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111.
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The scope of this study is to present results of an experimental investigation on the behaviour of critical external beam–column joints repaired or/and strengthened with a combination of epoxy resin injections and carbon‐fibre‐reinforced plastics (C‐FRP) sheets and to extract useful and practical conclusions. The experimental program comprises 12 external beam–column joint connection subassemblages tested in cyclic loading. From the observed responses of the examined specimens it can be deduced that the technique of epoxy resin injections is appropriate for the total rehabilitation of the joints seismic capacity, since no damages have been observed at the joint area of the specimens after the repair. The combination of this technique with the use of C‐FRP sheets leads to a significant improvement of the loading capacity, the energy absorption and the ductility and finally it leads to improved type of damages compared with the damage modes of the specimens during the initial loading. Shortcomings of the application of C‐FRP sheets for practical use are also pointed out. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
113.
钢筋混凝土桥墩震后修复技术研究综述 总被引:1,自引:0,他引:1
介绍了近几次破坏性地震中钢筋混凝土桥墩的典型震害,总结了国内外利用FRP材料、钢套管、狗骨式杆等新型建筑材料对发生弯曲破坏、剪切破坏、纵筋搭接破坏以及空心截面桥墩的震后修复技术.研究表明,采用合适的修复方案,可以对地震损坏的桥墩进行成功修复,使其承载力和延性得到较好的恢复.文中提到的桥墩震后修复方案可为地震、火灾、爆炸以及腐蚀老化后遭受损坏的钢筋混凝土结构的修复提供参考. 相似文献
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基于三频伪距相位和无几何相位组合周跳探测与修复的基本原理,分别推导周跳探测的阈值条件,研究组合量的优化选取模型|以组合量标准差最小为原则并综合历元间电离层延迟误差,选取适合于北斗三频数据的伪距相位和无几何相位组合。实验结果表明,两种方法均能实时探测和修复所有模拟的周跳|综合算法计算量、复杂性和舍入误差,首选伪距相位组合法。 相似文献
116.
An alternative approach for the seismic rehabilitation of existing RC buildings using seismic isolation
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Usually, buildings with seismic isolation are designed to comply with an operational building performance level after strong earthquakes. This approach, however, may limit the use of seismic isolation for the seismic rehabilitation of existing buildings with low lateral strength or substandard details, because it often requires invasive strengthening measures in the superstructure or the use of expensive custom‐made devices. In this paper, an alternative approach for the seismic rehabilitation of existing buildings with seismic isolation, based on the acceptance of limited plastic deformations in the superstructure under strong earthquakes, is proposed and then applied to a real case study, represented by a four‐storey RC frame building. Nonlinear response‐time histories analyses of an accurate model of the case‐study building are carried out to evaluate the seismic performances of the structure, comparing different rehabilitation strategies with and without seismic isolation. Initial costs of the intervention and possible (future) repair costs are then estimated. Based on the results of this study, values of the behavior factor (i.e. response modification factor) higher than those adopted in the current codes for base‐isolated buildings are tentatively proposed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
117.
Post‐repair effect of column jackets on aftershock fragilities of damaged RC bridges subjected to successive earthquakes
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In light of recent earthquakes, structures damaged during an initial seismic event (mainshock) may be more vulnerable to severe damage and collapse during a subsequent event (aftershock). In this paper, a framework for the development of aftershock fragilities is presented; these aftershock fragilities define the likelihood that a bridge damaged during an initial event will exhibit a given damage state following one or more subsequent events. The framework is capable of (i) quantifying the cumulative damage of unrepaired bridges subjected to mainshock–aftershock sequences (effect of multiple earthquakes) and (ii) evaluating the effectiveness of column repair schemes such as steel and fiber‐reinforced‐polymer jackets (post‐repair effect of jackets). To achieve this aim, the numerical model of repaired columns is validated using existing experimental results. A non‐seismically designed bridge is chosen as a case study and is modeled for three numerical bridge models: a damaged (but unrepaired) bridge model, and two bridge models with columns repaired with steel and fiber‐reinforced polymer jackets. A series of back‐to‐back dynamic analyses under successive earthquakes are performed for each level of existing damage. Using simulated results, failure probabilities of components for multiple limit states are computed for each bridge model and then are used to evaluate the relative vulnerability of components associated with cumulative damage and column repair. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
118.
Multiple hazard incidents lifecycle cost assessment of structural systems considering state‐dependent repair times and fragility curves
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The performance and serviceability of structural systems during their lifetime can be significantly affected by the occurrence of extreme events. Despite their low probability, there is a potential for multiple occurrences of such hazards during the relatively long service life of systems. This paper introduces a comprehensive framework for the assessment of lifecycle cost of infrastructures subject to multiple hazard events throughout their decision‐making time horizon. The framework entails the lifecycle costs of maintenance and repair, as well as the salvage value of the structure at the end of the decision‐making time horizon. The primary features of the proposed framework include accounting for the possibility of multiple hazard occurrences, incorporating effects of incomplete repair actions on the accumulated damage through damage state‐dependent repair times, and requiring limited resources in terms of input data and computational costs. A dynamic programming procedure is proposed to calculate the expected damage condition of the structure for each possibility of the number of hazard incidents based on state‐dependent fragility curves. The proposed framework is applied to a moment‐frame building located in a region with high seismicity, and lifecycle costs are evaluated for six retrofit plans. The results displayed variation in the ranking of the retrofit actions with respect to decision‐making time horizon. Furthermore, the sensitivity analyses demonstrated that disregarding repair time in the lifecycle cost analysis can result in false identification of unsafe retrofit actions as optimal and reliable strategies. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
119.
分析了辽河油田油水井套管损坏的原因,介绍了辽河油田几种较先进的套损检测方法,提出了几种常用的修复工艺,对辽河油田因地制宜地采取套管修复措施,恢复套损井的正常生产具有一定的借鉴意义。 相似文献
120.
Breakage-induced shell repair and drilling were studied in 548 shells belonging to 24 species of gastropod from the Ripley Formation (latest Campanian-Maastrichtian) of the south-eastern U.S.A. Frequencies of repair are high even by Recent standards. These is no relationship between the frequency of shell repair and shell architecture. Repair increases in frequency with increasing shell length. Drilling, which is less common in Ripley gastropods than in most warm-water Tertiary species, decreases in frequency with increasing shell length. 相似文献