Hasil untuk "Structural engineering (General)"

Chaomei Chen, Rachael Dubin, Meen Chul Kim

Kevin P. Murphy, Stuart J. Russell

S. Kapoor, S. Kundu

G. Vogt, Stefanie Woell, P. Argos

Sung Min Kang, Nathaniel S. Hwang, Jihyeon Yeom et al.

Pedram Bazrafshan, Kris Melag, Arvin Ebrahimkhanlou

Abstract This paper investigates the application of pre-trained Vision-Language Models (VLMs) for describing images from civil engineering materials and construction sites, with a focus on construction components, structural elements, and materials. The novelty of this study lies in the investigation of VLMs for this specialized domain, which has not been previously addressed. As a case study, the paper evaluates ChatGPT-4v’s ability to serve as a descriptor tool by comparing its performance with three human descriptions (a civil engineer and two engineering interns). The contributions of this work include adapting a pre-trained VLM to civil engineering applications without additional fine-tuning and benchmarking its performance using both semantic similarity analysis (SentenceTransformers) and lexical similarity methods. Utilizing two datasets—one from a publicly available online repository and another manually collected by the authors—the study employs whole-text and sentence pair-wise similarity analyses to assess the model’s alignment with human descriptions. Results demonstrate that the best-performing model achieved an average similarity of 76% (4% standard deviation) when compared to human-generated descriptions. The analysis also reveals better performance on the publicly available dataset.

Ignacio González Varas

En las investigaciones desarrolladas en el área de Composición Arquitectónica de la Escuela de Arquitectura de Toledo hemos tratado distintos temas vinculados con el patrimonio construido y el paisaje urbano. Situados en este ámbito de investigación, durante los últimos años nos hemos ocupado de un sistema patrimonial complejo como es el formado por los conventos urbanos de la ciudad de Toledo. Estos conjuntos arquitectónicos que llegaron a sumar algo más de medio centenar en la ciudad y de los que actualmente subsisten los edificios de una treintena de ellos, han contribuido de modo decisivo a la formación de la estructura urbana de Toledo así como a la caracterización de su prevalente imagen como ciudad conventual. Todos estos complejos arquitectónicos asumen un carácter de microciudades aisladas y autosuficientes y se articulan en torno a una pieza fundamental como es el claustro conventual. Nuestra investigación, sin obviar las líneas habituales de clasificación tipológica, morfológica y estilística de los claustros conventuales, presenta la originalidad de centrarse en el análisis del papel desempeñado por el claustro conventual en un doble sentido: en primer lugar, como elemento arquitectónico fundamental para entender la estructura, carácter y composición de los conventos de Toledo y en segundo lugar, en cuanto al papel ejercido por el claustro y/o patio conventual para otorgar orden y composición a la ciudad hasta el punto de erigirse el claustro en uno de los elementos más característicos del patrimonio cultural del conjunto histórico de Toledo.

Li Yu, Honghao Wu, Shumei Zeng et al.

Abstract Background Annulus fibrosis (AF) defects have been identified as the primary cause of disc herniation relapse and subsequent disc degeneration following discectomy. Stem cell-based tissue engineering offers a promising approach for structural repair. Menstrual blood-derived mesenchymal stem cells (MenSCs), a type of adult stem cell, have gained attention as an appealing source for clinical applications due to their potential for structure regeneration, with ease of acquisition and regardless of ethical issues. Methods The differential potential of MenSCs cocultured with AF cells was examined by the expression of collagen I, SCX, and CD146 using immunofluorescence. Western blot and ELISA were used to examine the expression of TGF-β and IGF-I in coculture system. An AF defect animal model was established in tail disc of Sprague-Dawley rats (males, 8 weeks old). An injectable gel containing MenSCs (about 1*106/ml) was fabricated and transplanted into the AF defects immediately after the animal model establishment, to evaluate its repairment properties. Disc degeneration was assessed via magnetic resonance (MR) imaging and histological staining. Immunohistochemical analysis was performed to assess the expression of aggrecan, MMP13, TGF-β and IGF-I in discs with different treatments. Apoptosis in the discs was evaluated using TUNEL, caspase3, and caspase 8 immunofluorescence staining. Results Coculturing MenSCs with AF cells demonstrated ability to express collagen I and biomarkers of AF cells. Moreover, the coculture system presented upregulation of the growth factors TGF-β and IGF-I. After 12 weeks, discs treated with MenSCs gel exhibited significantly lower Pffirrmann scores (2.29 ± 0.18), compared to discs treated with MenSCs (3.43 ± 0.37, p < 0.05) or gel (3.71 ± 0.29, p < 0.01) alone. There is significant higher MR index in disc treated with MenSCs gel than that treated with MenSCs (0.51 ± 0.05 vs. 0.24 ± 0.04, p < 0.01) or gel (0.51 ± 0.05 vs. 0.26 ± 0.06, p < 0.01) alone. Additionally, MenSCs gel demonstrated preservation of the structure of degenerated discs, as indicated by histological scoring (5.43 ± 0.43 vs. 9.71 ± 1.04 in MenSCs group and 10.86 ± 0.63 in gel group, both p < 0.01), increased aggrecan expression, and decreased MMP13 expression in vivo. Furthermore, the percentage of TUNEL and caspase 3-positive cells in the disc treated with MenSCs Gel was significantly lower than those treated with gel alone and MenSCs alone. The expression of TGF-β and IGF-I was higher in discs treated with MenSCs gel or MenSCs alone than in those treated with gel alone. Conclusion MenSCs embedded in collagen I gel has the potential to preserve the disc structure and prevent disc degeneration after discectomy, which was probably attributed to the paracrine of growth factors of MenSCs.

Mohamad Kharseh, Fayez Moutassem, Kadhim Alamara et al.

Accurately predicting the Ultrasonic Pulse Velocity (UPV) in concrete is important invarious fields, including construction, engineering and non-destructive testing. This research paper proposes a novel mathematical model based on Artificial Neural Networks (ANN) applied to accurately predict the UPV of concrete. The proposed model was formulated and validated through comprehensive experimental measurements, which were divided into three subsets for training, validating and testing the model. The training process involved adjusting the model’s parameters through iterative optimization techniques to minimize prediction errors. A separate group of measurements was used to validate the model’s precision and generality. The results demonstrate that the suggested equation matches the data from experiments well. Remarkably, the model achieved a high level of accuracy in predicting UPV values, with an error rate of less than 2% when compared to the measured experimental values. These results validate the effectiveness of the developed ANN model for accurate UPV predictions in concrete structures. The practical applications of the model extend to concrete characterization and non-destructive testing, enabling efficient quality control and assessment of structural integrity. Additionally, the model facilitates concrete characterization and mix design optimization, developing more durable and sustainable structures.

S. Vogel, Annette Ferrari

Seyed Mohammad Farnam, Mohsen Khorshidi

The use of shear walls is one of the diverse approaches to deal with lateral forces, and composite shear walls are among the different types of these walls. Composite walls consist of two steel sheets and a concrete core between them joined by shear connectors. In this system, the concrete cover can also participate in the load-bearing of the section. Shear connectors are used for bonding concrete to the steel sheet in the wall. Due to the necessity of creating a composite functionality, these connectors play an important role in the behavior of the system. Moreover, the effect of J-hook connectors on steel-concrete composite shear walls is investigated. For this aim, an experimental model is simulated and validated in the ABAQUS software. After verifying the accuracy of the model, a parametric analysis is defined and further studies are performed by using a nonlinear in-crescent static method (pushover method). The results of this study show that the J-Hook connector positively affects increasing load capacity and reducing the out-of-plane displacement of the composite shear wall. Additionally, the number and location of the connectors have a great impact on the both load and buckling capacity of the steel plate. Above all, adding concrete to the steel shear wall which consists of two steel sheets, not only rise the wall's bearing capacity by 14 percent, but improve the performance of the interaction between materials by about 17%.

He Li, Lulu Ren, Yao Zhou et al.

Hexagonal boron nitride nanosheets (BNNSs) are two-dimensional nanomaterials with graphitic-like layered nanostructures, high surface areas, and large aspect ratios. Owing to their excellent thermal conductivity, electrical and mechanical strengths, BNNSs are emerging as multifunctional fillers in polymer dielectrics. In this article, the authors review the recent progress in the BN-containing polymer nanocomposites designed for high-performance film capacitors. While general synthetic approaches to BNNSs and polymer/BNNS nanocomposites are summarized, particular attention is placed on structure-property correlation and rational structural design of the composites with optimized dielectric properties and capacitive performances. In stark contrast to the polymer composites employing high dielectric constant fillers to enhance the electric displacement, a new design concept based on the utilization of BNNSs with a wide bandgap to impede electrical conduction and consequently improve breakdown strength and charge-discharge efficiency of the polymer composites, is highlighted. The significance of developing dielectric capacitors with desirable thermal conductivity and thermal stability to ensure their robust and efficient operation is emphasized. The merits and challenges regarding the existing polymer dielectrics containing BNNSs for energy storage are identified. An outlook for future research opportunities and engineering applications is also presented in this review.

Maycon Vinicius Damasceno de Oliveira, Renan Machado Furtado, Kauê S. da Costa et al.

Peptidoglycan is a cross-linked polymer responsible for maintaining the bacterial cell wall integrity and morphology in Gram-negative and Gram-positive bacteria. The peptidoglycan pathway consists of the enzymatic reactions held in three steps: cytoplasmic, membrane-associated, and periplasmic. The Mur enzymes (MurA-MurF) are involved in a cytoplasmic stage. The UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) enzyme is responsible for transferring the enolpyruvate group from phosphoenolpyruvate (PEP) to UDP-N-acetylglucosamine (UNAG) to form UDP-N-acetylglucosamine enolpyruvate (EP-UNAG). Fosfomycin is a natural product analogous to PEP that acts on the MurA target enzyme via binding covalently to the key cysteine residue in the active site. Similar to fosfomycin, other MurA covalent inhibitors have been described with a warhead in their structure that forms a covalent bond with the molecular target. In MurA, the nucleophilic thiolate of Cys115 is pointed as the main group involved in the warhead binding. Thus, in this minireview, we briefly describe the main recent advances in the design of MurA covalent inhibitors.

Jagan Jayabalan, Manju Dominic, Ahmed M. Ebid et al.

Steel plates are used in the construction of various structures in civil engineering, aerospace, and shipbuilding. One of the main failure modes of plate members is buckling. Openings are provided in plates to accommodate various additional facilities and make the structure more serviceable. The present study examined the critical buckling load of rectangular steel plates with centrally placed circular openings and different support conditions. Various datasets were compiled from the literature and integrated into artificial intelligence techniques like Gene Expression Programming (GEP), Artificial Neural Network (ANN) and Evolutionary Polynomial Regression (EPR) to predict the critical buckling loads of the steel plates. The comparison of the developed models was conducted by determining various statistical parameters. The assessment revealed that the ANN model, with an R² of 98.6% with an average error of 10.4%, outperformed the other two models showing its superiority in terms of better precision and less error. Thus, artificial intelligence techniques can be adopted as a successful technique for the prediction of the buckling load, and it is a sustainable method that can be used to solve practical problems encountered in the field of civil engineering, especially in steel structures.

E. Mohseni

Abstract The aim of this project is to build and use a concrete with minimum irritating impacts on the environment, reasonable price and optimal properties. Geopolymer concrete is new class of mineral binder that due to the high durability, very low energy consumption, very low CO2 emission, low investment cost and also special properties, is distinguished of other mineral binder such as Portland cement. In this study, after construction of metakaolin-based geopolymer concrete containing 0.3, 0.5 and 1% polypropylene (PP) fibers with monomer ratios of 2, 2.5 and 3, engineering properties including compressive strength, flexural strength, displacement, Si/Al ratio, water absorption and electrical resistivity were assessed. Microstructural and structural changes of geopolymers as a result of lead addition/immobilization were evaluated via scanning electron microscopic (SEM) and X-ray Diffraction (XRD) tests. The obtained results showed that using PP fiber in geopolymer samples increased the flexural strength by 28%. Furthermore, as evidenced by XRD diffractogram, the compressive strength improved by increasing the SS/SH ratio due to the formation of crystalline nepheline in the geopolymer specimens. In addition, images of electron microscopy of hardened geopolymer paste confirmed the remarkable increase in the density and uniformity of polymer products in the presence of suitable monomer ratios. In general, it is reported that using 1% PP fibers along with the sodium silicate to sodium hydroxide ratio of 3 had an acceptable outcome in improving geopolymer concrete performance from point of view of environmentally, structurally and economically.

WANG Zhikai, CHEN Jin, YAO Xiongliang, JIANG Zifei

Aimed at the reconstruction problem of foreign large-scale warships, the spacing and minimum plate thickness of some profiles of large-scale warships are obtained by adopting the grey theory method and taking the data in the design code of warships as samples. Based on the advantages of the grey theory in dealing with small data and uncertainties, the grey models of different captains and their corresponding profile parameters are built and compared with the data of foreign large ships. The results show that the method has a high accuracy in calculating structural parameters with a strong correlation with the total longitudinal strength. The reason for the deviation in calculating structural parameters with local strength as the main consideration factor lies in the fact that the captain parameters as the reference for modeling are highly correlated with the total longitudinal strength. The magnitude of the deviation by calculating the grey relational degree between the structural parameters and the captain is described, and the results obtained are of engineering application value.

J. Salvi, Fabio Pioldi, E. Rizzi

Abstract Tuned Mass Damper (TMD) devices are widely adopted as a valid mechanical solution for the vibration mitigation of structural systems and buildings under dynamic excitation. In the specific challenging context of seismic engineering, TMDs may represent a convenient option for both aseismic structural design and seismic retrofitting. However, the expectable efficiency rate of TMDs in that context is still debated. Besides, potential Soil-Structure Interaction (SSI) effects may become crucial in the mechanical system, and should properly be taken into account for the optimum TMD design, in order to avoid possible de-tuning. This work contributes to this framework, by investigating the effectiveness of an optimum TMD in reducing the linear structural response to strong-motion earthquakes of a given set of Multi-Degree-Of-Freedom (MDOF) low- and high-rise shear-type frame structures, by embedding SSI within the dynamic and TMD optimisation model. The TMD is seismically tuned through a dedicated two-variable optimisation procedure, for each specific case (primary structure, seismic event and soil type), therefore providing the optimum device setting for each given context. Average primary structure response indices are specifically targeted to that purpose, while maximum ones are monitored. A quite considerable range of optimisation cases is considered (eighty instances), to outline rather general considerations and average trends on TMD optimisation and effectiveness within the seismic SSI framework, for both low- and high-rise buildings. Such an investigation shall provide useful guidelines for a comprehensive tuning of TMDs in mechanical systems and specifically in the presence of seismic SSI, to be consulted in view of real-case applications.

A. El-Serwi, E. Sayed-Ahmed