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非连续介质力学模型预测煤层井眼稳定性 被引量:20
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作者 陈勉 赵海峰 +2 位作者 金衍 丁云宏 王永辉 《石油学报》 EI CAS CSCD 北大核心 2013年第1期145-150,共6页
煤层为割理、裂缝发育的非连续介质,井壁失稳是煤层气钻井难题之一,目前利用连续介质力学模型预测钻井液安全密度窗口,实际应用效果较差。为此,针对煤层为非连续介质的特点,基于非连续介质力学方法建立了煤层坍塌压力的离散构元模型,进... 煤层为割理、裂缝发育的非连续介质,井壁失稳是煤层气钻井难题之一,目前利用连续介质力学模型预测钻井液安全密度窗口,实际应用效果较差。为此,针对煤层为非连续介质的特点,基于非连续介质力学方法建立了煤层坍塌压力的离散构元模型,进而推导出用地应力、割理间距、割理倾角、井眼尺寸、面割理黏聚力和面割理摩擦角等弱面参数表达的坍塌压力、破裂压力非连续煤层数学方程,并定义了方程中与井眼液柱压力、坍塌压力相关的井壁稳定系数。分析表明,井壁稳定系数为正时,可以采用提高液柱压力稳定井壁;否则,不可单一采用提高液柱压力稳定井壁,还需要提高地层的承压能力。另外,坍塌位置对井眼尺寸较敏感,而坍塌压力受井眼尺寸影响较小。 展开更多
关键词 煤层 井壁稳定 构元模型 坍塌压力 尺寸效应
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一种基于物理机制的后继屈服面演化模型 被引量:7
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作者 付强 刘芳 +1 位作者 张晶 梁乃刚 《力学学报》 EI CSCD 北大核心 2010年第5期880-888,共9页
考虑滑移为晶体塑性的主要变形机制,推广晶体塑性理论至多晶体,建立滑移构元模型,研究了后继屈服面的移动和畸变等演化规律.基于滑移构元的潜在硬化和包氏效应的影响,后继屈服面的前端凸出,尾部缩进,呈现"前凸后扁"的特征.计... 考虑滑移为晶体塑性的主要变形机制,推广晶体塑性理论至多晶体,建立滑移构元模型,研究了后继屈服面的移动和畸变等演化规律.基于滑移构元的潜在硬化和包氏效应的影响,后继屈服面的前端凸出,尾部缩进,呈现"前凸后扁"的特征.计算了单轴拉伸、纯扭转和拉-扭组合比例/非比例加载下的后继屈服面演化过程,与已有实验结果相符合. 展开更多
关键词 滑移构元模型 后继屈服面 包氏效应 潜在硬化 非比例加载
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Novel damage constitutive models and new quantitative identification method for stress thresholds of rocks under uniaxial compression
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作者 DU Kun YI Yang +3 位作者 LUO Xin-yao LIU Kai LI Peng WANG Shao-feng 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第8期2658-2675,共18页
Four key stress thresholds exist in the compression process of rocks,i.e.,crack closure stress(σ_(cc)),crack initiation stress(σ_(ci)),crack damage stress(σ_(cd))and compressive strength(σ_(c)).The quantitative id... Four key stress thresholds exist in the compression process of rocks,i.e.,crack closure stress(σ_(cc)),crack initiation stress(σ_(ci)),crack damage stress(σ_(cd))and compressive strength(σ_(c)).The quantitative identifications of the first three stress thresholds are of great significance for characterizing the microcrack growth and damage evolution of rocks under compression.In this paper,a new method based on damage constitutive model is proposed to quantitatively measure the stress thresholds of rocks.Firstly,two different damage constitutive models were constructed based on acoustic emission(AE)counts and Weibull distribution function considering the compaction stages of the rock and the bearing capacity of the damage element.Then,the accumulative AE counts method(ACLM),AE count rate method(CRM)and constitutive model method(CMM)were introduced to determine the stress thresholds of rocks.Finally,the stress thresholds of 9 different rocks were identified by ACLM,CRM,and CMM.The results show that the theoretical stress−strain curves obtained from the two damage constitutive models are in good agreement with that of the experimental data,and the differences between the two damage constitutive models mainly come from the evolutionary differences of the damage variables.The results of the stress thresholds identified by the CMM are in good agreement with those identified by the AE methods,i.e.,ACLM and CRM.Therefore,the proposed CMM can be used to determine the stress thresholds of rocks. 展开更多
关键词 stress threshold acoustic emission damage constitutive model damage element quantitative method
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Optimization method for evacuation zone with network reconfiguration based on dynamic simulation 被引量:1
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作者 赵星 任刚 +1 位作者 张小丽 李岩 《Journal of Southeast University(English Edition)》 EI CAS 2016年第3期373-378,共6页
Abstract: With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method c... Abstract: With a determinate danger zone and evacuation demand caused by an emergency, an optimization method for the evacuation zone with network reconfiguration based on dynamic simulation is proposed. The method contains three modules. First, the network in the evacuation zone is optimized by a model with the integrated strategy of lane reversal and intersection conflict elimination. Secondly, the dynamic evacuation simulation model based on the cell transmission model is applied to simulate the dynamic propagation process of evacuated vehicles in the network in the evacuation zone. The evacuation time for all evacuated vehicles leaving the danger zone is obtained and the setting of the current evacuation zone is fed back. Thirdly, the arrival distributions of evacuated vehicles at critical intersections of the evacuation zone are also obtained to estimate the delay at critical intersection to determine whether the intersection should be taken as the critical intersection in the next iteration. The evacuation zone is expanded gradually through iteration, and the reasonable evacuation zone and the optimal evacuation network is confirmed. Based on the survey of the parking lot and urban street network around Nanjing Olympic Sports Center, the models and the iterative algorithm were applied to obtain the optimal plan of the evacuation zone with network reconfiguration in an evacuation situation to verify the validity of the proposed method. 展开更多
关键词 evacuation zone cell transmission model traffic network reconfiguration intersection delay
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AN UPDATING METHOD FOR LOCAL MODEL ERRORS
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作者 李书 冯太华 范绪箕 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1995年第2期129-133,共5页
The location of model errors in a stiffness matrix by using test data has been investigated by the others.The present paper deals with the problem of updating stiffness elements in the erroneous areas. Firstly,a model... The location of model errors in a stiffness matrix by using test data has been investigated by the others.The present paper deals with the problem of updating stiffness elements in the erroneous areas. Firstly,a model that bears relation to erroneous elements only is derived.This model is termed local errors model,which reduces orders and computational loads compared with global stiffness matrix. Secondly,an inverse eigenvalue method is used to update model errors. The results of a numerical experiment demonstrate that the method is quite effective. 展开更多
关键词 finite element methods STRUCTURES inverse problem updating method MODEL
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Constitutive model of rock based on microstructures simulation 被引量:3
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作者 叶洲元 洪亮 +1 位作者 刘希灵 尹土兵 《Journal of Central South University of Technology》 EI 2008年第2期230-236,共7页
The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads.It is resumed that rock contains many microstructures and a structure of Bingham.The... The constitutive model of rock can be built by mechanics elements because there are many kinds of damages in rock under varied loads.It is resumed that rock contains many microstructures and a structure of Bingham.The microstructure consists of two embranchments that are the unit of a spring and a gliding slice in series and the unit of a spring and a cementation bar in series,the two units connect each other in parallel.These microstructures are arranged disorderly or in the order of a certain state.A certain distribution of microstructures represents one type of rock.Two kinds of rock's constitutive relationship were deduced by using the model.One is the model in which many parallel microstructures and a structure of Bingham connect in series.And it is used to homogeneous rock.The other is the model in which many microstructures and a structure of Bingham connect in series.And it is used to the rock with much crack or microcrack in a certain direction.The two kinds of constitutive relationship were verified by the studied cases.The constitutive model of rock built by using mechanics elements is verified to be reasonable.Moreover,different types of rocks may be described with mechanics elements with different distributions. 展开更多
关键词 constitutive model MICROSTRUCTURE mechanics element connecting type
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Study on Dynamic Response of the “Dualistic” Structure Rock Slope with Seismic Wave Theory 被引量:5
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作者 CHEN Zhen-lin XU Qiang HU Xiao 《Journal of Mountain Science》 SCIE CSCD 2013年第6期996-1007,共12页
Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the "Dualistic" structure roek slope. The analysis presented here provides insight into the dynamic response of t... Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the "Dualistic" structure roek slope. The analysis presented here provides insight into the dynamic response of the "Dualistie" structure rock slope. By investigating the principle of energy distribution, it is shown that the effect of a joint plays a significant role in slope stability analysis. A dynamic reflection and transmission model (RTM) for the "Dualistic" structure rock slope and explicit dynamic equations are established to analyze the dynamic response of a slope, based on the theory of elastic mechanics and the principle of seismic wave propagation. The theoretical simulation solutions show that the dynamic response of the "Dualistic" structure rock slope (soft-hard) model is greater than that of the "Dualistic" strueture rock slope (hard-soft) model, especially in the slope crest. The magnifying effect of rigid foundation on the dynamic response is more obvious than that of soft foundation. With the amplitude increasing, the cracks could be found in the right slope (soft-hard) crest. The crest failure is firstly observed in the right slope (soft-hard) during the experimental process. The reliability of theoretical model is also investigated by experiment analysis. The conclusions derived in this paper could also be used in future evaluations of Multi-layer rock slopes. 展开更多
关键词 Reflection and transmission waves Dualistic structure Seismic wave Dynamic response
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Longitudinal forces of continuously welded track on high-speed railway cable-stayed bridge considering impact of adjacent bridges 被引量:32
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作者 戴公连 闫斌 《Journal of Central South University》 SCIE EI CAS 2012年第8期2348-2353,共6页
A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile fini... A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment. 展开更多
关键词 high-speed railway continuously welded track cable-stayed bridge simply-supported beam
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Deformation Analysis of LRC Underground Gas Storage 被引量:1
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作者 Primoz Jelusic Bojan Zlender 《Journal of Civil Engineering and Architecture》 2011年第6期548-554,共7页
The risk during construction and in the operation of the underground gas storage (UGS) was analyzed. One of most important risk which should be prevented is large deformation or destruction of the steel lining. The ... The risk during construction and in the operation of the underground gas storage (UGS) was analyzed. One of most important risk which should be prevented is large deformation or destruction of the steel lining. The specific deformation of the steel lining needs to be inside the acceptable value. This paper presents lined rock cavern (LRC) concept and specific deformations, which can occur under operation of underground gas storage. Analysis is performed with different (3D model and axis symmetrical) FEM models and analytical model. We made a comparison between analytical calculation and FEM calculation. Concrete wall is mechanically not regarded as reinforced concrete structure which means that concrete will crack. Finally, we determined the minimum value of Young's modulus, which satisfies the condition of maximum deformation of steel lining. 展开更多
关键词 Underground gas storage lined rock cavern interaction concrete-rock rock mass properties rock mechanics.
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Dynamic analysis and nonlinear identification of space deployable structure 被引量:1
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作者 郭宏伟 刘荣强 邓宗全 《Journal of Central South University》 SCIE EI CAS 2013年第5期1204-1213,共10页
The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum mod... The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies. 展开更多
关键词 deployable structure finite element model equivalent continuum model NONLINEAR dynamic analysis
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Progressive Collapse Analysis of Concrete-Filled Steel Tubular Frames with Semi-rigid Connections
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作者 徐嫚 张素梅 +1 位作者 郭兰慧 王玉银 《Transactions of Tianjin University》 EI CAS 2011年第6期461-468,共8页
A 9-story concrete-filled steel tubular frame model is used to analyze the response of joints due to sudden column loss. Three different models are developed and compared to study the efficiency and feasibility of sim... A 9-story concrete-filled steel tubular frame model is used to analyze the response of joints due to sudden column loss. Three different models are developed and compared to study the efficiency and feasibility of simulation, which include substructure model, beam element model and solid element model. The comparison results show that the substructure model has a satisfying capability, calculation efficiency and accuracy to predict the concerned joints as well as the overall framework. Based on the substructure model and a kind of semi-rigid connection for concretefilled square hollow section steel column proposed in this paper, the nonlinear dynamic analyses are conducted by the alternate path method. It is found that the removal of the ground inner column brings high-level joint moments and comparatively low-level axial tension forces. The initial stiffness and transmitted ultimate moment of the semi-rigid connection are the main factors that influence the frame behavior, and their lower limit should be guaranteed to resist collapse. Reduced ultimate moment results in drastic displacement and axial force development, which may bring progressive collapse. The higher initial stiffness ensures that the structure has a stronger capacity to resist progressive collapse. 展开更多
关键词 substructure model concrete-filled steel tubular frame semi-rigid connection alternate path method dynamic analysis
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Parameter fitting of constitutive model and FEM analysis of solder joint thermal cycle reliability for lead-free solder Sn-3.5Ag 被引量:1
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作者 周萍 胡炳亭 +1 位作者 周孑民 杨莺 《Journal of Central South University》 SCIE EI CAS 2009年第3期339-343,共5页
The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--... The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--strain curves were compared to those of solder Sn-37Pb. The parameters in Anand model for solder Sn-3.5Ag were fitted based on experimental data and nonlinear fitting method, and its validity was checked by means of experimental data. Furthermore, the Anand model was used in the FEM analysis to evaluate solder joint thermal cycle reliability. The results show that solder Sn-3.5Ag has a better creep resistance than solder Sn-37Pb. The maximum stress is located at the upper right comer of the outmost solder joint from the symmetric center, and thermal fatigue life is predicted to be 3.796 × 10^4 cycles under the calculated conditions. 展开更多
关键词 lead free solder Sn-3.5Ag alloy Sn-37Pb alloy constitutive model TENSILE FEM analysis thermal cycle reliability
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A Study on the Effect of Welding Sequence in Fabrication of Large Stiffened Plate Panels 被引量:1
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作者 Pankaj Biswas D. Anil Kumar +1 位作者 N.R.Mandal M.M.Mahapatra 《Journal of Marine Science and Application》 2011年第4期429-436,共8页
Welding sequence has a significant effect on distortion pattern of large orthogonally stiffened panels normally used in ships and offshore structures. These deformations adversely affect the subsequent fitup and align... Welding sequence has a significant effect on distortion pattern of large orthogonally stiffened panels normally used in ships and offshore structures. These deformations adversely affect the subsequent fitup and alignment of the adjacent panels. It may also result in loss of structural integrity. These panels primarily suffer from angular and buckling distortions. The extent of distortion depends on several parameters such as welding speed, plate thickness, welding current, voltage, restraints applied to the job while welding, thermal history as well as sequence of welding. Numerical modeling of welding and experimental validation of the FE model has been carried out for estimation of thermal history and resulting distortions. In the present work an FE model has been developed for studying the effect of welding sequence on the distortion pattern and its magnitude in fabrication of orthogonally stiffened plate panels. 展开更多
关键词 elasto-plastic analysis welding distortion 3-D finite element analysis stiffened panel weldingsequence
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Software development of modeling assistant for continuous suspension bridges with multi-pylon 被引量:1
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作者 Zhong Jianchi Chen Ke +1 位作者 Chen Yunhai Lu jianming 《Engineering Sciences》 EI 2012年第3期55-59,71,共6页
Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is d... Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is developed based on .Net platform, with VB.Net, C# language and OpenGL graphic technique. With parameterized modeling method, finite element model of this kind of bridge can be built quickly and accurately, and multi-type element modeling with uniform parameters is realized. With advanced graphic technique, three-dimensional model graph can be real-timely previewed for intuitive data check. With an example of practice project, the accuracy and feasibility of this modeling method and practicality of this software are verified. 展开更多
关键词 bridge engineering continuous suspension bridge with multi-pylon parameterized modeling software development finite element method (FEM)
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Constitutive equations and finite element implementation of strain localization in sand deformation 被引量:2
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作者 黄林冲 徐志胜 王立川 《Journal of Central South University》 SCIE EI CAS 2009年第3期482-487,共6页
A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity t... A recently proposed model coupling with the solid-fluid of the saturated sand was utilized to study the deformation band. Based on the critical state plasticity model by Borja and Andrade, the hydraulic conductivity tensor was naturally treated as a function of the spatial discretization matrix about the displacement and the stress field, allowing a more realistic representation of the physical phenomenon. The fully Lagrangian form of the Darcy law was resolved by Piola algorithm, and then the flow law was gained, leading to the implementation of a modified model of the saturated sand. Then the criterion for the onset of localization was derived and utilized to detect instability. The constitutive model was implemented in a finite element program coded by FORTRAN, which was used to predict the formation and development of shear bands in plane strain compression of saturated sand. At last, the formation mechanism of the shear band was discussed. It is shown that the model works well, and the simulation sample bifurcates at 1.18% axial strain, which is in a good qualitative agreement with the experiment. The pore pressure greatly affects the onset and development of the deformation band, and it obviously increases around the localization-prone regions with the direction toward the outer side of the normal of the shear band, while the pore stress flows nearly horizontally and is distributed equally far away the shear band region. 展开更多
关键词 constitutive equations deformation band finite elements hydraulic conductivity SAND
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Study on LQR control algorithm using superelement model 被引量:3
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作者 XU Qiang CHEN Jian-yun +2 位作者 LI Jing YUAN Chen-yang ZHAO Chun-feng 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2429-2442,共14页
The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of free... The conventional linear quadratic regulator(LQR) control algorithm is one of the most popular active control algorithms.One important issue for LQR control algorithm is the reduction of structure's degrees of freedom(DOF). In this work, an LQR control algorithm with superelement model is intended to solve this issue leading to the fact that LQR control algorithm can be used in large finite element(FE) model for structure. In proposed model, the Craig-Bampton(C-B) method, which is one of the component mode syntheses(CMS), is used to establish superelement modeling to reduce structure's DOF and applied to LQR control algorithm to calculate Kalman gain matrix and obtain control forces. And then, the control forces are applied to original structure to simulate the responses of structure by vibration control. And some examples are given. The results show the computational efficiency of proposed model using synthesized models is higher than that of the classical method of LQR control when the DOF of structure is large. And the accuracy of proposed model is well. Meanwhile, the results show that the proposed control has more effects of vibration absorption on the ground structures than underground structures. 展开更多
关键词 linear quadratic regulator (LQR) control algorithm component mode synthesis (CMS) Craig-Bampton (C-B) method superelement vibration control
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Calculating models of mass action concentrations for structural units or ion couples in RbCl-H_2O binary system and RbCl-RbNO_3-H_2O ternary system 被引量:1
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作者 郭汉杰 杨学民 赵伟洁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第6期1112-1120,共9页
Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and... Thermodynamic models of calculating mass action concentrations for structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions were developed based on the ion and molecule coexistence theory at 298.15 K.A transformation coefficient is needed to compare the calculated mass action concentration and the reported activity because they are obtained at different standard states and concentration units.The results show that the transformation coefficients between the calculated mass action concentrations and the reported activities of the same structural units or ion couples in RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions change in a very narrow range.The transformed mass action concentrations of structural units or ion couples in RbCl-H2O binary system are in good agreement with the reported activities. The transformed mass action concentrations of RbCl and RbNO3 in RbCl-RbNO3-H2O ternary solution are also in good agreement with the reported activities,aRbCl and 3RbNOa,with different total ionic strengths as 0.01,0.05,0.1,0.5,1.0,1.5,2.0,3.0 and 3.5 mol/kg,respectively.All those results mean the developed thermodynamic model of strong electrolyte aqueous solutions can reflect structural characteristics of RbCl-H2O binary and RbCl-RbNO3-H2O ternary strong electrolyte aqueous solutions and the mass action concentration also strictly follows the mass action law. 展开更多
关键词 mass action concentration ACTIVITY ion and molecule coexistence theory RbCl-H2O RbCl-RbNO3-H2O structural unit ion couple
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Effect of Modeling Range on Structural Analysis for Powerhouse of Hydroelectric Power Plant by FEM 被引量:1
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作者 张启灵 伍鹤皋 杨华全 《Transactions of Tianjin University》 EI CAS 2009年第5期388-392,共5页
In this paper,three different modeling ranges were selected in the structural analysis for a hydropower house.The analysis was carried out using ABAQUS 6.6.The modeling range has a remarkable effect on finite element ... In this paper,three different modeling ranges were selected in the structural analysis for a hydropower house.The analysis was carried out using ABAQUS 6.6.The modeling range has a remarkable effect on finite element method(FEM) calculation result at the middle position of typical cross-sections where the concrete is relatively thin,and at the region close to turbine floor.If the ventilation barrel,floor slabs and columns above turbine floor are excluded from FEM model,the maximum rise difference of pedestal structure increases by about 24% compared with that of the whole model.It is indicated that different modeling ranges indeed affect FEM calculation result,and the structure above turbine floor in the FEM model should be included. 展开更多
关键词 hydraulic structures hydroelectric power plants POWERHOUSE modeling range FEM structural analysis
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Study of Vertical Breakwater Reliability Based on Copulas 被引量:1
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作者 DONG Sheng LI Jingjing +1 位作者 LI Xue WEI Yong 《Journal of Ocean University of China》 SCIE CAS 2016年第2期232-240,共9页
The reliability of a vertical breakwater is calculated using direct integration methods based on joint density functions.The horizontal and uplifting wave forces on the vertical breakwater can be well fitted by the lo... The reliability of a vertical breakwater is calculated using direct integration methods based on joint density functions.The horizontal and uplifting wave forces on the vertical breakwater can be well fitted by the lognormal and the Gumbel distributions,respectively.The joint distribution of the horizontal and uplifting wave forces is analyzed using different probabilistic distributions,including the bivariate logistic Gumbel distribution,the bivariate lognormal distribution,and three bivariate Archimedean copulas functions constructed with different marginal distributions simultaneously.We use the fully nested copulas to construct multivariate distributions taking into account related variables.Different goodness fitting tests are carried out to determine the best bivariate copula model for wave forces on a vertical breakwater.We show that a bivariate model constructed by Frank copula gives the best reliability analysis,using marginal distributions of Gumbel and lognormal to account for uplifting pressure and horizontal wave force on a vertical breakwater,respectively.The results show that failure probability of the vertical breakwater calculated by multivariate density function is comparable to those by the Joint Committee on Structural Safety methods.As copulas are suitable for constructing a bivariate or multivariate joint distribution,they have great potential in reliability analysis for other coastal structures. 展开更多
关键词 vertical breakwater RELIABILITY Archimedean copula goodness of fit bivariate logistic Gumbel distribution bivariateLognormal distribution multivariate distribution
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Analysis of structural hot-spot stress in orthotropic plates
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作者 Chen Ce Ji Bohai Xu Hanjiang 《Engineering Sciences》 EI 2012年第3期88-92,共5页
On the basis of the actual steel deck structure of Taizhou Bridge, this paper carries out hot-spot stress analysis on some key spots by using the finite element model which simulates local structure of orthotropic ste... On the basis of the actual steel deck structure of Taizhou Bridge, this paper carries out hot-spot stress analysis on some key spots by using the finite element model which simulates local structure of orthotropic steel bridge decks. A finite element model is established for local structure of orthotropic steel bridge decks, and in the analysis of linear elasticity of the structure, face load is employed to simulate the loads from vehicle wheels. Analysis results show that main stresses are relatively heavy at the joints between diaphragm plates, top plates and U-shaped ribs and the joints between diaphragm plates and U-shaped ribs. These joints shall be regarded as key points for hot-spot stress analysis. Different mesh densities are adopted in the finite element model and the main stresses at different hot spots are contrasted and linear extrapolation is carried out using extrapolation formulae. Results show that different mesh densities have different influences on the hot-spot stresses at the welded seams of U-shaped ribs. These influences shall be considered in calculation and analysis. 展开更多
关键词 steel bridge deck local structure mesh density hot-spot stress
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