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Nowadays, with the widespread supply of very powerful laboratory and computer equipment, it is expected that the analyses conducted for geotechnical problems are carried out with very high precision. Precise analyses lead to better knowledge of structures' behavior, which, in turn, reduces the costs related to uncertainty of materials' behavior. A precise analysis necessitates a precise knowledge and definition of the behavior of the constituent materials, which itself requires applying an appropriate constitutive model to show the behavior of materials. Constitutive models used in the generalized plasticity framework are very powerful constitutive models for the simulation of sand behavior. However, the simulation of a cyclic behavior in these models, especially the simulation of the undrained cyclic behavior, is not well-recognized. In this study, in order to eliminate the weakness of generalized constitutive models under cyclic loading, a new equation is presented to substitute the so-called coefficient of the discrete memory factor to consider the loading history in such a way that the plastic modulus is modified during reloading and, as a result, more appropriate predictions of sand behavior are obtained. The performance accuracy of the proposed coefficient was evaluated in accordance with the experimental data. Finally, the results show that after using the modification of the loading history coefficient, predictions of the constitutive model are significantly improved. [ABSTRACT FROM AUTHOR]

Earthquake-induced pounding in bridges is a complex contact phenomenon in which the dynamic responses of structures, including collisions between deck and abutments, are strongly related to structural properties and earthquake excitation. The goal of this study is to develop and compare the seismic fragility curves of overall system and individual components of regular and irregular box-girder highway bridges in two cases: with pounding and without pounding. For this purpose, four levels of altitudinal irregularity, ranging from regular to highly irregular, are considered. To extend the results for all bridges in the same class, different sources of uncertainties related to earthquakes, structural geometries, and material properties are taken into account. The analytical fragility curves have been developed based on nonlinear time history analyses in OpenSees finite element software for the cases with and without pounding effects. The process has been repeated for each two-, three-, and four-span classes at four irregularity levels. The fragility function parameters for the two cases with and without pounding have been compared for all classes considered in this study. Using fragility functions, this paper clarifies the interactive roles of irregularity and pounding between deck and abutments for seismic vulnerability of multi-span box-birder highway bridges. The results indicate that collisions often show an adverse effect on all structural components. It has also been observed that the detrimental effect of pounding on seismic fragility is more apparent in irregular bridges when compared with regular ones. In addition, the study introduces a conversion coefficient to clarify the effects of pounding on the fragility of bridge components and the overall system. This coefficient can be applied in both conventional analytical methods like static or simplified analysis and technical earthquake models like HAZUS, adjusting fragility values for pounding and irregularity effects. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of the soil type on the torsional response of buildings experiencing torsional pounding due to earthquake excitations. Six buildings (one 4-storey building and five 6-storey buildings) with different configurations have been considered. First, pounding between different structures has been analysed for a specified soil type and the effect of the torsional pounding and the contact asymmetry on the torsional response of colliding buildings has been investigated. Then, these pounding cases have been considered for different soil types to study the effect of the soil type on the torsional response of buildings experiencing torsional pounding. Five soil types have been considered, i.e. hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil. The results of the study indicate that the earthquake-induced torsional pounding causes an increase in the peak storey rotation of the colliding buildings as compared to the symmetric pounding in all cases. Higher peak storey rotations have been experienced for colliding buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock. [ABSTRACT FROM AUTHOR]

Pounding between adjacent structures has been repeatedly observed during major earthquakes. The phenomenon may cause some local damage at the points of interactions, it may also lead to substantial destruction, permanent deformations or total collapse of colliding structures. The effects of earthquake‐induced structural pounding have been studied for more than three decades now. However, most of the studies concerned masonry as well as reinforced concrete structures and investigations on steel structures are very limited. The aim of the present paper is to show the results of the shaking table experimental investigation focused on earthquake‐induced pounding between three models of steel structures in a row. The models were constructed out of four steel columns made from rectangular box section with additional steel skew bracings so as to prevent transverse and torsional vibrations. To obtain different dynamic characteristics of the models, additional plates were added at the top of each tower. Two configurations were investigated. In the first one, two plates were mounted on the external structures and only one plate at the top of the middle tower. In the second configuration, only one plate was mounted at the top of external towers and two plates on the middle structure. Firstly, the free vibration tests were conducted. Then, the steel towers with different in‐between gap sizes were tested under different earthquakes. The results of the study confirm that interactions between insufficiently separated steel structures may significantly influence the structural behaviour during earthquakes. In most of the cases, pounding has resulted in the increase in the peak responses. In some cases, however, it has played a positive role leading to the decrease in the structural response under seismic excitation. Anyway, even if the response is reduced, interactions should be prevented at the design stage of steel structures since they may result in considerable damage at the points of impacts. [ABSTRACT FROM AUTHOR]

This article presents a novel approach to estimate the flexural capacity of reinforced concrete-filled composite plate shear walls using an optimized computational intelligence model. The proposed model was developed and validated based on 47 laboratory data points and the Transit Search (TS) optimization algorithm. Using 80% of the experimental dataset, the optimized model was selected by determining the unknown coefficients of the network-based computational structure. The remaining 20% of the data was used to evaluate the accuracy of the model, and the best-performing structure was selected. Furthermore, the final neural network details were subjected to statistical analysis to extract a user-friendly formula, making it easier to apply in practice. The proposed ANN model and the proposed user-friendly formula were then compared with the AISC 341-16 and experimental results and demonstrated their efficacy in predicting the flexural behavior of composite shear walls. Overall, the proposed approach provides a more reliable and efficient framework for estimating the flexural behavior of composite shear walls. [ABSTRACT FROM AUTHOR]

The best approach to avoid collisions between adjacent structures during earthquakes is to provide sufficient spacing between them. However, the existing formulas for calculating the optimum seismic gap preventing pounding were found to provide inaccurate results upon the consideration of different soil types. The aim of this paper is to propose new equations for the evaluation of the sufficient in-between separation gap for buildings founded on different soil conditions. The double-difference formula has been taken into account in this study. The seismic gap depends on the correlation factor and on the top displacements of adjacent buildings. The correlation factor depends on the ratio of the periods of adjacent buildings (smaller period to larger period). The modification of the correlation factor has been introduced for buildings founded on five different soil types. Five soil types were taken into account in this study, as defined in the ASCE 7-10 code, i.e., hard rock, rock, very dense soil and soft rock, stiff soil, and soft clay soil. The normalized root mean square errors have been calculated for the proposed equations. The results of the study indicate that the error ranges between 2% and 14%, confirming the accuracy of the approach. Therefore, the proposed equations can be effectively used for the determination of the optimum seismic gap preventing earthquake-induced pounding between buildings founded on different soil types. [ABSTRACT FROM AUTHOR]

This paper investigates the reduction of bending moment in critical members by adding some extra members in the optimum location. Instead of enlarging the size of members to resist the moment, eight additional members are added in the optimum location to reduce the bending moment in the critical members. The total weight of the proposed structure with extra members is less than that of the original structure that resists the induced bending moment. Moreover, the location of the additional bars significantly reduces the nodal displacements. This paper investigates the effect of placing extra members on vertically and/or horizontally loaded egg-shaped single-layer frames. An egg-shaped structure is designed based on the maximum induced moment; in such frames, the bending moment is the dominant internal force. Then some extra members are suggested to be added to the structure to reduce the maximum bending moment to the lowest possible value; thus, the designed cross-sectional area is minimized. Furthermore, the optimized structure's total weight and shape deformation is less than the ordinary structure's. The study results show that the extra bars' location depends on the loadings' direction. Moreover, the weight of the horizontally loaded egg-shaped structure can be optimized by up to 28%. The results were verified by MATLAB and SAP2000 software. [ABSTRACT FROM AUTHOR]

Fiber-Reinforced Polymers (FRP) were developed as a new method over the past decades due to their many beneficial mechanical properties, and they are commonly applied to strengthen masonry structures. In this paper, the Artificial Neural Network (ANN), K-fold Cross-Validation (KFCV) technique, Multivariate Adaptive Regression Spline (MARS) method, and M5 Model Tree (M5MT) method were utilized to predict the ultimate strength of FRP strips applied on masonry substrates. The results obtained via ANN, KFCV, MARS, and M5MT were compared with the existing models. The results clearly indicate that the considered approaches have better efficiency and higher precision compared to the models available in the literature. The correlation coefficient values for the considered models (i.e., ANN, KFCV, MARS, and M5MT) are promising results, with up to 99% reliability. [ABSTRACT FROM AUTHOR]

This paper presents an application of L-moment statistics and the respective L-moment ratio diagrams (LMRD) to assess control performance, in particular, in terms of control system sustainability. L-moment diagrams are common in extreme events analysis and are considered a very powerful tool in this field at the regional level. Control system assessment is a well-established research area that investigates approaches and methodologies for measuring the quality of control systems. Statistical moments can be used to assess the effectiveness of control systems. The same principle applies to L-moments, with a possible further application to the assessment of control system robustness. The incorporation of the time impact into the analysis allows us to examine the evolution of control systems. In this context, measuring sustainability is only one step away. In this research, L-moments and L-moment ratio diagrams are used to assess the quality of PID-based control systems. In addition, the evolution of their performance over time is depicted visually. Moreover, a robust discordance measure is proposed to measure the robustness, evolution, and sustainability of control systems. The proposed approach is successfully validated using real industrial data obtained from PID basic regulatory control within the hierarchical advanced process control (APC) structure of a large ammonia production plant. [ABSTRACT FROM AUTHOR]

Multifunctional materials, which exhibit diverse physical properties, are candidates for the new generation of smart devices that realize many tasks simultaneously. Particular attention is given to single-phase multifunctional materials that offer the new physical effects induced by the coupling between introduced properties. Complexes of lanthanide(3+) ions are an attractive source of multifunctionality since they combine luminescent functionalities related to their f–f or d–f electronic transitions with magnetic anisotropy that originates from spin–orbit coupling and crystal-field effects. The resulting luminescent single-molecule magnets (SMMs) link the area of functional luminophores, applicable in light-emitting diodes or sensing, with the field of molecular magnets, applicable for high-density data storage, and offer additional advantages, e.g., fruitful magneto-optical correlations and the switching of emission by a magnetic field. It was recently shown that luminescent lanthanide SMMs can provide multifunctionality that is richly expanded towards their sensitivity to solvent exchange, temperature, or light, as well as the generation of electrical properties, such as super-ionic conductivity and ferroelectricity, or non-centrosymmetricity- and chirality-related effects, e.g., second-harmonic generation and circularly polarized luminescence. Here, we discuss the pioneering reports on multifunctional materials that use luminescent lanthanide SMMs, with the emphasis of our contribution relying on the functionalization of 4f metal complexes through their insertion into heterometallic d–f coordination compounds. [ABSTRACT FROM AUTHOR]

In this paper, the idea of using polymer adhesive as a damping layer is proposed. An experimental study of two aluminium cantilevered beams has been conducted. One of them presents a plain cantilevered beam, while the second one considers two aluminium beams bonded with a polymer adhesive of different thickness (0,5; 1,2; 1,75; 3,1 and 5 mm). The polymer adhesive considered in the study is a specially designed flexible two-component grout, which has high damping properties. The aim of the study is to determine dynamic parameters, such as natural frequencies and damping ratios of both beams, based on the tests in which analyzed elements have been induced to vibrations by a modal hammer. The behaviour of the beams under different additional weight, installed at the end of elements, has been studied. The results of the study clearly show that the response of the composite aluminium beam with polymer adhesive inside is substantially different then the response of the plain beam. The application of polymer adhesive leads to significant increase in structural damping. Based on the results, the method of using the polymer adhesive can be considered as an effective one in reduction of structural vibrations.

The article presents the results for cast iron columns used as floor supports in the former financial office building in Kwidzyn (Poland). The stocktaking drawings provided the general and detailed data about the 19th century designer’s decisions. During the research, architectural and structural analysis was carried out. The graphics were used as a starting material for preparing 3D calculation models. The FEM-based numerical simulations were conducted using ABAQUS software. It was shown that the selection of such a structural solution in the building allowed arranging the interior space in an innovative way. The results of the study prove the thesis put forward of a low application extent of the load-bearing capacity of cast iron column used.

Hydrotechnical structures are important components in water management system and general flooding safety. Their reliability should be ensured since potential damage might lead to catastrophic consequences. Weir gates are considered to be highly vulnerable elements of each hydro power plant, with regard to its dynamic resistance. The aim of the paper is to compare different numerical models and their influence on the results of a computational modal analysis of a steel radial gate. The investigation has been conducted for models using beam and shell elements, while assuring the same geometry, material properties and boundary conditions. The results of the comparative computational analysis indicate that the eigenmode shapes are similar for both models, while the corresponding eigenfrequencies are considerably different. These differences are important from the point of view of dynamic analysis, especially that the first eigenfrequency falls within the energy range typical for earthquakes and mining tremors.

The present paper summarizes the preliminary results of the experimental shaking table investigation conducted in order to verify the effectiveness of a new base isolation system consisting of Polymeric Bearings in reducing strong horizontal machine-induced vibrations. Polymeric Bearing considered in the present study is a prototype base isolation system, which was constructed with the use of a specially prepared flexible polymer with improved damping properties. Dynamic oscillatory tests, during which a concrete base slab supported by four Polymeric Bearings was subjected to horizonal sinusoidal excitations characterized by different frequencies and amplitudes, were conducted in order to determine the damping properties of Polymeric Bearings and their effectiveness in mitigating structural vibrations. Equivalent damping ratios for every excitation frequency considered were determined using the experimentally obtained hysteresis loops. Final conclusions are presented and the results discussed.

The structural pounding caused by an earthquake may damage structures and lead to their collapse. This study is focused on the pounding between two adjacent asymmetric structures with different dynamic properties resting on the surface of an elastic half-space. An exploration of the relationship between the effects of the seismic analysis with the impact response to the torsional pounding between adjacent buildings under different SSI effects has been presented. In this paper, the authors have proposed a procedure for analyzing the response for adjacent buildings subjected to the pounding effects, considering systems with multiple degrees of freedom and modal equations of motion with four types of soil. All the calculations have been performed based on the fourth-order Runge–Kutta method. The novelty of the present study is related to the fact that the rigorous and approximate methods are used to examine the effects of pounding and SSI simultaneously. As a result, these two methods have been thoroughly investigated for both effects and the results have been compared. The results show that the approximate method produces results that are slightly different from those obtained by the rigorous direct integration method in the case of small SSI effects due to an increase in the pounding force. The efficiency of the method is also validated using numerical examples. [ABSTRACT FROM AUTHOR]