轻钢增层结构地震剪力的简化计算方法

利用振型分解法，并考虑阻尼的影响，推导出了一种轻钢增层结构增层部分底部抗震剪力的计算公式，为轻钢增层结构的合理设计提供了一种较为精确的简化计算方法。     

利用结构增层聚焦和耗散能量

本文采用能量集中与耗散的方法，提出了增层结构的优化刚度和质量，降低原结构的动力反应、达到了利用增层减振的效果。     

某教学楼框架结构的抗震加层加固设计

介绍了某混凝土框架结构教学楼使用屈曲约束支撑的加层改造和抗震加固设计。工程中采用钢结构将已有的4层混凝土框架结构增加到7层,增层后混合结构的自震周期加长,侧向变形增大,地震层剪力增大。设计中对原有混凝土梁柱和基础采取了包钢和加大截面等加固方法;通过增加屈曲约束支撑调整增层后结构的刚度分布,增加结构的冗余度,显著改善了结构破坏机制,提高了加层后结构的抗震能力。还给出了加层钢柱脚节点等关键构造的做法,为类似加固加层改造工程提供参考。     

浅谈建筑物加层中的抗震问题

叙述了建筑物增层的现实情况，提出建筑物尤其是处于地震重点监视防御区的建筑物增层时，必须考虑建筑物的场地、结构、材料等抗震因素。     

轻钢增层结构的实用抗震设计方法

轻钢增层结构属于复合结构，我国建筑抗震规范尚未对复合结构的抗震设计方法作出具体规定，传统的抗震设计方法偏于不安全。本文提出了轻钢增层结构的实模态强振型解耦法，并对现行规范的地震影响系数提出了修订意见。     

频高图F层异常分层现象的自动识别

频高图F层异常分层(增层)是指在常规电离层结构的基础上,由于电子密度被扰动而在频高图中出现多层回波结构,该F层异常分层(增层)现象在白天和晚上均可观测到.电离层异常分层(增层)主要由某种电动力学或者突发电离源导致电子密度出现扰动而形成,已经引起国内外学者的广泛关注和研究.目前从频高图中识别F层异常分层(增层)主要还是通过人工的方法,海量的频高图数据使该方法在研究F层异常分层(增层)统计特征时变得非常困难.有别于传统的图像分类算法中需要对图像特征进行提取,本文通过引入卷积神经网络(Convolution Neural Network, CNN),设计开发出一种能够自动识别存在F层异常分层(增层)频高图的方法,该方法可以直接输入频高图样本数据,省去了复杂的图像特征提取过程.本文设计的卷积神经网络经过训练以后F层异常分层(增层)识别率为85.82%,准确率90.36%.实验结果表明该卷积神经网络可以较好地自动识别出F层异常分层(增层)的频高图.     

套建增层预应力钢骨混凝土框架弹塑性地震反应分析

从套建增层改造实践中存在的问题出发,提出了一种新型外套增层结构型式,即以内置H型钢预应力混凝土组合梁为框架梁、以配置4个或8个角钢的角钢混凝土柱为框架柱的套建增层用框架结构,并给出了节点构造。根据不同的场地条件和地震设计分组,对基于现行设计标准设计的跨度为16m的新型套建增层框架进行了罕遇地震作用下的时程分析。分析结果表明,在满足常遇地震作用下的设计要求时,在7度和8度罕遇地震作用下,建造在I、II、III类场地上的部分套建增层框架将会倒塌。根据弹塑性反应分析结果,提出了在罕遇地震作用下避免这种套建增层框架发生倒塌的设计建议。     

利用惯容隔震系统的结构层间隔震研究

层间隔震技术对于结构竖向不规则以及结构增层等状况有良好的适用性。然而,层间隔震可能出现的较大隔震层变形会带来结构设计的困难。通过在隔震层中设置阻尼元件可以减少变形,但是过大的阻尼出力和过多的数量需求可能导致空间布置和安装不便。惯容元件为解决以上问题提供了一种新的途径。该研究提出采用惯容隔震系统作为层间隔震提高能量耗散效率的手段以控制地震响应,同时也给出了基于性能需求的惯容层间隔震的参数优化设计方法。并以一个标准钢结构模型验证了方法的有效性。结果表明:惯容元件的使用显著降低了上部子结构的地震响应和隔震层的变形,惯容系统实现了预期的耗能增效作用。     

新型外包加强型节点抗震性能试验研究

为了减小钢筋混凝土(RC)框架-轻钢增层混合结构的鞭梢效应,本文提出了一种用于该类结构的新型外包加强型节点,旨在加强对上部结构的约束,减小上下部结构的刚度突变。为了深入研究其抗震性能,与另一种外包锚固式节点进行了低周往复荷载作用下的对比性试验研究。结果表明:两种节点均表现为梁端塑性铰破坏,并能有效控制裂缝开展;新型外包加强型节点滞回曲线饱满,捏拢速度较慢,并能将塑性铰外移,有效保护了节点核心区,其刚度退化、等效黏滞阻尼系数、耗能能力等各项指标都较外包锚固式节点有不同程度的提升,提高了节点的承载力和刚度,具有更好的抗震性能。本文的研究可以为轻钢增层混合结构的推广应用提供科学依据和技术支持。     

ぶ柿坑凶愎坏闹厥?并注意搞好质量控制。现从三上方

澄鲈诮ㄖ┕ぶ腥绾未碜昕坠嘧⒆鱿值奈侍馓普窕?刘星;七煤集团建设工程总公司,七煤集团建设工程总公司 154600,154600施工;;桩基;;质量本文根据地区的地质特性和现场实践经验,简单阐述了造成桩基质量事故主要原因。0化工之友Friend of Chemical Industry17-18TU753.3C038;26;B;C;C038_26;唐振辉;13-14原有建筑物的增层加高王桂清;鸡西矿业集团公司审计事务部 154600增层加高超余安全度本文就如何对原有建筑物的增层加高问题进行了详细的叙述,并提出在加高后应考虑的几个方面。0化工之友Friend of Chemical Industry18TU746.3C038;26;B;C;C038_26;王桂清;14浅析钢筋混凝土的收缩变形刘星;唐振     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Earthquake Engineering and Engineering Vibration Aims And Scope

正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and     

Foreword

Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States.     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Enhancing remote sensing research on global change to improve our understanding on Earth system processes

正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases     

Dissolved Carbohydrate Concentration,Composition, and Bioavailability to Microbial Heterotrophs in Stream Water

Dissolved total carbohydrates (DTCH), dissolved free monosaccharides (DFMS), dissolved organic carbon (DOC), biodegradable DOC (BDOC), and humic substances (HS) were measured in White Clay Creek (WCC), a stream in southeastern Pennsylvania Piedmont, USA. Samples were collected over different seasons and under baseflow and stormflow conditions. DOC concentrations ranged from 1.0 to 12.8 mg/L C with the highest concentrations associated with stormflows. Carbohydrates ranged from 0.42 to 12.4 μM and accounted for 2.9 to 12.7% of the DOC. Humic substances represented the major DOC fraction, accounting for 55 to 72% of the DOC pool under all flow conditions. The humic fraction had a lower carbohydrate content (4.4%) than the non-humic fraction of DOC (7.2%). Stormflow DOC was enriched in carbohydrates relative to baseflow DOC, but the percentage of humic-C changed little. Carbohydrates were primarily present as dissolved polysaccharides (55%), but a significant fraction was bound to humic substances (40%), while a small proportion was present as monosaccharides (5%). The major monosaccharides in stream water, listed in order of decreasing concentration, included glucose, galactose, rhamnose, xylose, arabinose, mannose, and fucose. On average (30.6 ± 7.4)% (n = 44) of the stream water DOC was biodegradable, and carbohydrates accounted for 9.9 to 17.7% of the BDOC.