Design Of Engineering Structures Research Articles

Dynamic response mechanism of the hole subjected to the 3D point source disturbance in an isotropic formation

Accurate estimation of the effects of dynamic disturbances on stress concentration is crucial for the stability of rock engineering and the corresponding analytical approaches are needed. This study presents an analytical approach to calculate the relative stress distribution with a point source inside and outside a hole using the linear theory of elasticity. The Helmholtz potentials and Sommerfeld integral are employed to describe the displacement and stress components, and then formulate the equilibrium equations to solve the equivalent stress distribution around the hole. Numerical examples demonstrate the impact of model parameters on the equivalent stress, such as frequency, hole radius, source location, etc. It is found that sometimes high frequencies can make the equivalent stress greater far from the source than that close to the source. Additionally, when the ratio of the distance between the source and the hole axis to the hole radius exceeds ten, the equivalent stress distribution around the hole remains nearly constant. This approach can be used for the design and assessment of underground engineering structures' stability under dynamic disturbances.

Corrosion effects on bond strength in reinforced concrete with fly ash

Reinforcing steel bars provides additional strength and ductility to concrete by forming a strong bond with the concrete matrix. Corrosion of steel bars can significantly reduce the bonding effect between the steel bar and concrete, which can compromise the structural integrity and durability of reinforced concrete structures. An experimental investigation was performed to examine the influence of fly ash (FA) and corrosion on concrete–steel bond behavior. The accelerated corrosion method was employed to obtain the desired level of corrosion. The FA content, corrosion percentage, and presence of stirrups were considered significant factors influencing bond behavior. The bond–slip curves and bond toughness were used to discuss bond behaviors. The findings indicated that mild corrosion (below 2.5%) can enhance concrete–steel bond performance, and the addition of 20% FA leads to higher ultimate bond strength (τu ), significantly mitigating the decrease in bond strength caused by severe rebar corrosion. Also, this study analyzed the influence of stirrups on the bond strength of FA concrete and had a nearly insignificant effect compared to regular concrete. The results and discussions of the present study carry significant importance in the establishment of a bond–slip constitutive model under multifactor coupling conditions. Furthermore, it offers valuable insights into the design of engineering structures.

Case Studies – an Indispensable Source of Experience and Knowledge

Owing to the peculiarities of the design environment that structural engineers have to face – an environment where prototypes are designed and erected without intensive and purposeful development and testing – case studies of failures and/or near misses are an indispensable source of experience and knowledge and form the basis for enhancing and updating the set of technical rules and regulations. By discussing actual and historic case studies, the development of the tools and methods of forensic engineering as well as of the findings from these for the design, erection, supervision, inspection and maintenance of civil engineering structures will be addressed. The interface problems, when different parties are involved, are highlighted, and the necessity of establishing a good and reliable co-ordination mechanism is carved out. Because of the increasing fragmentation of the design process, in combination with the use of complex software tools and inevitable pressure of time, often a comprehensive design review process is the last line of defence to avoid incidents due to minor lapses or serious misjudgements.

Advanced bionic inverted coral solar evaporator: Enhancing sustainable water utilization with efficient and salt-resistant evaporation

Interfacial solar-driven steam generation technology shows great potential in addressing desalination and wastewater purification. However, there is a lack of advanced evaporators with high evaporation efficiency and salt tolerance, which is an obstacle to its widespread application. Drawing inspiration from marine coral structures, we develop a bionic inverted coral-type 3D solar evaporator with an array structure using structural engineering design. The microscopically porous vertical channel structure within the overall skeleton enhances the longitudinal reflux of salt ions and water evaporation, while macroscopic gaps in the bionic coral branching facilitate lateral advection–diffusion of salt ions. Numerical simulations confirm that this bionic coral structure design improves the diffusion rate of concentrated brine. Due to the localized surface plasma resonance and the Marangoni effect, the evaporator achieves remarkable water evaporation performance (evaporation rate: 2.72 kg m−2h−1, energy efficiency: 95.8 %) and operates reliably even under 20 % brine concentration (evaporation rate: 2.65 kg m−2h−1) without significant salt crystallization. Furthermore, it exhibits good wettability and robust mechanical properties, capable of withstanding a wide range of temperatures. The efficient and salt-resistant evaporation makes it valuable for applications including desalination, various wastewater treatments, and agricultural irrigation, thereby promoting the sustainable utilization of water resources.

Research on the influence of pits on the propagation law of explosion shock waves

To study the influence of pits on shock wave propagation and the propagation of shock waves within pits, numerical simulations were used to calculate the distribution of overpressure peak values at the bottom and rear of the pits at 5 depths and 5 explosion center distances. The results indicate that diffraction occurs when the explosion shock wave passes through the edge of the crater; The peak overpressure of the shock wave at the bottom of the pit exhibits a "spoon shaped" distribution, and the peak overpressure on the right side is significantly higher than that on the left side; There are two distinct boundary regions for the overpressure of the shock wave behind the crater due to the influence of the crater; The distance between the explosion centers has little effect on the distribution trend of the overpressure peak of the shock wave at the bottom and rear of the pit, mainly affecting the magnitude of the overpressure peak. The research results provide theoretical support for the analysis of the propagation law of explosion shock waves and guidance for the design of protective engineering structures, with significant engineering application value.

Advanced analysis and construction techniques for long-span spatial structures in steel engineering

This paper explores advanced analysis methods and construction techniques for long-span spatial structures in steel engineering. It delves into the principles of the Direct Analysis Method (DAM), emphasizing equilibrium, compatibility, plasticity, and stability, as well as load path and redundancy considerations. The DAM provides a robust framework for analyzing complex steel structures, ensuring stability, resilience, and efficiency. Furthermore, the paper discusses modeling techniques, including Finite Element Analysis (FEA), dynamic analysis, and nonlinear analysis, highlighting their significance in optimizing design solutions and predicting structural behavior under diverse loading conditions. Practical considerations in material selection, connection design, and construction are addressed, focusing on enhancing performance, durability, and constructability. Prefabrication and modular construction techniques are explored as effective strategies for accelerating project schedules, improving quality control, and enhancing site safety. Through a comprehensive review of literature and case studies, this paper provides valuable insights for engineers and researchers involved in the design and construction of long-span spatial structures in steel engineering.

Advanced Structural Engineering Design for Tailored Microporous Structure via Adjustable Graphite Sheet Angle to Enhance Sodium‐Ion Storage in Anthracite‐Based Carbon Anode

AbstractCarbon material has emerged as a highly promising anode for sodium‐ion batteries (SIBs) due to its abundance of resources, cost‐effectiveness, and high carbon yield. This work elaborately designs the precursor structure for the self‐assembly of melamine‐cyanuric acid on the anthracite surface through hydrogen bonding, and successfully constructs N‐doped carbon with tailored microstructure and expanded interlayer spacing. Serving as anode for SIBs, the optimized sample delivers high specific capacity (371.3 mAh g−1 at 0.05 A g−1), superior rate capability (295.8 mAh g−1 at 10.0 A g−1), and excellent ultra‐long cycling performance (the retention of 91.5% after 3000 cycles at 0.5 A g−1). The systematic investigations reveal the enhancement of sodium‐ion storage in the low‐voltage plateau region involving the interlayer intercalation coupled with nanopores filling. It is discovered that the microporous structure formed by the appropriate graphite sheet angle influences the migration and storage of sodium ions. Density functional theory calculations indicate that the adsorption capacity for sodium ion is enhanced and the migration energy barrier perpendicular to the graphite layer is reduced at the appropriate angle of 8°. This study provides novel insights into the sodium‐ion storage mechanism, offering guidance for the better design of anthracite‐based carbon anode with superior performance.

Experimental study of compression behavior and its correlation with the microstructure of a deep-water sediment

Understanding the volume change behavior of deep-water sediments is essential for the safety design of deep-water engineering structures. In this study, the volume change behaviors of marine sediments from the South China Sea were studied through oedometer and isotropic compression tests. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests have been conducted to investigate the microstructure evolution of two types of sediments under loads. The experimental results showed that the structural anisotropy of intact specimens is more pronounced in oedometer tests with the increase of stress, however, depolarization occurs in the isotropic consolidation test. The volume change after yield in the oedometer and isotropic consolidation tests comes from inter-aggregate pore variations associated with the adjustment of the soil fabric. The reconstituted specimen presents a more uniform distribution of pores than that of the intact specimen, and the macropores are more easily compressed for the reconstituted specimen than those of the intact specimen. With increasing stress, the oedometer compression and isotropic consolidation curves of intact specimens gradually approach those of the reconstituted specimen. The deformation mechanism under high stresses is that soil particles are reoriented and the variation of micropores.

Optimization of all-polymer/Sb2Se3 tandem solar cells for enhanced efficiency: a comprehensive TCAD modeling approach

Abstract This paper introduces a novel tandem configuration, utilizing an all-thin film all-polymer solar cell (all-PSC) with a wide bandgap of 1.76 eV for the front cell and Sb2Se3 with a narrow bandgap of 1.2 eV for the bottom cell. The design of this tandem is performed by comprehensive optoelectronic TCAD tools, essential for optimizing parameters across multiple layers to reach maximum power conversion efficiency (PCE). Experimental validation of models is conducted through calibration and validation against fabricated reference all-polymer and Sb2Se3 solar cells, yielding calibrated PCEs of approximately 10.1% and 10.5%, respectively. Subsequently, validated simulation models for both top and rear cells are utilized to design a 2-T all-polymer/Sb2Se3 tandem cell, which initially achieves a PCE of 10.91%. Through systematic optimization steps, including interface engineering and homojunction structure design, a remarkable PCE of 24.24% is achieved at the current matching point, showcasing the potential of our proposed tandem solar cell design. This study represents a significant advancement in the field of thin-film tandem solar cells, offering promising avenues for efficient and cost-effective photovoltaic technologies, particularly in applications requiring flexibility.

Nonlinear seismic response analysis of slopes considering the coupled effect of slope geometry and soil stratigraphy

SUMMARY To investigate the effects of slope geometric parameters and soil stratigraphic properties on the topographic amplification of ground motions, a large number of 2-D horizontally layered slope models are constructed. First, the linear and nonlinear seismic responses of a slope model are compared, and the result shows that the nonlinear characteristics of soils should be considered when studying the amplifying effect of slope topography on ground motions. Then, the nonlinear seismic responses of these slope models are analysed from four aspects: the maximum shear strain in the slopes, the effects of geometry and stratigraphy on the seismic response, the distance between the maximum topographic amplification indicators and the slope crest, and the influence range of slope topography behind the slope crest. The results indicate that the amplifying effect of slope topography on ground motions increases with increasing slope height or decreasing average shear wave velocity of the overlying soil layers. Besides, the variation of the topographic amplification effect with slope gradient is significantly influenced by soil stratigraphic properties. The distance between the maximum topographic amplification indicators and the slope crest is mainly in the range of 0–60 m, and the influence range of slope topography behind the slope crest is mainly in the range of 0–150 m. Subsequently, approximate relations are derived based on regression analyses of simulation results, which can provide meaningful references for the seismic design and seismic retrofitting of engineering structures behind the slope crest. Finally, the effects of slope geometric parameters and soil stratigraphic properties on ground motion modifications are further evaluated according to the prediction curves provided by the approximate relations.

DESIGNING FOR SUSTAINABILITY: A SHOPPING MALL ANALYZING LIFE CYCLE IMPACT OF STRUCTURAL DESIGNS AND MATERIALS

The lifespan of construction projects entails significant consumption of resources, energy, and space. Due to sustainability awareness throughout all stages of construction projects, Life Cycle Assessment (LCA) is one of the tools used for examining the impacts of a product or process at all stages of the product or process's life cycle, including conception, production, use, and disposal. In order to gain a deeper understanding of the choice of design and construction materials, a case study was conducted for a shopping mall. It included a comparison of the environmental impacts of utilizing the LCA approach throughout their lifespan for two structural engineering designs: concrete and steel. The life-cycle environmental impacts of the structures are evaluated throughout their life cycle using SimaPro software and the midpoint technique of the ReCiPe method. Based on the results, it was concluded that the concrete structure design had a greater negative environmental impact over the course of its life cycle than the steel structure design. As a result, the study emphasizes the significant environmental effects of building material choices as well as the value of life cycle assessment in selecting between various design options prior to the construction phase.

Fluidization characteristics of ore particles for downstream hydrogen mineral phase transformation equipment

Fluidized roasting is an effective way to deal with refractory iron ores. Fluidization is a prerequisite for the effective occurrence of physical and chemical reactions. This article conducts cold state experiments on Single-layer Overflow type Reaction Chamber, using hematite ore and quartz as bulk particles，processing pressure drop signals to analyze and explain gas-solid motion. The results indicate that the gas flow average pressure drop being stable is the criterion for the fluidized bed, the bulk properties significantly affect the critical fluidization characteristics. Pressure drop pulsation is an important characteristic of fluidized bed, fluidized gas velocity, initial bed height, and bulk properties all affect the amplitude of bed pressure drop pulsation, and the spectrum analyses of bed pressure drop signals all exhibit “High-energy and Low-frequency”. This study has certain guiding significance for the structural design optimization and engineering scaling of Downstream Hydrogen Mineral Phase Transformation Equipment.

Lessons Learned from the Greek Economic Crisis and the Changes in Organizational Behavior, Focusing on Motivation and Leadership Issues. The Case of Greek Structural Design Engineers

The modern business operates in an ever-changing environment that is strongly influenced by technological, political, social, economic, and scientific issues. Their future and success are based on their ability to manage properly and to develop their human resources. Because of the economic crisis that started on 2008 the work environment worldwide changed in a great number of organizations. This sudden change of organization generated new topics in the field of organizations. Leadership and motivation in the workplace are two of them. The current work paper focuses on the in-depth analysis of a small group of employees (qualitative research) in a workplace with a strong influence from the Greek economic crisis. In the first part is presented the social and working face of Greece, the timeline of Greek crisis and its consequences. Empirical research conducted within the changing environment, its results, conclusions, and recommendations complete the current paper. The outcome highlights the need of efficient leadership, communication, and intrinsic motivation within the economic crisis environment.

Vibration transmission characteristics of the pyramidal cylinder lattice truss structure

In this work, an innovative cylindrical metamaterial inspired by origami was developed. It featured arrays of pyramid units arranged both circumferentially and axially. The vibration transfer characteristics were determined using numerical method (Frequency Domain Frequency Response Solver of COMSOL) and dynamic testing (Scanning Vibrometer System). The results indicate that the structure effectively attenuates vibrations within the 0–6000 Hz range. Adjusting key geometric parameters can widen or shift vibration attenuation bands toward low–frequencies. Increasing the rod diameter weakens the vibration attenuation capability, while an increase in circumferential and axial angles has a positive impact on the frequency band for vibration attenuation. The significance of this work lies in providing an appropriate method to enhance vibration attenuation for the design and optimization of engineering structures.

Efficient Sizing and Layout Optimization of Truss Benchmark Structures Using ISRES Algorithm

This paper presents a comprehensive investigation into the application of the Improved Stochastic Ranking Evolution Strategy (ISRES) algorithm for the sizing and layout optimization of truss benchmark structures. Truss structures play a crucial role in engineering and architecture, and optimizing their designs can lead to more efficient and cost-effective solutions. The ISRES algorithm, known for its effectiveness in multi-objective optimization, is adapted for the single-objective optimization of truss designs with multiple design constraints. This study encompasses a wide range of truss benchmark structures, including 10-bar, 15-bar, 18-bar, 25-bar, and 72-bar configurations, each subjected to distinct loading conditions and stress constraints. The objective is to minimize the truss weight while ensuring stress and displacement limits are met. Through extensive experimentation, the ISRES algorithm demonstrates its ability to efficiently explore the solution space and converge to optimal solutions for each truss benchmark structure. The algorithm effectively handles the complexity of the problems, which involve numerous design variables, stress constraints, and nodal displacement limits. A comparative analysis is conducted to assess the performance of the ISRES algorithm against other state-of-the-art optimization methods reported in the literature. The comparison evaluates the quality of the solutions and the computational efficiency of each method. Furthermore, the optimized truss designs are subjected to finite element analysis to validate their structural integrity and stability. The verification process confirms that the designs adhere to the imposed constraints, ensuring the safety and reliability of the final truss configurations. The results of this study demonstrate the efficacy of the ISRES algorithm in providing practical and reliable solutions for the sizing and layout optimization of truss benchmark structures. The algorithm’s competitive performance and robustness make it a valuable tool for structural engineers and designers, offering a versatile and powerful approach for complex engineering optimization tasks. Overall, the findings contribute to the advancement of optimization techniques in structural engineering, promoting the development of more efficient and cost-effective truss designs for a wide range of engineering and architectural applications. The study’s insights empower practitioners to make informed decisions in selecting appropriate optimization strategies for complex truss-design scenarios, fostering advancements in structural engineering and sustainable design practices.

Complexity biomechanics: a case study of dragonfly wing design from constituting composite material to higher structural levels.

Presenting a novel framework for sustainable and regenerative design and development is a fundamental future need. Here we argue that a new framework, referred to as complexity biomechanics, which can be used for holistic analysis and understanding of natural mechanical systems, is key to fulfilling this need. We also present a roadmap for the design and development of intelligent and complex engineering materials, mechanisms, structures, systems, and processes capable of automatic adaptation and self-organization in response to ever-changing environments. We apply complexity biomechanics to elucidate how the different structural components of a complex biological system as dragonfly wings, from ultrastructure of the cuticle, the constituting bio-composite material of the wing, to higher structural levels, collaboratively contribute to the functionality of the entire wing system. This framework not only proposes a paradigm shift in understanding and drawing inspiration from natural systems but also holds potential applications in various domains, including materials science and engineering, biomechanics, biomimetics, bionics, and engineering biology.

Simulation and analysis of rust expansion cracking of reinforced concrete

Reinforced concrete is used in complex environment, and the damage of concrete protective layer caused by steel corrosion will seriously reduce the durability of the structure. In order to deal with the different corrosion morphology of steel bars in engineering, three different function expressions are proposed to describe the uniform and non-uniform corrosion of steel bars. Based on PF_CZM phase field model and adaptive refinement mesh technology, the cracking of concrete protective layer caused by different corrosion types of steel bars is simulated. The simulation results are close to the experimental or actual observed crack propagation. The research shows that the non-uniform corrosion coefficient (α) of steel bars affects the crack propagation form of protective layer. When α=1,2, the thinnest part of the protective layer will be penetrated by the main crack, and two secondary cracks will be produced on both sides. The characteristic displacement in the process of crack propagation is similar, and the maximum expansion displacement of steel bar is less than 125 μm when there is obvious crack in the protective layer. When α=4,8, the protective layer will produce two main cracks. The corrosion characteristic displacement is also similar, and the maximum expansion displacement of steel bars exceeds 180 μm when there are obvious cracks in the protective layer. However, with the increase of non-uniform corrosion coefficient, the amount of steel corrosion required for obvious damage and cracks gradually decreases, and the structure is more likely to be damaged. When non-uniform corrosion occurs in both longitudinal and transverse directions of steel bars, cracks will originate from the most serious corrosion of steel bars and spread to both sides. Compared with the two-dimensional simulation results, the simulated crack propagation morphology and the predicted structural durability results are more accurate. The coarse mesh is used to verify the adaptability of the method to the project, which provides reference for the engineering design and durability research of concrete structures.

Lightweight cellular multifunctional metamaterials with superior low-frequency sound absorption, broadband energy harvesting and high load-bearing capacity

Multifunctional materials are highly desired for the design of compact engineering structures, such as aircraft where weight reduction, sound absorption, load carrying, and energy harvesting are key considerations. However, design challenge remains in the balance of multiple functionalities. Here, we combine the sandwich structure with the neck-embedded cavities to design a cellular metamaterial having sound-absorption, compression/impact resistance and energy harvesting functionalities. For sound absorption, an autoencoder-like neural network is constructed to generate an instant design, after which a probabilistic module is inserted to optimize it by searching solutions in a slightly expanded design space. This inverse design has been experimentally validated, showing broadband sound absorption from 400 to 650 Hz merely with nine ultra-thin resonators. Beyond serving as absorber, the resonant cavities, once installed with well-tuned piezoelectric membranes, can gather broadband acoustic energy at low frequencies. Additionally, the cellular metamaterial inherits the excellent mechanical properties of honeycomb cores, having a low density of 0.64 g/cm3 yet displaying a high yield strength (21.2 MPa) in out-of-plane compression test and a superior energy absorption capability (8.6 J/cm3) in low-velocity impact tests. This work presents an effective approach to design lightweight metamaterials of superior mechanical and acoustic functionalities highly sought-after in practical engineering.

Characterizing vibrations and associated wake structures of tandem square cylinders at different angles of incidence

Finite element computations were conducted to investigate the transverse vibrations of three identical tandem square cylinders and the associated wake patterns at a Reynolds number Re = 150. The reduced velocities ranged from U*=3 to 20, and the angles of incidence were set at α=0°, 22.5°, and 45°. The streamwise gaps for these three α were Lx=5H, 3.8H, and 3.5H, respectively, where H represents the projected dimension of the cylinder normal to the freestream. The mass ratio of the cylinders was fixed at m*=2, and damping was neglected to allow the cylinders to attain maximum amplitudes. In the presence of primary vortices being shed from all three cylinders, the upstream cylinder at α=22.5° and 45° exhibits three distinct vibration regimes: initial excitation and upper and lower response regions. On the other hand, due to interaction with the upstream vortices, the two downstream cylinders display four response regions. In the case of α=0°, the dynamic response of the upstream cylinder appears in only two regimes, but with a higher peak amplitude compared to α=22.5° and 45°. Vibration and shedding frequencies closely synchronize with the natural frequency of the spring-mass system in the second regime, leading to high amplitude oscillations for the most upstream cylinder with α=22.5° and 45°. The third response regime for the two downstream cylinders is associated with the lock-in phenomenon. In α=0° and 22.5° configurations, the shedding mode is 2S in all response regimes, while at α=45°, the shedding mode shifts to P + S during the second regime. Up to the second regime, lift and vortex forces are in-phase with the cylinder's oscillation for α=0° and 22.5°, but they go out of phase beyond that. In the case of α=45°, although lift remains in-phase with the displacement in the second regime, the vortex force is found to be out of phase. This study is expected to enhance the understanding of fluid–structure interaction phenomena involved in multiple structures and can aid in the design of stable structures in civil engineering, offshore engineering, and development of energy harvesting devices.

Analysis of load-bearing characteristics of bi-modulus composite stiffened plates: Numerical simulation method and large-scale experimental verification

A large number of experiments show that composite materials usually show different modulus properties in tension and compression (bi-modulus). However, for actual composite engineering structures, especially complex models, the numerical simulation calculation is usually based on a single modulus. In order to consider the different modulus characteristics of composite materials in tension and compression, researchers put forward simplified constitutive models of dual-modulus materials. However, these constitutive models have not been verified by a large number of experiments, especially by complex models. In this paper, the GWFMM model is simplified and used to analyze complex structures with different modulus in tension and compression. The experimental results of stiffened plate show that the improved GWFMM model can be used to analyze different modulus of tension and compression of complex stiffened structures. In addition, the influence of elastic modulus ratio in tension and compression under different experimental load conditions is further explored, and the influence law of bending and torsion on structures with bi-modulus is discussed. The relevant conclusions provide reference for the design and optimization of full-scale composite structures in marine engineering.