Experimental study of screw connections in CFS-calcium silicate board wall panels

Cold-formed steel (CFS) wall panels with different board materials are used extensively in residential and commercial buildings to resist lateral loads by in-plane shear, in addition to helping the studs resist gravity loads. Generally the screw connection between the board and CFS skeleton frame, which experience shear, dictates the behaviour and strength of such panels. In this paper, details of an experimental study on behaviour and strength of the screw connections between the cold-formed steel profiles and calcium silicate boards, under monotonic and cyclic shear loading, are presented. The objectives of the experimental study are: (a) to develop a new test procedure that realistically represents the behaviour and failure of screw connections in CFS wall panels; (b) to investigate the effect of edge distance of the screws and thickness of the boards on behaviour and strength; (c) to study behaviour under monotonic and cyclic loading; (d) to develop the values of the important parameters that determine the load–deformation behaviour of the screw connection in such wall panels under in-plane shear; and (e) to develop design equation to evaluate the ultimate shear strength and its resistance factor required in load resistance factor design (LRFD).     

高强超薄壁冷弯型钢低层住宅足尺模型振动台试验

进行了两层高强超薄壁冷弯型钢住宅结构足尺模型的振动台试验,模型采用屈服强度550 MPa、厚度2 mm以下超薄壁冷弯型钢龙骨,外墙内外侧覆面板分别采用12 mm厚石膏板和0.42 mm厚屈服强度550 MPa带肋波纹钢板,内墙两侧覆面板均为12 mm厚石膏板。试验选取3条实测地震波记录和1条人工合成地震波,地震加速度考虑7度多遇到9度罕遇的烈度水平。试验结果表明：结构破坏均发生在连接部位和覆面板的局部区域,破坏模式为自攻螺钉的脱落和石膏板的局部破裂,而内部主体型钢龙骨基本无破坏;结构水平刚度虽有较大削弱,但在地震作用下结构无倒塌危险;采用双面覆板构造的复合墙体结构,能够满足抗震设防地区“大震不倒”的要求;墙体开洞部位为结构的薄弱区域,结构设计时应加强门、窗等开洞部位的构造措施以及自攻螺钉连接的可靠性。     

矿棉吸声板的生产发展现状和展望

矿棉吸声板是集众吊顶材料之优势于一身的室内天棚装饰材料,广泛用于各种建筑吊顶、贴壁的室内装修。本文简述了矿棉吸声板在现代新型建筑装饰材料中的应用和地位,阐明了矿棉吸声板的发展、生产工艺、性能特点和应用,介绍了矿棉吸声板的产品规格、技术性能和指标;结合国内外两个具有代表性的生产商的矿棉吸声板产品较系统、直观地说明了矿棉吸声板的原料配方和内部结构特点。今后矿棉吸声板的发展将保持良好的增长势头,我国矿棉吸声板的需求量仍将呈上升趋势,不同地区和应用领域的需求量的增长不同;针对当前我国矿棉吸声板的生产和销售提出了一些建议。     

Schall‐Längsleitung im Holz‐Mischbau

Flanking transmission of timber elements in the building shell with concrete construction parts. The following article describes the test of the flanking transmission of timber elements in the building shell with concrete construction parts for high rise buildings and the effects of different construction methods, like multi‐storey elements, separation boards and the influence of installation layers. The version with the junction of the elements on a level with the ceiling elements and the design of an installation layer cause an substantial improvement of the normalized sound pressure level difference.     

Thermal comfort and energy consumption of the radiant ceiling panel system.: Comparison with the conventional all-air system

The purpose of this study is to investigate the various characteristics of a radiant ceiling panel system and their practical application to office buildings. The radiant ceiling panel system and conventional air-conditioning system were compared in terms of thermal comfort, energy consumption, and cost. Thermal environment, along with human response, was tested by using a small meeting room equipped with radiant ceiling panels. The responses were collected by questionnaires given to the male subjects in the room. The experiment for the female subjects was conducted separately. Results show that the radiant ceiling panel system is capable of creating smaller vertical variation of air temperature and a more comfortable environment than conventional systems. When using a cooled ceiling, a small volume of supplied air creates a less draught environment, which reduced the discomfort of feeling cold in the lower part of the body. Numerical simulation of yearly energy consumption and cost estimation were conducted. Typical office rooms located on the 3rd, 4th, and 5th floor of a six-floor building in the Tokyo area were simulated. Since part of the sensible heat load is handled by radiant ceiling panels, the volume of supplied air can be reduced, leading to lower energy consumption for air transport. By using the radiant ceiling panel system in one of the three floors of the simulated building, energy consumption can be reduced by 10%. Estimated pay back time was from 1 to 17 years depending on the market price of the radiant ceiling panel.     

Stereoscopic 3D exploration of freeform architecture

As freeform architecture becomes popular, the observation method for complex geometries is also becoming important. In particular, stereoscopic 3D is one of the most useful approaches to explore 3D space realistically with extrusion and depth feelings. In this work, we propose a stereoscopic 3D exploration to observe an internal space structure of freeform architecture effectively. For a visually comfortable stereoscopic 3D navigation, we analyze causes of visual discomfort and control perceived depth by adjusting virtual camera separation and virtual screen depth in a stereo scene. Since a user notices rapid changes of a scene, we measure JND (Just Noticeable Difference) for the optimal changes of virtual camera separation and virtual screen depth. For the camera movement in complex and curved pathways, we use automated navigation utilizing cubic Bézier curves. During the navigation, the camera parameters are controlled automatically in order to produce visually comfortable stereoscopic 3D scenes. We also performed a user study to verify the effectiveness of the proposed explorations using famous freeform architectural models such as the Guggenheim Museum and the Jubilee Church.     

Eggcrate UV: a whole ceiling upper‐room ultraviolet germicidal irradiation system for air disinfection in occupied rooms

A novel whole ceiling upper‐room ultraviolet germicidal irradiation (UVGI) system [eggcrate ultraviolet (UV)] has been developed that incorporates open‐cell ‘eggcrate’‐suspended ceiling panels and bare UV lamps with a ceiling fan. Upper‐room UVGI is more effective for air disinfection than mechanical ventilation at much lower installation and operating costs. Conventional upper‐room UVGI fixtures employ multiple tightly spaced horizontal louvers to confine UV to the upper‐room. These louvered fixtures protect occupants in the lower‐room from UV‐induced eye and skin irritation, but at a major cost to fixture efficiency. Using a lamp and ballast from a conventional upper‐room UVGI fixture in the eggcrate UV system, the germicidal efficacy was markedly improved even though the UV radiation emitted by the lamp was unchanged. This fundamental change in the application of upper‐room UVGI air disinfection should permit wider, more effective application of UVGI globally to reduce the spread of airborne infection.     

Druckbeanspruchte Winkelprofile mit Ein‐Schrauben‐Anschluß – Bemessung nach den Normen DIN 18800‐2 und EC 1993‐3‐1 (Türme und Maste)

Dimensioning of pressed angle steel with one screw joint based on the standards DIN 18800 vol. 2 and EC 1993‐3‐1 (towers and masts). There are different kinds of methods for the structural analysis of the stability of angle steel in mast constructions in DIN 18800 vol. 2 and Eurocode 1993‐3‐1. It depends on the kind of joint with one or two screws. The calculated loading capacities for a one screw joint based on Eurocode are significant higher than the results based on DIN . Comparing calculating with the Finite Element Method as well as experiments with equal‐leg angles show the simplified method of the EC 1993‐3‐1 for the one screw joint in the existing form is not wise to be used in practice.     

Mit Schrauben Bewehren – Neue Ergebnisse

Self‐tapping screws as reinforcement – new results. Self‐tapping continuously threaded screws can be used as elements for reinforcement or joints in timber construction because of their high axial strength and excellent bonding properties. The layout of the reinforcing or joining screws can be derived from strut‐and‐tiemodels which are common in concrete design and follow the internal flow of forces. Several series of tests in 2007 already showed the high potential of this construction method on various joint details and reinforced timber elements. Based on this success in 2008 further tests were taken out on joints and timber beams with altered and more sophisticated screw configurations. Hereby the load‐bearing capacity of timber beams reinforced with steel lamellas and rigid frame corners connected with self‐tapping screws was extraordinary and demonstrated once more the high potential of this design method.     

Behaviour of cold-formed steel shear wall panels under monotonic and reversed cyclic loading

This paper presents the results of an experimental study on the behaviour and strength of the cold-formed steel shear wall panel (CFSSWP) with calcium silicate board as sheathing, when subjected to monotonically increasing and reversed cyclic in-plane shear deformation. These specimens were specifically designed to reach the strength as governed by the strength of the screw connection between the board and the CFS framing and avoid all other modes of failure, ahead of this. The main objectives of the experimental study are (a) to study the influence of board thicknesses and the distance of the screws from the nearest free edge of the board on the wall panel behaviour and strength; (b) to study the behaviour of different wall board configurations normally used in construction practice (c) to develop the values of the important parameters that determine the load-deformation behaviour of the wall panels under in-plane shear and (d) to determine the different limit states in the failure of the screws connecting the board and the CFS framing in such CFSSWP. In addition, a simplified design equation is proposed to evaluate the ultimate shear strength of CFSSWP based on the strength of the screw connection obtained from a sub assemblage shear strength test.     

胶合木-混凝土组合梁斜向螺钉连接件受剪性能研究

为研究斜向螺钉连接件在胶合木-混凝土组合梁中的受剪性能，对8组24个采用斜向螺钉连接件的胶合木-混凝土组合试件进行了推出试验，分析了嵌入方式和嵌入角度对螺钉连接件的破坏模式、荷载-滑移特性和受剪性能的影响。研究结果表明：沿剪力方向单向倾斜螺钉连接件的破坏模式主要为螺钉单铰弯曲破坏和螺钉双铰弯曲破坏；斜交螺钉连接件的破坏模式主要为受压剪作用螺钉的周围混凝土锥体破坏和受拉剪作用螺钉拔出破坏；随着斜向螺钉连接件与界面夹角逐渐增大，螺钉连接件的受剪承载力和抗剪刚度逐渐减小；沿剪力方向45°单向倾斜螺钉连接件的受剪承载力和抗剪刚度较垂直嵌入木梁的螺钉连接件的受剪承载力和抗剪刚度分别提高了21.8%和51.6%；±45°斜交螺钉连接件的受剪承载力与垂直嵌入木梁的螺钉连接件的受剪承载力相差不大，但其抗剪刚度较垂直嵌入木梁的螺钉连接件的抗剪刚度提高了76.6%。在试验研究的基础上，提出了胶合木-混凝土组合梁斜向螺钉连接件受剪承载力的计算方法，该公式的计算结果与试验结果吻合较好，并验证了现有抗剪刚度计算公式的适用性。     

Sewer Discharge Estimation by Stereoscopic Imaging and Synchronized Frame Processing

A system for fully automatic contact‐less image‐based measurement of volumetric flow rate in urban drainage structures is presented. The hardware includes two original equipment manufacturer cameras and a single‐board computer on which our custom image processing software is running. The value of water discharge depends on the surface velocity, water level and channel's geometry. The level of the flow is estimated as the difference between distances from the camera to the water surface and from the camera to the channel's bottom. Camera‐to‐water distance is recovered automatically using large‐scale stereo‐matching, whereas the distance to the channel's bottom is measured upon installation. Surface velocity is calculated using cross‐correlation template matching: individual natural particles in the flow are detected and tracked throughout the sequence of images recorded over a fixed time interval. The relative discharge computation error is lower than 1.34% of the theoretical maximal discharge for a given location, which makes our system competitive to commercial components such as ultrasonic flow meters, while using cheaper technologies.     

Hamburger Sichel – Das neue Dach des Zentralen Omnibusbahnhofs

The Hamburg Boomerang – The new roof for the central bus station. Located in the city of Hamburg the unique design of the new roof for the central bus station ZOB will be a landmark with its own cooperate identity. The arrangement of the bus‐pockets led to the significant and individual half‐moon shaped geometry of the roof. Like an huge boomerang almost 200 m long, the roof hovers above the service buildings and the entire bus‐stations. The roof structure is supported 12 m above ground by a colonnade of slender steel columns, following the curvature of the multi‐rib steel shell structure that carries the cantilever beams. Transparent glass panels are fixed underneath the steel purlins spanning between the filigrane cantilevers. This article describes the structural design, the structural behaviour and selected highlights of the fabrication and erection.     

极限荷载条件下螺旋桩的螺距设计与承载力计算

螺旋桩基础在工程中有一定应用。但目前对于极限荷载条件下螺旋桩基础的地基破坏模式、桩型设计、单桩和群桩极限承载力的计算,以及合理的螺距(叶片间距)与叶片直径比等问题的研究尚少,有待进一步完善。经分析,螺旋桩的桩型设计核心问题是螺距设计,在极限荷载条件下,建立其地基的破坏模式,推导出了螺距(叶片间距)与叶片直径的比例关系,即最小螺距和控制螺距,并得出了不同的螺距情况下的单桩和群桩极限承载力计算方法。通过同群桩基础的静载试验结果对比,桩基础极限承载力估算值与试验结果拟合较好,说明本文提出的螺旋桩地基破坏模式接近于实际破坏情况,其极限承载力计算方法可用于工程设计中。     

Verbundverhalten von Vollgewindeschrauben in Brettschichtholzbauteilen

Bond behaviour of self‐tapping screws being used as reinforcement in glue‐laminated timber elements – Part 2: Analytical and numerical investigations as well bond model derivation for the calculation of anchorage length In favor of the investigation of bond behaviour, force transfer and anchorage length of self‐tapping screws, several tests have been realized at the Chair of Structures and Structural Design in cooperation with the Institute for Building Material Research of the RWTH Aachen University. The experimental investigations comprise more than 160 pull‐out tests of screws with long embedment length and over 84 load distributions tests. Additionally, several tests displaying the effect of longitudinal cracks in the surrounding wood as well as the effect of the screw tip have been conducted. Through various analyses of the bond behaviour, the experimental investigations form the basis for the calibration and evaluation of the numerical models and allow a prediction of the force transfer of the screws in glue‐laminated elements. Design rules that enable the application of the self‐tapping screws as reinforcement in timber elements have been derived from the knowledge obtained in the experimental and numerical investigations. This paper, which results from a research project funded by the German Research Foundation [1], presents the results of investigations on the bond behavior of self‐tapping screws in glue‐laminated timber elements. Part 1 elaborates on the experimental investigations [2] whereas part 2 illustrates the numerical analyses and presents a bond model, which enables the design of the anchorage length and the safe application of the screws as reinforcement in timber elements.     

Investigating the contribution to fire growth of combustible materials used in building components

Recent work at the UK Fire Research Station has provided a measure of the possible contribution to fire growth from the combustion of such components as wall or ceiling panels rather than the well-known contribution from surface spread of flame on wall and ceiling linings.

The oxygen depletion technique is used to assess the rate of heat release from panels with a range of facing materials and different cellular polymer cores. The paper discusses how such an experimental approach may be adapted to direct validating modelling techniques with certain components but must take account of the variablity in existing building practices.     

基于LabVIEW 的爆破板应变研究方法

为研究爆破板在粉尘爆炸时的应变,实现全智能化控制和采集,设计了一种基于LabVIEW的爆破板应变研究方法。该方法利用惠斯通电桥将布置在爆破板上应变片的应力变化转换为电信号,同时通过LabVIEW软件、数据采集卡等使红外相机、高速相机和压力传感器的工作同步,实现了爆炸过程中罐内爆炸压力、爆破板应变数值与该时刻爆破板图像的对比分析。实验结果表明：该方法满足同步性、多样性、准确性等实验要求,具有模块化程度高、实时性强、可扩展性好的特点,有助于改进爆破板的结构。