many cross-coupling terms. A 2-D coupled porochemothermoelastic example of drilling in shales is solved by using a COMSOL-based simulator, which is the first engineering tool that performs partial differential equation-based multiphysics modelling in an interactive environment. The evolutions of borehole stresses, pore pressure, temperature and solute concentration in the vicinity of the borehole due to cooling and the difference of ion concentration between formulation fluid and drilling mud are presented to demonstrate the significant thermo-chemical effects on stress and pore pressure distributions.
Related Articles | Metrics
NUMERICAL SIMULATION OF DAMAGE PROCESS OF STEEL FRAMES UNDER EARTHQUAKE EXCITATION
DUAN Hong-xia;;LI Shou-ju;LIU Ying-xi
Engineering Mechanics    2011, 28 (2): 198-204.  
Abstract1267)      PDF(pc) (678KB)(984)       Save
The paper simulates the damaging process of a 9-story steel frame under EI-Centro earthquake ground motion using ABAQUS. In the analysis, the plastic damage model is combined with the nonlinear isotropic/kinematic hardening criteria and the damage evolution law of plastic displacement. The results show that the beam ends of upper floors undergo obvious plastic deformation and incur the appearance of damage domains. This observation is consistent with the observed seismic damage of high-rise steel structures during the Northridge earthquake.
Related Articles | Metrics
STUDY ON THE KEY PARAMETERS OF THE JOHNSON-HOLMQUIST CONSTITUTIVE MODEL FOR CONCRETE
XIONG Yi-bo;CHEN Jian-jie;HU Yong-le;WANG Wan-peng
Engineering Mechanics    2012, 29 (1): 121-127.  
Abstract2240)      PDF(pc) (1107KB)(977)       Save
As for the quantitative analysis in protective engineering, it is a key issue to determine appropriate constitutive parameters of concrete to guarantee the reliability of calculation and design. For this purpose, theoretical analyses, experimental tests and numerical simulations are carried out to calibrate the parameters of the Johnson-Holmquist (JH) model for concrete. The key parameters of the JH model are identified preliminarily by sensitivity analysis. The three-segment empirical equation of state was determined by summarizing relevant experimental data from literature and statistical analysis. The method to obtain the failure surface parameters A, B, N, and Smax was established through pseudo triaxial tests, and the corresponding parameters of concrete with various strengths were acquired by material tests and literature data. The strain rate effect was analyzed based on the SHPB tests with passive pressures, and the fitting rate-dependent constant was presented at strain rates of about 200 s-1-500 s-1. Finally, the JH model parameters were recommended for engineering calculation, and three numerical examples were given.
Related Articles | Metrics
TECHNICAL CHALLENGES AND REFINEMENT RESEARCH ON WIND RESISTANCE OF LONG-SPAN BRIDGES
GE Yao-jun
Engineering Mechanics    2011, 28 (增刊Ⅱ): 11-23.  
Abstract1481)      PDF(pc) (6751KB)(970)       Save
With the rapid development of long span bridges in China in past three decades, this paper presented technical challenges of wind resistance on three type long-span bridges, including flutter instability and control of suspension bridges, wind induced vibration of cable stayed bridges and control of wind-rain induced cable vibration, vortex induced vibration and control of arch bridges, and the refinements on aerodynamic flutter and buffeting of super long span bridges. It can be concluded that the intrinsic limit of a span length due to aerodynamic stability is about 1,500m for suspension bridges, and beyond or even approaching this limit, designers should be prepared to improve its aerodynamic stability. The cable-stayed bridges with a main span over 1000m have high enough critical flutter speed, but the main aerodynamic concern is the rain-wind induced vibration of long stay cables. Except one example of vortex-induced vibration, long-span arch bridges have no wind resistance problem. The refinement research on wind resistance of long-span bridges was also introduced with a full-mode flutter analysis method, the bridge buffeting frequency-domain analysis under skew wind action, the bridge flutter and buffeting reliability evaluation method based on second order theory and first passage theory, and the unveiling of a bridge flutter evolution process, generation mechanism and control law.
Related Articles | Metrics
NONLINEAR STATIC RESPONSES OF FGM BEAMS UNDER NON-UNIFORM THERMAL LOADING
MAO Li-juan, MA Lian-sheng
Engineering Mechanics    2017, 34 (6): 1-8.   DOI: 10.6052/j.issn.1000-4750.2015.10.0868
Abstract226)      PDF(pc) (759KB)(965)       Save
Due to the variation in material properties through the thickness of functionally graded material (FGM) structures, an FGM beam simply supported at both ends exhibits characteristics quite different from those of a FGM beam clamped at both ends. An exact, closed form solution is obtained for nonlinear static responses of FGM beams subjected to non-uniform in-plane thermal loadings. The equations governing the axial and transverse deformations of FGM beams are derived based on the nonlinear classical beam theory and the physical neutral surface concept. The two equations are reduced to a single nonlinear fourth-order integral-differential equation governing the transverse deformation. For an FGM beam clamped at both ends, the equation and the corresponding boundary conditions lead to a differential eigenvalue problem, whereas for an FGM beam simply supported at both ends, an eigenvalue problem does not arise due to the inhomogeneous boundary conditions. This consequently results in quite different behavior between a clamped and a simply supported FGM beams. The nonlinear equation is directly solved without any use of approximation and a closed-form solution for thermal bending deformation is obtained as a function of the applied thermal load. By using the exact solutions, the nonlinear deformation problems for buckling, postbuckling and nonlinear bending of the beam can be investigated. Finally, the numerical analyses are carried out to investigate the effects of material gradient properties and thermal loads on the nonlinear static responses of FGM beams.
Reference | Related Articles | Metrics
A REVIEW OF MODERN ROTOR/SEAL DYNAMICS
CAO Shu-qian;;CHEN Yu-shu;
Engineering Mechanics    2009, 26 (增刊Ⅱ): 68-079.  
Abstract1687)      PDF(pc) (5476KB)(964)       Save
A review of rotor/seal dynamics is given, focusing on the problems, contents, and main results achieved in modern rotor/seal dynamics. Researches of modern rotor/seal dynamics are divided into four parts: 1) modeling and calculation methods of the seal force; 2) identification of the eight lumped parameters of the seal force (the eight dynamic coefficients of the seal); 3) effect of different structure of seals (including damp-reduced structure and pre-swirl) on rotor stability; and 4) modeling and analysis of rotor/seal dynamic, especially the nonlinear dynamics of the rotor/seal model. The achieved main results are summarized as follows: 1) proposing the lumped parameter seal force model by Muszynska and Bently; 2) obtaining some techniques to identify the lumped parameters of the seal force; 3) studying some complex behaviors including bifurcation and chaos on some simple rotor/seal models; and 4) applying CFD (Computational Fluid Dynamics) to seal force calculation and rotor/seal dynamic analysis. Over one hundred of references are listed at the end of the paper. This review will be helpful for researchers of rotor/seal dynamics.
Related Articles | Metrics