加强抗震观念 减轻地震灾害

本文根据唐山地震及汶川地震的震害分析,结合《建筑抗震设计规范》(GB 50011-2001 2008年版)提出抗震设计时应注意的几点看法。呼吁全社会加强抗震观念,从而减轻地震灾害。     

On-Line Learning Failure-Tolerant Neural-Aided Controller for Earthquake Excited Structures

This paper presents an on-line learning failure-tolerant neural controller capable of controlling buildings subjected to severe earthquake ground motions. In the proposed scheme the neural controller aids a conventional H∞ controller designed to reduce the response of buildings under earthquake excitations. The conventional H∞ controller is designed to reduce the structural responses for a suite of severe earthquake excitations using specially designed frequency domain weighting filters. The neural controller uses a sequential learning radial basis function neural network architecture called extended minimal resource allocating network. The parameters of the neural network are adapted on-line with no off-line training. The performance of the proposed neural-aided controller is illustrated using simulation studies for a two degree of freedom structure equipped with one actuator on each floor. Results are presented for the cases of no failure and failure of the actuator on each of the two floors under several earthquake excitations. The study indicates that the performance of the proposed neural-aided controller is superior to that of the H∞ controller under no actuator failure conditions. In the presence of actuator failures, the performance of the primary H∞ controller degrades considerably, since actuator failures have not been considered for the design. Under these circumstances, the neural-aided controller is capable of controlling the acceleration and displacement structural responses. In many cases, using the neural-aided controller, the response magnitudes under failure conditions are comparable to the performance of the H∞ controller under no-failure conditions.     

控制点地震前后稳定性研究方法探讨

通过对某项目连续观测数据进行精密处理,对基线向量变化进行定性、定量及统计分析,研究各控制点在地震前后稳定性变化规律,探索稳定性分析方法,确保项目的顺利开展。     

Seismic microzonation of the historic peninsula of İstanbul

In this study, the geological and geotechnical conditions of old Istanbul (Fatih and Eminönü provinces) were investigated in detail and a seismic microzonation study was undertaken for this historical peninsula, which is the site of many ancient structures. Dynamic site response, liquefaction potential and slope stability analyses were carried out, based on field and laboratory tests and earthquake time histories computed with respect to probabilities of exceedance of 10 and 40% in 50 years. The output data obtained from the analyses were evaluated by GIS techniques, and ground shaking, liquefaction susceptibility and landslide hazard maps were prepared.     

Initial analysis of the mechanism of the Wenchuan Earthquake (Southwest China), 12 May 2008

This short paper reports some initial fieldwork carried out in four locations shortly after the M8.0 Wenchuan Earthquake which took place on 12 May 2008 in Southwest China. The field evidence, notably that obtained in the town of Xiaoyudong, suggests that the primary motion was related to vertical movement along the Longmenshan Fault. The damage seen was consistent with a right-lateral strike-slip component.      

基于集对分析模型的岷江上游流域震后水质综合评价

汶川大地震是我国建国以来强度最大、破坏最严重的一次地震,给我国带来巨大的人员伤亡和经济损失。岷江上游流域生态环境较为脆弱,地震、泥石流、滑坡、崩塌等地质灾害经常发生,极易造成突发性水源污染。通过引入基于熵权改进的集对分析模型,对岷江上游流域映秀镇周边水源地进行综合评价,最好、平均、最差三种情况评价结果均为Ⅰ级。结果表明,"5.12"汶川特大地震对岷江上游流域部分水源地水质影响不大,震后岷江上游流域水质无明显变化。     

四川茂县维城乡后山古滑坡形成机制及稳定性评价

结合灾后应急勘察,通过大比例尺工程地质测绘及钻探等手段对维城乡后山堆积体结构进行了系统调查,认为后山堆积体为一古滑坡。滑坡形成前为一变质砂岩和千枚岩构成的顺向坡且顺坡面走向陡倾长大结构面发育,峡谷期河流的快速下蚀作用使斜坡前缘形成陡立临空面,重力作用下,坡体后缘顺层滑移拉裂并最终整体滑动形成古滑坡,运用理正软件搜索古滑坡潜在不稳定滑面．并对其稳定性进行计算和评价,认为其局部复活但整体处于稳定状态。     

汶川地震中西安高层建筑震害调查及分析

汶川大地震中,西安地区大部分高层建筑遭到程度不同的损坏,为了进一步分析高层建筑物的安全性能,以破坏比较明显的西安北郊赛高国际大厦为例进行分析。在震害调查的基础上,对该结构运用专用分析软件ETABS进行了地震作用下反应谱分析和弹性时程分析,对结构的安全性能和抗震能力进行了评估。结果表明,结构的各项指标均能符合规范要求,但其扭转效应较为明显,反映出结构剪力墙布置偏少且不均匀,部分非结构构件做法欠妥,应在构造措施上予以改善。赛高国际表现的问题具有普遍性,损坏主要集中在结构抗震缝、填充墙、外装饰层和装饰柱等非结构构件,主体结构抗震性能满足规范要求。     

State Estimation in Structural Systems with Model Uncertainties

This paper presents an observer designed under the assumption that differences between predicted and measured outputs arise from discrepancies between the real structural system and the nominal model used to represent it. The observer gain is independent of the assumed model error parametrization and proves to be the transpose of the state to output matrix of a state space formulation. The estimated state with the proposed observer is shown to be identical to that obtained by exciting the nominal model with the known input while adjusting the measured portion of the state to match the measurements at the start of every step. Numerical experiments suggest that the proposed observer can provide state estimates that are substantially more accurate than results predicted by projecting the measurements in a truncated modal space.     

“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。