钢管混凝土框架-核心筒混合结构连续倒塌非线性动力分析   总被引：1，自引：0，他引：1       下载免费PDF全文

魏国强  郑龙  王文达  宋子龙 《地震工程学报》2019,41(3):581-587

为研究钢管混凝土框架-核心筒混合结构在局部构件失效后的连续倒塌机制,基于ABAQUS纤维梁单元和分层壳单元,采用课题组开发的材料本构子程序iFiberLUT,进行了一栋33层钢管混凝土框架-核心筒混合结构在1、17、33层柱和核心筒墙体失效工况下的连续倒塌非线性动力分析,研究了典型柱和剪力墙失效后剩余结构的抗连续倒塌机制。结果表明:33层构件失效时上部节点位移反应最大,17层次之,1层最小,相比核心筒墙体失效,柱失效时上部节点竖向位移更大,震荡更明显;各工况作用对核心筒影响均较小,且核心筒的存在增强了楼板的薄膜效应,提高了结构抗倒塌能力,失效位置距核心筒越近提高越显著;典型构件失效后结构的传力路径遵循"就近原则"向周围构件传递,楼板和核心筒有力的提高了结构的冗余传递路径和整体性。  相似文献   

CFRP加固对预制节段拼装桥墩抗震性能的影响          下载免费PDF全文

马煜  张于晔 《地震工程学报》2020,42(4):847-855

为提升预制节段拼装桥墩的抗震性能,采用碳纤维增强复合材料(CFRP)对预制节段拼装桥墩在地震中易损伤部位进行加固。基于既有试验,建立缩尺的预制节段拼装桥墩三维实体有限元模型,分析预制节段拼装桥墩在循环往复荷载情况下的恢复力特性以及破坏情况。分别采用箍筋加密和外包CFRP布对预制节段拼装桥墩底部节段进行加固,对比两种加固方式对预制节段拼装桥墩抗震性能的影响。研究结果表明,CFRP包裹桥墩底部节段能够增强桥墩整体刚度和承载能力,并且使得桥墩的刚度退化更加平缓,有利于预制节段拼装桥墩在地震作用下保持自身力学特性的稳定,确保桥梁整体的安全。  相似文献   

植入式光纤传感器在隧道结构中的边界效应研究     

侯公羽  李子祥  胡涛  周天赐  肖海林 《岩土力学》2020,41(8):2839-2850

为探究植入式光纤传感器与隧道衬砌的应变传递的边界效应,分别从理论、试验和现场应用3个方面进行研究,并在实际工程中进行了验证。构建了光纤在混凝土衬砌中的应变传递模型,进行光纤应变传递机制分析,计算了光纤应变传递效率,并与数值计算结果对比,验证了力学计算模型的准确性。使用钢筋混凝土梁模拟隧道的混凝土衬砌,在其表面植入分布式光纤,进行了2组试验。对试验梁进行分级加载并使用BOFDA技术对光纤进行测试。试验结果表明：植入式光纤传感器存在边界效应,结构两端为光纤的低效率应变传递区,不能完全传递试验梁的应变;试验梁中部为光纤的高效率应变传递区,能够完全传递试验梁的应变。基于以上研究成果,在北京市新机场线地铁暗挖隧道CRD工法区间,采用植入式工艺在隧道衬砌内布设了分布式光纤传感器,进行了工程应用研究。监测结果表明,边界效应对工程监测结果影响很小,分布埋入式光纤布设工艺是可行的。该研究可为分布式光纤技术在地下工程结构监测中的应用提供参考。  相似文献   

一种基于微细光缆的固定式深海观察系统   总被引：1，自引：0，他引：1  

王磊  杨申申  刘涛  沈明学  马伟峰 《海洋工程》2009,27(3):127-130

介绍一种利用微细光缆实现深海观察的小型装置.阐述其系统组成、工作方式及利用微细光缆实现深海视频信号和数据的传输过程以及其研制的关键技术,展望了此种深海观察站的发展前景.  相似文献   

Production and transport of long-chain alkenones and alkyl alkenoates in a sea water column in the northwestern Pacific off central Japan     

Ken Sawada  Nobuhiko Handa  Takeshi Nakatsuka 《Marine Chemistry》1998,59(3-4)

Sinking particles collected from year-long time-series sediment traps at 1674, 4180, 5687 and 8688 m depths, the underlying bottom sediment at 9200 m depth, and suspended particles from surface and subsurface waters in the northwestern North Pacific off Japan were analyzed for long-chain alkenones and alkyl alkenoates (A&A) which are derived mainly from Gephyrocapsacean algae, especially Emiliania huxleyi and Gephyrocapsa oceanica. Alkenone temperature records in sediment trap samples at 1674 m were almost similar to observed sea surface temperatures (SST) with a time delay of one half to one full month. However, alkenone temperatures in trap samples were about slightly lower than measured SST in late spring to early fall. The lowering might be caused by formation of the seasonal thermocline. Nevertheless, these temperature drops observed in trap samples were smaller than those actually observed in a subsurface layer off central Japan. Vertical profiles of A&A concentrations and alkenone temperatures in suspended particles collected from the subsurface waters in early fall indicated that these compounds were produced mostly in a surface mixed layer above the depth of the chlorophyll maximum even in warm seasons. These results suggested that alkenone temperatures strongly reflected SST rather than the temperatures of thermocline waters in these study areas even in such a warm season. Pronounced maxima in A&A fluxes found in sediment trap samples at 1674 m in late spring to summer showed that A&A productions were highest during the periods of spring bloom, according to a time delay between alkenone temperatures and observed SST. Seasonal patterns of alkenone records in trap samples at 4180 and 5687 m could also preserve SST signals well, suggesting that A&A in deep sea waters were mainly derived from primary products in the surface layer. A&A fluxes tended to decrease with water depth, and the ratios of A&A to particulate organic carbon (POC) rapidly decreased in underlying bottom sediment. This clearly indicates that A&A were decomposed and diluted by other refractory organic materials in either the water column or the sediment–water interface. However, A&A compositions were consistently uniform between the trap samples and the underlying bottom sediments, so that A&A could not qualitatively alter during early diagenetic processes.  相似文献   

地球气测量的若干问题   总被引：6，自引：0，他引：6  

卢荫庥  白金峰 《物探与化探》1999,23(6):401-407

从分析测试的角度,就影响地球气测量新技术推广应用的原因进行了讨论.认为集气材料的纯度和分析测试中使用试剂的纯度,以及在野外采气作业与室内分析时可能引起的污染是影响这一技术推广的关键所在.  相似文献   

光纤化学传感器及其在海水有机物监测中的应用   总被引：2，自引：0，他引：2  

张志忠 《海洋技术学报》1999,18(2):42-48

光纤化学传感器以其优良的抗电磁干扰性、耐久性以及多功能性而倍受重视。本文在简单介绍光纤化学传感器的原理和应用的基础上,重点介绍了中红外光纤化学传感器在２～２０μｍ这一光谱范围内使用的若干成就。论述了基于该传感器的测量系统对海洋有机污染物实现实时、现场连续监测的重要意义  相似文献   

Der Einfluß des Bibers (Castor fiber albicus) auf die Fauna (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) von Mittelgebirgsbächen in Hessen (Deutschland)     

Mark Harthun 《Limnologica》1999,29(4):449-464

Due to the return of the beaver an increasing number of brooks become restored to a natural condition. It is characterized by an alternation of flowing and standing sectors. In the summer of 1995, different groups of organisms (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) of two brooks in the Spessart mountains (Hesse, Germany) were studied to compare the composition of invertebrates in beaver homeranges and in the non-influenced sectors above. The new living conditions resulted in the disappearance of some species (Drusus anulatus, Trich., Sericostoma personatum, Trich., Radix peregra, Gastr.). Nevertheless the beaver homeranges accommodate a significant higher number of species of dragon flies and damsel flies, molluscs and caddis flies than the brooks above the homeranges. The heterogeneity of natural river systems make a coexistence of running water and silent water organisms possible. The examinations result in a significant higher group dominance of ephemeras (i.p. Cloeon dipterum) in a beaver pond than in lenitic sectors conditioned by the gradient without beaver influence. Here the dominance of chironomids was much higher. High current sectors with their characteristic organisms are also present in the beaver homeranges. The higher number of insects is the basis of nourishment for predatory insects and fishes. The potential effects of beaver ponds on fishes are discussed.  相似文献   

Buckling and postbuckling of composite ship panels stiffened with preform frames     

Sarah E. Mouring 《Ocean Engineering》1999,26(8):793

The U.S. shipbuilding industry recently has started incorporating composite materials in the construction of both military and commercial ships due to the advantages of composite construction. These advantages include the reduction in total life costs, corrosion resistance, high strength- and stiffness-to-weight ratios, and improved stealth for military applications. One disadvantage is the higher costs of composites compared to steel and other conventional materials. Therefore, new higher quality materials with lower costs and new fabrication methods need to be developed before composite materials will be fully accepted for the construction of large ships. A new composite preform framing technology shows promise in the reduction of fabrication costs for large ship construction. There already has been significant cost savings using this framing technology in the construction of small recreational boats and large yachts. This framing technology involves casting a dry glass fiber-reinforced plastic (GRP) fabric into shape in a closed mold with a foam core. One unresolved issue using this framing technology is the orientation of the fiber for the frames. This paper summarizes experimental results of the testing of composite panels stiffened with preform frames under in-plane uniaxial compressive loads. Biaxial (0,90), quadaxial (0,90,+45,−45), and triaxial (+45,−45,0) laminates were used in the frames.  相似文献   

基于高能量耗散型脉冲掺铒光纤激光器的实验研究     

王擂然  刘雪明  宫永康 《海洋学报》2010,32(9):6200-6204

在正色散掺铒光纤激光器中,利用非线性偏振旋转技术实现自启动锁模,得到了具有极大光谱宽度的高能量、无波分裂耗散型脉冲.该耗散型脉冲的形成是腔内增益、损耗、非线性偏振旋转、正色散和其他非线性效应等共同作用的结果,其形成机理与传统的负色散激光器完全不同.当抽运功率为500 mW时,该类型脉冲的光谱覆盖了1530—1660 nm范围,半高全宽光谱宽度可达42 nm以上.脉冲具有极大的正啁啾,其时间带宽积为483,而单脉冲总能量最大可达34.4 nJ.  相似文献