Test of screw fastened profiled roofing sheets subject to simulated wind uplift

Screw fastened light gauge steel profiled roofing sheets are predominantly subjected to wind suction, i.e., wind uplift, and may fail locally in the vicinity of screw fasteners under strong or sustained fluctuating wind uplift. A series of static tests was performed on three types of profiled roofing sheets to investigate their structural behaviour and profile effects under simulated wind uplift. The considered sheeting profiles were arc-tangent, trapezoidal and ribbed, and an alternate (or equivalent alternate) sheeting crest fastening system was adopted. It was found that structural behaviour of the roofing sheets under uplift loads was greatly dependent on the sheeting profiles including the shape and height of the crest. Both arc-tangent and trapezoidal type roofing sheets exhibited a large cross-sectional distortion stage and a deflection hardening stage, following a local plastic collapse in the vicinity of the screw fasteners at the central support. The ribbed roofing sheet, however, had a final failure mode of sudden fracture with cracks under the screw fastener head at the central support. The use of cyclone washers with screw fasteners reduced local plastic deformations and, in general, increased initial failure loads of the roofing sheets. Increasing the roofing span only slightly reduced the limit values of the reaction force per fastener at the central support due to the local failure characteristic of the screw fastened profiled roofing sheets.     

Plant fibre reinforced cement components for roofing

Composites of blast furnace slag (BFS) based cement mortar reinforced with vegetable fibres are presented. Roofing components are produced with these composites through a simple and low-energy consuming method, including ordinary vibration and curing in a wet chamber. Composites reinforced with eucalyptus pulp, coir fibres and with a mixture of sisal fibre and eucalyptus pulp gave a suitable performance, with compressive strength higher than 20 MPa and modulus of rupture (MOR) higher than 3 MPa. The performance of tiles made with these composites is in accordance with international requirements, with maximum load higher than 450 N, in wet conditions.     

Elastodynamic behaviour of fibre-reinforced cement

The elastodynamic properties of anisotropic, short fibre-reinforced, thin cement sheets have been determined by frequency measurements in the vicinity of longitudinal, flexural and torsional resonance frequencies of rod samples in their different modes of vibration. The experimental techniques described in the present paper provide results of good accuracy. In-plane and transverse tensile and shear moduli are given for one type of material with plastic and cellulose fibre reinforcement and the influence of humidity, age and temperature on damping and stiffness are discussed.     

世博会阿联酋国家馆异形金属屋面防水设计

本文介绍了有关2010上海世博会中阿联酋国家馆屋面工程中的防水设计,提出了解决异形金属屋面防水节点构造的做法,总结了此类工程防水设计的经验。     

Long-term performance of recycled PET fibre-reinforced cement composites

This study investigated the long-term durability performance of recycled polyethylene terephthalate (PET) fibre-reinforced cement composites. Specifically, chloride permeability, repeated freeze–thaw, and various chemical environment tests were conducted. Five types of chemical environments were considered, alkaline, salt, CaCl₂, sulfuric acid, and sodium sulfate. Recycled PET fibre-reinforced cement composite was not different from plain concrete in terms of chloride permeability. The repeated freeze–thaw test results showed excellent endurance characteristics of recycled PET fibre-reinforced cement composite. Recycled PET fibre-reinforced cement composites showed reduced compressive strength in alkaline and sulfuric acid environments. However, recycled PET fibres and recycled PET fibre-reinforced cement composites were largely unaffected by salt, CaCl₂, and sodium sulfate environments.     

混凝土现浇板裂缝原因及防治措施

分析了混凝土楼屋面板裂缝产生的原因，并从楼面上层钢筋网防护、预埋线管处裂缝防治等方面论述了裂缝的防治措施，指出只有加强施工过程质量控制，才能确保结构安全与使用功能。     

水泥稳定半刚性路面基层裂缝防治措施

通过对水稳类半刚性基层裂缝形成原因的分析，从原材料、施工工艺、养生等方面提出了防止基层裂缝产生的具体措施以及对基层裂缝有针对性的处治方法，从而有效地阻止基层裂缝向沥青混凝土面层的反射，提高路面的质量。     

屋面整浇水泥聚苯保温隔热层的研制与应用

１材料制备及其技术性能１．１原材料４２５#、５２５#普通硅酸盐水泥 ,质量符合ＧＢ１７８ -８５要求 ;泡沫塑料颗粒 ,粒径５～３０ｍｍ ,松散密度１５～２０ｋｇ／ｍ３,是泡沫塑料生产的下脚料及回收的废泡沫塑料（已除净处理）经专用机械破碎成颗粒状 ;另有适量的稳泡剂、发泡剂、增强剂、憎水剂等。１．２生产工艺材料准备 ,做发泡剂 ,按配料搅拌 ,净水控制在１０ %～１５ % ,当拌合物具有良好的粘聚性时 ,在３０ｍｉｎ左右浇注拍打抹平 ,然后洒水养护３～７ｄ ,即为现场发泡整浇成型。一般保温层厚度５０～２００ｍｍ ,分层操作最厚也…     

玻璃纤维增强氯氧镁水泥板材的耐久性研究

为了研究玻璃纤维增强氯氧镁水泥材料的长期强度,正确评价玻璃纤维增强氯氧镁水泥材料的耐久性能,采用SIC(Strand In Cement)试验方法,对玻璃纤维增强氯氧镁水泥材料进行了加速老化试验.利用反应动力学中的Arrhenius方程,预测出玻璃纤维增强氯氧镁水泥材料在不同气候条件下的服役寿命.     

水泥混凝土路面裂缝的形成及预防

分别从力学角度、施工工艺、原材料化学分析三个方面,分析了水泥混凝土路面裂缝产生的原因,从施工过程中的环境条件、组成材料的配比,以及施工程序、工艺等方面进行简要叙述,提出相应的防治措施,以减少裂缝的形成,提高水泥路面质量。     

A general solution for the shear flexibility of profiled sheets. II: Applications of the method

Part I of this paper presented a comprehensive general theory for predicting the shear flexibility of profiled metal sheets and justified it by comparison with the results of finite element analyses and tests. In Part II, this theory is applied to profiles with web and flange stiffeners, which have not previously been amenable to analysis, and to arc and tangent profiles, for which some results by other authors are available.     

Local buckling behaviour of trough girders composed of an assemblage of profiled steel sheets

The local buckling behaviour of profiled trough girders in bending, made from cold formed profiled steel sheeting and used for profiled composite beams, is studied using an elastic finite strip method. The simplified method assumes that there is no shear stress present within the buckling half-wavelength, and is thus applicable to the uniform bending case where no moment gradient exists. Three typical types of profiled steel sheeting configurations are studied in the form of profiled trough girders, and these are investigated comparatively. The variation of the elastic local buckling coefficient with the cross-sectional parameters is demonstrated for each of the three typical rib shapes. An example of the local buckling of a typical profiled through girder is given.     

Expansive cement couplers : A means of pre-tensioning fibre-reinforced plastic tendons

Fibre reinforced plastics describes a group of materials composed of inorganic or organic fibres embedded in a resin matrix. are strong, non-magnetic, light-weight and for the most part, non-corrodable. There is great scope for the use of as concrete reinforcement and the high strength of the materials is conducive to prestressed applications. However, finding a suitable method of anchoring the tendons without inducing stress concentrations in the fibres has been identified as a problem. The current paper investigates the potential for the use of expansive cement couplers as a means of pretensioning tendons. An experimental study was carried out on couplers to join steel reinforcing bars and then extended to include the coupling of materials to steel prestress wire.     

水泥混凝土路面裂缝的处治技术

通过对水泥混凝土路面病害的调查，对水泥混凝土路面裂缝问题进行了研究，分析了裂缝的产生机理，对混凝土路面的日常养护和病害处治等问题提出了解决方法，从而提高路面施工质量。     

A general solution for the shear flexibility of profiled sheets. I: Development and verification of the method

A general solution is presented for the flexibility of profiled metal sheets of arbitrary cross-section when subjected to an in-plane shear force. Solutions are obtained by means of a minimum energy method using displacement functions which accurately model the actual deflected shape. They are shown to be both more accurate and more general than those currently used in, for instance, the European Recommendations for the Stressed Skin Design of Steel Structures.     

水泥路面沥青加铺层的裂缝研究

对水泥路面沥青加铺层的裂缝进行了分析,从沥青加铺层裂缝形成机理和防治两方面进行论述,进行了沥青加铺层裂缝形成原因和扩展类型的研究,并结合施工经验总结了防治沥青加铺层裂缝的措施,以延长水泥路面沥青加铺层的使用寿命。     

水泥混凝土道路路面裂缝分析与防治

对水泥混凝土路面裂缝进行了分类,从路基、混凝土收缩、温度应力、材料、运输等角度分析了水泥混凝土道路路面产生裂缝的原因,并探讨了裂缝的防治方法,以减少路面裂缝现象的产生,保证道路行车的舒适性与安全性。     

水泥楼地面裂缝的防治

介绍了水泥楼地面裂缝通常表现出的几种情况，从楼地面的基本构成、楼地面的基本设计要求、不同形式的楼地面裂缝的防治等方面进行了探讨，提出了水泥楼地面裂缝的防治措施。     

水泥混凝土路面早期裂缝的防治

针对水泥混凝土路面裂缝的危害性,从振捣过程、基层施工、施工温度三方面分析了混凝土路面产生裂缝的原因,介绍了相应的预防措施,对路面基础的处理、路面的修补和振捣提出了相应的处理方法,从而保证路面的质量.     

浅析水泥混凝土施工温度裂缝预防

分析了水泥混凝土产生裂缝的原因，从温度控制和改善约束条件两方面介绍了温度裂缝的控制和预防措施，论述了防止混凝土开裂的其他施工措施，以减少裂缝的发生，保证构件的刚度和结构整体性。