傅里叶时频分析的建筑物沉降预测

针对时间序列自回归(AR)模型在高层建筑物沉降预测中出现的对于历史资料分析和利用不充分的情况,提出了一种基于傅里叶时频分析的沉降预测模型。以桂林市某在建的高层建筑物的沉降变形为例,在分别从时域和频域两个方面充分分析资料的基础上,对建筑物的沉降观测数据进行建模分析,得到了均方误差为0.107 9 mm的预测精度,很好地克服了AR模型在应用中存在的问题,提高了预测精度。     

北斗/GPS组合定位方法

随着北斗卫星导航系统的逐渐完善,有关北斗系统定位的研究越来越深入,为了对比分析北斗系统和全球定位导航系统(GPS)定位的差异性,充分利用北斗地球静止轨道卫星(GEO)和倾斜地球同步轨道卫星(IGSO)高轨道卫星的特殊性,本文提出一种新的组合选星方法,选取卫星数较少且Position Dilution of Precision(PDOP)最小的北斗/GPS组合,分别对比分析北斗系统、GPS系统及其组合系统在楼顶开放环境和楼间恶劣环境下的定位效果。实验结果表明:北斗比GPS有更加稳定的定位效果,依据本文组合选星方法,利用少量卫星即可获得较好的定位精度。     

Testing of Sydney dimension sandstone for use in the conservation of heritage buildings

This paper deals with the scientific assessment of the physical properties of sandstone used in the conservation of Sydney's historic heritage sandstone buildings. The local Hawkesbury Sandstone has been widely used for all manner of constructions since the early days of the first settlement. In the nineteenth century, dimension sandstone quarries existed all over the Sydney region, and the demand for the stone was great. During this time, a true ‘freestone’ known as ‘yellow block’ sandstone, in which bedding planes were absent, was quarried extensively. This sandstone is also known as a ‘self-colouring’ sandstone, where the rock, although grey when quarried, turns a yellow–brown after a few months exposure to the atmosphere. It can be easily carved and was eminently suitable for the ornate Victorian architecture of the time. There are very few quarries within the Sydney region today capable of producing ‘yellow block’ sandstone. Whenever possible, sandstone from suitable building excavations, particularly on the Pyrmont Peninsula, is used for this work. Conservation work is extremely expensive and the building elements that most need replacement, the overhanging and decorative elements, are usually those that cost the most. It is essential that the most durable replacement stone be selected. Thus, a strict regime of scientific testing is used for any major conservation project, in order to determine the physical properties of possible replacement stone. This is the province of the geologist and involves visual observation in the quarry or excavation, which is a simple, cost-effective means of weeding out poor quality stones, followed by laboratory engineering tests to establish the physical parameters of a sandstone and finally, petrographic analysis. The results of such tests, combined with careful sampling, ensure the best possible quality of replacement material.     

云南漾濞6.4级地震公共建筑的震害特征

2021年5月21日云南漾濞发生6.4级地震,成为继2014年6.5级鲁甸地震和6.6级景谷地震之后云南省内时隔7年的又一次震级大于6级的破坏性地震。漾濞地震虽然与鲁甸地震在震级、震源深度和震源机制等方面均较相似,但漾濞地震震中附近的地面运动强度远不及鲁甸地震,且漾濞县的抗震设防烈度远高于鲁甸;相应地,漾濞地震对抗震设防建筑造成的破坏也远轻于后者。本文首先通过比较这三次地震震中附近的强震记录的反应谱,并结合公共建筑的震后应急评估结果,说明漾濞地震和鲁甸地震中公共建筑破坏程度的显著差异。进而以位于漾濞县城的两栋钢筋混凝土公共建筑为例,介绍此次地震中砌体填充墙和吊顶等典型非结构构件的震害。     

芦山地震中校舍建筑的震害特点与分析

本文对芦山地震中的校舍建筑震害进行调查和分析.调查发现,汶川地震后重建的框架结构,由于按照新的抗震规范进行设防,大多数没有出现结构性损伤,震害集中在填充墙等非结构构件上.建于汶川地震前的框架结构,当不符合规范的强制条文时,破坏严重,特别是单跨框架,个别发生首层柱端破坏.砖混结构校舍中的宿舍楼,由于开间小,横墙多,多设置了构造措施,虽有结构破坏,但均可修复.砖混结构教学楼采用砖墙-框架柱混合承重的结构体系,大多在汶川地震后得到加固,未加固的教学楼有严重的结构破坏,而加固后的校舍建筑则表现较好,但是这些结构体系多采用预制空心板,整体性较差,已经被规范禁止用于校舍建筑.场地对结构震害有重要的影响,密实的持力层、妥善的地基处理和整体性好的基础形式,可以大幅度减轻结构的震害.本文建议:应加强校舍建筑基于性能设计的研究,进一步明确其设防目标;研究填充墙与框架的相互作用,设计新型的填充墙体系以实现校舍建筑在不同地震水平下的功能要求.     

Building Green: The Emerging Geography of LEED-Certified Buildings and Professionals

One of the most important attempts to reduce the environmental impacts of the built environment is through the construction of green buildings. This article examines the geography of the emerging green building industry through a study of the spatial distribution of two different elements of that industry. The first element is the location and diffusion of green buildings themselves as certified by the U.S. Green Building Council (USGBC) through their Leadership in Energy and Environmental Design (LEED) standards. There is a clear shift from an original concentration in major coastal cities to a more even distribution across the country, with broad representation across commercial, public, and nonprofit owners. The second area of study is the spatial distribution of LEED-accredited professionals, who are accredited by the USGBC to oversee the certification process. The distribution of these professionals matches existing concentrations of population, suggesting two different geographies of building green.     

大坡度并小半径曲线盾构连续穿越建筑群沉降施工控制

以天津地铁三号线水上北路站一吴家窑站盾构区间左线施工为背景,针对盾构施工区间遇到的大坡度并小半径曲线且连续穿越建（构）筑群盾构施工的综合难题,利用施工过程中积累的各种数据,采用归纳总结分析和数理统计的方法,分析了地面建筑物沉降与地质、推力、注浆、纠偏等参数的关系,得出了影响建筑物沉降的因素主要为曲线和纠偏时的超挖、推进速度、注浆参数及注浆方法,总结了控制地面建筑物沉降的管理与技术措施。     

高层钢结构基于均匀损伤设计的整体抗震能力提高方法

本文主要研究如何通过合理设计来提高高层钢结构的整体抗震能力。首先,给出了高层钢结构的非线性计算模型;其次,建立了高层钢结构在强地震动作用下的倒塌失效模式的极限状态判别准则;然后,通过模态pushover分析,研究了高层钢结构在水平地震作用下的损伤规律;最后,重点研究了高层钢结构的整体抗震能力的提高方法,提出了均匀损伤的设计方法,该方法通过消除结构的薄弱层,来达到提高高层钢结构的整体抗震能力的目的。通过对两栋20层的高层钢框架结构进行极限时程分析和极限pushover分析,验证了文中提出的均匀损伤的设计方法的可行性。本文的工作可为高层钢结构的抗地震倒塌设计提供参考依据。     

Earthquake induced pounding between adjacent buildings considering soil-structure interaction

Many closely located adjacent buildings have suffered from pounding during past earthquakes because they vibrated out of phase.Furthermore,buildings are usually constructed on soil;hence,there are interactions between the buildings and the underlying soil that should also be considered.This paper examines both the interaction between adjacent buildings due to pounding and the interaction between the buildings through the soil as they affect the buildings’ seismic responses.The developed model consists of adjacent shear buildings resting on a discrete soil model and a linear viscoelastic contact force model that connects the buildings during pounding.The seismic responses of adjacent buildings due to ground accelerations are obtained for two conditions:fixed-based(FB) and structure-soil-structure interaction(SSSI).The results indicate that pounding worsens the buildings’ condition because their seismic responses are amplified after pounding.Moreover,the underlying soil negatively impacts the buildings’ seismic responses during pounding because the ratio of their seismic response under SSSI conditions with pounding to those without pounding is greater than that of the FB condition.     

探地雷达在地下考古遗存探测中的实验与应用

近年来,探地雷达被越来越多地应用于考古探查中。由于反演多解性问题的存在,雷达图像上的异常既可能是考古目标引起的,也可能是由于地下环境介质的不连续性引起的,所以探究不同类型的考古遗存在探地雷达图像上的典型异常响应,有助于准确识别雷达图像上的“真”异常,剔除一些“假”异常。首先,本文基于西北干旱-半干旱区文物埋藏环境,在河北省怀来县遥感综合试验站试验区设计实施了地下目标体探地雷达探测实验,分析了不同材质的小尺度目标体及夯土结构在探地雷达图像上的响应特征;然后,进一步将探地雷达应用于悬泉置遗址地下城墙基址的探测,对城墙在雷达图像上的响应特征进行了分析。实践表明,探地雷达技术在埋藏浅、小尺度、物性差异不大的考古探查中具有很好的效果,得到并解释了点状、线状、面状等不同考古目标体在探地雷达图像上的响应规律。