Reliability Evaluation for Bulk Power System Including Dependent Outage of Transmission Line

In order to calculate and analyze the effect of two transmission lines in parallel on the reliability evaluation of bulk power system, a model including independent outage, common mode outage and dependent outage of these lines is deduced and a new algorithm corresponding to the model is presented. Two transmission lines in parallel including common mode outages and dependent outages can be really simulated as a multi-state component. While reliability indices are calculated, the probability and frequency of independent outage, common mode outage and dependent outage of a system failure state can be calculated at the same time, and computation complexity is reduced. The proposed model and algorithm are applied to the RBTS system, IEEE One Area RTS96 system and a real power system for reliability computation and analysis. Results show that the new algorithm is credible and validity.     

Probability Analysis of Failure Cause for Light Weight Steel Structure under Snow Disaster

In the current unified standard for reliability design, it lacks full considerations of the range of load effect ratio for reliability analysis of light weight steel structures. Firstly, a computational method based on stress was proposed to calculate load effect ratio, which solves the problem that which kind of load effects can be chosen to calculate load effect ratio when the member fails with actions of several kinds of internal forces. Then, the range of load effect ratio was studied for light weight steel structures after some analyses of several members with this method. It is found that the load effect ratio of light weight steel structures can adopt large values under the disadvantage distributions of snow load. The reliability was also calculated for light weight steel structures designed with current partial factors. Its result shows that the reliability of light weight steel structure is low. Finally, the reliability was analyzed for light weight steel structures with different load effect ratios when snow load exceeded the design standard level. It indicates that the reliability is low for light weight steel structures with large load effect ratio. This provides some complementary explanations for the phenomena that the light steel structures are more likely to fail under snow disaster.     

Experimental Analysis on Time dependent Law of Surface Chloride Ion Concentration of Concrete

Immersion in sodium chloride solution was adopted to periodically test chloride ion concentration at the surface of concrete and regression analysis was completed.And time dependent law of surface chloride ion concentration of concrete with time was investigated.Influences of sodium chloride solution concentration, water to cement ratio and fly ash content on size and accumulation rate of surface chloride ion concentration were also analyzed.It is found that surface chloride ion concentration gradually grows with the of time increase the of time and reaches a steady state finally.With the increase of sodium chloride solution concentration, surface chloride ion concentration reaches the steady state more quickly and then increases numerically.Bigger water to cement ratio means quicker accumulation of surface chloride ion concentration and greater surface chloride ion concentration.Fly ash replacement could fasten accumulation of surface chloride ion concentration and surface chloride ion concentration increases with the increase of fly ash content.An improved model was proposed by comparison and correction of current models.     

Appropriate Technology and Corresponding Design Strategies for the Steel Construction Congregated Apartments

In this paper,notions on appropriate technology for the Steel Construction Congregated Apartments are proposed in order to deal with the technical impediment that arises from applying steel structural techniques to the congregated apartments.The appropriate technology for the steel construction congregated apartments is defined as systematic technologies that are in harmony with the status quo of Chinese productive force level,social culture and building technology,and as the strategies of choosing or balancing technology according to sustainable development principle.The principal design and constructing strategies of appropriate technology are as follows:(1) organization of residential space combined with steel construction techniques,(2) suitable structural system,(3) a new idea of fire resistance,and(4) kit building technique etc.A technological concept analysis about an ideal model of a steel construction system congregated apartment combined with the appropriate technology is also presented.     

Earthquake of Steel Frames-the Seismic Performance of Composite Structural Systems of Concrete Core wall

The steel fame-concrete core wall combination of structural system is outside the framework with steel inner cylinder with concrete shear wall, steel frame-concrete inside the tube system. In this paper ,the finite element software ANSYS earthquake seismic response analysis and stability analysis, the 25-story steel frame-concrete core wall combination of structural system data results show that the structural system performance than the purity steel framework structure is superior.     

蠕变模型对约束钢梁抗火性能分析的影响

钢材在高温和荷载作用下产生明显蠕变变形,影响火灾中结构的变形和受力性能。现有的蠕变模型较多,但没有一个广泛适用的蠕变模型。不同的蠕变模型对钢结构抗火分析结果有很大影响。为了量化蠕变模型对约束钢梁抗火性能分析的影响,对5种常用的蠕变模型进行了对比分析。采用编写的约束钢梁计算程序,分别计算5种蠕变模型下约束钢梁的抗火性能并与试验数据进行对比。结果表明,采用Norton蠕变模型的计算结果与试验数据吻合最好。最后对影响约束钢梁抗火性能参数进行了研究,研究发现,Harmathy蠕变模型对约束梁抗火性能分析结果影响最大;不同蠕变模型对不同荷载比、约束刚度下的约束钢梁抗火性能影响程度均不同。     

Mechanical Behaviors of Large Span Space Structures in the Construction Process

Traditional structural design emphasizes checking whether a loaded structure satisfies design requirements without considering the construction process. There is a great difference in structures between the states in construction processes and design, however. To solve the above problems, a method of nonlinear time varying mechanics was adopted to analyze the construction process of a structure. The structural characteristics in each construction stage were analyzed by time varying mechanics and the variations of internal force and displacements obtained. We conclude that designs will not be safe if the time varying effect in the construction process analysis is not considered. We offer advice on the design and construction of large span structures.     

Refined Probabilistic Model of Resistance of RC Eccentric Compression Members

The probabilistic model of resistance in the current unified standard for reliability design is imprecise for RC members subjected to eccentric compression. The reason is that it lacks full considerations of influences of varying eccentricities. An improved probabilistic model of resistance with different eccentricities and reinforcement ratios is obtained by using the Monte Carlo sampling method and the current probabilistic models of all resistant factors. The results indicate that it is accurate to fit the probabilistic distribution of resistance with normal distribution. Given that, the applicability of the improved model is analyzed for reliability analysis of RC members subjected to eccentric compression with random eccentricities. It shows that when the design value of eccentricity is close to or larger than the eccentricity producing balanced failure, there would be large errors in reliability analysis if the probabilistic model of resistance given in the current reliability unified standard is used. However, it is accurate when using the proposed probabilistic model. The results also show that the design of RC members subjected to large eccentric compression is unsafe based on the current reliability unified standard because it lacks full considerations of effects that the resistance decreases as eccentricity increases.     

高烈度区斜拉桥横向约束方案优化分析

为了确定强震作用下斜拉桥合理的横向抗震约束体系,以可克达拉大桥为工程背景,采用非线性时程分析法,分析了4种横向约束体系即横向滑动体系、全限位体系、位移相关型减震体系和速度相关型减震体系对强震区大跨度桥梁地震响应的影响,重点对钢阻尼器的屈服荷载和黏滞阻尼器的位置及相关参数进行优化分析,并与其他体系的地震响应进行了对比。结果表明：在强震作用下,对于大跨度桥梁横向滑动体系和全限位体系均不是理想的抗震体系;而在墩梁、塔梁之间设置减隔震装置可以有效减少横桥向的墩梁、塔梁的相对位移及地震剪力和弯矩;然而,从桥梁正常使用的角度来看,塔梁之间布设横向钢阻尼器装置优于黏滞阻尼器装置。     

Existing Frame Structure in Reconstruction and ExtensionProject in Security Analysis

Structure security is the most main structural reliability, at the request of active service in time to make a frame structure security assessment, in safe premise to prolong the service life, and has a certain social significance and economic benefits. Combining with the actual situation reconstruction projects, using the theory analysis frame structure of the active safety, the finite element SAP2000 on the original structure and rebuilt structure modal analysis, the effect of the structure security index that contrast reconstruction of the frame structure than the frame structure of the security it can improve.     

Wind Damage Estimation and Prediction of Light Steel Industrial Buildings

Wind hazard damage estimation was addressed for light steel industrial buildings which were the typical wind vulnerable structures in southeast coastal cities. With parametric analysis of wind damage and the structural failure features, the envelop elements and the connecting elements were determined as the pivots of the damage analysis. Upon the consideration of the co effect of exterior wind pressure, wind induced internal pressure and windborne debris damage, a typhoon load model was proposed. And with the calculation method of the element resistance from the regulation, the procedure of the damage estimation was described and the damage classification of industrial buildings was specified with detailed indicators. Finally, the proposed method was approved with the actual data of typhoon CHANCHU (0601).     

Dynamic quantitative trait loci underlies isoflavone accumulation in soybean seed

Most of quantitative trait loci (QTL) underlying soybean seed isoflavone contents were derived from the harvest stage of plant development, which uncover the genetic effects that were expressed in earlier seed developmental stages. The aim of this study was to detect conditional QTL associated with isoflavone accumulation during the entire seed development. A total of 112 recombinant inbred lines developed from the cross between ‘Zhongdou 27’ (higher seed isoflavone content) and ‘Jiunong 20’ (lower seed isoflavone content) were used for the conditional QTL analysis of daidzein (DZ), genistein (GT), glycitein (GC) and total isoflavone (TI) accumulations through composite interval mapping with mixed genetic model. The results indicated that the number and type of QTL and their additive effects for individual and total isoflavone accumulations were different among R3 to R8 developmental stages. Three unconditional QTL and six conditional QTL for DZ, four unconditional QTL and five conditional QTL for GT, six unconditional QTL and five conditional QTL for GC, six unconditional QTL and seven conditional QTL for TI were identified at different developmental stages, respectively. Unconditional and conditional QTL that affect individual and total isoflavone accumulations exhibited multiple expression patterns, implying that some QTL are active for long period and others are transient. Two genomic regions, Satt144‐Satt569 in linkage group F (LG F; chromosome 13, chr 13) for DZ, GC, GT and TI accumulations and Satt540‐Sat_240 in LG M (chr 07) for TI and GC accumulations, were found to significantly affect individual and total isoflavone accumulations in multiple developmental stages, suggesting that the accumulation of soybean seed isoflavones is governed by time‐dependent gene expression.     

基于GIS的广西暴雨灾害风险实时评估技术研究

为了科学应对广西暴雨灾害频发、影响日趋严重这一问题,选用广西自动站实时降雨量数据、历年暴雨灾情数据、广西社会经济数据及基础地理数据,采用主成分分析法、层次分析法等方法,结合GIS技术,研究了暴雨灾害危险度实时评估的技术方法,并基于暴雨灾害实时危险度、孕灾环境脆弱度、承灾体易损度和抗灾力等4个因子,构建了广西农业暴雨灾害风险度实时评估模型,选择2011年的一次暴雨过程对模型进行验证,验证结果表明：评估结果与实际灾情较为吻合,模型实践检验效果较好。     

Calculation Methods for Steel Frame Structure Based on the Structural Ultimate Bearing Capacity

The existing problems in calculation approach for multi-story and high-rise steel frame structure are summarized. As the shearing deformation is considered, the analysis methods for steel frame structure are put forward based on the structural ultimate bearing capacity, which is on the basis of second order inelasticity analysis for steel structure. In the approach, the tangent module brought forward by Bleich, F. is used, the second-order refined plastic hinge method presented by Liew, J. Y. R. is modified.     

ANSYS/PDS风电齿轮箱收缩盘联接可靠性分析

笔者建立了某风电齿轮箱主轴收缩盘联接的轴对称参数化有限元模型,并结合主轴扭矩作用应用ANSYS非线性接触对该模型进行了强度分析。由于材料属性、制造过程、边界条件以及载荷等设计参数的不确定性会影响计算的精确性,应用ANSYS/PDS模块,根据失效模式确定整体功能函数并由此建立结构极限状态方程,采用蒙特卡罗超拉丁采样方法对收缩盘联接进行可靠性分析,得到整体联接的可靠度和失效率,并给出累积概率分布。研究结果表明:收缩盘传扭联接性能和结构件强度均满足设计要求,其联接的可靠度达到94.8%,达到了工程设计要求,对风电齿轮箱收缩盘联接的可靠性设计具有一定的指导意义。     

FEA of the Loading Capacity of Monolithic Composite Slim Floors with Deep Decks

Steel concrete composite slim floors with the steel beam encased in concrete floor slabs have many advantages, including low structural height, high fire resistance and rapid construction times. These features make such floors a promising for use in multi storey steel buildings. We established a 3D finite element model of a monolithic composite slim floor using the ANSYS software package. We analyzed the loading capacity, deformation behavior, natural vibration frequency, the influence of reinforcement, and the concrete in the floor rib under a uniformly distributed vertical load. We calculated the effective width of mid girder and secondary beams. The following conclusions can be drawn from the analysis results: First, monolithic composite slim floors possess high loading capacity for common buildings. Second, the concrete rib and reinforcement ratio in the rib have significant effects on floor loading capacity. Third, calculation of effective primary beam width should be based on analysis of monolithic floors rather than single beams.     

Service Life Prediction of Concrete Structures under Chloride Environment

The problems rendered from the conventional time marching, referring to stepwise time marching scheme (STMS) adopted in boundary element method (BEM) for chloride diffusion in concrete structures, were investigated, and a new time marching, referring to initial time marching scheme (ITMS) in BEM, was developed for evaluation of service life of the concrete structures under chloride environment. Results of the numerical examples show that the ITMS-BEM proposed can eliminate domain integral and simplify the computational model, so that the stability in iteration process can be improved, resulting in better efficiency and accuracy, compared with the STMS-BEM. It can also be concluded that the dimensions of the diffusion of chloride can affect the service life of the concrete structure significantly, which should be taken into account in structural design.     

An ALgorithm of the Second Kind Fuzzy Reliability

Based on L.A.Zadeh's idea of fuzzy probability operation in his language probability which space is fuzzy probability,the concrete algorithm of the second kind fuzzy reliability of engineering structure/system is researched.The calculating equation of the fuzzy probabiliy of the second kind fuzzy reliability is given out by using the extension principle for fuzzy sets.The fuzzy set decompose theorem,which satesfies the closed probability operation,is given out and proved.The method calculating fuzzy reliability of that structure/system is studied,where the resistance and load effect of the structure/system have probability.The analysis indicates that the calculation of the second kind fuzzy reliability for a structure/system can be transformed into a series of solving optimum programming.The result of the example indicates the rationality of above algorithm.     

structural optimization of high power marine gearbox

Taking the influences of joggle forces and gravity into account, a static model of a high power marine gearbox was established using the finite element method. The gearbox workload capacity was calculated in four working states. Gearbox strength and structural rigidity were analyzed. Combining theories of optimization and reliability design, the gearbox optimization model was obtained based on the intensity principle. To insure a safe structure, optimization designs were put in practice to improve the gearbox structure. As a result, the gearbox weight was reduced 1 060 t by structural optimization. The strength of the improved gearbox is more symmetrical and the structure of the improved gearbox is more reasonable than previoius designs, indicating the method has certain theoretical and practical engineering values.     

Simulation of Wind Loading for Large - span Bridge Structures

Wind speed time series obtained with numerical simulation methods are adopted in structural analysis of wind - induced vibration. In this paper, based on the natural wind properties and the correlativity of nodal wind speed time series, AR model is employed to simulate wind speed time series, and the AIC rule is used to fix the rank of the AR model. Statistical analysis results of numerical wind speed time series show that AR model is efficient in simulating nodal wind speed time series which has time and space correlativity, and that the simulation precision, simulation efficiency and calculation stability answer the needs of practical engineering.