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。     

局部荷载作用下钢化夹胶玻璃板极限承载力研究

对四边简支钢化夹胶玻璃板在局部均布荷载作用下的力学性能进行试验研究.以单层钢化玻璃厚度、支承端长度和加载端长度为变量共设置64个试件.测得试件在局部均布荷载作用下的荷载-挠度曲线及板内应力分布情况.随着加载端长度的增加试件破坏模式发生改变,不同破坏模式对应试件的极限荷载区别较大.试件应力分布情况与弹性板受弯时规律基本一...     

点支式钢化玻璃火灾下受力性能试验研究

为研究单层索网点支式玻璃幕墙中点支式单片、中空和夹胶钢化玻璃在火灾下的破裂过程,分别对点支式单片、中空和夹胶等3组开孔钢化玻璃进行了相同火灾条件下的负载试验研究。重点考察试验过程中玻璃位移随温度的发展情况、玻璃的破坏模式和破坏时间,以及其破裂过程等。通过将试验数据与相同类型的不开孔玻璃进行对比,研究了角部开孔对钢化玻璃在火灾下受力性能和破裂过程的影响。结果表明：火灾下,玻璃由于受热膨胀不均匀在表面产生的拉应力是其破坏的主要原因;玻璃面板承受的均布荷载将在玻璃内部产生荷载应力,并导致其面外变形增大;玻璃开孔,使其在四角点孔洞边缘形成大量微裂纹,造成玻璃面板孔边材料强度下降和应力集中,加剧了玻璃的破坏;点支式玻璃面板的固定支座约束限制了四边变形,加快了其中心点位移的增长。     

Verbund im Glasbau – Neues und Bewährtes

Laminated glass – novel and well‐tried. With increasing safety specifications, glass laminates become more important in the use of glass for structural elements. The requirements of laminated glass includes safety against fall arrest, post breakage behaviour and bomb blast resistance. In addition to the structural aspects, laminates of two or more glass panes are nowadays increasingly used for sound insulation, protection against direct or diffuse sunlight etc. Various design possibilities (coloured or printed interlayer, embedding of fabric, papers meshes etc.) are available for a wide range of architectural applications. Parallel to the rising requirements and possibilities of laminated glass, scientific studies concentrated on the mechanical properties of laminates with Polyvinylbutyral (PVB) interlayer and development of new interlayers by the industry. This article compares laminates with different interlayers and shows the results of scientific research.     

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.     

四边简支玻璃面板模爆法的试验研究

针对幕墙玻璃的结构特点,分别对四边简支的单片钢化玻璃面板、夹胶钢化玻璃面板和夹胶中空钢化玻璃面板进行了爆炸冲击荷载作用下的动力响应试验。试验研究了不同玻璃面板的破坏形式,以及不同爆炸冲击波的压力峰值和作用时间对玻璃面板破坏特征的影响。     

点支式钢化玻璃在循环荷载下的试验研究

为研究四点支承玻璃面板在循环荷载下的力学性能,对11块采用浮头式驳接头连接方式的钢化玻璃面板,进行施加面外均布循环荷载的破坏试验,对整个循环荷载作用下玻璃面板关键点的动静态应力变化进行测量。试验表明,钢化玻璃在循环荷载作用下的荷载-应力呈线性关系,随着循环次数的增加,板内应力略有变化,表现为高脆性破坏。     

浮法玻璃应变率相关的动态本构关系

采用改进的SHPB(分离式Hopkinson压杆)技术测试了较高应变率范围内浮法玻璃的动态应力-应变曲线,探讨了其动态力学性能.结果表明:浮法玻璃为弹脆性材料,其动态应力-应变关系呈非线性特征.在较高的应变率范围内,浮法玻璃动态应力-应变关系与应变率相关,其弹性模量随应变率的增大而增大.基于损伤力学的基本理论,并根据SHPB测试结果,拟舍得到了浮法玻璃应变率相关的动态本构方程.     

Mechanical Property Degradation of Naval Composite Materials

The effect of heat and fire on the mechanical properties and failure of polymer composite materials used in naval ship structures is investigated. Coupled thermal-mechanical models are presented for predicting the loss in strength and failure of load-bearing polymer laminates when heated from one-side. The thermal component of the models predicts the temperature and decomposition rate of a laminate. Using this information, several mechanical models based on progressive softening analysis or laminate analysis can be used to predict the reduction in strength and time-to-failure. A coupled thermal-mechanical model that is solved using finite element analysis is also presented. Experimental fire-under-load tests are performed on several types of polymer laminate materials to evaluate the accuracy of the models. The tests were performed at different heat flux levels between 10 kW/m² and 75 kW/m², which is equivalent to surface temperatures between about 250°C and 700°C. The temperature, mass loss and char formation of a laminate can be accurately predicted for a wide range of thermal conditions using the models. The models can also predict the time-to-failure of laminates under static tension or compression loading. The models presented in this chapter are considered useful analytical tools for naval architects to estimate the loss in mechanical performance and time-to-failure of composite ship materials in fire.     

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.     

Stochastic analysis of laminated composite plate considering stochastic homogenization problem

This paper discusses a multiscale stochastic analysis of a laminated composite plate consisting of unidirectional fiber reinforced composite laminae. In particular, influence of a microscopic random variation of the elastic properties of component materials on mechanical properties of the laminated plate is investigated. Laminated composites are widely used in civil engineering, and therefore multiscale stochastic analysis of laminated composites should be performed for reliability evaluation of a composite civil structure. This study deals with the stochastic response of a laminated composite plate against the microscopic random variation in addition to a random variation of fiber orientation in each lamina, and stochastic properties of the mechanical responses of the laminated plate is investigated. Halpin-Tsai formula and the homogenization theory-based finite element analysis are employed for estimation of effective elastic properties of lamina, and the classical laminate theory is employed for analysis of a laminated plate. The Monte-Carlo simulation and the first-order second moment method with sensitivity analysis are employed for the stochastic analysis. From the numerical results, importance of the multiscale stochastic analysis for reliability evaluation of a laminated composite structure and applicability of the sensitivity-based approach are discussed.     

正交胶合木-混凝土螺栓连接力学性能试验研究及参数分析

为研究正交胶合木(CLT)-混凝土螺栓连接的力学性能,对12个顺纹连接试件和12个横纹连接试件进行了单调加载和低周往复加载试验,总结了连接典型的破坏模式,得到了连接的初始刚度、承载力及延性系数等力学性能;利用ABAQUS软件对连接进行非线性参数分析,研究螺栓直径、螺栓强度等级及CLT层板厚度等参数对连接力学性能的影响。结果表明：连接的破坏模式与厚径比(CLT厚度与螺栓直径之比)相关,当厚径比不大于6.56时,主要发生单塑性铰屈服、木材销槽承压及局部承压破坏;螺栓直径一定时,增加CLT层板厚度可有效提高连接承载力;当厚径比大于6.56时,主要发生螺栓双塑性铰屈服与剪断破坏;增加层板厚度对连接初始刚度、承载力和破坏模式无明显影响。针对螺栓屈服破坏模式,增大螺栓直径可提高连接的初始刚度与承载力;提高螺栓强度等级对初始刚度影响较小,但可提高连接承载力。     

玻璃钢化工艺过程与钢化应力的研究

选用浮法透明玻璃和Low-E镀膜玻璃制成试样,分别在电辐射水平钢化炉和强制对流—辐射混合加热式水平钢化炉内,用不同的操作参数对其进行钢化处理,并用GASP-132表面应力仪测定试样的表面应力,用SM-100应力仪观测试样的应力图像．结果表明：用强制对流-辐射方式加热Low-E玻璃,其钢化应力分布较为均匀．     

Experimental study on GFRP pipes under axial compression

Fiber reinforced polymer (FRP) is suitable for structures in corrosive environment and long-span light-weight structures due to its high-strength, light-weight, and anti-corrosive qualities. The behavior of pultruded glass fiber reinforced polymer (GFRP) pipes, which are the members of long-span lattice structures, under axial compression was investigated by tests. Short GFRP pipes were first tested to determine the basic mechanical properties. Then the stability of long GFRP pipes was studied by axially compressive tests in four groups with different slenderness ratios, twelve specimens totally. Based on the results of the tests and literature, the formula of the buckling load of composite pipes under axially compressive load was presented based on Perry formula. It can well predict the buckling failure load GFRP pipe under axial compression.     

单向带抗剪键叠合板的力学性能及设计方法

针对现有钢筋桁架叠合板钢筋用量多、成本偏高的不足,提出了一种新型带混凝土抗剪键的叠合板,并通过对1块现浇板和6块叠合板的静力加载试验,分析了有无抗剪键、抗剪键沿横向个数和抗剪键结构形式对叠合板力学性能的影响。采用有限元软件ABAQUS模拟了试验中部分试件的受力过程,验证了有限元模拟方法的可行性。结果表明:与无抗剪键叠合板相比,设置一定数量抗剪键的叠合板和现浇板力学性能相近; 抗剪键个数越多,叠合板的极限承载力与现浇板越接近,其破坏特征也与现浇板基本相同; 不同结构形式的抗剪键均能保证预制底板与现浇层间的有效连接; 预制底板与现浇层的接触面间采用绑定接触时有限元模拟结果与试验结果更加接近; 考虑到结构设计的可靠性,在有限元模拟过程中,当叠合板的预制底板与现浇层间设置为摩擦接触时,改变抗剪键沿横向个数、抗剪键沿纵向个数和抗剪键截面面积,叠合板的屈服荷载和屈服位移均发生变化,但当三者增加到一定程度时,变化趋势不再明显; 改变现浇层混凝土强度等级、抗剪键混凝土强度等级和接触面摩擦因数,叠合板的屈服荷载和屈服位移基本未发生变化; 建立了带抗剪键叠合板的抗弯承载力和屈服位移简化计算式。     

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。     

岩盐储库建腔期难溶夹层的软化规律研究

 为揭示盐岩水溶造腔过程中难溶夹层力学特性与卤水浸泡时间的关系,更好地了解夹层的软化规律和范围,为预测和控制夹层的破坏垮塌提供理论支持,以云应盐矿中的泥质硬石膏夹层为研究对象,进行不同浸泡时间下的单轴压缩和巴西劈裂软化试验研究,发现其力学强度随卤水浸泡时间劣化明显,其中,单轴抗压强度、弹性模量、泊松比与卤水浸泡时间呈显著的DoseResp函数关系,抗拉强度与浸泡时间呈显著的Slogistic1函数关系,且试件的单轴压缩及巴西劈裂试验的破坏形式随浸泡时间的增加有从张拉破坏向剪切破坏的渐变趋势。通过分析试验结果发现,卤水对夹层力学强度的软化作用与夹层可溶物含量、夹层成分遇水膨胀的不均性、卤水的润滑作用和矿物晶键的软化作用均存在密切相关。推导了基于浸泡时间的夹层损伤演化方程,建立夹层轴向和径向的软化深度模型,并将其应用于水溶造腔过程中难溶夹层软化范围的划定。此外,基于夹层抗拉强度与卤水浸泡时间的关系,给出判定和预测夹层局部软化破坏的最大拉应力强度准则。     

天然裂隙性流纹岩三轴力学特性试验研究

 作为隧道裂隙性围岩开挖扰动滞后性破坏特性研究的基础,对含天然微裂隙的流纹岩进行三轴加卸围压试验和单轴预加载后再进行常规三轴压缩试验,在得到2种应力路径和不同裂隙发育流纹岩试样破裂特征和应力–应变曲线基础上,对流纹岩三轴试验下的破裂特征和力学参数进行分析,分析结果表明：(1) 天然裂隙性流纹岩表现出强烈的脆性特征,没有明显的屈服阶段;(2) 2种应力路径下,裂隙初始发育特征及优势方向对流纹岩力学性能影响表现为：初始优势发育方向近垂直于最大主应力方向的裂隙不易扩展贯通,试样的力学性能较好;(3) 初始优势发育方向与最大主应力方向夹角较小,并且初始连通或相互交叉搭接呈树枝状的裂隙极易贯通形成宏观拉裂面,显著削弱试样的力学性能;(4) 常规三轴压缩作用下,裂隙初始优势角为46°时,流纹岩的力学性能最差;(5) 单轴预加载使试样内部横向微裂隙闭合,再进行常规三轴压缩时,其强度、弹性模量和变形模量都增大,泊松比基本不变,而脆性特征更加明显。     

不同应力路径下结构性土的力学特性

天然土在受荷过程中会经历不同的应力路径，开展结构性土在不同的应力路径下的力学特性的试验研究可以为建立复杂应力路径下的合理结构性本构模型提供试验依据。对结构性土样在不同应力路径下的力学特性进行试验研究。所用土样是人工室内制备的结构性土试样，共进行不同的固结应力状态下常围压、减小围压和增大围压时施加竖向应力直至土样破坏的固结排水和固结不排水三轴试验，对结构性土样在不同的应力路径下的强度特性、破坏特性和变形特性进行探讨和分析。     

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