A frequency-domain regression method for estimating building foundation heat transfer

In this article, the Interzone Temperature Profile Estimation solutions are first utilized to carry out a frequency analysis for the foundation heat transfer to determine the effect of indoor air and ambient air temperature fluctuations on the variation of the foundation heat loss/gain. Then, a frequency-domain regression-based method is used to develop transfer functions for ground-coupled surfaces. The regression frequency-domain method is tested and validated using one-dimensional heat transfer for above-grade walls. It is found that the proposed method provides a more effective alternative than numerical methods to estimate conduction transfer function coefficients for building foundations and thus can be easily implemented in whole-building simulation programs.     

Efficiency concept for upgrading the lateral stiffness of reinforced concrete wall systems

This paper presents a new concept, the efficiency concept, for upgrading the lateral stiffness of reinforced concrete walls connected by a coupling system that is partially or not effective in flexure. The efficiency concept is based on the capacity of the connecting medium to reduce the overall drift. By definition a system of uncoupled walls has an efficiency of 0, whereas a system of fully coupled walls has a maximum efficiency of 1. Based on this concept, it is proposed to upgrade the wall systems with adequate beams, which are capable of transferring the additional forces between the walls. The stiffness, the number and the location of these added beams are optimized using the efficiency concept by which the overall drift is controlled. Results of the study are presented as easy‐to‐use charts for the practising engineer. These charts allow a rapid choice of an efficient structure, which can then be refined using any discrete structural analysis method. The method is efficient, convenient and cost‐effective as it minimizes the number of coupling beams to be added to the system to achieve a targeted drift. It also maximizes the clearance along corridors, particularly in buildings with low interstorey height. A practical example, following a step‐by‐step procedure, is provided to demonstrate the applicability of the concept. Copyright © 2002 John Wiley & Sons, Ltd.     

基于主动控制的高层结构最优抗侧刚度

传统的结构抗震设计方法需要设计者凭经验来试算抗侧刚度,被动且耗时、费力.本文基于振型分解反应谱理论,提出了主动控制结构抗侧刚度的计算方法,严格推导出求解控制刚度的迭代公式,并证明高层建筑结构各层层间位移达到最大层位移限值时其刚度分布即为最优.针对实际情况,提出了高层结构优化设计的建议.     

冷弯型钢骨架墙体抗侧移刚度计算方法研究

为了获得冷弯型钢骨架墙体抗侧移刚度实用计算公式,将墙体墙面板等效为拉压斜杆,并基于其他一些基本假定提出了冷弯型钢骨架墙体抗侧移刚度简化计算模型,在弹性分析的基础上得到了墙体抗侧移刚度理论计算公式,并结合试验数据和有限元分析结果进行了弹塑性修正,得到单面覆石膏板墙体、单面覆OSB板墙体、单面覆带肋钢板墙体在水平风荷载、水平多遇、水平罕遇地震作用下抗侧移刚度实用计算公式,墙体抗侧移刚度实用计算公式计算结果与试验、有限元分析结果吻合较好。同时,提供了冷弯型钢骨架墙体抗侧移刚度实用计算公式应用算例,以供设计参考。     

高层建筑结构侧向刚度规则性计算方法研究

GB50011-2001《建筑抗震设计规范》提出的"层间剪力位移比"的计算方法对侧向刚度规则性的判断存在局限性,在一些特殊情况下会得出不正确的结论,为了解决侧向刚度规则性判断的问题,提出了"层间剪力位移角比"的侧向刚度计算方法,结合算例可以看出,对于以弯曲变形为主的结构,此方法结构概念明确,得出的结论符合工程经验,是对规范方法的很好的补充。     

基于台风过程的建筑围护结构设计风压估算方法

为了降低基于台风过程的建筑围护结构设计风压估算方法——Storm passage方法的复杂性且不减弱其高精度,假定各次风暴引起的结构风荷载极值之间相互独立,得到了形式更加简洁更易于理解的用于Storm passage方法的结构风压年极值概率分布表达式。并从理论上将改进前后的Storm passage方法进行了对比,以证明两者在高重现期下的精度基本相同。在此基础上,结合一工程实例,将改进方法、原Storm passage方法、未考虑台风过程的Monte Carlo模拟方法以及三种工程上常用的简算方法进行了对比。研究结果表明,对于50年重现期设计风压,改进方法与原Storm passage方法之间误差极小,可忽略不计;不考虑台风过程将导致结构设计风压估值偏小,大部分结果的偏小程度在10%以内;工程中常用的最不利法过分保守,有时甚至可偏大100%;风向折减因子法可给出经济性和安全性都适当的结果,但应谨慎使用,不合理的风向折减因子取值可能导致估计结果的安全性不足。     

A generalized method for estimating drifts and drift components of tall buildings under lateral loading

A generalized method for estimating the drifts of tall buildings composed of planar moment‐resisting frames and coupled shear walls under lateral loading is presented. This method establishes the stiffness equations at the story levels by assuming that all the nodes in the same floor of a planar lateral‐force‐resisting unit have an identical lateral displacement, an identical rotation component due to the axial deformations of the columns, and an identical rotation component due to the flexural and shear deformations of the beams. By adopting this simplification, the story drifts contributed by different types of deformations, namely, the axial deformations of the columns or wall piers, the flexural and shear deformations of the beams, and the double‐curvature bending and shear deformations of the columns or wall piers, can be identified. In the formulation of the stiffness matrix, the P‐Delta effects were also incorporated. Through comparisons between the lateral displacements and story drifts computed using the proposed method and those computed using the structural analysis software Midas/Gen, the proposed method is proved to have high accuracy in estimating the drifts of tall building structures.     

高层主次结构受力特点及刚度计算方法

近年来,主次结构广泛应用在超高层建筑中,但对其受力特点和刚度形成机制的系统研究却很少。为明确主次结构刚度形成机制、指导主次结构结构设计,通过有限元分析对主次结构受力特点进行研究,给出主次结构抗侧刚度形成机制,并推导主次结构刚度计算方法。以巨型框架结构、主次框架结构、主次框架-单斜撑结构、主次框架-X斜撑结构为研究对象,以构件内力分布特点、变形特性、刚度贡献为重点关注指标。研究结果表明,主次结构在竖向及水平荷载作用下均表现出显著的二级受力特性。水平荷载作用下,主柱沿模块高度呈现弯剪型变形,主次框架-单斜撑、主次框架-X型支撑结构表现出显著的桁架受力特点。次柱轴力沿高度呈周期性分布,次结构传递荷载对主结构变形和内力影响不大,但是其对结构整体刚度贡献不可忽略。分析结果表明,主次结构抗侧刚度关键参数为支撑轴向刚度、主柱轴向刚度、主框架抗剪刚度、次框架抗剪刚度。基于刚度形成机制,给出主次结构刚度简化计算方法,并与有限元方法结果进行对比,验证了刚度形成机制及刚度简化计算方法的有效性。     

桩的抗压刚度结构

为得到计算受压桩的沉降、承载力并能分析压力在桩中传递规律的方法,对受压桩的物理现象进行研究。运用系统论中的结构方法,将桩和土作为桩-土受压系统,并建立该系统的抗压刚度结构,来揭示桩与桩侧土和桩底持力层三元素抗压功能之间的内在联系,揭示桩的抗压功能的构成方式,创造性地获得桩-土系统的"集成抗压刚度"数学模型,并且提出了受压桩简明、实用的计算方法。用试验数据进行计算,结果与实测相符。研究表明,建立的桩的抗压刚度结构,具有普遍性,符合客观规律,它的抗压功能,反映了抗压桩的功能;集成抗压刚度在概念上和理论方面,比目前采用的方法要完善得多。桩的抗压刚度结构的建立,是研究抗压桩机理的有效途径,它为桩基的设计计算,提供了新思路,搭设了新的研究平台。     

基于山地建筑结构特点下的地震动输入与侧向刚度控制思路构建

伴随着我国居民生活质量的稳步提升,我国的工程建设单位加强了对于工程建设施工技术以及工艺的创新,并在实际的操作过程中加强了建筑结构形式的优化改造,确保建筑质量以及功能的提升。事实上,由于我国的山地地形较多,故而导致山地建筑日益增多。在这样的背景之下,需要工程设计单位以及人员在实际的作业过程中从地震动输入以及侧向刚度控制角度进行作业,促进其质量以及性能的稳步提高。     

带边框RC低矮抗震墙实用计算方法

带边框低矮抗震墙在建筑结构设计中应用广泛,其受力性能复杂,在地震作用下一般发生剪切破坏.以试验研究及有限元分析结果为基础,分析了带边框低矮抗震墙的承载机理.利用等效斜压杆的方法,给出了无洞及开洞带周边框架RC低矮抗震墙的受剪承载力和不同受力阶段刚度的计算公式,并与试验结果进行了比较.研究结果可供设计计算时参考.     

多种结构抗侧刚度计算方法对比

对常见的剪切刚度、楼层剪力与层间位移比、剪弯刚度三种结构抗侧刚度计算方法展开分析,探究各方法的适用性及优缺点,结果表明,剪切刚度为剪弯刚度简化计算方法,其可应用于结构方案阶段,当1≤h/b≤4时,计算误差较大;按楼层剪力与层间位移的比值计算侧向刚度时,由于存在无害位移影响,其计算结果往往偏小;采用剪弯刚度可以较为精确合理计算结构抗侧刚度,其计算代价也较高。     

建筑工程量快速准确计算的教学

建筑工程造价文件的编制速度与质量 ,取决于一个极为重要的方面 ,即建筑工程量的快速、准确计算。关于建筑工程量的快速、准确计算 ,着重在八个方面加以注意 ,教学时亦贯穿这一思路 ,达到了事半功倍之效     

Optimal design method for building energy systems using genetic algorithms

In this paper, a new optimal design method for building energy systems is proposed. This method provides the most efficient energy system, best combination of equipment capacity and best operational planning for cooling, heating, and power simultaneously with respect to certain criteria such as energy consumption, CO₂ emission, etc. Specifically for this paper, the authors apply this method to a sample building as a case study. The “Genetic Algorithms (GA)” optimization method, which can resolve nonlinear optimization problems, is adopted for this optimization analysis. Also its applicability is analyzed in a case study. In order to validate the accuracy of this method, the correct optimum solution based on comprehensive inquiries is also calculated. A comparison of the GA solution with the correct solution demonstrates fairly good agreement. The results show that the proposed method is sufficiently capable of determining the optimal design and has the potential to be applied to very complex energy systems with appropriate modifications.     

Virtual in-situ calibration method in building systems

Sensors play an important role in guiding building systems to achieve desired operation and efficiency. However, sensors are subject to continuous degradation and failures over time. Although a periodical calibration is needed, it is exceptionally difficult and/or impractical to many sensors with a conventional manual approach. Uncalibrated problematic sensors could significantly compromise the systems' performance and lead to unintended loss of energy efficiency in buildings. We propose a methodology, termed virtual in-situ calibration, to solve this critical issue. It is developed by mathematically extracting the characteristics of essential aspects involved in a calibration, including the environment assessment, benchmark establishment, and uncertainty quantification. A case study of a supply air temperature sensor in rooftop units illustrates the implementation process; the erratic uncertainty is reduced from ± 19.2 °C to ± 0.7 °C after the virtual in-situ calibration. The calibration method can be implemented online to significantly improve the reliability of sensor networks in buildings.     

大底盘双塔楼结构刚度控制方法研究

结合成都某大厦结构设计，定量分析了大底盘双塔楼结构水平侧移的规律，从而提出对称大底盘双塔楼结构刚度控制的方法。经算例验证，其精度能满足工程要求。     

带转换层结构侧向刚度计算的规范方法研究

根据现行规范,楼层侧向刚度的计算方法有3种。3种刚度的概念不相同,计算结果的差异也较大。本文结合实际工程对3种刚度计算方法进行了定量分析和比较,在此基础上,明确了不同刚度计算方法的适用范围。     

A method for estimating changes in the visibility of land cover

An inventory of resources that includes the contribution made by land cover to the visual landscape can be used in monitoring and assessing the impacts of change in land cover on the visual landscape of an area. A method is presented for assessing the visual resources of the landscape as applied to a case study area in the western part of the proposed Cairngorm National Park in Scotland. The method is based upon measuring the extent of the land from which different land cover types may be visible, on a cell-by-cell basis, using high resolution Digital Elevation Models combined with interpreted land cover data as inputs. The results show a reduction in the overall contribution of scattered, natural woodland to the visual landscape, and an increase in the visual contribution of plantation woodland at the expense of heather moorland. The geographical distribution of the changes in visibility of land cover types is shown and the potential of the method for providing a spatial context for expressing the results of landscape preference modelling is discussed.     

肋环型索穹顶初始预应力分布的快速计算法

肋环型索穹顶是美国工程师Geiger根据Fuller的张拉整体结构思想开发的一种新型预张力结构，并最早应用在汉城奥运会的体操馆和击剑馆。考虑到该结构是一种轴对称结构，本文提出了确定初始预应力分布的快速计算法．该法从平面径向桁架节点平衡关系入手，推导了不设和设有内拉环的肋环型索穹顶预应力杆内力一般性的计算公式．对特定参数的索穹顶结构还给出了内力计算用表．通过本文提供的分析方法、计算公式和内力计算用表，可方便快速的确定肋环型索穹顶结构的初始预应力分布，为该类结构的进一步设计和力学性能分析提供基础．