粉煤灰加气混凝土浇注稳定性探讨

加气混凝土浇注稳定性是加气混凝土生产至关重要的一环,浇筑稳定性的优劣直接影响加气混凝土制品的质量、产量。它在加气混凝土生产中起着决定性的作用,对制品的性能、生产效率都有着重大影响,保证浇筑稳定性是提高加气混凝土质量的重要技术关键。     

苏联的硅酸盐建筑制品

目前,苏联生产的三种蒸压硅酸盐建筑制品是加气混凝土、密实硅酸盐混凝土和硅酸盐砖。1983年有96家企业共生产蒸压硅酸盐混凝土(包括加气混凝土和密实硅酸盐混凝土)599.88万米~3,其中密实硅酸盐混凝土的产量为46.65万米~3,加气混凝土的产量为553.23万米~3。在加气混凝土生产中     

砂、粉煤灰复合硅质材料生产蒸压加气混凝土砌块工艺条件探讨

以砂、粉煤灰复合硅质材料为基本原料生产蒸压加气混凝土砌块,对蒸压加气混凝土生产的基本原理进行总结,重点讨论砂、粉煤灰复合硅质材料生产蒸压加气混凝土过程中各个阶段的工艺条件的控制,生产出合格的蒸压加气混凝土砌块。     

加气混凝土的十大特性

加气混凝土是我国正在大力发展的一种新型轻质建筑材料。虽然这种材料的研究和生产在我国已有20多年的历史了,但是,许多人,包括生产和设计施工的专业人员,至今对于加气混凝土还缺乏了解。了解加气混凝土,首先要认识加气混凝土材性上的特点,这对于加气混凝土的生产和使用都具有重要的意义。目前有些工厂满足于在生产中不塌模,而不重视使各项质量指标达到国家     

石灰品质在加气混凝土生产中的影响作用

从加气混凝土生产的最主要原材料石灰的影响情况,阐述如何生产出优质的加气混凝土生产用石灰,以及在生产中如何运用好石灰的多种作用。     

采用混磨工艺提高粉煤灰加气混凝土的浇注稳定性研究

浇注稳定性是影响加气混凝土产品质量的关键因素,由于加气混凝土生产所需原材料的多样性、浇注配料的复杂性、蒸压养护的不可见性,使得在实际生产中加气混凝土质量波动较大。对生产用原材料及废料相互混合磨细来提高浇注稳定性的实际应用情况进行研究分析,研究结果表明,采用粉煤灰同各种配料混磨工艺可提高加气混凝土浇注稳定性。     

加气混凝土的延续产品和加气混凝土的应用

文章阐述了利用加气混凝土生产过程中产生的废边角料生产轻骨料砌块、专用砂浆等产品的方法，以及利用加气混凝土生产的原材料生产轻板的方法；文章还以自己的体会，介绍了加气混凝土的施工方法。     

利用陶瓷生产尾泥制备高铝质蒸压加气混凝土

在蒸压加气混凝土中掺含18%(质量分数)Al2O3的陶瓷生产尾泥替代一部分含94%(质量分数)SiO2的石英砂,研究不同替代率下蒸压加气混凝土力学性能的变化,并采用X射线衍射、扫描电镜对蒸压加气混凝土的矿物组成和微观结构进行了研究.结果表明:使用陶瓷生产尾泥替代40%(质量分数)石英砂制备的高铝质蒸压加气混凝土各项性能均优于未使用陶瓷生产尾泥的混凝土试块.陶瓷生产尾泥能促进蒸压加气混凝土水化产物的结晶,优化其各项力学性能.     

加气混凝土砌块的生产控制及常见质量问题剖析

本文就加气混凝土砌块的生产中间控制进行了阐述,对生产中常发生的质量缺陷进行了分析,并提出了解决问题的办法。加气混凝土砌块的生产,由于受原材料的变化、工艺条件的不同,各厂的生产控制也不尽相同,但生产过程、生产控制原理区别不大,都需经过原材料处理、配料浇注、发泡静停、切割蒸养这几道工序,生产控制中出现的质量问题也有类同之外。深圳展翼公司年产15万立方米加气混凝土砌块生产线,采用了JH0.9米切割机组,曾先后生产过粉煤灰加气混凝土、火山灰加气混凝土、砂加气混凝土及混合硅质材料的加气混凝土,积累了不少经验。下面就本生产线的生产控制及发生的常见的质量问题略做阐述,供同行参考。     

废建筑加气混凝土在水泥中的应用

众所周知，加气混凝土是一种重要的新型建筑材料．由硅质原料与石灰或水泥配料经蒸压而成，可制成墙板、砌块等。然而在生产和施工中会产生废加气混凝士。就其利用而言，由于生产中产生的废加气混凝土数量少，在生产现场直接粉碎后二次利用，但拆房施工中产生的废加气混凝土（下称废建筑加气混凝土），因其数量大，除少部分破碎后用作道路工程外，大部分被当作废物处理.     

玻璃钢锚杆托盘及螺母极限应力和位移分析

为了研究支护用锚杆在极限应力作用下力学特性,建立了锚杆托盘及螺母的有限元模型,采用ANSYS程序对螺母及托盘的应力、位移进行了数值仿真分析。研究了托盘及螺母在极限应力下的接触特征;绘制了托盘及螺母的应力云图,得到了托盘及螺母内部的应力、位移分布情况。结果表明,托盘边缘及托盘内部大小圆盘连接位置较为危险;螺母中间位置由于受托盘的挤压容易发生破坏;加肋可以提高锚杆的极限承载力,为结构的优化提供借鉴。     

Relational competence in complex temporary organizations: The case of a French hospital construction project network

Large and complex project networks are characterized by the collaboration of heterogeneous organizations and individuals. In addition to project management techniques and complementary skills, relational competence, i.e. the ability to actively create and develop collaborative relationships is an essential asset for managing project networks. Networks represent structured role systems which may be a substitute for stable organizational structures and routines. This study investigates relational competence in the network of a large construction project of a French hospital. Based on network data and qualitative interviews, we compare the formal roles and positions of actors in the network to their actual roles and positions and analyze how relational competence promotes the coordination of project work. We find several actors whose network position and relational competence correspond to the formal organization and several actors with a mismatch between the formal organization and the actual role and position. In the latter cases, other network members step in and contribute to an effective coordination. The concept of relational competence in combination with network analysis contributes to a better understanding of the functioning of project networks. In particular, it reveals dysfunctions in the project network and allows for identifying the reasons for failure.     

冻融环境中饱和岩石的热量传递与温度平衡规律

 冻融环境中温度是岩石性态变化的关键影响指标之一,而冻融试验中岩石的热量传递和温度变化规律国内和国际都未形成统一认识。为探究岩石在冻融环境中的热量传递和温度变化规律,利用室内试验和数值计算方法分别研究冻结和融化过程中试样温度平衡的过程和时程规律。利用3种岩石进行饱和态的冻融循环试验,试样中心温度监测表明,冻结和融化过程的试样温度均存在显著的3段式变化特征,其中相变过程是一个较为特殊和重要的阶段,相变温度均在0 ℃～－1 ℃范围。随着试验温度区间增大,冻结和融化各阶段时长显现出不同规律,冻结过程总时间逐渐降低,而融化过程总时间先降低后升高。基于第3类热传导边界条件,利用Comsol Multiphysics有限元数值计算平台,分析考虑相变阶段的冻结和融化过程,数值计算结果与试验结果吻合较好。数值计算结果显示,试样不同位置的冻结与融化特征主要体现在相变阶段差异,而试样孔隙率对该阶段的影响最大,剩余温度势造成对称温度区间和非对称温度区间的冻结、融化特征的显著差异。     

Nonlinear analysis of integral infilled frames

The nonlinear behaviour of integral infilled frames, in which the infill and the frame are bonded or connected together, is studied both experimentally and analytically. In the theoretical study, a finite-element method is used and the nonlinearities of the materials and the structural interface are taken into account. The entire range of load-deflection behaviour is investigated. Besides stiffness and strength, the stress distribution, crack patterns and collapse modes are also studied. Particular attention is directed towards the stress redistribution before collapse. The effects of the connectors are investigated in relation to the stiffness and strength of the infilled frames. Theoretical stiffness and strength predictions are compared with experimental results.     

Environmental affordances and children’s needs: Insights from child-friendly community streets in China

With rapid urbanization in China, an increasing building density has squeezed the urban public space. Community streets are occupied by motor vehicles or other functions, and can no longer sufficiently support children to carry out safe and independent activities. As an important space for children’s daily natural contact and social activities, the lack of the spatial function of streets results in a decline in children’s subjective initiative and social abilities. The United Nations has stressed the importance of community as the basic unit of space for children’s daily activities in building child friendly cities. It is urgent to reshape child-friendly community streets and support children’s healthy growth. Integrating previous research results on affordance theory and design, children’s growth and environment, and street-game spaces, this study focuses on investigating 23 community streets in four residential communities in Nanjing through questionnaires, interviews, observations, and other methods. Then, from the perspective of cognitive affordance, functional affordance, and social affordance, it analyzes the behavioral possibilities provided by the environment and the needs of the children-user group. Finally, from the perspectives of openness and security, preference and diversity, positive and negative, and reality and potential, it proposes a method to assess the existing environment. This study aims to extract the significant characteristics of the built environment that effectively support and promote children’s outdoors activities, and explore the design strategy of improving street space sharing through optimizing space elements and structure at the medium and micro levels, so as to respond to multiple goals including livable city development from the perspective of child friendliness. This study also tries to change the logical way of design thinking and provide an eco-psychological perspective on how to build a child-friendly community.     

Displacements of column-supported embankments over soft clay after widening considering soil consolidation and column layout: Numerical analysis

The common challenges for constructing embankments on soft clay include low bearing capacity, large total and differential settlements, and slope instability. Different techniques have been adopted to improve soft clay, such as the use of foundation columns including stone columns, deep mixed columns, and vibro-concrete columns, etc. Due to increased traffic volume, column-supported embankments may be widened to accommodate the traffic capacity need. Adding a new embankment to an existing embankment generates additional stresses and deformations under not only the widened portion but also the existing embankment. Differential settlements between and within the existing embankment and the widened portion may cause pavement distresses. Limited research has been conducted so far to investigate widening of column-supported embankments. In this study, a two-dimensional finite difference numerical method was adopted. This numerical method was first verified against field data and then used for the analysis of widened column-supported embankments over soft clay. The modified Cam-Clay model was used to model the soil under the existing embankment and the widened portion. Mechanically and hydraulically coupled numerical models were created to consider the consolidation of the foundation soil under the existing embankment and the widened portion. Different layouts of foundation columns under the existing embankment and the widened portion were investigated. The numerical results presented in this paper include the vertical and horizontal displacements, the maximum settlements, the transverse gradient changes, and the stress concentration ratios, which depended on column spacing. The columns installed under the connection side slope were most effective in reducing the total and differential settlements, horizontal displacement, and transverse gradient change of the widened embankment.     

Magnetoelastische Spannkraftmessung in Bauwerken

Magnetoelastic Measurement of Prestressing Force in Civil Structures The knowledge of the tensile force of prestressing steel elements and its reliable and non‐destructive determination are of essential importance for the assessment of the structural health condition of prestressed concrete structures and tie‐back systems in terms of structural safety, serviceability and durability. For the evaluation of the prestressing force in steel tension members, the measurement technique presented in this contribution is using the magneto‐elastic effect (ME‐effect) of ferromagnetic materials. This effect describes the reverse‐proportional correlation between the mechanical stress and the magnetic properties of ferromagnetic materials. The cylindrical coiled sensors pushed over the tendon and the measuring device developed and practically optimized at the iBMB/MPA of the TU Braunschweig enable a fast and reliable measurement of the prestressing steel force after an initial calibration. In this contribution first the state of the art of prestress measurement techniques for steel tension members is presented. Afterwards, the ME‐measuring method with the basics and merits of magneto‐elastic prestressing force identification is shown. Further recent research results as well as several building applications will be discussed.     

堆土加卸载与基坑开挖叠加对既有隧道变形的影响研究

针对堆土加卸载与基坑开挖叠加效应导致既有地铁隧道变形较大的问题,建立考虑加卸载叠加效应影响的三维空间分析模型,研究不同堆土加卸载叠加基坑开挖卸载模式对邻近地铁隧道变形规律的影响,探讨隧道在堆土加载、移土卸载再叠加基坑开挖下的变形规律。结果表明:正上方堆土加卸载对隧道的竖向位移影响较大,是侧向堆土加卸载的3倍～5倍; 在经历堆土加卸载后,隧道会残留不可忽视的变形,其残留竖向位移约为加载后位移的62%; 堆土加卸载叠加侧方基坑开挖时,隧道变形受基坑开挖深度的影响较大,大于隧道埋深的开挖阶段会加剧隧道变形; 4种叠加模式中,正上方堆土加卸载-侧方基坑开挖卸载隧道最终竖向位移最大,约17 mm,侧方堆土加卸载-异侧基坑开挖卸载隧道最终水平位移最大,约8 mm,邻近隧道施工时应充分考虑叠加效应的影响,尽量避免这两种情况。     

增加，改造，修正：不断成长的博物馆

在２０世纪末期．欧美的博物得变成了一种“加法动物”不断进行着改建、扩建和加建．从而涌现出大量风格方式不间的建筑实例其中既有失败．也有成功。本文选择了部分典型案例如以分析，特别肯定了托马斯·毕比和西萨·佩里的设计概念和方法，并提出了未来的改．扩建将面向未来不断发展的观点。     

重庆某桥加固后荷载试验分析

为保证重庆某桥加固后运营的可靠性、验证加固后桥梁结构是否满足承载力的设计要求,对该桥进行了静力荷载实验。本文介绍了试验的范围及内容,对控制荷载进行了说明、计算,进而确定了加载的荷载、工况以及加载的顺序。将Midas Civil 2010计算的理论应力和挠度值与实测值进行比较分析,结果表明该桥加固后营运安全可靠,刚度和强度满足设计要求。