模型相似材料内部应变光纤量测应变传递

应用光纤传感技术测量模型相似材料内部应变,必须解决光纤与相似材料耦合的问题。传统的研究中普遍存在应变传递理论分析结果无法通过试验检验的问题。设计实现了一种基于光纤-胶体-相似材料3层应变传递结构的光纤Bragg光栅（FBG）相似材料一维传感器。通过对该传感器应变传递特性和标定方法的研究探索解决光纤与相似材料耦合性的问题。该传感器采用无涂覆层的光纤Bragg光栅作为传感元件,将光纤埋入相似材料应变试件内部直接测量轴向中心应变。通过应变传递理论分析、数值模拟以及全新设计的标定试验研究3种方法研究了该相似材料光栅传感器的应变传递特性。平均应变传递率结果显示3种方法所得到的数值非常接近,表明该传感器的光纤、胶体、相似材料具有良好的耦合性以及应变测量的准确性。该方法为解决模型相似材料内部三维应变测量提供了可行方案。     

三(明)-福(州)高速公路K196+425～+640段路堑右侧边坡滑坡治理

三(明)-福(州)高速公路三明段为国道G104主干线京-福高速公路在福建省三明市境内的一期工程。是一条在山岭重丘区修建的高速公路。三-福高速公路三明段SA7合同段K196 425~ 640段路堑右侧边坡原设计为6级半高边坡,并在第2和第3级设计了锚索地梁锚固。待施工至第1级时,高边坡产生较大规模滑坡,估计体积约12.5万m3。滑坡产生的主要原因是坡体工程地质和水文地质条件差。其次是源于区内连续降雨。再其次是设计锚固深度不足。后经中铁西北科学研究院论证制定了一套较完整的包括刷方减载、放缓边坡、加宽平台、分台整治、预应力锚索框架加固、仰斜坡体排水孔疏水以及地表完善的截排水系统等综合治理方案。所有加固工程完成后,在该高边坡共布置监测断面6条。至今已分别进行了4次深孔位移监测,并经1a多的检验,治理效果良好。     

合理确定梁端塑性铰弯矩值及改进钢框架梁连接设计

多次强震震害表明,梁破坏时梁端截面并未能形成理想塑性铰,而是在梁柱连接处发生脆性破坏。提出了改进钢框架梁连接设计的具体作法,即局部加大梁端焊缝截面的同时,在梁端一定距离处又适当削弱梁翼缘尺寸,合理确定梁端塑性铰弯矩,按梁两端出现同向塑性铰求出钢框架梁柱连接、梁的拼接处的内力(M、V)作为多遇地震作用下的调整内力设计值,改进梁柱连接、梁拼接的设计,供工程设计和修订相应规范作参考。     

Seismic demand sensitivity of reinforced concrete shear‐wall building using FOSM method

The uncertainty in the seismic demand of a structure (referred to as the engineering demand parameter, EDP) needs to be properly characterized in performance‐based earthquake engineering. Uncertainties in the ground motion and in structural properties are responsible for EDP uncertainty. In this study, sensitivity of EDPs to major uncertain variables is investigated using the first‐order second‐moment method for a case study building. This method is shown to be simple and efficient for estimating the sensitivity of seismic demand. The EDP uncertainty induced by each uncertain variable is used to determine which variables are most significant. Results show that the uncertainties in ground motion are more significant for global EDPs, namely peak roof acceleration and displacement, and maximum inter‐storey drift ratio, than those in structural properties. Uncertainty in the intensity measure (IM) of ground motion is the dominant variable for uncertainties in local EDPs such as the curvature demand at critical cross‐sections. Conditional sensitivity of global and local EDPs given IM is also estimated. It is observed that the combined effect of uncertainties in structural properties is more significant than uncertainty in ground motion profile at lower IM levels, while the opposite is true at higher IM levels. Copyright © 2005 John Wiley & Sons, Ltd.     

Geographies of the tropical Internet: An overview

The literature on the geography of cyberspace has focused heavily on the economically developed countries in the mid-latitude regions of the world. This paper addresses the spatiality of the Internet among countries located in the tropics. It charts the network of optical fibre lines that make access possible and the critical role played by telecommunications deregulation. It also accounts for the rapidly changing pools and explosive growth of Internet users between 2000 and 2005 in relation to the socioeconomic variables closely associated with access: costs, wealth, literacy and telephone penetration rates. Finally, the paper also looks at government censorship in various regional contexts and summarizes the status of e-commerce and e-government in different regions within the tropics.     

Multi‐scale modelling approach for the pushover analysis of existing RC shear walls—Part I: Model formulation

This work focuses on the modelling issues related to the adoption of the pushover analysis for the seismic assessment of existing reinforced concrete (RC) structures. To this purpose a prototype reference structure, one of the RC shear walls designed according to the multi‐fuse concept and tested on shaking table for the CAMUS project, is modelled at different levels of refinement. The meso‐scale of a stiffness‐based fibre element and the micro‐scale of the finite element (FE) method are herein adopted; in the latter separate elements are adopted for the concrete, the steel and the steel–concrete interface. This first of the two companion papers presents in detail the wall under study, illustrating the design philosophy, the geometry of the wall, the instrumentation set‐up and the test programme. The two modelling approaches are then described; the most important points in terms of element formulation and constitutive relations for materials are presented and discussed for each approach, in the light of the particular design of the wall and of its experimental behaviour. Copyright © 2007 John Wiley & Sons, Ltd.     

流动注射在线罗丹宁纤维预浓集快速测定地质样品中痕量金

应用流动注射在线罗丹宁纤维预集火焰原子吸收法快速测定地质样品中痕量金。选用微型细柱，内装有新型螯合罗丹宁纤维，在２０％王水质中，样品流速为７．９ｍｌ／ｍｉｎ，上柱４０ｓ；用０．０２５％硫脲就可洗脱，洗脱液流速为２．６ｍｌ／ｍｉｎ，分析速度为６０Ｎ／ｈ，浓集倍数为２５（浓集效率为２５ＥＦ／ｍｉｍ）。对于０．２０μｇ／ｍｌ Ａｕ测定２１次，ＲＳＯ为１．９％。方法检出限（３σ）为０．００１μｇ／ｍｌ Ａ     

光纤地下水动态监测系统的初步研究

深井中地下水监测是地震预报的一种重要手段。本文初步研究了一个光纤地下水动态多参量监测系统。该系统测量参量包括水温、混浊度、气泡度、酸碱度、氢气浓度、甲烷浓度、岩石声辐射以及它们的分布。     

Back-analysis of roof conditions in the Great Northern Seam,Newcastle Coal Measures,Australia, using voussoir beam theory

Summary A typical roof profile for mine openings in the Great Northern Seam consists of a thin coal layer and several metres of claystone. From field evidence and shear flow analysis, the anchorage of fully grouted roof bolts in the claystone may fail. If so, the claystone may act as an extra load on the coal beam. Using voussoir beam theory, the relation between the minimum thickness of the coal beam, the thickness of the failed claystone and the width of the entry has been determined. The analysis is satisfactory for field performance observed in a number of case studies. Proposals are made on possible improvements to mining techniques.     

钢筋混凝土连梁的抗震性能研究

进行了3个剪跨比等于3．0的钢筋混凝土连梁模型的伪静力试验，结合前一批试验^[1]的部分试验结果，考察了提高配箍参数、降低纵筋配筋率和增加核心钢骨对改善连梁抗震性能的效果。通过与其他学者的试验结果进行比较和分析。建立了连梁破坏位移角的回归计算公式。