首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 218 毫秒
1.
Experiments were performed as part of a larger study to develop the “sacrificial ply” design concept for laminated architectural glass. This concept allows windborne debris impacts in severe windstorm environments to break the outer laminated architectural glass ply while the inner ply is preserved in order to carry the design wind pressure. Steel ball size and inner/outer glass ply type (level of thermal tempering) were varied to determine their effects on the impact resistance of the inner glass ply of laminated architectural glass when impacted on the outer glass ply. A mean minimum breakage velocity (MMBV) was determined for each variation in steel ball size and glass temper level, which defines the mean debris impact velocity on the outer glass ply that causes breakage in the inner glass ply. A 46% reduction in MMBV was observed for an increase in steel ball size from 2 g (7.9 mm diameter) to 8.4 g (12.7 mm diameter), and a 65% reduction in MMBV was observed for an increase in steel ball size from 2 g (7.9 mm diameter) to 28.2 g (19.1 mm diameter). Laminated architectural glass constructed with heat-strengthened or fully tempered inner glass plies, regardless of outer-glass-ply type, was found to have a significantly higher MMBV than laminated architectural glass constructed with annealed glass plies. In contrast, changing the outer glass ply from annealed to fully tempered glass was found to reduce the MMBV, regardless of the inner glass ply type. Relating these results to those in a previous impact study by Kaiser et al. suggests that the order of importance for design variables that most influence the inner glass ply impact resistance of sacrificial ply laminated architectural glass is the following, starting with the most important: (1) inner glass ply type; (2) inner glass ply thickness; (3) polyvinyl butyral (PVB) interlayer thickness; and (4) outer glass ply thickness.  相似文献   

2.
Experimental results of low velocity, small steel ball impact tests on laminated architectural glass units are presented. These tests are part of an ongoing effort to develop a design method for laminated architectural glass units to resist windborne debris from sources such as roof gravel, as required in several current and proposed U.S. building codes and standards. A design concept known as “sacrificial ply” permits the exterior-facing, outer glass ply of a laminated glass unit to fracture during windborne debris impacts, but prevents fracture of the inner glass ply. This concept also depends on an inner glass ply designed to resist lateral wind pressures for the remainder of the windstorm so that the integrity of the building envelope is preserved. In these experiments, inner and outer glass ply thicknesses and polyvinyl butyral interlayer thickness were varied to determine their effects on the impact resistance of the inner glass ply of laminated architectural glass when impacted on the outer glass ply. Results show that inner glass ply thickness and PVB interlayer thickness have stronger effects on the impact resistance of the inner glass ply than does outer glass ply thickness.  相似文献   

3.
Despite the increased use of laminated glass (two monolithic layers of glass joined with an elastomeric interlayer—usually PVB—to form a unit) as a cladding material for architectural glazing applications and by now as a structural material, the mechanical properties and the structural capabilities of PVB laminated glass are not well known. This paper presents an analytical model that predicts stress development and ultimate strength of laminated glass beams involving a multilayered system that allows displacements in the shear flexible interlayer. The model may be applied to laminates of arbitrary shape and size under prevailing uniaxial bending. No specific simplifying assumption is made in formulating the procedure, so the modeling inaccuracy is marginal, as proved by comparing theoretical model predictions with test results. The model was then used for assessing the safety and predicting the failure strength of laminated glass products available in the architectural glass marketplace, in order to identify the basis for rational design with glass-polymer laminates. The closed form of the model permits us to both explain the behavior of laminated glass, and correlate the structural performance with the geometrical and mechanical parameters.  相似文献   

4.
A theoretical model to predict the response of laminated cement-based composites is developed. The micromechanical model simulates the mechanical response of a multilayer cement-based composite laminate under uniaxial, biaxial, and flexural loading modes. Tsai-Wu Criterion is used for each lamina and the stacking sequence is utilized to obtain the overall stiffness matrix. The effect of distributed cracking on the stiffness degradation of the cross ply layers under tensile loading is measured using a scalar damage parameter that is empirically related to the apparent strain. The model is calibrated by predicting the load versus deformation response of unidirectional, cross ply, and angle ply laminates under tensile and flexural loading. Results are then compared to the experimental results cross ply and angle composites with various stacking sequences.  相似文献   

5.
In-plane dynamic racking crescendo tests were performed on full-scale curtain wall mock-ups dry glazed with six different insulating glass unit (IGU) configurations and one laminated glass unit configuration. The tests were conducted to determine the serviceability and ultimate limit state behaviors of these configurations tested under simulated earthquake-induced lateral drifts. All IGU configurations tested were manufactured with an annealed monolithic pane and a laminated pane with an argon fill and an anodized aluminum spacer between the panes. Several parameters were varied in the laminated pane of each configuration including glass lite thickness and glass type in the laminated pane (annealed, heat strengthened, and fully tempered), and PVB interlayer thickness for the laminated pane. Properties of the annealed inside pane were not varied. For each configuration, average drift values for the occurrence of glass cracking in each IGU pane, glass fallout from the monolithic pane, and pullout and fallout of the entire glass unit are reported. Relevant damage to the aluminum framing is also reported. Results of these tests can be used to assess the seismic resistance of similarly glazed architectural glass panels in practice and to improve the design of asymmetric IGU configurations for use in seismic regions.  相似文献   

6.
The structural characterization of hybrid fiber-reinforced polymer (FRP)–glued laminated (glulam) panels for bridge deck construction is examined using a combined analytical and experimental approach. The structural system is based on the concept of sandwich construction with strong and stiff FRP composite skins bonded to an inner glulam panel. The FRP composite material was made of E-glass reinforcing fabrics embedded in a vinyl ester resin matrix. The glulam panels were fabricated with bonded eastern hemlock vertical laminations. The FRP reinforcement was applied on the top and bottom faces of the glulam panel by wet layup and compacted using vacuum bagging. An experimental protocol based on a two-span continuous bending test configuration is proposed to characterize the stiffness, ductility, and strength response of FRP-glulam panels under simulated loads. Half-scale FRP-glulam panel prototypes with two different fiber orientations, unidirectional (0°) and angle-ply (±45°), were studied and the structural response correlated with control glulam panels. A simple beam linear model based on laminate analysis and first-order shear deformation theory was proposed to compute stiffness properties and to predict service load deflections. In addition, a beam nonlinear model based on layered moment-curvature numerical analysis was proposed to predict ultimate load and deflections. Correlations between experimental results and the two proposed beam models emphasize the need for complementing both analytical tools to characterize the hybrid panel structural response with a view toward bridge deck design.  相似文献   

7.
The effect of blast loading on civilian structures has received much attention over the past several years. The behavior of architectural glazing is of particular interest owing to the disproportionate amount of damage often associated with the failure of this component in a blast situation. This paper presents the development of a simple yet accurate finite element-based tool for the analysis of architectural glazing subjected to blast loading. This has been achieved through the creation of a user-friendly computer program employing the explicit finite-element method to solve for the displacements and stresses in a pane of glass. Both monolithic and laminated panes have been considered, in single and insulated unit configurations, and employing several types of glass. In all cases, the pane of glass has been modeled as a plate supported by an array of boundary conditions that include spring supports, and two failure criteria are employed. Furthermore, the program is designed to predict the hazard level, given a particular glazing configuration and blast load.  相似文献   

8.
Currently, the ASTM design methodology to determine the load resistance of annealed window glass incorporates a probability distribution to model glass load resistance. A probability of 8 lites per 1,000 broken at the first occurrence of the design load was selected to match a load resistance consistent with a historical design factor of 2.5. The historical use of a factor relationship leads to the misconception that the design methodology follows an allowable stress procedure. The misconception has led to another common misconception among architects and engineers that a constant maximum principal stress exists, associated with the load resistance for any combination of lite thickness, aspect ratio, and surface area. This paper presents the relationship between the maximum principal stress in glass lites associated with their design loads for a probability of breakage of 8 lites per 1,000. The relationship clearly shows that the maximum principal stress is not constant for a single lite thickness for varying rectangular dimensions much less for all lite geometry combinations. A series of charts illustrates the trends in magnitude and location of the maximum principal stress as a function of lite thickness, aspect ratio, and surface area.  相似文献   

9.
The problem of pollution within Earth’s orbital environment has gained considerable recognition over the past decades. Determining adequate passive protection schemes is an unending process that attempts to meet different objectives for widely varying types of missions. Significant amounts of resources have been expended toward development of numerical and analytical models that model the response of a variety of target systems under high-speed orbital debris impacts. The objective of the study whose results are presented herein was to improve upon an existing oblique hypervelocity impact model that characterizes the various secondary debris clouds created in such an impact. This was accomplished by reducing the model’s dependence on empirical user-defined parameters and by correcting an error in one of its equations. Predictions of the improved model are compared with numerical simulations generated during previous impact studies under comparable conditions. It is found that the improved model does a reasonable job of predicting the characteristics of the secondary debris clouds created in an oblique hypervelocity impact.  相似文献   

10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号