Hybridization of genetic algorithm with immune system for optimization problems in structural engineering

Optimization is the task of getting the best solution among the feasible solutions. There are many methods available to obtain an optimized solution. Genetic algorithm (GA), which is a heuristic type of optimization method, is discussed in this paper. The focus of the paper is the use of GA for large dimensionality design problems, where computational efficiency is a major concern. The motivation of this paper is to hybridize GA with an immune system mechanism by avoiding the implementation of penalty constants, which are highly sensitive to the choice of algorithm parameters. The principal advantage of the immune system is in its seamless integration with GA-based search for optimal design. It is being hybridized with the immune system mechanism. The hybrid GA and immune system is applied for the design of the optimal mix of high-performance concrete (HPC), which is still based on trial mix and for which no rigorous mathematical approach is available. As such, to infer the values of strength and slump, a wavelet back propagation neural network or wavelet neural network is used for any HPC mix. It is necessary to minimize the cost of HPC/unit weight of HPC subjected to strength and slump constraints. The interwoven algorithm is also applied to obtain optimal sectional areas for minimum weight of space trusses subjected to static loading. Formian programming language is used for the generation of the space trusses, and Feast package is used for the static analysis of the trusses. In addition to the induction of immune system in the GA for constraint handling, it is being applied in this particular application for improving the search of GA in obtaining the best optimal solution. For obtaining the optimal sections of space trusses subjected to earthquake loading, SAP 90 package is used, and reliable results are obtained.     

“5·12汶川大地震”带给我们的反思

文章通过对“5.12汶川大地震”灾区的实地考察,从建筑规划选址、结构、材料与施工等环节分析了部分建筑遭受破坏的原因,并指出加强建筑设计、施工与管理,提升建筑质量,从而提高建筑的防灾能力。     

汶川和芦山地震灾区农村民房震害分析与重建建议

5.12汶川特大地震和4.20芦山强烈地震中,农村民房的震害造成了巨大的人员伤亡和经济损失。基于震害现场调研,概述了近年来中国西南地区的几次地震中农房总体受损情况,从农房的建设选址不当造成的震害、灾区常见的几种农房结构类型的震害特征等两个方面分析了农房震害的主要原因,即地表破坏、缺少必要的结构设计环节、施工质量低劣、抗震构造措施差和房屋抗震意识薄弱。在此基础上,从农村建设场地的科学规划、具有良好抗震性能的农房结构方案和农房建设过程中的科学管理等方面提出了重建建议。     

基于性能的输电塔地震易损性分析

本文以某高压输电塔为研究对象,同时考虑了结构本身的随机性和地震作用的随机性,采用了非线性屈曲分析及动力响应分析对结构的抗震性能、地震反应进行了分析。在基于性能的分析框架下,通过蒙特卡罗数值模拟获得了输电塔的抗震能力曲线,并分析了其统计特性,计算得到结构的地震易损性曲线,为输电塔的抗震防灾规划提供风险评估的数据基础。     

锅炉膨胀中心的设置与导向载荷计算方法的研究

本文主要讨论了导向载荷的计算方法及过程，重点论述了风载荷和地震作用的计算，采用了竖直向下的计算模型。通过对NG－220/9．8－M15锅炉的计算表明，这方法是可行的。图3表3     

Analysis of earthquake management design for nuclear power plants (NPPs) incorporated with artificial intelligence (AI) method

It has been studied to analyze the operations in nuclear power plants (NPPs) where the human error could make a trigger to the nuclear disaster following the earthquake in South Korea. The earthquake warning system and its related control algorithm are modeled by the machine learning (ML) of artificial intelligence (AI) where the neural networking is done as a major role. The AI-based control system could give the very good performance in the earthquake incident which is shown by the system dynamics (SD) based simulations. Hence, the nuclear safety system needs the AI based alarming technology which could be a much more advanced control system incorporated with the conventional multiple-barrier concept in NPPs.     

天地基综合观测的东日本大地震电离层异常分析

介绍了地震电离层前兆的主要特性,并给出了掩星电离层电子密度峰值位置的标高估计技术。利用天地基电离层观测数据,综合分析了2011年3月11日日本9.0级大地震发生前的电离层异常变化,发现地震前3天内电离层f0F2异常扰动、相对垂直总电子含量(VTEC)扰动以及电子密度峰值处标高(Hs)增加等多种异常现象。分析了地磁活动和太阳活动等因素后,认为其可能与地震有一定关联,表明电离层异常变化对于地震短期预报具有重要参考意义。     

Probabilistic loss assessment of light-frame wood construction subjected to combined seismic and snow loads

In some areas, e.g., mountainous areas in the western United States, both seismic and snow loads are significant. Limited research has been conducted to investigate the seismic risk of light-frame wood construction in those areas considering the combined loads, particularly the snow accumulation. An object-oriented framework of the risk assessment for light-frame wood construction subjected to combined seismic and snow hazards is proposed in this paper. A typical one-story light-frame wood residential building is selected to demonstrate the proposed framework. Economic losses of the building due to the combined hazards are evaluated using the proposed framework. It is found that in areas with significant snow accumulation, the snow load has significant effects on the seismic risk assessment for light-frame wood construction.     

Random vibration of a train traversing a bridge subjected to traveling seismic waves

Non-stationary random vibration of 3D time-dependent train-bridge systems subjected to multi-point earthquake excitations, including wave passage effect, is investigated using the pseudo-excitation method (PEM). The motion equation of such a system is established by coupling the train and bridge through wheel-rail contact relationships and accounting for the phase-lags between pier excitations. The horizontal and vertical earthquake excitations are both assumed to be uniformly modulated, fully coherent random excitations with different phases, while the excitation due to track irregularities is assumed to be a 3D, fully coherent random excitation with velocity-dependent time lags. PEM is first proven to be applicable to such time-dependent systems, and is then used to transform the random excitations into a series of deterministic pseudo excitations. By solving for the corresponding deterministic pseudo responses, various non-stationary random responses, including the time-dependent power spectral density functions (PSD) and standard deviations (SD), can be obtained easily. A case study is then presented in which the China-Star high-speed train traverses a seven-span continuous bridge that is being excited by an earthquake. The results show the effectiveness and accuracy of the proposed method by comparison with a Monte Carlo simulation. Additionally, the influences of seismic apparent wave velocity and train speed on the system random responses are discussed.     

Estimating optimum parameters of tuned mass dampers using harmony search

In this paper, the optimum parameters of tuned mass dampers (TMD) are proposed under seismic excitations. Harmony search (HS), a metaheurestic optimization method, which has been successfully applied for several engineering problems, is revised for tuning passive mass dampers. A Matlab program is developed for numerical optimization and time domain simulation. Optimization criteria are the peak values of first storey displacement and acceleration transfer function. In order to find best results, all properties of TMD are searched. For a fast and general optimization, a harmonic loading is utilized for numerical iterations. Also, final TMD parameters are checked under earthquake excitations. This new approach is compared with several other documented methods. Comparisons show that the new approach is more effective than other documented methods and more feasible due to smaller TMD parameters.