Results Of Dynamic Analysis Research Articles

НЕЛИНЕЙНЫЙ СЕЙСМИЧЕСКИЙ ОТКЛИК ЖЕЛЕЗОБЕТОННЫХ КАРКАСНЫХ ЗДАНИЙ

A methodology for seismic performance evaluation of a 10-story reinforced concrete frame building is presented. The comparison between the results of nonlinear dynamic analysis and simplified modal nonlinear static method is carried out. The proposed methodology can be used to correctly estimate the maximum expected moments during a maximum considered earthquake. It is noted that traditional methods of analysis strongly underestimate seismic demands in comparison with nonlinear methods, especially in the middle part of the height of structures.

Polyurethane Elastomers Strengthened by Pseudo[1]rotaxanes Based on Pillararenes.

As a unique property of the interlocked structures, rotaxane allows for intramolecular motions between its wheel and axle components. Introduction of rotaxanes into polymers can endow them with distinctive macroscopic features and outstanding mechanical properties. Here, we prepare a copillar[5]arene with a hydroxyl and an amino-group on each end, which can spontaneously form a pseudo[1]rotaxane through intramolecular hydrogen bonds. This pseudo[1]rotaxane possesses a releasable extra alkyl chain, which is then incorporated into a linear polyurethane by reacting with a diisocyanate to prepare polyurethane elastomers with spring-like structures. The results of stress-strain test and dynamic mechanical analysis all indicate that sliding motions of the axle part on the pseudo[1]rotaxane in the polymer skeleton can greatly dissipate energy, which endows the elastomers with higher toughness and better fatigue resistance. Moreover, the addition of moderate amount of cuprous bromide to form cuprous-thioether coordination in the polymers can further improve the mechanical properties.

Simplified Equations to Safety Evaluate Integral Lifting Construction for Large-Span Steel Corridors via Stochastic Dynamical Analysis Results

Simplified Equations to Safety Evaluate Integral Lifting Construction for Large-Span Steel Corridors via Stochastic Dynamical Analysis Results

Seismic Analysis of Non-Regular Structures Based on Fragility Curves: A Study on Reinforced Concrete Frames

The seismic performance and expected structural damage in reinforced concrete (RC) frames, as in many others, is a critical aspect for design. In this study, a set of RC frames characterized by increasing in-plan and in-height non-regularity is specifically investigated. Four code-conforming three-dimensional (3D) buildings with varying regularity levels are numerically analyzed. Their seismic assessment is conducted by using unscaled real ground motion records (61 in total) and employing non-linear dynamic simulations within the Cloud Analysis framework. Three distinct intensity measures (IMs) are used to evaluate the impact of structural non-regularity on their seismic performance. Furthermore, fragility curves are preliminary derived based on conventional linear regression models and lognormal distribution. In contrast with the initial expectations and the typical results of non-linear dynamic analyses, the presented comparative results of the fragility curves show that the non-regularity level increase for the examined RC frames does not lead to progressively increasing fragility. Upon these considerations on the initial numerical findings, a re-evaluation of the methodology is performed using a reduced subset of ground motion records, in order to account for potential biases in their selection. Moreover, to uncover deeper insights into the unexpected outcomes, a logistic regression based on a maximum likelihood estimate is also employed to develop fragility curves. Comparative results are thus critically discussed, showing that the herein considered fragility development methods may lead to seismic assessment outcomes for code-conforming non-regular buildings that are in contrast with those of raw structural analyses. In fact, the considered building code design provisions seem to compensate non-regularity-induced torsional effects.

The dual role of mannosylerythritol lipid-A: Improving gelling property and exerting antibacterial activity in chicken and beef gel

Gel meat products are important in the meat market. To develop high-quality meat gel products, mannosylerythritol lipid-A (MEL-A) was added to chicken and beef gels, and their physicochemical and biological properties of the composite gel formed by heating were determined in this study. The results of texture analysis showed that MEL-A could significantly improve the hardness, gumminess and chewiness of meat gels and reduce water loss (P < 0.05). In addition, rheological and differential scanning calorimetry (DSC) analysis showed that MEL-A not only improved the rheological properties of meat gel, but also improved its thermal stability. The results of dynamic rheological analysis also showed that MEL-A improved the gel strength of meat gel, and the gel strength of chicken was the highest after adding 1.5 % MEL-A while the gel strength of beef was the highest after adding 2 % MEL-A. The image of scanning electron microscopy (SEM) and protein molecular weight distribution measurement indicated that MEL-A induced protein aggregation, resulting in fewer pores in the meat gels and a more compact network structure. These results suggest that different meat gels show good gel properties, so MEL-A has a lot of potential for gel product development.

A Perspective on the Process and Turbomachinery Design of Compressed Air Energy Storage Systems

Abstract The present paper will describe the Baker Hughes experience in the development of the turbomachinery equipment for Hydrostor's advanced compressed air energy storage (A-CAES) system. At the core of a compressed air energy storage (CAES) plant, there is an air compressing system, followed by an air expander used to recover the stored energy. To achieve a reliable and effective solution, the expander is obtained from the architecture of Baker Hughes steam turbines, which was adapted to match the specific process needs. The criticalities that were addressed and solved to derive the expanders from the original steam turbine are presented. Specifically, the paper describes the activities performed to optimize the inlet and exhaust sections of each segment, the development of the blades for high atmospheric volume flow, and the implications that thermal transients have on the machine reliability. The inlet and exhaust sections were arranged according to the layout constraints, which were set to mitigate the effects of the thermal stresses and to reduce the weight to facilitate the machine transportation, while maintaining high aero-performance. As for the expander, a single-body configuration was selected to optimize capital expenditures and reduce leakage to atmosphere. A new set of blades derived from Baker Hughes's Steam Turbine stages were developed. This new stage is characterized by rotating blades with high radius ratio (HRR); therefore, an optimization strategy was adopted to include the mechanical constraints from the beginning of the design cycle and obtain a final geometry that can be used with different flow path and operating conditions. Finally, the three-dimensional full Navier Stokes Computational fluid dynamics analysis was used to assess the performance of the new stages in nominal and off-design conditions. A detailed analysis of the thermal transient of the expander parts with finite element analysis methods was performed to assess the life expectations of the equipment. The finite element analysis results are discussed in the paper to show the capability of the machine to sustain an extremely fast start up sequence. Compressor train is characterized by a multiple body configuration. A detailed optimization was performed to improve the efficiency and the availability of the selected solution. The low-pressure axial compressor discharge section has been optimized to reduce losses and a detailed study of rotor has been performed to evaluate the capability to withstand a high number of start and stop cycles.

NONLINEAR DYNAMIC ANALYSIS OF WIND ACTIONS ON A CABLE-STAYED GLASS FAÇADE SYSTEM

This paper presents the results of a nonlinear dynamic analysis of wind actions on a cable-stayed glass façade. The wind impact was determined by a transient eddy-resolving numerical simulation using a hybrid RANS-LES model SBES. The revealed dynamic response of the façade system confirms the relevance of dynamic calculations compared to simplified static approaches.

Controlled localization of graphene oxide to improve barrier, biodegradation and mechanical properties of PBAT/EVOH

AbstractIncorporating graphene oxide (GO) with controlled localization into poly(butylene adipate‐co‐terephthalate) (PBAT) blends with poly(ethylene vinyl alcohol) (EVOH) aimed to improve barrier properties, biodegradability, and mechanical strength of PBAT. The PBAT/EVOH/GO nanocomposites containing 0 to 1 wt% of GO were prepared by a reactive mixing process in internal mixer. Microscopic images confirmed that the GO nanoplatelets are mainly localized in PBAT phase and then at the interface, contrary to the thermodynamic affinity of GO toward EVOH. The reactive nature of PBAT/EVOH/GO nanocomposites was confirmed via time‐sweep rheological studies where specific changes were observed in melt viscosity over time. The results of microscopic studies, rheometry, tensile test, and dynamic mechanical thermal analysis (DMTA) confirmed that localizing GO at the interface establishes strong interactions between PBAT and EVOH. By the addition of 0.75 wt% GO, tensile and yield strength were improved by 19% and 45%, respectively. Increasing GO significantly increased the hydrolysis degradation rate of the nanocomposites. Furthermore, the addition of GO considerably decreased the oxygen and water vapor permeability of the blends by up to 40% at 1 wt% GO.

A simplified model for seismic risk assessment of three-dimensional irregular steel moment frame buildings

Seismic risk assessment of irregular buildings requires nonlinear dynamic analysis and three-dimensional (3D) models. However, creating and analyzing such models can be intricate and time-consuming, making the assessment process challenging. Furthermore, this complexity escalates when evaluating building stocks or generating a dataset of buildings with diverse attributes for use in learning algorithms. Therefore, this paper proposes an energy-based model for irregular steel moment-resisting frame buildings to simplify 3D models and improve the time efficiency of structural assessment compared to conventional 3D models. The proposed model is derived from the fish-bone model but has enhanced configuration, elastic, and inelastic properties. These improvements aim to broaden its applicability to encompass 3D irregular mid-rise buildings. Four-, six-, and nine-story irregular buildings in plan and height are utilized to validate the proposed model. The responses investigated in these buildings include eigenvalues, pushover curves, time history responses, incremental dynamic analysis results, fragility curves, and risk analysis outcomes. The findings demonstrate that the simplified model responses are in close agreement with those of 3D models. The comparison of results between the proposed simplified model and existing models indicates that the accuracy of the simplified model is at least 2.2 times that of the existing models. Moreover, it provides an average error reduction of 60 % in contrast to the existing models. These advancements have been achieved while the proposed simplified model maintains a level of time efficiency comparable to the current models. The results from the analysis of the created buildings using the proposed simplified model indicate that the model is suitable for application in the seismic risk assessment of building inventories and generating datasets for future research involving machine learning-based methodologies.

Improved PBPD method for dual steel system considering the global effect of space frames

Performance-based plastic design (PBPD) method has been proposed to design single bay planar frames for twenty years. For a dual steel system, such as an eccentrically braced frame (EBF) structure, there will be both EBF bays and moment resisting frame (MRF) bays. So, the global effect between different frame bays cannot be considered when designing the global structure using the traditional PBPD method. In this paper, a ten-story high-strength steel composite K-shaped eccentrically braced frame (HSS-K-EBF) structure was firstly used for performance design and analysis based on a single bay EBF. The results show that the global structural model obtained by direct performance design of the single bay model cannot achieve the desired performance objectives. To this end, an improved PBPD method for the dual steel system was proposed considering the global effects of space frames. The elastic and elastic–plastic shear distribution relations were calculated for different bays of the frames including EBFs and MRFs. The performance objectives of the global structure were designed and evaluated more accurately by considering the over-strength contribution of shear links and the plastic development rate index ξ of energy dissipation members. The improved PBPD method was used to design the ten-story global HSS-K-EBF structure. The results of nonlinear dynamic time history analysis show that the improved PBPD method can ensure that the plastic damage distribution of energy dissipation members of different bays is more uniform and the plastic damage degree is more consistent with expectations.

The Impact of Dynamic Effects on the Results of Non-Destructive Falling Weight Deflectometer Testing.

The article investigates the impact of applying a dynamic computational model that considers inertia forces on pavement deflections under rapidly changing loads over time. This study is particularly relevant to the modelling of falling weight deflectometer (FWD) testing. Initially, the article examines the deflection values obtained from computational models under loads with varying frequencies. In this context, considering inertia forces was significant for load durations shorter than 0.04 s. In such cases, the results of static and dynamic analyses differed considerably. One application of FWD measurement results is determining the stiffness moduli of pavement layers using backcalculation. The study explored the impact of incorporating inertia forces into the pavement model on the estimated values of stiffness moduli obtained via backcalculation. The results revealed differences of several percent between the stiffness moduli calculated using dynamic and static numerical models. Subsequently, the key pavement deformations and fatigue life were determined using the obtained moduli. Again, significantly different results were observed between dynamic and static cases. Based on these findings, it can be concluded that dynamic effects should not be ignored when using FWD testing for backcalculation. Additionally, the article addresses the sensitivity of backcalculation results, which is crucial for the accurate interpretation of the obtained data.

Assessment of a Force Method for the Resilient Seismic Design of Special Moment-Resisting Steel Frames with Hysteretic Energy Dissipation Devices

In this paper, the authors present the results of nonlinear dynamic analyses of twelve building models designed according to a methodology based upon the force method, capacity design principles and the concept of structural fuses to achieve resilient seismic designs for special moment-resisting steel frames with hysteretic energy dissipation devices mounted on chevron steel bracing. It is demonstrated that the resilient design mechanism previously checked with pushover analyses is also attained for most studied models with nonlinear dynamic analyses using an acceleration record which is compatible with the elastic design spectrum. Also, it is corroborated that the planned second line of inelastic defense is activated if the seismic action surpasses the considered design spectrum. Based upon the obtained results, it is confirmed that it is possible to perform a resilient seismic design for the studied system under the proposed methodology, even for tall and slender buildings. Therefore, the proposed initial stiffness ratio parameters and the global design parameters previously proposed by the authors to use in a code-oriented force method can be used with confidence for the resilient seismic design of this structural system.

Subharmonic response suppression of a quasi-zero stiffness system

Quasi-zero stiffness (QZS) isolators can effectively suppress low-frequency vibration due to high-static-low-dynamic stiffness (HSLDS) characteristics. The existence of nonlinearity induces intricate nonlinear phenomena in QZS isolators, particularly under conditions of small damping and large excitation. These nonlinear characteristics can seriously affect the vibration isolation performance, which has rarely been focused on in existing studies. This study examines a typical QZS isolator with nonlinear damping. The modified incremental harmonic balance (IHB) method is applied to directly analyze its dynamic characteristics and investigate the suppression of the subharmonic response. The dynamic analysis results indicate multiple subharmonic vibration intervals, including the 1/2, the 1/3, and the 1/9 subharmonic vibration. The basin of attraction at different excitation frequencies shows that subharmonic vibration is highly likely to occur. The effect of different damping on the transmissibility proves to be different. Simultaneously, rational parameter matching can guarantee the absence of subharmonic vibration while maintaining the primary resonance frequency and amplitude unchanged. The research results of this study provide theoretical support for the parameter selection of QZS isolators. In addition, the higher-order approximations of most isolators have the same form, so these results can guide other QZS isolators in suppressing subharmonic vibrations and improving their operating range.

Dynamical Analysis of Mathematical Model of Social Behavior with Law Enforcement and Religious Approaches

Mathematical models could be used to describe various phenomena, one of which is social phenomena. One of the interesting social phenomena to study is criminal behavior. By dividing the total population into several compartments based on their social behavior status, a mathematical model could be constructed to depict social dynamics. These social dynamics could be understood through dynamical analysis and numerical simulation. In this study, numerical simulations were conducted using Maple 2022 software and the Runge-Kutta method. Based on the results of dynamical analysis and numerical simulations, it is known that by implementing law enforcement and religious approaches, criminal activities within a population could be reduced or even eliminated.

Determination of Ambient Air Vaporizers’ Performance Based on a Study on Heat Transfer in Longitudinal Finned Tubes

Ambient air vaporizers (AVVs) are the most commonly used type of heat exchanger for cryogenic regasification stations. The transfer of heat from the environment for heating the liquefied gas and its vaporization is a cost-free and efficient method. Designing ambient air vaporizers for regasification or fueling stations requires accepting the size and related thermal power of the AVV considering the operating conditions and the type of liquefied gases to be vaporized. The nominal capacity of the ambient air vaporizer depends on its design, the frosting of longitudinal finned tubes, and the airflow through the vaporizer structure. This paper presents the results of experimental studies and computational fluid dynamics (CFD) analysis on determining the heat output of AVV longitudinal finned tubes depending on their design. This experiment was conducted in order to establish a numerical model. The relation between the longitudinal finned tubes thermal power and the air flow velocity is demonstrated and the beneficial effect of forced convection is proved. The obtained results are used for verification calculations of ambient air vaporizers’ performance depending on the size of the AVV, the profile cross-section, and the airflow velocity for different liquefied gases. Under conditions of forced convection, profiles with 12 equal-height fins were discovered to be the most efficient for higher airflow velocity providing up to 7% higher heat rate than profiles with 8 equal-height fins. However, at low air velocity, profiles with 8 equal-length fins showed a comparable heat output to profiles with 12 equal-length fins. Profiles with 8 and 12 unequal high fins differ in average heat output by about 28%. The profile with 12 unequal high fins turned out to be the least effective when 2D airflow was considered in this analysis.

Achieving Optimal Order in a Novel Family of Numerical Methods: Insights from Convergence and Dynamical Analysis Results

In this manuscript, we introduce a novel parametric family of multistep iterative methods designed to solve nonlinear equations. This family is derived from a damped Newton’s scheme but includes an additional Newton step with a weight function and a “frozen” derivative, that is, the same derivative than in the previous step. Initially, we develop a quad-parametric class with a first-order convergence rate. Subsequently, by restricting one of its parameters, we accelerate the convergence to achieve a third-order uni-parametric family. We thoroughly investigate the convergence properties of this final class of iterative methods, assess its stability through dynamical tools, and evaluate its performance on a set of test problems. We conclude that there exists one optimal fourth-order member of this class, in the sense of Kung–Traub’s conjecture. Our analysis includes stability surfaces and dynamical planes, revealing the intricate nature of this family. Notably, our exploration of stability surfaces enables the identification of specific family members suitable for scalar functions with a challenging convergence behavior, as they may exhibit periodical orbits and fixed points with attracting behavior in their corresponding dynamical planes. Furthermore, our dynamical study finds members of the family of iterative methods with exceptional stability. This property allows us to converge to the solution of practical problem-solving applications even from initial estimations very far from the solution. We confirm our findings with various numerical tests, demonstrating the efficiency and reliability of the presented family of iterative methods.

Theoretical and experimental research on the rocking truss system with post-tensioned rocking connection

The weak story failure often occurs in steel frame structures and the collapse risk of the frames will increase because of concentrated plastic deformation in the soft story. The work presented in this paper aims to avoid the soft story mechanisms and the improve self-centering capacity of steel frames by employing the innovative rocking truss. Compared with the previous rocking system, it is more flexible in application and suitable for retrofit of existing buildings. The theoretical approach to quantifying the stiffness demand of the rocking truss was proposed and presented two critical parameters (equivalent bending stiffness ratio η and the rotation stiffness ratio λ) for the design of the rocking truss. The 1/3 scaled steel frame with rocking truss (SFRT) was tested and theoretical analysis results were validated by test results. The finite element model of SFRT was built following the boundary conditions of the test specimen. The numerical results are consistent with the experimental observations. The nonlinear static and dynamic analysis results of the SFRT were compared with those of the same steel frame (SF) with a bracing system. It was found that the rocking truss can reduce the maximum and residual drifts of the main frame as expected, and the plastic development of the RBS at the beam end in SFRT is less than that in SF with a bracing system. The parametric analysis of the rocking connections with different values of prestressing force was carried out. The results confirm that the rotational stiffness and load-bearing capacity of the rocking connection can be accurately evaluated by the theoretical force-displacement curve. The effect of the equivalent bending stiffness ratio η and the rotation stiffness ratio λ on the lateral deformation pattern of structures was discussed by theoretical analysis, and the design procedure of the rocking truss is recommended to satisfy the demand of uniform inter-story drift and self-centering capacity.

Probabilistic evaluation of spectral acceleration demands on light secondary systems supported by partially self-centering structures

Partially self-centering structures are promising seismic resilient structural systems by reducing residual inter-story drifts with low initial construction costs. Comprehensive studies focused on structural design and performance evaluation, but no research was conducted to investigate the design of nonstructural components in partially self-centering structures. This research focuses on developing the probabilistic spectral acceleration demands for the nonstructural design in partial self-centering structures. 320 near-fault recorded ground motions were adopted for considering the uncertainties of seismic excitations. The spectral accelerations of the light nonstructural component were obtained through comprehensive dynamic analyses. The logarithmic normal distribution can be used for describing the probabilistic distribution of floor spectra for partially self-centering structures under earthquakes, validating through the Anderson-Darling test. The influences of design parameters (including structural period, hysteretic parameters, structural damping, the ratio of the structural period to the nonstructural period, and nonstructural damping) on the probabilistic distribution of floor spectra were investigated through parametric dynamic analysis results. Artificial neural network (ANN) models were developed for predicting the probabilistic floor spectra for partially self-centering structures. The analysis results indicate that ANN models can achieve excellent accuracy with a coefficient of determination larger than 0.99. Comparative analysis results reveal that the ASCE method may underestimate the acceleration demand of light secondary systems supported by partially self-centering structures. The developed ANN models were interpreted using the shapely additive explanations. It has been found that the fundamental periods of the main structure and nonstructural components and the response modification factor show significant effects on the median and deviation of the probabilistic floor spectra for partially self-centering structures. The software FloorSpecPS was established to predict the probabilistic floor spectra for partially self-centering structures using the developed ANN models in practical application.

Seismic response of expanded polystyrene (EPS) sandwiched concrete panels system in buildings: Damage distribution and correlation analysis of parameters

Lightweight wall panels and connectors between them and load-bearing structures are often significantly damaged during moderate-intensity seismic events. However, generally applicable methods and models for predicting and assessing the damage are lacking. A seismic analysis and assessment framework for the interaction among lightweight partition wall panels, energy-dissipating connectors, and main structural elements was established via the Maximum Information Coefficient method. Experiments and numerical simulations were conducted to investigate the nonlinear behavior and hysteresis-based energy-dissipation features of connectors in Expanded Polystyrene sandwiched concrete panels. A system model incorporating lightweight wall panels, connections designed to absorb energy, and load-bearing structures is proposed to elucidate their collaborative interactions. The distribution pattern of seismic damage in the Expanded Polystyrene sandwiched concrete panels system was also investigated. Based on the characteristics of the incremental dynamic analysis results, a correlation evaluation of the seismic parameters and structural damage was conducted using the refined Maximum Information Coefficient method. The proposed analysis framework can be used for the damage evaluation and prediction of assembled nonstructural elements.

Preparation and Properties of Epoxy Adhesives with Fast Curing at Room Temperature and Low-Temperature Resistance.

Developing a highly efficient multifunctional epoxy adhesive is still an enormous challenge, which can rapidly cure at room temperature and has excellent low-temperature resistance performance and is crucial for the epoxy adhesive and electrical sealing fields during severe cold seasons. Herein, diglycidyl phthalate (DP) was synthesized with phthalic anhydride (PA) and epichlorohydrin (ECH) to enhance the curing rate and low-temperature resistance of bisphenol A diglycidyl ether (DGEBA) adhesive. The modified DP/DGEBA adhesives were systematically analyzed by gel time, mechanical properties, and aging resistance (time, temperature, and dry/wet treatment). The results showed that DP with highly active ester groups significantly accelerates the curing speed of DP/DGEBA. DP's rigid aromatic ring-benzene ring and flexible group-ester group gave the adhesive better low-temperature resistance. When the addition of DP was 10 wt % (based on the mass of DGEBA), the gel time of DP/DGEBA epoxy adhesives was reduced by 58 min compared to unmodified DGEBA epoxy adhesive, and after aging at low temperature (-20 °C) for 7 days, the tensile shear strengths of polyvinyl chloride (PVC) and aluminum plate increased by 76.2 and 80.6%, respectively. The results of non-isothermal curing kinetics and dynamic mechanical analysis suggested that when the amount of DP was 10 wt %, the reaction activation energy of DP/DGEBA epoxy adhesive decreased by 4.0%, and the cross-linking density increased by 8.9%. Moreover, the toughness of the modified adhesive was also improved. This study opens up a feasible way for the development of a low temperature-resistant epoxy adhesive cured rapidly at room temperature in practical application.