Glass Failure Prediction Model Research Articles

Effects of Fixed Edge Conditions on the Load Resistance of Single Glass Lites

The load resistance (LR) of glass lites is determined in the United States by use of standards based on a probabilistic model of glass breakage. These standards generally restrict design to rectangular glass lites continuously supported along one, two, three, or four sides. In addition, these standards treat single glass lites as simply supported flat rectangular plates. Historically, rigid window frames supported single glass lites holding them in place with neoprene or similar gasket material. This attachment method approximated simply supported edges that rotate about an axis parallel to the simply supported edges, deform in the plane of the glass lite, and do not deflect out-of-plane. Advances in structural silicone make it possible to produce rectangular single flat glass lites with edge fixity somewhere between that of simply supported edges and fully fixed edges. The authors applied the glass failure prediction model (GFPM) to a nonlinear finite-element model developed previously by the authors to determine the probability of breakage for selected single glass lite geometries with fully fixed edges under uniform lateral loads. The paper presents comparisons between results of analyses of lites with fixed edges with analyses of lites with simply supported edges. The comparisons indicate that not all single glass lite geometries benefit from fully fixing edges, but the benefits of doing so appear to increase as lite aspect ratio (AR) increases. The comparisons bracket benefits that can accrue from the partial fixity provided by structural silicone supports. The actual degree of fixity provided by structural silicone can only be determined experimentally, which lies outside the scope of this paper.

Coupled glass and structure response of conventional curtain walls subjected to blast loads: validation tests and analysis

This paper presents comparisons of analysis predictions and shock tube test results from a recent dynamic test program involving a conventional Enclos curtain wall system designed solely for wind and gravity loads. Measured blast wave induced glazing response and mullion deflections are compared to response predictions made using fast running nonlinear finite element analysis (FEA) techniques incorporating LS-DYNA based finite element analysis of structural mullions and FEA implementation of statistical glass fracture prediction techniques. The design-level nonlinear finite element analysis was performed using WhAM [window (hazard) analysis module], a fast-running, web-based design tool for blast-loaded curtain wall systems. WhAM was developed by Protection Engineering Consultants (PEC) with support from the Enclos Advanced Technology Studio. Post-test comparisons between measured and predicted system and component-level response were carried out to (a) evaluate the accuracy of WhAM, and (b) illustrate how the precision test data can be used to enhance certain features of the WhAM software such as its glass material model (an LS-DYNA user-defined constitutive model with probabilistic failure criterion based on the ASTM E1300 glass failure prediction model and dynamic test data) and simplified modeling techniques for connection details. Note that SI units are used throughout the text of this paper. American/imperial units are also provided in tables when raw data was originally recorded in those units. Data plots resulting from raw data are also presented in American/imperial units.

Method to Determine the Probability of Failure for Annealed Monolithic Window Glass Loaded with a Uniform Wind Load

AbstractASTM E1300-09 uses a glass failure prediction model (GFPM) to quantify the probability that a critical surface flaw with a certain location and orientation will initiate a facture in the glass for a given lite geometry and uniform design load. The nonfactored load charts in ASTM E1300-09 are calibrated to a GFPM probability of breakage of 8/1,000 (0.008) at the first occurrence of the design load. The GFPM probability of breakage only addresses the material properties of the annealed monolithic window glass and does not incorporate the probability of the occurrence of the design load. Because window glass is typically designed to resist wind loads, the probability of the occurrence of the design load was based on ASCE 7-05. Using a Monte Carlo simulation to evaluate the limit-state equation, this paper presents a procedure to quantify the probability of failure incorporating the probability of the wind load and the probability of the window glass load resistance from the GFPM for window glass lite...

Examination of Load Resistance in Window Glass Design

The glass failure prediction model has been used as a calculation method for the load resistance (LR) of glass specified in North American design codes. However, because of the technology available, this model has only been experimentally proven under ramp loading. The model also has several defects, which have been pointed out in recent years, some of which may originate from this insufficient experimental validation. Thanks to the newly developed technology at the University of Western Ontario, glass strength modeling was revisited with sufficient experimental results, including fluctuating wind loads of long time duration. In addition, the value of LR specified in the current North American design codes was examined in light of several assumed parameters used in its calculation.

Effects of spatial variability of glass strength in ring-on-ring tests

The strength of window glass is sometimes assessed using ring-on-ring tests that are conducted by placing a glass plate on a circular support ring and then applying loads through a smaller concentric loading ring. Ring-on-ring test results clearly demonstrate that the spatial variability of glass strengths has a very significant effect on the effective strength of a glass plate. The article shows how the effects of the spatial variability of glass strength in ring-on-ring tests can be modelled using a probabilistic glass failure prediction model (based on a Weibull model of glass strengths). In particular, it is shown that the model can be used to predict the proportions of failures that occur inside and outside the loading ring, and to predict the influence that spatial variability has on the test strength statistics. It is shown that the probability distributions of test strengths are identical for failures originating inside or outside the loading ring (or combined), even if the local strength distributions inside and outside the loading ring are not the same, provided the Weibull shape parameter is constant. If the local strength distributions inside and outside the loading ring are not the same, the only indication is given by the proportions of failures inside and outside the ring. The theoretical results are shown to agree with some ring-on-ring test results for 4 mm annealed glass. Also, some apparently anomalous test results for 6 mm annealed glass are presented, and a possible explanation is given, consistent with the theoretical model.

Basis for ASTM E 1300 Annealed Glass Thickness Selection Charts

In the early 1980s, a glass failure prediction model (GFPM) was introduced to resolve differences in U.S. industry procedures used to determine the minimum thickness of glass required to resist a specified uniform lateral pressure. The differences in these industry procedures continue to cause problems for designers who are forced to choose between two different glass thickness selection methods that result in different specified thicknesses of glass for the same loading. Since its introduction, the GFPM has helped resolve industry conflicts as it has gained increasing acceptance. In the late 1980s, the GFPM was used to develop glass thickness selection information that is incorporated in ASTM E 1300-94. The purpose of this paper is to provide documentation for the ASTM E 1300-94 glass thickness selection procedure and to propose improvements. The proposed improvements include modifications to the optional procedure for calculating the probability of failure of a rectangular glass plate, and the presentat...

Development of a new glass thickness selection procedure

There are currently significant differences in glass strength information presented by major United States glass manufacturers. These differences have caused considerable confusion among glass designers. Several years ago a glass failure prediction model was developed in an effort to provide a mechanism for restoring continuity to the glass design process. This failure prediction model allows the probability of failure of window glass to be specified in terms of surface flaw parameters and the stresses induced by lateral loads. For the past several years, a task group within ASTM has focused on developing a new set of glass design charts based on the glass failure prediction model. The result of this effort is a “Practice to Determine the Minimum Thickness of Annealed Glass Required to Resist a Specified Load.” The proposed practice presents a method for relating the probability of failure of a rectangular annealed glass plate subjected to a 60 second duration design load. This new ASTM practice is currently in the ASTM ballot process.

Discussion of “ Glass Failure Prediction Model ” by W. Lynn Beason and James R. Morgan (February, 1984)

Discussion of “ <i>Glass Failure Prediction Model</i> ” by W. Lynn Beason and James R. Morgan (February, 1984)

Discussion of “ Glass Failure Prediction Model ” by W. Lynn Beason and James R. Morgan (February, 1984)

Discussion of “ <i>Glass Failure Prediction Model</i> ” by W. Lynn Beason and James R. Morgan (February, 1984)

Glass Failure Prediction Model

There are significant differences in glass strength information presented by major United States glass manufacturers. These differences have caused considerable confusion among glass designers. The differences are the result of different simplifying assumptions in formulation of the respective glass design procedures. Presented in this paper is a glass failure prediction model which relates the probability of failure of glass to surface flaw characteristics and induced stresses. This is accomplished by combining a statistical failure theory for brittle materials with results of a geometrically nonlinear plate analysis. The model is formulated to include all factors which are known to significantly affect the strength of glass, such as load duration, surface area, etc. As such the model provides a basis for resolving current conflicts in the glass design process.