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101.
Rehabilitation of earthquake damaged external RC beam‐column joints by joint enlargement using prestressed steel angles 下载免费PDF全文
Jalil Shafaei Abdollah Hosseini Mohammad Sadegh Marefat Jason M. Ingham 《地震工程与结构动力学》2017,46(2):291-316
The effectiveness of a rehabilitation method based on joint enlargement using prestressed steel angles to enhance the seismic behavior of damaged external reinforced concrete beam‐column joints was experimentally investigated. Three half‐scale joints having either non‐seismic or seismic reinforcement details were tested both before and after rehabilitation by applying lateral cyclic loading of increasing amplitudes. Two defects were considered for the two non‐seismic units, being the absence of transverse steel hoops and insufficient bond capacity of beam bottom steel reinforcing bars in the joint panel zone. The damaged specimens were rehabilitated by injecting epoxy grout into existing cracks and installing stiffened steel angles at the re‐entrant corners of the beam‐column joint, both above and below the beam, that were mounted and held in place using prestressed high‐tensile strength bars. The test results indicated that the seismic performance of the rehabilitated specimens in terms of strength, stiffness, and ductility was fully recovered and comparable with the performance of the seismically detailed specimen. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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103.
Rapid repair of severely earthquake-damaged bridge piers with flexural-shear failure mode 总被引:1,自引:1,他引:0
An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged
bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear
mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers (CFRP). After about
four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated
and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both
shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure
mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based
on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that
the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake
if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is
provided. 相似文献
104.
针对BDS全星座播发三频信号的特点,利用1个三频载波伪距组合(1,4,-5)和2个三频无几何相位组合(1,1,-2)、(1,-2,1)联合的方法进行周跳探测,并结合最小2-范数确定整数周跳的搜索策略。实测数据表明,该方法对一般周跳、不敏感周跳及连续随机周跳均有较好的探测与修复效果。 相似文献
105.
针对历元间隔较大或电离层延迟较大的情况,采用两个无几何相位组合与一个最优无几何无电离层组合形成3个线性无关的探测量,将历元间高次差法引用到无几何相位组合探测量中,通过选取合适的探测阈值,使无几何相位组合能够正确探测到较大电离层影响情况下的不敏感周跳。此外,文中采用了一种特殊的无几何无电离组合观测量进行辅助修复,通过两次取整保证了周跳修复的准确性,避免了传统三频周处理中的搜索算法造成错误修复的问题,试验表明,文中算法可以正确探测与修复较大电离层影响情况下不同北斗卫星星座类型的所有小周跳组合以及不敏感周跳组合。 相似文献
106.
The philosophy of ‘working with nature’ and ‘working with the river’ is increasingly embedded in global management practice. However, what does this mean? Has real progress been made in operationalizing what is known, how scientists and practitioners work and how rivers are conceptualized as integral parts of landscapes, culture and society? The first sections of this commentary outline what this philosophy means to us (the authors) and briefly summarize the evolution of associated concepts and principles in recent decades. In the final section, we comment on what we believe needs to be done to ‘work with the river’ in practice. We are communicating to both river scientists and practitioners as a collective when we ask: Will we be brave enough to hold the course in the face of many global challenges, be ready to respond when called upon, and commit to creation of diverse, inclusive and open access communities of practice in geoethical programmes that ‘work with the river’? 相似文献
107.
以建筑平面图为数据源,提出了一种自动生成室内地图空间数据的方法。首先,结合室内地图空间数据的需求分析了建筑平面图的基本特征,提出了墙段、邻接节点和相邻墙段的概念,并在此基础上建立了自动生成室内地图空间数据的基本流程。然后,根据与柱子相交墙线的相邻关系,建立了与柱子关联墙体连通性的恢复方法;结合渐进扩张与图形推理判断门窗两侧墙体符号局部特征的类型,通过修正门窗外接矩形,建立了与门窗关联墙体连通性的恢复方法和将门窗转换为室内地图点状要素的方法。最后,基于相邻墙段中心线的几何关系,建立了墙体中线的提取算法。以某展览馆的建筑平面图为例进行试验,结果表明本文的方法针对多种复杂情况均有较好的适用性,有效实现了室内地图空间数据的自动生成。 相似文献
108.
近年来,先后开展了长江中下游长达1 643 km范围的GPS C、D级控制网点的修复工程,面对时间紧、埋石与观测工作量大、施工涉及区域较长等诸多问题,采用分组平行进行的施工组织方式,在确保测量精度下同时缩短了工期,节约了工程成本,本文对此经验与创新进行了总结,以供参考。 相似文献
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