No abstract is provided for this article.
No abstract is provided for this article.
<ns3:p>The article discusses the impact of seal failure in insulating glass unit (IGUs) and the resulting loss of filling gas on deflections as well as the operational safety of glass structures, with particular emphasis on roof glazing and skylights. The main objective was to demonstrate the critical role of the gas in ensuring composite action between the glass panes when transferring external loads. Numerical analyses were performed in the RF-Glass module of the RFEM 5 software for typical insulating glass configurations. The behavior of the glazing unit in a fully sealed state was compared with the situation after seal failure and gas loss, where the external load is borne solely by the outer pane. Additional comparisons of various structural variants (different thicknesses, tempering, lamination of inner and outer panes, as well as single-chamber and double-chamber arrangements) made it possible to assess how modifications to the glazing composition affect stiffness and stress levels. The results highlight that gas loss significantly worsens the working conditions of the outer pane and may lead to exceeding the ultimate limit state of load-bearing capacity. In extreme cases, this can result in sudden failure of the element and pose a risk to user safety. The article emphasizes the need for special care regarding the airtightness of insulating glass units and the rational selection of layer configurations in the design of modern metal-glass structures.</ns3:p>
The article presents the results of research aimed at evaluating the properties of asphalt binders recovered from material obtained during milling of polymer-modified SMA layers. Laboratory tests were carried out on asphalts recovered from RAP, on blends in defined proportions with fresh polymer-modified binders, as well as on binders recovered from SMA mixtures containing reclaimed asphalt. The study’s scope included standard classification tests of polymer-modified binders and an assessment of rheological properties using the MSCR method. An analysis of the results was performed to evaluate the condition of the recovered binders and to select binders for blending with fresh PMB and reclaimed aggregates for the design of SMA mixtures with RAP. The analysis of blends and recovered binders enabled a relative evaluation of binder properties, indicating variants that may potentially require the application of rejuvenators. The presented research constitutes one of the stages of the rSMA2 project focused on the recycling of SMA layers.
This paper proposes two chemical activators that are used to prepare mixtures for pothole repairs based on reclaimed asphalt. Repair mixtures, especially those used as “cold” mixes, must be characterized by special properties because they are primarily used in the winter period, i.e., at low temperatures and high humidity. The proposed additives W1 and W2 affect the functional and rheological properties of asphalts. Therefore, their influence on the behavior of asphalt 35/50 in three states, i.e., non-aged, after technological aging, and after service aging, was examined. At the same time, the issue of determining the optimal mass content of additives in relation to the aged binder was undertaken using the original methodology applying the MSCR test. In the latter part of the paper, the influence of additives W1 and W2 on asphalt recovered from reclaimed asphalt (aged in real conditions) was also analyzed and asphalt mixtures for pothole repairs were made. For these mixtures, the average contact stresses and tensile strength were determined as a function of time and conditioning temperature, giving positive results in terms of practical application of the proposed solution. The obtained mixtures were successfully used to fill potholes in winter weather conditions.
In the paper two classes of poly-convex stored energy functions for transversally isotropic hyper-elastic materials have been proposed. Within these classes, a simplified model of hyper-elastic materials with an isotropic matrix reinforced with fibre family was derived and implemented in finite element software ABAQUS/Standard. The two numerical examples proving correctness of the implementation and showing its positive physical features are presented.
No abstract is provided for this article.
No abstract is provided for this article.
The main goal of introducing the MSCR test was to estimate the rheological properties of pen grade and modified binders using the same measure. The conditions for this test were chosen at random (the length of creep and recovery period, the stress levels, as well as the test temperature). In most applications, the test temperature value was equal to 64 or even 70°Celsius. It is clear that for such high temperature values for softer binders the test interpretation is not always possible or burdened with a significant statistical error. Some time ago authors of this paper proposed a certain very similar test, but with different test parameters and with different interpretation of the test results. The test may be called a multiple shear creep long recovery (MSCLR) test and the main differences are the test temperature assumed as 10°Celsius and duration of creep and recovery period. In the first part of test, 10 cycles of creep-recovery periods are applied in the stress shearing mode on an asphalt binder sample. This part of the test ends with a long-term recovery period. The test is interpreted through the permanent deformation ratio determined on the basis of the maximum shearing strain observed during the test and the strain value after the long recovery period. In the paper the MSCR and MSCLR tests are conducted on highly-modified binders currently produced in Polish market. The obtained results are statistically analyzed, compared with each other and correlation functions between the results from MSCR and MSCLR tests are determined. Selected results are then presented in relation to results of modified and pen binders produced 8 years before (or some archival binders used for analysis in the paper [1]). Based on the analysis of the results, it is possible to observe some advantages of MSCLR test over MSCR test. One of them is a higher test sensitivity in distinguishing resistance to permanent deformations of individual binders and another one is the simplicity of interpretation of the test data.
W pracy przedstawiono analizę nośności stalowej
No abstract is provided for this article.
No abstract is provided for this article.
The paper contains a review of hydraulically bound layers fatigue resistance criteria that are commonly applied in designing the road pavement structures. The effect of the mechanical parameters applied in the respective criteria on the obtained fatigue resistances is analysed with their different nature underscored. Most of the fatigue criteria define the fatigue life through parameters which are related to it only indirectly (such as the tensile strength, the ultimate tensile strain, etc.) instead of using the results of fatigue tests. The results obtained with different criteria are compared and correlated with the results obtained with the methodology used in preparation of “The Catalogue of Typical Flexible and Semi-rigid Pavements”, a Polish pavement design guide published in 2014. It is demonstrated that the differences between predictions generated with the different empirical fatigue models are noticeably greater in the case of lower traffic classes (service levels), converging for higher traffic classes.
No abstract is provided for this article.
The FWD is commonly used to conduct a non-destructive evaluation of the capacity of the pavement. The layered pavement is loaded locally by falling weight, and deflection at many points is recorded. Based on these results, knowing the pavement geometry, the mechanical properties of the pavement may be determined using the back-calculation approach. Some methods are used for back calculation, such as analytical, numerical, or ML. An analytical solution for a multi-layered structure leads to non-linear relationships for the thickness or stiffness of each layer, but gives an accurate solution. The other methods, like numerical or ML methods, are just approximation methods with different levels of accuracy. In this paper, the robustness of the XGBoost ML regression model in predicting mechanical and geometrical pavement parameters was estimated. The database was generated from a static analytical solution of an axially symmetrical problem implemented in the form of JPAV software and then explored by training regression models to predict moduli and thickness of pavement layers. Two other databases were created using PCA (Principal Component Analysis) and FDM (Feature Difference Method) to compare models trained with the complete deflection database. The results showed that models trained with the complete deflection database had the best average prediction performance compared to the other two. In contrast, models trained with the database pre-processed by PCA showed predicting performance similar to the previous models, but with a little precision loss. Models trained with the database pre-processed by FDM exhibited excellent prediction on some features but worse on the rest.
