Glass fibre reinforced plastic (GFRP) rebars for concrete structures

The study described is a part of a large-scale experimental and theoretical programme on the application of fibre reinforced plastic ( ) reinforcement for concrete structures initiated at the Université de Sherbrooke (Sherbrooke, Canada). The programme is being carried out to gain an insight into the flexural behaviour of concrete beams reinforced with glass fibre reinforced plastic ( ) rebars. Results of experimental study on 3.3 m long beams reinforced with two different types of rebars are presented and compared to that of conventional steel reinforced concrete beams. Three series of reinforced concrete beams were tested in flexure. The beams were 200 mm wide and respectively 300, 450 and 550 mm high. The paper also attempts to present the properties of and its components and to give an oversight of relevant research activities involving rebars as reinforcement for concrete units.     

封闭阳台对夏季室内热环境的影响

论述了封闭阳台的夏季热过程。从构成建筑室内热环境的4个要素的角度出发,简单分析了封闭阳台在夏季对室内热环境产生的不利影响,针对如何降低封闭阳台对室内热环境的不利影响提出了几点建议。     

埋地承插玻璃钢管施工方法

玻璃钢管产品断更新换代，现行的验收规范没有完整的验评标准，因此不埋地承插玻璃钢管的具体施工准备、沟槽开挖、管材检验、管道的安装及其稳管、试压、管沟加填几方面进行了介绍，并结合实际施工过程提出了玻璃钢管在施工中应注意的问题及其预控措施。     

Modellbildung zur Simulation von Stahlfaserbeton unter hochdynamischer Belastung

Modelling of Steel Fibre Reinforced Concrete under High Dynamic Loadings For structural protection against extraordinary loads it is important to find construction materials that offer properties that are especially applicable to the problem. One of these materials is steel fibre reinforced concrete. However, for high dynamic loads like from impact or detonation steel fibre reinforced concrete is not yet investigated sufficiently. This article describes a new empirical material model for the simulation of steel fibre reinforced concrete under high dynamic loadings. This material model also includes a damage model which describes the degradation of stiffness and strength in consequence of plastic (compaction and shear) strain. The model is implemented in a hydrocode and validated by a multitude of contact detonation tests. From these results it could be shown that the numerical simulations carried out with the new steel fibre reinforced concrete model are capable to complement or to reduce the expensive and time‐consuming experiments, respectively.     

玻璃钢管与预应力钢筋混凝土管的比选

结合工程实际，对预应力钢筋混凝土管和研发时间短、实际应用少的玻璃钢管进行了比较，分析了这两种管材的特点和应用条件，提出管材的选择应根据工程的不同进行选择。     

Buckling characteristics of pultruded glass fibre reinforced plastic columns under moment gradient

The authors present the results of 10 full-size tests designed to investigate the behaviour of eccentrically loaded columns of pultruded glass fibre reinforced plastic. The major axis tests were carried out on 203 × 203 × 9.53 mm wide flange profiles at a single column height of 4.8 m. The choice and magnitude of the moment gradients are described, together with details concerning the design and operation of a purpose-built test rig. Salient results are given for loads, deflections and strains, and conditions at failure are described. The results are assessed for the their relevance to the development of design procedures suitable for manuals or design codes.     

Structural analysis of FRP reinforced polymer concrete material

The paper deals with a study of precast elements made of polyester polymer concrete (PPC) reinforced with glass fibre rebars (GFRP). The paper describes the properties of the materials, which were tested on a microscopic scale using different experimental techniques such as porosimetry, scanning electron microscopy and petrography. Likewise, characterisation in a macro-scale was carried out to define the mechanical properties of the material (modulus of elasticity, stress–strain curve, ultimate strength and bond). Based on the latter properties, a relatively simple method is presented to estimate the ultimate bearing capacity of beams under bending load. The calculation method has been verified by testing beams and full-scale elements.     

Mechanical Characterization of Fibre Reinforced Polymers Materials at High Temperature

One of the greatest impediments to using fibre reinforced polymer (FRP) composites in buildings and parking garages is their susceptibility to degradation when exposed to elevated temperatures and the limited knowledge on the thermal and mechanical properties of these composites at such temperatures. Glass FRP (GFRP) tensile coupons and single lap-splice coupons were tested in tension to study the mechanical properties under steady-state and transient thermal conditions. Tests were conducted at a range of temperatures between room temperature and +200°C. In terms of tensile strength, approximately half of the strength of the FRP was lost near the glass transition temperature of the epoxy resin matrix. However, 40% of the room temperature strength of the GFRP was still retained at 200°C. The lap-splice tests showed that the FRP-to-FRP bond strength was affected even more by high temperature exposure with 90% loss in lap-splice near the glass transition temperature. An analytical model is also presented in this paper characterizing the mechanical properties at elevated temperature, which in turn will be used in numerical fire endurance models developed by the authors.     

Thermal isolation and mechanical properties of fibre reinforced mud bricks as wall materials

Fibre reinforced mud bricks, which are studied in this paper, provide the expected technical performance for the thermal isolation and mechanical properties, according to ASTM and Turkish standards. The mechanical properties of waste materials and some stabilisers were investigated thoroughly and some concrete conclusions were drawn. The fibre reinforced mud bricks fulfill the compressive strength and heat conductivity requirements of the ASTM and Turkish standards. Mud bricks with plastic fibers showed a higher compressive strength than those with straw, polystyrene and without any fibers. Basaltic pumice as an ingredient was found to decrease the thermal conductivity coefficient of fibre reinforced mud bricks. The fibre reinforced mud brick house has been found to be superior to the concrete brick house for keeping indoor temperatures stationary during the summer and winter.     

高强玻璃纤维/碳纤维混杂复合材料加固混凝土梁的抗弯试验研究

以高强玻璃纤维 (SGF)布与碳纤维 (CF)布混杂加固混凝土梁 ,进行对比试验研究 ,结果表明 ,与单一CF布加固相比 ,SGF/CF布混杂加固不仅使梁的延性显著提高 ,加固成本大幅降低 ,而且承载力也略有提高 ,仅刚度略为降低。简要讨论了耐久性问题     

Assessment of coconut fibre insulation characteristics and its use to modulate temperatures in concrete slabs with the aid of a finite element methodology

This paper presents the assessment of coconut fibre thermal characteristics and its use to modulate temperatures in concrete slabs in the construction industry. Fibre is abundantly available in tropical regions, extracted from the husk of coconut fruits and manufactured at 115.54 MPa to obtain specimens. A first thermal conductivity of k = 0.048 (W/m K) is obtained by solving the heat diffusion equation with experimental temperatures as boundary conditions. A second value k = 0.0499 (W/m K) is obtained by solving the Fourier's law by using a known heat flux and temperature histories in the specimen. The maximum error between the first and second k values was 3.8%. However, the k = 0.048 (W/m K) was used for numerical analysis.Experimental work was done to find density and heat capacity, 174 kg/m³ and 2600 J/kg K, respectively. Further numerical work was carried out to modulate temperature in concrete slabs. This showed that fibre put on the concrete external surface allows room temperatures to fall within the comfort range. Density, thermal conductivity and heat capacity of coconut fibre were varied in a wide range to investigate the sensitivity of temperature to such changes. This showed that temperature can be considered sensible only to thermal conductivity variations.     

简易阳光间的太阳能应用分析

住宅的南向阳台对于住户来说,虽然使用面积有限,但带来的益处是人所共知的,可供人们眺望户外景致、打破的闭塞感以及丰富建筑立面造型等。如果合理地把阳台封闭起来,形成一个附加的过渡空间,在冬季,夜间有利于保持室内温度,减少热损失;白天还可收集太阳直接辐射并转化为热能,对房间起到加热作用,提高室内热环境水平。同样在夏季,利用封闭阳台与室内温度不同产生的热压作用,亦可达到通风致凉的目的。若再采取适当构造措施,如增加吸风口、扩大气流出入口的高度差,就可以大大改善室内通风效果。然而,寒冷、严寒地区封闭阳台在改善室内热环境方面有利人们早已认同,但对其原理却知之甚少,也没有理论、技术来指导设计和建设。因此,该文通过理论分析,总结出一些合理的构造措施,来指导设计、建设,使南向封闭式阳台能真正成为简易阳光间,改善室内热环境。     

玻璃钢夹沙管在某长距离输水工程中的应用

通过玻璃钢夹沙管在城市给水工程中的实际应用,详细地阐述了其它的特点。     

手糊环氧玻璃钢的施工

介绍了环氧玻璃钢的性能，组合材成分和施工工具，阐明了手糊玻璃钢的施工工艺流程，质量要求和施工注意事项，指出了环氧玻璃钢应用的广泛性。     

箍筋锈蚀钢筋混凝土柱受火后抗震性能试验研究及有限元分析

为研究箍筋锈蚀钢筋混凝土柱的火灾反应及其火灾后的抗震性能,设计并制作4根尺寸及配筋相同的钢筋混凝土柱,以锈胀裂缝为损伤指标,对混凝土柱的箍筋进行电化学加速锈蚀试验,得到箍筋不同锈蚀率的混凝土柱.对RC柱进行限时受火试验,研究箍筋不同锈蚀率的混凝土柱的高温反应.对历经高温的钢筋混凝土柱进行低周水平反复荷载试验,并利用AN...     

Faserbewehrte Putze auf hochdämmenden Untergründen

Fibre reinforced rendering for high insulating external walls. Today's common high insulating “External Thermal Insulation Composite Systems” (ETICS, e.g. brickwork with special porosity‐enhancing material) lead to an increased thermal‐hygric load of the rendering. A reinforcement of the brittle rendering is necessary to enable lasting acceptance of occurring tensile and bending tensile stress. The following article describes material properties as well as usability of fibre‐reinforced light‐weight rendering. By adding a sufficient quantity of high‐strength fibres the brittle rendering matrix with very low ultimate tensile strain turns into a “ductile” material with elastic‐plastic material behaviour. The thermal‐hygric influence on the rendering surface due to natural weathering leads to high stress and strain on the rendering layer. Large‐scale tests with artificial weathering of external wall constructions as well as FEM‐computations show, that only overcritical fibre‐reinforced renderings are able to guarantee a sufficient weather protection of the exterior wall.     

混凝土骨料种类和边界条件对截面温度场的影响

为了正确分析钢筋混凝土构件截面温度场,以矩形柱为对象,以标准火作用为受火条件,采用数值计算方法,研究混凝土骨料种类和边界条件对截面温度场的影响。研究结果表明:因热参数差别较大,硅骨料构件截面温度明显高于碳骨料,而法国规范推荐混凝土的温度接近硅骨料混凝土的温度,温度值越高其间差别越小;是否考虑边界单元格热储存对温度场影响不大。     

The structural characteristic of a polymer composite cellular box beam in bending

Pultruded glass fibre reinforced polyester composite systems are currently being considered for large scale structures such as footbridges, sign gantries over motorways and lightly trafficked road bridges. This paper discusses the experimental and numerical analyses of the short term loading performance up to failure of the cellular box beam under a four-point loading configuration. The non-linear numerical analyses utilize, as input data, the mechanical property values of coupon specimens of the material; the values are not given in the paper. It is shown that there is satisfactory agreement between the two methods of analysis. The beam displayed non-linear behaviour above a moment value of 860 kN m. The weakest part of the structure was the connection at the support end.     

Evaluation of inside surface condensation in double glazing window system with insulation spacer: A case study of residential complex

Aluminum spacer used to keep the glass panes apart acts as a thermal bridge that increases the risk of inside surface condensation due to its high thermal conductivity. In this study, the inside surface condensation in double glazing window systems with conventional aluminum spacer and insulation spacers made of thermally broken aluminum and thick-walled plastic, respectively, is evaluated. Evaluation method and judgment criteria for preventing inside surface condensation are suggested. Thermal characteristics of window system in residential unit are analyzed and two-dimensional steady state heat transfer simulation is carried out in order to obtain the lowest inside surface temperature. The results show that the application of insulation spacer can substantially increase the lowest inside surface temperature, temperature difference ratio and inside air humidity for preventing inside surface condensation and satisfy the required minimum temperature difference ratio.     

Numerische Simulation des Verhaltens von Betontragwerken unter Brandeinwirkung

Numerical Simulation of the Response of Fire Exposed Concrete Structure The proposed numerical model for concrete and reinforced concrete structures subjected to fire comprises the transient thermal and mechanical analysis considering the temperature dependent material properties of concrete and reinforcing steel within the framework of the phenomenological approach of the Eurocode 2, part 1‐2. A concrete model, based on the combination of plasticity and damage theory, serves as the basis for the material model of concrete for high temperatures. For reinforcing steel a standard elastic‐plastic material model is employed. The proposed model is validated by the numerical simulation of fire tests on plain concrete specimens and by the numerical simulation of a large scale fire test on a reinforced concrete slab. Furthermore it is used to determine the structural integrity of a tunnel structure, put up by the cut‐and‐cover method, exposed to fire.