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排序方式: 共有166条查询结果,搜索用时 15 毫秒
1.
介绍了钢筋混凝土结构,钢结构和钢骨钢筋混凝土结构建筑在坂神地震中的破坏情况,了建筑结构的震害与建筑年代及建筑规范的变迁有关,高层建筑中的薄弱层和东同结构型式的转换层是震害的集中部位。  相似文献   
2.
唐山城市防灾的地质灾害分区评价   总被引:4,自引:1,他引:3  
根据唐山市区曾发生过的地质灾害及其相关的活动构造、第四纪沉积物厚度和地貌条件,从城市建设和安全的角度进行唐山市地质灾害分区评价。  相似文献   
3.
基础提离、滑移对结构地震反应影响的探讨   总被引:4,自引:0,他引:4  
采用分布参数法对土-单自由度结构相互作用体系的基础提离、滑移对其地震反应影响作了较详尽的探讨.此外,对基础提离与滑移之间的相互影响也作了讨论.  相似文献   
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Information about interpopulational variation of diet is important for thoroughly understanding the ecological niche of a species, the possible attributes that have allowed it to live in different habitats and ecosystems (if it is the case) and the degree of dietary specialization. This study compared dietary composition and diversity, size of prey consumed and feeding intensity between two geographically proximate populations of Craugastor alfredi, inhabiting contrasting habitats: one located in a remnant tropical rainforest and the other population located within a cave entrance, in eastern Mexico. A total of 118 frogs (50 from rainforest and 68 from cave) were stomach-flushed and, from those, 86 had at least one prey item (42 from rainforest and 44 from cave). Consumption proportions of orthopterans differed between habitats, with frogs from the cave having higher importance values of this prey than frogs from the rainforest. Additionally, both dietary diversity and feeding intensity were higher in the rainforest population. It was concluded that the generalized diet of C. alfredi, besides the high consumption of orthopterans by the cave population, may have contributed to its success in cave entrances. Nonetheless, other non-feeding attributes like small body size, direct development and semiarboreality may also facilitate the use of rock crevices in caves for foraging and reproduction.  相似文献   
6.
随着我国经济的发展,超限高层建筑越来越多,如何评估和保证其在地震作用下的可靠性,是众多结构抗震工作者研究的课题。本文针对某超限高层办公楼采用静力弹塑性和动力弹塑性分析方法进行了研究分析。结果表明:对于超高层结构,由于高阶振型的影响显著,push—over方法中荷载的加载方式等需进一步研究,以使其分析结果满足设计要求。动力弹塑性分析方法即弹塑性时程分析方法,由结构初始状态逐步积分直至地震作用结束,能够计算结构构件在每个地震波记录时刻的地震反应。尽管这种分析的工作量是相当大的,但随着计算机技术的发展,弹塑性时程分析方法有广泛的应用前景。本文在目前研究成果的基础上,对某超限高层进行了分析,得到了满意的结果,对指导设计起到积极的作用。  相似文献   
7.
The Mexican species of the braconid subfamily Cardiochilinae are reviewed. Forty-five species are recognized from Mexico, though many of these remain undescribed. Seven species are described as new and one, Toxoneuron levis (Mao), is redescribed. Species-groups are delineated for the New World species of Toxoneuron Say and Retusigaster Dangerfield, Austin and Whitfield and the genera are re-defined with respect to one another. Two new species are described in both Retusigaster and Toxoneuron. The atypical nature of the two included in Toxoneuron is discussed. Hansonia, Heteropteron and Schoenlandella are newly recorded for Mexico with one new species described for each. The placement of all New World species previously included in Schoenlandella is discussed, and several of these species are returned to Cardiochiles s. s. Distribution patterns of the Mexican species are discussed and an annotated key is presented for the 28 described species recorded from Mexico.  相似文献   
8.
《Journal of Natural History》2012,46(16):2119-2131
Recent surveys of the plethodontid salamander fauna of Oaxaca, Mexico, disclosed the existence of a new, morphologically distinct arboreal species of the genus Pseudoeurycea. The new species, described here, is from the Sierra Mazateca in northern Oaxaca. Sequences of 1833 base pairs of the 16S, cytochrome b and ND4 mitochondrial DNA (mtDNA) genes from the new taxon were used to assess its phylogenetic position. Previous phylogenetic analyses based on mtDNA supported recognition of four clades within Pseudoeurycea: P. bellii, P. gadovii, P. juarezi and P. leprosa-Lineatriton species groups. One additional species, P. unguidentis, was not closely allied to any of the four groups. Re-analysis including the additional sequences reported here establishes a sister-group relationship between the new species and P. unguidentis. Moreover, it supports this clade as part of the P. juarezi species group.  相似文献   
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分缝拱坝的地震响应分析   总被引:6,自引:2,他引:6  
采用非线性有限元法研究了带有横缝的拱坝在El Centro波地震作用下的响应。研究中认为坝体混凝土是线弹性体,对于横缝模拟了其连续,张开,闭合,相对滑移以及初始压力等多种受力状态。用有限元和半无限元相结合求解拱坝与库水的动力相互作用问题,算例给出了拱坝关键部位的应力和位移响应,考虑了不同水位,初始压力,抗拉强度等因素的影响,并与相应的线弹性情况的结果进行比较,最后通过综合分析对带有横缝拱坝的地震响  相似文献   
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