夹层玻璃金属植入节点抗拉拔性能研究

结构玻璃一般采用夹层玻璃。对于夹层玻璃构件,可采用金属植入节点来实现构件间的连接,但目前缺少成熟的金属植入式节点承载力设计方法。为此,设计并制作了5个采用离子性中间层的夹层玻璃金属植入节点,通过静力试验研究金属植入节点的抗拉拔性能,得到了节点的破坏形态及节点在拔出过程中的荷载-位移曲线。试验中节点破坏由胶片脱黏控制,且具有一定的延性破坏特征。通过理论推导得到了考虑胶片拉伸及剪切变形协调的胶片内力计算方法和节点承载力计算方法,将拉伸黏接面脱黏时定义为金属植入节点的承载能力极限状态,建议设计时应保证外层玻璃具有足够的强度。通过试验结果与理论计算结果进行对比,验证了所提出承载力计算方法的合理性。     

Tragverhalten von bewitterten Verbund‐Sicherheitsglas‐Scheiben

Load bearing performance of weathered laminated safety glass panes. Beside known influences on the shear behavior of laminated safety glass (LSG) as interlayer temperature, loading rate and load duration, further effects result from climatic load (e.g. long‐term exposure of ultraviolet radiation, moisture and air temperature), especially for outdoor applications. Experimental investigations showed that moisture penetration of PVB‐interlayer at the glass edge zones is a major negative factor on the durability of LSG. Hence, shear behavior and adhesion characteristics deteriorate. Concerning large‐scale architectural LSG panes carrying wind, snow and dead load no significant endangering of their structural safety occurs due to a local deterioration of the interlayer, only. In order to avoid visual damage of LSG in environments with access of high humidity (e.g. rain), it is recommended to protect edges thoroughly and effectively. Aging of the interlayer due to UV‐radiation and air temperature is dependent on its intensity and duration, however, resulting in a stiffer material behavior, but not affecting the structural safety.     

Versuche zur Ermittlung der Eigenschaften von gebrochenem Verbundsicherheitsglas (VSG) und Berechnung der Resttragfähigkeit eines Glasbogens

Tests to determine the characteristics of broken laminated safety glass and a calculation of the remaining structural capacity of a glass arch. The aim of this work is to show, in an exemplary way, using a glass arch with tension rod possibilities to calculate the remaining structural capacity of broken laminated glass. To achieve this aim tensile and bending tests on PVB‐foil and broken laminated safety glass were carried out at 10 °C. Furthermore experiments to determine the friction between broken laminated glass and steel and neoprene were performed.     

Progressive damage and fracture of laminated glass beams

The use of laminated glass is increasing due to the realization of transparent load-bearing elements for architectural glazing applications. In laminated glass, two or more layers of glass are bonded to thin thermoplastic interlayers to improve the post-breakage characteristics of the glass. After breakage, the residual load-carrying capacity of the laminate depends on the mechanical properties of the laminate constituents. Three-point bending tests are presented on laminated glass specimens, made with an internal float glass and two external equal tempered glass panels. The laminated glass specimens, of equal cross section, were characterized by three different combinations of annealed float and fully thermally tempered glass plies. In addition, two sets of specimens were constructed with two different interlayers having significantly different mechanical properties. The flexural load was applied parallel to the lamination plane (in-plane loading) and the tests were conducted at room temperature. The post-failure response and the failure mechanisms detected are presented and discussed.     

Untersuchungen zum Einfluß natürlicher und künstlicher Bewitterung auf den Schubmodul von Verbund‐Sicherheitsglas

Influence of natural and accelerated weathering on shear modulus of laminated safety glass. The load bearing behaviour of laminated safety glass (LSG) is mostly determined by the shear strength of the intermediate material layer, (normally) Polyvinylbutyral (PVB). Beside the known influences on the shear behaviour, such as temperature and loading rate, there are also climatic, partially long lasting loads dependent on application of LSG outdoors or inside of buildings. Since PVB is a polymeric material, climatic loads, e.g. UV‐radiation, humidity and varying air temperature etc., cause aging processes and thereby chemical changes in the polymeric material. To clarify the aging stability of LSG and the long term stability of the compound effect, respectively, with the help of the shear modulus, experimental research was conducted on weathered or aged test pieces, resp., in dependence of the loading speed. Comparatively, there are test results at disposal from new or non‐aged LSG elements, resp., from the same batch. The tests have shown that LSG is differently resistant to UV‐radiation depending on its intensity and ambient temperature. Humidity, as opposed to that, penetrates over the edges to the inside and leads to separation of the PVB‐interlayer around the LSG edge area (approx. a stripe of 50 mm). The experimental tests for this paper were conducted at the Structural Testing Laboratory of the Structural Engineering Institute at Ruhr‐Universität Bochum. The authors thank Dr. Koll and Dr. Stenzel, HT Troplast AG, for the supply of the test samples and valuable information concerning that topic.     

Fail-safe point fixing of structural glass. New advances

The intrinsic brittleness of glass renders its architectural use in monolithic panels quite problematic. For this reason, glass plies are usually laminated with polymeric interlayers that can maintain coherent fragments after glass breakage, so avoiding sudden collapse (fail-safe response). However, the safety performance disappears if the connection to the rear load-bearing structure is not able to retain the panels in their place after glass breakage. To this aim, an innovative point-fixing system for frameless glass glazing has been developed, that exploits the enhanced mechanical properties of a new generation of ionoplast polymer interlayers. Bending tests on small scale glass beams have been performed at various levels of loading, temperature and aging. Laminated glass connected with the new device exhibit a noteworthy resistance and interesting post-glass-breakage performances.     

Verbundglasplatten – Schubverbund und Membrantragwirkung – Teil I

Laminated glass plates – shear compound and membrane action – Part I. The mechanical behaviour of laminated glass plates is governed by the interlayer shear stiffness and membrane action. The objective of the present work is the analysis of these two parameters and the development of a simple, safe and economic method for determining glass dimensions. In partI a temperature and load‐duration dependant shear modulus is determined for PVB from experimental data. Chapter 3 contains an analytic solution for two side supported laminated plates, based on sandwich theory and describes the creep‐buckling problem of compression elements. The part II (No. 2/2005) investigates the non‐linear behaviour of laminated plates. The load‐stress diagrams show that the curves for plates with a flexible shear interlayer are quite close to, or even exceed, the curve for a layered configuration with no interaction between panes. For this reason an overall boundary curve is developed, which applies conservatively to all the configurations. Owing to the flexibility of shear transfer between the glass panes, non‐linear action is exhibited at an earlier stage than with a monolithic condition. This flexibility significantly influences the actual strength of laminated glass units: when the shear transfer is poor – i.e. at high temperature or long load duration the strength lost in bending action is compensated by gains through membrane action.     

Tragfähigkeit von Lochleibungsverbindungen vorgespannter Glasscheiben zur Ausbildung von Anschlüssen im Konstruktiven Glasbau

Strength of bearing connections in toughened glass plates for the structural use. In steel structures due to their “infinite'” ductility the bearing connections are standard components of joints. Their design rules are based on simple engineering models. However if analogous bearing connections are subject of glazing structures the requirements on the materials' ductility cannot be met. Therefore interlayers out of mortar etc. in the hole surrounding the bolt have to be introduced such that a ductile load deformation behaviour can be reached reducing stress peaks and avoiding steel‐glass‐contact. On this basis design rules are to be established to predict the load carrying capacity of bolts in glass bearings. The following investigations describe the experimental and theoretical works to derive an engineering model for this purpose.     

Verbundglasplatten – Schubverbund und Membrantragwirkung – Teil II (Fortsetzung aus Heft 1/2005 und Schluß)

Laminated glass plates – shear compound and membrane action. The mechanical behaviour of laminated glass plates is governed by the interlayer shear stiffness and membrane action. The objective of the present work is the analysis of these two parameters and the development of a simple, safe and economic method for determining glass dimensions. In partI a temperature and load‐duration dependant shear modulus is determined for PVB from experimental data. Chapter 3 contains an analytic solution for two side supported laminated plates, based on sandwich theory and describes the creep‐buckling problem of compression elements. The part II investigates the non‐linear behaviour of laminated plates. The load‐stress diagrams show that the curves for plates with a flexible shear interlayer are quite close to, or even exceed, the curve for a layered configuration with no interaction between panes. For this reason an overall boundary curve is developed, which applies conservatively to all the configurations. Owing to the flexibility of shear transfer between the glass panes, non‐linear action is exhibited at an earlier stage than with a monolithic condition. This flexibility significantly influences the actual strength of laminated glass units: when the shear transfer is poor – i.e. at high temperature or long load duration the strength lost in bending action is compensated by gains through membrane action.     

Finite element modelling of architectural laminated glass

Laminated glass (LG) comprises two or more glass plates bonded together with elastomeric interlayer. Automobile and aircraft industries have used LG for years because of its ability to maintain closure of window openings following fracture. In the last decade, the architectural industry began to utilise the potential of LG as the best glazing material for building fenestrations that might experience extreme loadings. Polyvinyl butyral (PVB) interlayer and recently advanced polymer interlayer have relatively small thickness in comparison with that of the glass plates in LG. In addition, the structural properties of the interlayer materials vary radically from those of window glass. These issues make analysis of LG difficult. This article presents a higher order finite element model (FEM) to analyse LG under uniform loading. The formulated model can analyse LG with different glass plate types and different interlayer thicknesses over a wide temperature range. While not as comprehensive as some analytical techniques for LG, this model has the advantage of being able to handle different shapes (rectangular, trapezoidal, triangular, etc.) and boundary conditions.     

Das Biegedrillknickverhalten von Glasträgern aus Verbundglas

The LTB‐behaviour of beams made of laminated glass. In many cases the lateral torsional buckling is governing the design of beams made of laminated glass. Then the question arises of how to consider the composite effect of the PVB‐layers between the glass panels, which always shows a strong time‐ and temperature‐dependant behaviour. Also the combination and sequence of permanent and variable load and temperature phenomena plays an important rule for the prediction of the LTB‐behaviour, as these effects have significant influence on the stability load capacity of laminated glass. In the following paper the most important steps for the solution of a new developed design concept [1] are presented, by which the complex time dependant LTB‐capacities of beams of laminated glass can be verified. On the basis of the experimentally obtained time‐ and temperature dependant stiffness‐behaviour of the interlayer the load capacities of these beams can analytically be predicted. Comparisons with large scale tests and simulations show good agreements with the results. Finally the design procedure is able to take into account also sequence effects due to variable loads as well as temperature.     

Eine Vollglaskonstruktion – Möglichkeiten und Probleme

An All‐Glass construction – possibilities and problems. Presented are the design and realisation of a consequent self bearing glass construction without steel framing or safety elements. No column or girder should derogate the transparent appearance of the face, which lead to realizing those parts in glass as well. The structural elements are glued together. Glue also connects the glass structure with the neighbouring building. Local loading at the bearing glass plates without any additional constructive elements is tested numerically and experimentally. The experimental construction was built to test constructive solutions and to gain substantiated experiences in the usage and erection of such kind of buildings.     

On the size and shape of initial out-of-plane curvatures in structural glass components

For many structural glass components, buckling is known to be a major design issue, which is influenced significantly by several parameters. The latter include boundary conditions, slenderness and geometrical imperfections, in particular initial curvatures. However, in spite of their importance for building practice, experimental data for the latter are very poorly documented. Consequently, an extended experimental campaign is presented in which initial curvatures of 312 monolithic and laminated glass beams with a variable length, height, glass thickness, glass type and – wherever applicable – interlayer, have been accurately measured and analysed. Major conclusions have been drawn regarding the shape and the size of initial curvatures.     

Sicherheitsverglasungen als Hybridbauteil

Security glazing as hybrid element. Hybrid elements play a more and more significant role in building construction. The systematic combination of different materials forming a composite element enables the engineer to adjust and optimise the desired structural properties for a specific application, which a single building material might not be able to cope with. When using glass in building construction, its combination with more ductile materials effectively contributes to broaden the range of applications beyond the limitations of the base materials involved. The material properties of security glazing units and especially their resistance against external attack can be significantly improved by using hybrid elements made of glass and polycarbonate. The composite panels are more slender and weigh less than conventional panes made of laminated safety glass. As part of the investigation on hybrid elements, experimental testing was carried to examine the composite panel's load capacity and residual strength. The test results provide a basis for the development of an analytical design approach of composite panels made of glass and polycarbonate. The investigation of hybrid building elements with glass forms a major part of the current research activities at the Institute of Building Construction at Technische Universität Dresden.     

夹板式夹层玻璃抗风压性能试验研究

夹板式夹层玻璃具有良好的安全性能,已得到了越来越广泛的应用。现有关于夹板式夹层玻璃的研究还比较有限,国内现行规范尚未规定夹板式夹层玻璃的设计。本文从夹板式夹层玻璃的抗风压性能出发,以某夹板式玻璃幕墙工程抗风压性能试验为基础,研究了不同压力差对夹板式夹层玻璃作用下的挠度分布规律,并将试验结果与规范JGJ102—2003的点式玻璃计算方式的结果进行对比,并对夹板式夹层玻璃的挠度计算进行了探讨,为今后规范的进一步完善、修订及夹板式夹层玻璃在玻璃幕墙工程中的应用提供了试验依据。     

玻璃幕墙及采光顶结构设计若干问题探讨

针对玻璃幕墙及采光顶结构设计中作用(荷载)计算、作用效应组合、安全玻璃定义、不同作用下玻璃强度取值、夹层玻璃计算方法、结构胶缝计算方法等,指出了存在的问题,探讨、研究了解决问题的方法或思路,供参考。     

The effects of bend–twist coupling on the post-buckling characteristics of composite laminated plates using semi-energy finite strip approach

In composite laminated plates various mechanical properties may be attained by changing the lay-up arrangement. The bent–twist coupling is one of the significant properties which dominate the mechanical performance of a laminated plate structure in large out-of-plane deformations. The effects of bend–twist coupling on the post-buckling behavior of composite laminated plates have been studied in this paper by implementing a finite strip approach based on the concept of a rigorous post-buckling solution for composite plates and plate structures, namely the semi-energy approach. All the plates are assumed to be symmetrically balanced laminates having uniform in-plane stiffness properties. As far as the out-of-plane stiffness properties are concerned, all the properties, except for the bend–twist coupling terms which are assumed to change from one laminate to another, are the same among different laminates. The orthotropic solutions have also been determined by precluding the bend–twist coupling terms. A comprehensive set of parametric studies have been carried out to investigate the effects of bend–twist coupling terms on the post-buckling load–displacement path, post-buckling deformations and stress distribution. The comparison between the results revealed markedly different behaviors among different laminates due to the bend–twist coupling effects. The outcome of the paper can help structural designers to have a better understanding of the effects of bend–twist coupling terms on the post-buckling behavior of laminated composite plates at the design stage.     

Structural performance of laminated and unlaminated tempered glass under monotonic transverse loading

A total of thirty six bending tests have been conducted on 1220 × 460 mm sheets of glass, 9.5-, 12.7- and 15.9-mm thick, using slow-rate monotonic loading. Twenty four specimens were laminated on one side using either one or two 0.36-mm thick polyester transparent laminates. The study showed that lamination has significantly changed the failure mode of glass from a catastrophic failure, where fragments of glass shatter in different directions, to one which is still brittle yet safer, as the fractured glass remains fully intact. The average gains in flexural strength, stiffness and strain energy, as a result of lamination, were 20%, 10% and 34%, respectively, while the maximum gains in flexural strength, stiffness and strain energy were 36%, 33% and 52%, respectively. Because of the scatter of data, no specific correlation between the gains and reinforcement ratio (expressed as the ratio of laminate-to-glass thickness) could be established. The load–deflection behaviour of both laminated and unlaminated glass was linear up to failure. No rupture or delamination of the laminates were observed     

含软弱夹层盐岩型盐力学特性试验研究

 为研究不同夹层特征对含软弱夹层盐岩力学特性的影响规律,在现场取芯不易获得试样的情况下,采用压制型盐的办法制备出具有规则夹层特征的层状盐岩型盐,然后对其进行单轴及三轴压缩试验。试验结果表明,当夹层的厚度比和夹层的分布特征发生规则变化时,含软弱夹层盐岩型盐的强度、弹性模量、泊松比等力学参数及型盐体的变形和破损特征均发生一定规律性的变动。得到的结论如下：(1) 含软弱夹层盐岩型盐的单轴抗压强度和弹性模量均随着夹层厚度比的增加而呈现下降趋势。(2) 夹层厚度比一定时,3层夹层型盐的强度高于1和2层夹层型盐;而多夹层型盐随着夹层层间距的增加,其强度和弹性模量逐渐减小,但减小趋势变缓。(3) 强度低的夹层部分径向应变大于强度高的纯盐层,破坏面总是始于强度高的纯盐层。试验结果为在室内开展层状盐岩地下储库的稳定性分析提供一种新方法。     

中空玻璃用硅酮结构胶标准解读

中空玻璃用硅酮结构密封胶的性能和质量对于中空玻璃及其工程的安全和节能至关重要,因此对其性能指标的要求有别于建筑用硅酮结构密封胶.本文对最新制定的该产品标准进行了介绍,包括制定原则、主要控制指标等等.