近断层滑冲地震作用下纤维加强钢筋混凝土结构的抗震分析
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摘要
最近的地震记录表明,近断层地震与普通地震不一样,它具有非常大的能量或指向波。该波能导致相当严重的地震破坏,尤其对于自振周期接近地震周期的结构。近断层地震作用下现代工程结构的倒塌说明了目前钢筋混凝土结构抗震性能较差。这可能因为这些结构主要使用由持续时间较长,震源更远的地震形成的现有标准设计谱进行设计。因此,为了在近断层地震作用下性能保持良好,许多结构可能需要加强。由于安装简捷、生命周期成本低和零维护的优点,纤维增强复合材料是可行的选择。阐述了典型的钢筋混凝土结构近断层地震响应的研究结果和对纤维加强结构进行重要改进的可行方案。结果表明,通过纤维加强能成功实现结构刚度、强度、横向变形能力的提高。这表明,对于自振周期范围广的结构的优化,采用纤维加强方式是非常有效的。
Recordings from recent earthquakes have provided evidence that ground motions in the near field of a rupturing fault differ from ordinary ground motions,as they can contain a large energy,or "directivity" pulse.This pulse can cause considerable damage during an earthquake,especially to structures with natural periods close to those of the pulse.Failures of modern engineered structures observed within the near-fault region in recent earthquakes have revealed the vulnerability of existing RC buildings against pulse-type ground motions.This may be due to the fact that these modern structures had been designed primarily using the design spectra of available standards,which have been developed using stochastic processes with relatively long duration that characterizes more distant ground motions.Many recently designed and constructed buildings may therefore require strengthening in order to perform well when subjected to near-fault ground motions.Fiber Reinforced Polymers are considered to be a viable alternative,due to their relatively easy and quick installation,low life cycle costs and zero maintenance requirements.This paper presents the results of a study of the response of typical existing RC buildings to near-fault ground motions and the potential improvements achievable after FRP retrofitting of the buildings.Results demonstrate the successful implementation of FRP with an improvement in stiffness,strength and lateral displacement capacity of the rehabilitated structure.It is demonstrated that strengthening with FRP is very effective in reducing drift demands for structures for a wide range of natural periods.
Recordings from recent earthquakes have provided evidence that ground motions in the near field of a rupturing fault differ from ordinary ground motions,as they can contain a large energy,or "directivity" pulse.This pulse can cause considerable damage during an earthquake,especially to structures with natural periods close to those of the pulse.Failures of modern engineered structures observed within the near-fault region in recent earthquakes have revealed the vulnerability of existing RC buildings against pulse-type ground motions.This may be due to the fact that these modern structures had been designed primarily using the design spectra of available standards,which have been developed using stochastic processes with relatively long duration that characterizes more distant ground motions.Many recently designed and constructed buildings may therefore require strengthening in order to perform well when subjected to near-fault ground motions.Fiber Reinforced Polymers are considered to be a viable alternative,due to their relatively easy and quick installation,low life cycle costs and zero maintenance requirements.This paper presents the results of a study of the response of typical existing RC buildings to near-fault ground motions and the potential improvements achievable after FRP retrofitting of the buildings.Results demonstrate the successful implementation of FRP with an improvement in stiffness,strength and lateral displacement capacity of the rehabilitated structure.It is demonstrated that strengthening with FRP is very effective in reducing drift demands for structures for a wide range of natural periods.
引文
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