Structural Glass Research Papers - Academia.edu (original) (raw)

In modern buildings, the use of glass as a load-bearing material is increasing compared to the traditional materials for some reasons such as the thermal, light, energy and aesthetic performance of glass. Extreme dynamic loads can have catastrophic effects on glass buildings. Therefore, much attention should be devoted to the response of glass structures against severe loads. The main goal of this project is performance assessment of different laminated glass panels under various extreme loads such as earthquake, fire, blast, etc. Some parameters including ductility and energy dissipation of LG panels, different thicknesses and dimensions in the two phases of pre-crack and post-crack are investigated accurately.

- by
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- Structural Glass, Structural Glass Facades, Laminated Glass, Extreme Loads
- by paolo spinelli
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- Design, Structural Glass

This study aims to investigate the adhesion phenomena between glass and composite materials, which-if they work in synergy-can increase the performance of glass structures, as regard both structural elements and the manufacture of joints. The experimental programme consisted of shear traction tests on all samples: glass-glass singlelap shear adhesion, glass-GFRP double-lap shear adhesion and glass-SRP shear adhesion. Different types of adhesive and various interface geometries were also tested to evaluate the ultimate force and identify fracture patterns with different bonding lengths. It was possible to identify the effective bonding length for each type of resin used to prepare test samples, by taking fracture load and average peel stress into account. Bonding length variations were also recorded. This enabled the values of bonding length to be verified analytically. Based on experimental results, a formula for the evaluation of delamination resistance and the optimal bonding length is proposed.

- by Zeal Press
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- Adhesion, Structural Glass, GFRP (Glass Fibre Reinforced Plastic)

Nickel Sulfide (NiS) inclusions can provoke the rupture of thermally treated glass due to a phase transformation with volume increase that stresses the surrounding glass. Starting from a Pareto statistics for the population of inclusion sizes, from an assumed kinetics of the phase transformation, a micro-mechanically motivated model provides the statistical characterization of the probability of spontaneous failure of glass during lifetime. A distinction based upon the composition of NiS is used to discuss the effects of the heat soak test (HST), where glass remains at high temperature for a certain time to speed-up the phase transformation and destroy those elements with critical inclusions. Three functions à la Weibull for the probability of spontaneous rupture during lifetime are theoretically derived for the case of no HST, short HST, and long HST. In particular, the probability of collapse for long HSTs depends upon the holding time in the oven. An explanatory example shows the potentiality of the model for optimizing the HST parameters toward a target probability of failure, but experimental campaigns are needed for a proper calibration.

- by Gabriele Pisano
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- Statistical Mechanics, Failure Analysis, Spontaneous Collapse, Structural Glass

An example is given for the calculation of glazing curtain wall with insulated glass units under wind action. Limit states for breakage and deflection is performed for double glazing panels according to the Standard prEN 16612. Limit... more

In this fifth edition, all chapters have been rewritten, some chapters in previous versions of the handbook have been removed due to recent developments in design or construction practices, and 12 new chapters have been added. The new chapters cover structural loads, fracture mechanics of concrete and composites, railroad bridges, health monitoring of structures, building information modeling (BIM), structural fire engineering, progressive collapse and blast-resistant design, strengthening of concrete using fiber-reinforced polymer (FRP), structural glass, design of foundations for machines, value engineering, and stone cladding.
The 33 chapters of the handbook have been written by 66 contributors. They have presented their material in a ready-to-use form with flowcharts to show step-by-step procedures wherever possible. Therefore, derivations of formulas are omitted in all but a few instances, and many worked-out examples are given. Background information, descriptive matter, and explanatory material have been condensed or omitted. Because each chapter treats a subject that is broad enough to fill a book by itself, the contributors have had to select the material that, in their judgment, is likely to be the most useful to the greatest number of users. References and sources of additional material are noted for most of the topics that could not be treated in sufficient detail.
The constant search to maximize the transparency of the façades resulted in larger glass windows forcing concrete and steel load-bearing systems to become smaller over time.
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When subjected to tensile stress, glass break with any plastic flow because it is a brittle material. The break occurs at a stress level much lower than the theoretical value calculated from the strength of the atomic bonds. The glass is unique since its fracture occurs in entirely different ways from other materials. Glass failure generally starts at a specific surface flaw which is as a stress multiplier in a region of high tensile stress.
Failure prediction methods based on allowable areas for each thickness of glass as a function of uniform duration pressure have been replaced by modern methods that have the advantage of providing a consistent framework for all previous testing as also explains most of the phenomena associated with laterally loaded thin glass plates ...

The characteristic value of the strength of annealed float glass, to be used in structural calculations, is assessed by standards on the basis of a classical experimental campaign using the Coaxial Double Ring (CDR) test with additional overpressure. Experimental data were regressed according to the 2-parameter Weibull distribution, assuming that the induced state of stress is equibiaxial in practice. We show that, by splitting the data in two categories according to the surface under tensile stress (either the ''tin" or the ''air" side), a more accurate statistical interpretation can be obtained. Comparisons with the normal and log-normal distributions are made with the chi-square goodness-of-fit test. Moreover, we observe that the calibration curve suggested by the test standard is not precise, and that the stress state in the testing configuration is not equibiaxial. Therefore the rough data need to be further corrected and re-scaled to a common reference condition, according to a criterion of equal failure probability, by determining the effective area of the loaded specimen. Doing so, the considered statical distribution are able to fit to the data with much more accuracy. Considering that for very low failure-probabilities the tails of the statistics are the most important, and observing that the 2-parameters Weibull function fails to interpret a lower bound for the strength of glass that can be inferred from experiments, the use of a 3-parameter Weibull distribution is proposed. After having derived the corresponding expressions for the effective area, we present a new statistical characterization of glass strength that provides the best fit with the experimental data, at least for the air-side.

When the visual presence of materials decreases, the maximal transparency creates astounding beauty. In order to enhance transparency, clearer and lighter structures should be used. Although glass is extremely noteworthy as a transparent load bearing material, the structural use of glass is still unfamiliar to architects. Since the advancement in architecture requires knowledge about the path of developments, this study was conducted in order to discern the potential of improvement in glass structures as a result of scientific and technological advances. Through analysis of existing challenges and opportunities, this study aims to investigate the possibility of constructing completely transparent buildings in the near future. The findings indicate that improvements in the field of materials, selection of appropriate forms, the advent of innovative techniques, plus fine-tuning the existing technologies can improve structural efficiency, safety, durability, and transparency of glass buildings, so that the imagination of modern architecture can be realized.

The performance of laminated glass, which consists of two or more glass plies bonded together by polymeric
interlayers, depends upon shear coupling between the plies through the polymer. This is commonly
considered by defining the effective thickness, i.e., the thickness of a monolithic beam with
equivalent bending properties in terms of stress and deflection. General expressions have been proposed
on the basis of simplified models by Newmark and Wölfel–Bennison, but they are either difficult to apply
or inaccurate. Here, a variational approach to the problem is presented. By choosing appropriate shape
functions for the laminated-beam deformation, minimization of the strain energy functional gives new
expressions for the effective thickness under any constraint- and load-conditions, embracing the classical
formulations as particular cases. Comparisons with numerical experiments confirm the better accuracy of
the proposed approach with respect to the previous ones.

In contemporary buildings, the architectural demand for a complete dematerialisation of load bearing structures can be satisfied only in limited cases with the exclusive structural use of glass. Otherwise, for challenging applications such as long spanned or high-rise structures, the use of hybrid glass-steel systems is mandatory. Glass, fragile but highly compressive resistant, is associated with steel, ductile and tensile resistant. The present research shows the feasibility study for a fully glazed pavilion made of six TVT (Travi Vitree Tensegrity) portal frames longitudinally braced by pre-stressed hybrid glass panels. The frames are about 20 m in span and 8 m in height. Appropriate multiscalar FEM numerical analyses, calibrated on the collapse tests performed on previous TVT large-scale prototypes, stated that the structural performance would be able to withstand heavy static and dynamic loads and stated the observance of the Fail-Safe Design principles.

- by Francesco Laccone and +1
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- Tensegrity Structures, Glass, Structural Glass, Bracing systems

Glass plies can be bonded together by polymeric interlayers to form laminated glass. Thanks to the capacity in finding alternative stress paths after partial breakage, it is commonly accepted that the more the layers are, the higher the safety level is. However, a negative aspect is that the tensile strength of glass carries a size effect in terms of surface area, which increases with lamination. Here we evaluate these competing factors by calibrating the partial safety factors to be used in semi‐probabilistic (level‐I) design, through comparison with probabilistic (level‐III) methods in paradigmatic case‐studies under wind, snow, and dead weight. Starting from a two‐parameter Weibull distribution for glass strength, the “failure modes” approach determines the statistical distribution of strength for a multi‐laminate as a function of the number of plies, which interferes with the statistics for actions. As a function of the target probability of failure for the assigned class of consequence, we introduce a new coefficient in the verification formula of level‐I, to account for the effects of lamination with dependence upon the number of plies. We find that there is strong gain when passing from a monolith to a two‐ply laminate, but the advantage fades by increasing the number of layers. Verification formulas of this type could avoid overconservative design.

No presente documento apresentam-se os principais aspectos relacionados com o dimensionamento da espessura de painéis de vidro simples ou duplo -- envidraçados -- em fachadas e ou coberturas, tendo presente a norma ASTM E1300.
São apresentados os procedimentos necessários da adaptação desta norma à regulamentação europeia.
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In this paper we present the main aspects related to the design of single or insulating glass panels - glazing - for facades and roofs according the ASTM E1300 standard.
The necessary procedures adaptation of this standard to European norms are presented.

Abstract - Nothing‖ as a building! Is it structurally possible?
"Less is more!" When visual presence of materials decreases, maximal transparency and lightness creates astounding beauty. However, the less we use to design with, the more knowledge and experience we need. Undoubtedly, the black holes in knowledge and experience can be found and filled only through research. In order to enhance transparency and lightness, not only cladding but also structures should be clear and light. Glass, in this regard, is an extremely noteworthy material due to its very high compressive strength, durability, resistance to weathering, corrosion and high temperature. Its high transparency also offers energy savings solutions; the widespread use of glass allows natural lighting to be used, insulated glass units provides excellent thermal insulation, and the use of photovoltaic glass in building facades produces energy. All these aspects, which play a central role in the aim of environmental sustainability, make the glass a notable material in contemporary architecture. Although the structural use of glass has increased in recent decade; but, glass as a load bearing material is still not well known for designers because of its brittle behavior and limited tensile capacity. Presenting experience from researchers’ laboratory studies and advanced glass structures built all over the world, this paper aims to highlight structural glass design innovations and methods of solving challenges in order to optimize the glass constructions and determine may glass close the gap between modern architecture’s imagination and realization of nothing as a building"?

The use of glass as a structural element is a new subject that needs to be studied. ‘Glass’ has been a key word in the building industry with its unique feature of transparency throughout history. With the opportunities offered by the technological developments that have taken place over time, the structural glass has become an attractive material for engineers and architects. In this study; structural glass is examined according to physical, chemical and mechanical properties; application techniques; the issues to be considered when designing. The most striking examples that have been applied up to now from the first use of glass as a structural material is presented in the tables. Despite the fact that the examples related to the subject are new, it still continues to develop in the field of construction and its examples are increasing day by day. This study will be a guide to architects and engineers to develop the design methods and to disseminate the practice of glass as a structural element.

- by Burcu Buram Çolak
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- Materials Science, Glass Structure, Structural Glass

In the past few decades, the use of glass in buildings has remarkably increased. As a result, several transparent buildings have been constructed, in which the materials have almost disappeared. Given that the advancement of architecture is inextricably linked to the acquisition of general knowledge on future developments, this study was conducted to predict the paths of development that glass structures are likely to take in the future. Investigations such as this increase the possibility of advancing both design and construction at the same speed as technology. To achieve this goal, this study evaluates the present situation by investigating new possibilities and assessing their effect on the development of glass buildings. The findings of this study show that the durability, safety, appearance, and efficiency of transparent buildings can be improved through continuous refinement of designs, replacement of aged elements, prompt repair of damaged protective coatings, and greater exploitation of double-sided screens.

- by Fatemeh Pariafsai
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- Self-healing, Glass Structure, Adhesive, Plates and shells

In the last decades, the use of glass in construction has been increased unbelievably as if material has been vanished from transparent buildings. Since the advancement in architecture requires knowledge about the path of future developments, this study was conducted in order to discern the potential of improvements to glass structures as a result of scientific and technological advances. In this way, it increases the chance to move forward in both fields of design and construction at the same speed as technology does. In order to achieve this aim, the study investigated the potential for removing the problems with design and construction of transparent buildings. By this method, it indicated that new possibilities for design optimization and reduction in both probability and risk of damage make it possible to build more beautiful, safer, and more durable glass structures.

- by Gianni Royer Carfagni
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- Civil Engineering, Statistical Mechanics, Structural Design, Building

The potential presence of Nickel Sulfide (NiS), which contaminates glass melt, can provoke "spontaneous" rupture even after years from installation. This is why most standards recommend that glass panels bearing a safety risk are subjected to the Heat Soak Test (HST): they are exposed to a certain temperature for a certain time so to destroy the glass panes affected by critical NiS inclusions before installation. A micro-mechanically motivated model for assessing the risk of spontaneous failure of thermally-treated glass is here proposed. This correlates the statistical expectation of finding a critical NiS inclusion with the breakage consequent to its volumetric expansion due to phase transformation. Three functions à la Weibull for the probability of spontaneous rupture during lifetime are derived for the case of no HST, short HST and long HST. This analysis may contribute to solve the long-standing problem of defining the risk of spontaneous breakage in glass due to NiS inclusions, by assessing the optimal holding time of the HST as a function of the risk reputed acceptable for the particular application of glass. A parametric analysis shows the potentiality of the proposed approach.

- by Gabriele Pisano
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- Statistical Mechanics, Heat Treatment, Failure Analysis, Thermal Stresses

Laminated structures are parallel (or redundant) systems, i.e. failure occurs when all the elements (glass plies) reach, in cascade, the ultimate limit state. Following the failure mode approach, the reliability analysis is consequent to the identification of all possible rupture modes of the glass plies, where each mode is identified by the sequence of collapse, synthetically schematized as an event-tree. The event "structural fail-ure" is the union of all the possible failure modes. The static theorem of limit analysis guarantees that the more the structure is divided into load bearing elements acting in parallel, the safer it is, but this conclusion holds only for ideal ductile systems. For brittle glass it is often assumed that lamination gives a beneficial contribution in all cases, but glass strength is affected by a size effect in terms of area, because surface micro-cracks govern the overall capacity of the material. Taking this into account, we show through the failure mode approach, under some simplifying assumptions, that lamination can decrease the strength of a plate made of annealed glass, since the higher the number of plies is, the larger is the surface area under tensile stress. This finding focalizes the attention on the importance of an accurate characterization of the size effect in glass strength.

- by Gabriele Pisano
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- Statistical Mechanics, Redundancy, Strength of materials, Structural Glass

Partial material factors need to be calibrated to guarantee the target failure probability of glass structures according to the semi-probabilistic (level I) methods of design. Calibration is made by comparison with results obtainable with the full probabilistic approach (level III) on paradigmatic case studies. Considering the results of previous work that assessed the validity of various statistical models of glass strength, we use a generalized distribution of the Weibull type to derive new partial factors that account for a lower bound for glass strength or not. The partial factors so calculated are much lower than those previously obtained from the classical two-parameter Weibull distribution, and are in agreement with the coefficients commonly used in practice. Moreover, the variation of the partial factors with respect to changes in failure probability is similar to what is applied to other ù building materials.

- by Gabriele Pisano
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- Statistical Mechanics, Structural Design, Strength of materials, Structural Glass

Because the strength of glass is governed by randomly distributed surface flaws that can propagate catastrophically when the applied stress reaches a critical value, the weakest-link-in-the-chain rationale is the universally accepted interpretation of its significant variability. The two-parameter Weibull extreme value distribution is currently the most commonly used model for structural design, although it is recognized that it fails to capture the experimental data within the region of small failure probabilities, associated with the lowest strengths. However, the precise characterization of this left-hand-side tail of the distribution is crucial for structural applications, for which only very low probabilities of failure are accepted. Experiments have provided evidence of the existence of a lower bound for the strength of glass, a finding that, if proved, could revolutionize the approach to the safety of glass structures. Referring to the large-scale experimental program of the Technical Committee 129-Working Group 8 of the European Committee for Standardization (CEN/TC129/WG8), various generalized statistical distributions like Weibull, either prescribing a strength limit or not, are compared in their ability to interpolate the experimental data using the chi-square goodness-of-fit test. Arguments are presented that support the existence of a minimal strength, which can be reduced, but not annihilated, by the inevitable degradation of the glass surface produced by aging and in-service-related damage.

- by Gabriele Pisano
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- Strength of materials, Structural Glass, Weibull distribution

Structural glass beams and fins are largely used in buildings, in the form of primary load-bearing members and bracing systems for roof or facade panels. Several loading and boundary conditions can be efficiently solved by means of bonded composites that involve the use of laminated glass sections. Additionally, the so-obtained glass members are often characterized by high slenderness. To this aim, several literature studies were dedicated to the lateral-torsional buckling (LTB) behavior of laterally unrestrained (LU) glass elements, with the support of full-scale experiments, analytical models, or finite element (FE) numerical investigations. Standardized design recommendations for LU glass members in LTB are available for designers. However, several design issues still require "ad hoc" (and often expensive) calculation studies. In most of the cases, for example, the mechanical interaction between the structural components to verify involves various typologies of joints, including continuous sealant connections, mechanical point fixings, or hybrid solutions. As a result, an accurate estimation of the theoretical LTB critical moment for such a kind of laterally restrained (LR) element represents a first key issue toward the definition and calibration of generalized design recommendations. Careful consideration should be spent for the description of the intrinsic features of materials in use, as well as for a combination of geometrical and mechanical aspects (i.e., geometry, number, position of restraints, etc.). In this paper, the attention is focused on the calculation of the elastic critical buckling moment of LR glass beams in LTB. Existing analytical approaches of the literature (mostly developed for steel constructional members) are briefly recalled. An additional advantage for extended parametric calculations is then taken from finite element (FE) numerical analyses, which are performed via the LTBeam or the ABAQUS software codes. The actual role and the effect of discrete mechanical restraints are, thus, explored for selected configurations of practical interest. Finally, the reliability of simplified calculation approaches is assessed.

- by Dario Santo
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- Glass, Structural Glass, LTB

It is customary to assume that the characteristic design value for heat-treated glass is represented by the sum of the characteristic values of the annealed glass strength and of the heat-induced surface prestress, even though experiments have provided evidence that the resulting strength may be much higher. Here, we investigate the statistical interference between an assumed two-parameter Weibull distribution for the annealed glass strength and a Gaussian distribution for the surface pre-stress. We show how the compound distribution confirms the experimental findings and, in particular, that the type of stress induced by the applied loads, i.e., uniaxial versus biaxial, has an important role. This effect, which is more relevant for "weak" than for "strong" glasses, is the mechanical counterpart of the well-known principle of diversification of investments in economy, and leads to a critical consideration of the design approach commonly suggested by structural standards.

- by Gabriele Pisano
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- Statistical Mechanics, Heat Treatment, Strength of materials, Thermal Stresses

کاهش حداکثری حضور بصری مصالح مستلزم دانش جامعی است که تنها با پژوهش قابل دستیابی است. به منظور افزایش شفافیت نه تنها پوشش ها، بلکه سازه ها نیز باید شفاف ساخته شوند. از این لحاظ شیشه به واسطۀ ویژگی هایی که دارد مادۀ ارزشمندی به شمار می رود. با وجود افزایش استفادۀ سازه ای از شیشه در دهه های اخیر، این متریال به عنوان یک مادۀ سازه ای هنوز برای طراحان کاملا شناخته شده نیست. هدف این مقاله، بررسی تازه های بهره برداری سازه ای از شیشه و راه حل های نوین در طراحی با آن بوده است تا از این طریق نشان دهد چگونه این ماده قادر خواهد بود شعار معماری مدرن – less is more! - را محقق کند.

- by Giampiero Manara
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- Design, Structural Glass

The macroscopic properties of float glass are governed by the opening of surface cracks in mode I. To bypass the influence of crack orientation and defectiveness of the borders (due to the cutting process), in the experimental measurement of the material strength the panacea would be to induce an equibiaxial state of stress in the core of the specimen. The Coaxial Double Ring (CDR) test achieves this ideal condition when geometric non-linearities are of minor importance. To compensate for second-order spurious components, ASTM C1499-09 indicates a CDR configuration with variable geometry according to the specimen thickness, whereas EN 1288-2 proposes the application of an additional overpressure. An analytic theoretical study of the non-linear effects in a CDR test is here presented. Assuming a Weibull statistical distribution of defects, for the CDR configuration with no overpressure, we obtain expressions in closed form for the effective area, a parameter that allows the re-scaling of the experimental data to a reference condition (equibiaxial stress on a unitary area) according to a criterion of equal failure probability. This method is used to propose a new standardized CDR testing method, with fixed geometry and no overpressure. Since the procedure of EN 1288-2 is proved to be ineffective because the induced stress state is not uniform and equibiaxial, a supplementary experimental campaign is reputed necessary, considering that the reference strength of glass in product standards has been determined with this testing method.

- by Gabriele Pisano
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- Plates and shells, Strength of materials, Structural Glass

Partial safety factors for actions and resistances are used in the semi-probabilistic approach (level I method) for structural calculations. The partial factors associated with the surface prestress in heat-strengthened and thermally toughened glass proposed by standards come from practical experience and consolidated practice. Here, we attempt at a calibration by comparison with full-probabilistic (level III) methods in paradigmatic examples under environmental actions (wind and snow). The theoretically-derived factors are in general very low, as a consequence of the statistical interference between the material-strength and surface-prestress. This finding, albeit far from being exhaustive, highlights the great potentialities of heat-treated glass, that appear to be underestimated by current standards.

- by Gabriele Pisano
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- Statistical Mechanics, Heat Treatment, Structural Design, Partial Safety Factors

In structural design the bending strength of heat-treated glass is in general calculated as the simple sum of the characteristic values of the strength of annealed glass and of the thermally-induced pre-stress, considered as the 5% quantiles of the corresponding statistical distributions. However, the probability that two stochastic variables attain small values simultaneously is quite low; therefore, it is expected that the 5% quantile of the heat-treated glass strength is higher than the simple sum of the 5% quantiles of the two constituent distributions. Here, we theoretically confirm this result by assuming a two-parameter Weibull distribution for the population of annealed glass strengths and a Gaussian distribution for the thermal stresses. Although recent studies have confirmed that the two-parameter Weibull distribution cannot properly interpret the left-hand-side-tail of the annealed-glass strength population, it is here shown that the statistical competition with the surface pre-stress lowers the importance of a very precise interpretation of the left-hand-side tail. Remarkably, since glass strength is governed by the opening of surface cracks in mode I, the expected statistical interference is strongly affected by the type of stress state. If the stress state induced by external actions is equibiaxial, all cracks have the same opening stress, but if it is uni-axial, many cracks will remain closed under the sole effect of the prestress, which is in general uniform and equibiaxial. The higher the surface compression is and the closer to the uniaxiality the stress state is, the higher the number of "not-active" cracks will be. We believe that this study will promote and guide the design of ad hoc experimental campaigns for experimental validation .

- by Gabriele Pisano
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- Heat Treatment, Strength of materials, Thermal Stresses, Structural Glass

- by Roberto Ballarini
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- Civil Engineering, Statistical Mechanics, Structural Design, Building