Neural Networks for Decentralized Control of Cable-Stayed Bridge

The system identification and vibration control of a cable-stayed bridge are considered difficult to achieve due to the bridge’s structural complexity and system uncertainties. In this paper, based on the concept of decentralized information structures, a decentralized, nonparametric identification and control algorithm with neural networks is proposed for the purpose of suppressing the vibration of a documented six-cable-stayed bridge model induced by earthquake excitations. The control strategy proposed here uses the stay cables as active tendons to provide control forces through appropriate actuators. Each individual actuator is controlled by a decentralized neurocontroller that only uses local information. The feature of decentralized control simplifies the implementation of the control algorithms and makes decentralized control easy to practice and cost effective. The effectiveness of the decentralized identification and control algorithm based on neural networks is evaluated through numerical simulations. And the adaptability of the decentralized neurocontrollers for different kinds of earthquake excitations and for a damaged cable-stayed bridge model is demonstrated via numerical simulations.     

Statistical evaluation of the damage potential of earthquake ground motions

This study focuses on the damage potential of earthquake ground motions based on the inelastic dynamic response of equivalent single degree of freedom structures. Their yield resistances are selected in accordance with seismic design codes. An index accounting for the accumulation of damage due to inelastic excursions is used to represent structural damage. A set of 94 ground motions are employed for this analysis, which are all scaled to the same peak ground acceleration of 0.4 g. Earthquake ground motions are classified with respect to both the ratio of peak velocity to peak acceleration (V/A ratio) and their effective excitation duration. The effect of these parameters on damage potential is investigated by using sensitivity analysis and probabilistic techniques. It is concluded that both V/A ratio and effective duration significantly influence the damage potential of earthquake ground motions, although they are not represented appropriately by the spectral definitions of earthquake excitations in seismic design codes.     

Dynamic Behavior of Steel Deck Tension-Tied Arch Bridges to Seismic Excitation

The dynamic responses of steel deck, tension-tied, arch bridges subjected to earthquake excitations were investigated. The 620 ft (189 m) Birmingham Bridge, located in Pittsburgh, was selected as an analytical model for the study. The bridge has a single deck tension-tied arch span and is supported by two bridge piers, which in turn are supported by the pile foundations. Due to the complex configuration of the deck system, two analytical models were considered to represent the bridge deck system. Using the normal mode method, seismic responses were calculated for two bridge models and the results were compared with each other. Three orthogonal records of the El Centro 1940 earthquake were used as input for the seismic response analysis. The modal contributions were also checked in order to obtain a reasonable representation of the response and to minimize computational cost. Displacements and stresses at the panel points of the bridge are calculated and presented in graphical form.     

试揭世界三大自然之谜之一──明代京师王恭厂火药厂爆炸探因

３７０年前，明王朝京师王恭厂火药制造厂发生大爆炸，北京城百姓死亡逾万人，该事故被称为世界三大自然之谜的一个谜。我们在耿庆国等人的考证及分析基础上，从爆炸的力学效应入手，剖析了这次事故，并以此文来缅怀北京城３７０年前在灾难中罹难的先人。     

秭归水田坝等三条断裂关系及孕震强度评价

鄂西种秭归盆地是长江三峡地区重要的构造单元之一，盆地东侧水田坝断裂与其南部龙王冲断裂、北部新华断裂，经分析不属同一基底构造体系。尽管各断裂近期活动不甚明显，按活动断裂评价标准，均不属工程活动断裂，但不能排除发生中强地震的危险性。用经验公式法估算的最大构造地辱震级，水田坝断裂为５．５级、龙王冲断裂为６．０级、新会断裂为６．５级。     

小议教学楼抗震不利之处与震后评估方法

分析了教学楼对于抗震不利的几个特点．总结了在地震中导致教学楼发生破坏的主要原因。介绍了震后校舍的抗震性能评估方法和评估流程．通过采用该评估方法可以对震后教学楼进行归类,然后依照评估结果依次进行补强。这为震后加固和重建提供了一个很好的参考,具有很重大的实际意义。     

汶川地区遗产资源保护与利用的思考

汶川地震对震区的自然文化遗产造成了严重的破坏,遗产资源损坏的统计、修复、保护与开发利用工作十分紧迫。与此同时,也有必要归纳总结在地震前后的抢救、保护、开发中所做工作的经验和不足,逐步形成较为完整的应对灾害性破坏的遗产资源保护与利用的方法和理论。     

5．12汶川大地震中给排水管道的震害及其分析

本文介绍了给排水管道在汶川大地震中的震损情况,在分析总结管道地震破坏特点的基础上,对给排水管道抗震设计提出了建议,供工程设计人员参考。     

5．12四川汶川大地震中给排水结构的震害及其分析

本文介绍了给排水工程结构在2008年5月12日四川省汶川大地震中的震害情况,并分析总结了地震破坏的特点,从而对给排水工程结构抗震设计提出了建议,供工程设计人员参考。     

汶川震后重建之观念与技术探讨——以台湾集集9.21震灾为鉴

大地震造成生命财产重大损失之原因,虽说源自天灾,但造成生命财产之惨痛伤害者,则以人谋不臧所致之人祸居多!从台湾集集9.21震灾调查报告与本次四川汶川大地震之灾损状况之雷同,均可证实。造成汶川与集集之重大震灾原因,认为主要者应系全民防震观念尚未建立及建筑物之防灾抗震技术未曾落实与不完备二大人祸因素所造成。从全民防震抗震角度出发,先从观念层面上扼要探讨地震及震灾发生之基本原因,再从技术层面上探讨建筑物之防灾抗震技术,最后汇整所参与之《9.21集集大地震建筑物震害调查初步报告》,以提供汶川5.12大地震灾后检讨与重建之参考。