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INVESTIGATION OF FLEXURAL BEHAVIOUR OF STAINLESS STEEL CHANNEL SECTIONS

ce/papers 2024年第1-2期7卷 240-249页

作者： de Lima, Cláucio Gonçalves Rodrigues, Monique Cordeiro Pereira, e Fernanda Lins Gonçalves PGECIV – Civil Engineering Post-Graduate Program UERJ – State University of Rio de Janeiro Brazil Structural Engineering Department UERJ – State University of Rio de Janeiro Brazil

In this paper, the design of austenitic stainless steel channel sections subjected to minor axis bending, specifically with tension in the web ("u" orientation) is analyzed. The values of moment resistance are predicted using Eurocode 3 criteria and the Continuous Strength Method (CSM), which are then compared with numerical models to assess effectiveness. The modeling is performed through ANSYS and calibrated with literature tests. It was found that Eurocode presents a considerable disparity in results, as well as an overly cautious response (on average, half the numerical load). The CSM reflects the performance more accurately but still with a certain level of conservatism (on average, around 35% lower). © 2024 Ernst & Sohn GmbH.

关键词： Codes (standards)

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Multiscale investigation of seismic precursors before major earthquakes

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Mechanics Research Communications 2025年 147卷

作者： Leandro Ferreira Friedrich Mariana Hamdan Padilha Giuseppe Lacidogna Ignacio Iturrioz Department of Structural Geotechnical and Building Engineering Politecnico di Torino 24 Corso Duca degli Abruzzi 10129 Torino Italy Mechanical Post-Graduate Program Universidade Federal do Rio Grande do Sul Sarmento Leite 425 CEP 90050-170 Porto Alegre Brazil

In various mechanical systems, the study of damage processes can be approached from the perspective of continuous phase transition phenomena, a subject typically explored within the framework of statistical physics. This viewpoint enables a more refined interpretation of failure precursors, which are of great importance in the field. The present study investigates failure precursors through two case studies: the material failure process by using the Fiber Bundle Model and the seismicity of the 2023 Turkey Mw7.7 earthquake. To identify the criticality, two approaches are considered: (1) Natural Time (NT) analysis and (2) the Method of Critical Fluctuation-Based (MCF-B) approach. By comparing the evolution of precursors in both cases, the findings highlight their potential for predicting critical situations.

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Thermal modeling and monitoring of massive concrete foundations to prevent pathological manifestations

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Journal of Building Pathology and Rehabilitation 2023年第1期8卷 1-9页

作者： Vidal, Alexandre Machado, Amanda Babadopulos, Lucas Magalhães, Raquel Graduate Program in Civil Engineering (PPGEC) University of São Paulo (USP) São Paulo Brazil Graduate Program in Civil Engineering (PEC) Federal University of Ceará (UFC) Fortaleza Brazil Department of Structural Engineering and Civil Construction (DEECC) Federal University of Ceará (UFC) Fortaleza Brazil Graduate Program in Mathematics (PPG-MAT) University of São Paulo (USP) São Paulo Brazil

The increase in the scale of towers construction requires larger concrete foundations, wither for buildings or for other infrastructures such as those necessary for wind energy production. Heat generation by cement hydration, large dimensions and low heat dissipation capacity of concrete causes high internal temperatures in the foundations, which can lead to cracking due to thermal stresses at early ages or expansion due to delayed ettringite formation (DEF). This study aimed to develop and validate with experimental data a thermal simulation model of foundations for assessing the risk of pathological manifestations, track temperatures developed by the structure and investigate the effects of using fly ash (FA) and polyfunctional additive (PF) in the concrete mix, among other simulation conditions. Ansys software was used to develop a finite element model. Different calorimetric profiles were inserted as a function of the presence of FA and PF in the concrete. Real climate data was used to approximate the model to reality and to study the effect of weather conditions on the temperatures developed by the structure. The simulations showed that the replacement of Portland cement by FA reduced the maximum temperatures in the structure, and the use of PF delayed the start of heating but did not affect the maximum temperatures reached. The ambient temperature varying with time caused oscillations in the temperature of the border of the structure, in response to the heat exchanges. Wind speed affected the cooling potential and the intensity of the oscillations. Through an observation of collected data, the influence of environmental conditions on the behavior of the structure was confirmed. It was concluded that the model was able to represent the real situation well and that the control of heat exchange can aid the prevention of cracking of the massive concrete foundation. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Delayed ettringite formation Massive foundation Thermal crack Thermal simulation

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Comparison between different internal cross-sections for pulmonary secretion suction catheters

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Research on Biomedical engineering 2022年第3期38卷 965-975页

作者： dos Santos Lima, Bruna Luiza Tadeu Las Casas, Marina Spyer de Oliveira, Patrícia Muniz Huebner, Rudolf Rodrigues-Machado, Maria da Glória de Las Casas, Estevam Barbosa Department of Structural Engineering Federal University of Minas Gerais Belo Horizonte Brazil Department of Mechanical Engineering Federal University of Minas Gerais Belo Horizonte Brazil Faculty of Medical Sciences of Minas Gerais Post-graduate Program in Health Sciences Belo Horizonte Brazil

Introduction: Endotracheal suctioning is a procedure to remove pulmonary secretions, which can lead to complications such as hypoxemia. To minimize this risk, a double-lumen pulmonary secretion suction device was developed at the Biomechanics Laboratory of the University of Minas Gerais. The aim of the study is to evaluate the flow of the removal of pulmonary secretions by reducing the cross-section for the passage of mucus, considering catheters with three new, distinct internal cross-sections (circular, semicircular, and curved). Methods: The study was divided into two stages: computer simulations in the software Ansys Fluent using three new internal cross-sections in order to assess the flow rate, secretion removal, and the preparation of solutions of mucus simulators (polyethylene glycol) in three concentrations (semi-liquid, intermediate, and semi-solid) to be aspirated by 12 Fr catheters and by a printed circular catheter in the bench test. Results: It was verified in a bench test that the relationship between shear stress and deformation rate of mucus simulator solutions is not linear and that a suction pressure of less than 300 mmHg, performed by a standard catheter, generates moderate rates of removal of thicker solutions. It is possible to verify, by computer simulations, higher flow rate levels when reducing the length of the circular catheter from 0.5 to 0.4 m. Semicircular catheter produces high flow rates when compared to other proposed catheters. Conclusion: Based on the results obtained, a dual-lumen semicircular catheter can be designed and validated by computer simulation. © 2022, Sociedade Brasileira de Engenharia Biomedica.

关键词： Catheters

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ON SOME RECENT EVOLUTIONS IN PERSONAL SUPERCOMPUTING AND WORKSTATION GRAPHICS

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COMMUNICATIONS IN APPLIED NUMERICAL METHODS 1988年第3期4卷 373-378页

作者： HAJJAR, JF MARTHA, LF OCONNOR, TF ABEL, JF Program of Computer Graphics Cornell University Ithaca NY 14853 U.S.A. Graduate Research Assistant Department of Structural Engineering. Graduate Student Department of Structural Engineering. Visualization Engineer/Technical Specialist. Professor of Structural Engineering.

Recent hardware advances for both enhanced computing and interactive graphics are used to improve the effectiveness of three-dimensional engineering simulations. The two examples presented, drawn from structural engin... 详细信息

关键词： Computers, Personal

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Fiber reinforced polymers for historical bridges upgrading: a fatigue life assessment

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Journal of Building Pathology and Rehabilitation 2023年第1期8卷 1-11页

作者： Garcez, Mônica Regina Meneghetti, Leila Cristina Post-Graduate Program in Civil Engineering: Construction and Infrastructure Federal University of Rio Grande do Sul Porto Alegre Brazil Department of Structural and Geotechnical Engineering University of São Paulo São Paulo Brazil

Upgrading historical structures is one of the most interesting applications of fiber reinforced polymers in construction. Historical bridges are frequently post-strengthened to increase load carrying capacity of structural elements, aiming to bear heavier commercial traffic. Fatigue life becomes crucial since the lack of available fatigue models leads to superficial analysis considering the same S–N curves for different strengthening systems and steel stress ranges. This paper uses an extensive database with experimental data from the literature to adjust linear regression models to characterize the large scatter between the results of fatigue tests from different sources. Distinct fatigue models have been developed considering three categories: externally bonded reinforcement with strips/sheets and new surface-mounted reinforcement. The different declivities found for the adjusted fatigue life models accurately represent the fatigue behavior of the post-strengthened structural elements with the assessed systems and techniques. The results support design decisions to avoid future unnecessary interventions. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Fatigue life Fiber reinforced polymers Historical bridges Linear regression analysis

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A neural network modelling of steel joint block shear capacity

A neural network modelling of steel joint block shear capaci...

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9th International Conference on the Application of Artificial Intelligence to Civil, structural and Environmental engineering, AICivil-Comp 2007

作者： Rodrigues, F. Neto, L. Biondi Da S. Vellasco, P.C.G. De Lima, L.R.O. Vellasco, M.M.B.R. Post-Graduate Program in Civil Engineering Brazil Electronic Engineering Department Brazil Structural Engineering Department State University Rio de Janeiro Brazil Electrical Engineering Department Pontifical Catholic University Rio de Janeiro Brazil

ISBN: (纸本)9781905088201

Despite the multiple failure modes associated to bolted steel joints the block shear failure is frequently the controlling limit state of gusset plates, tension members and coped beam joints. The block shear rupture is characterised by a condition where a steel block area, nearby the holes of bolted joint region, reaches its maximum capacity dictated by a tension to shear interaction. If the joint is loaded beyond this limit a steel block is eventually separated from the main structure. Many models have been proposed to avoid shear block failure in steel design. These models incorporate a combination of the various hypotheses that control the structural rupture. In the majority of cases, it involves a combination of rupture and yielding in the tension and shear planes of the designed joint. Various design formula for this structural engineering problem were proposed all over the years but a closed solution has not yet been reached, due to the influence of several independent parameters. Many studies have already been carried out with the available experimental data, however, non negligible errors are still present in the current design formulae. The main objective of the present paper is to present a back propagation neural network evaluation of the block shear phenomenon. The main neural network input parameters were the geometrical and material variables that control the block shear design. The neural network output parameter was the block shear capacity. The neural network training was based on experimental results present in literature and adopted cross validation techniques to avoid the neural network overfitting. The neural network results were promising, with reduced associated errors and confirmed the possibility of using this methodology to generate trustworthy data. These new data, coupled with the existent experiments, can help the production of more accurate design formulae. © Civil-Comp Press, 2007.

关键词： Neural networks

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Investigation of the supply chain of prefabricated wooden doors

Investigation of the supply chain of prefabricated wooden do...

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18th Annual Conference of the International Group for Lean Construction, IGLC 18

作者： De Melo, Reymard Sávio S. Da Alves, Thais C.L. Graduate Program in Structural Engineering and Construction Federal University of Ceará Fortaleza CE Brazil J.R. Filanc Construction Engineering and Management Program Department of Civil Construction and Environmental Engineering San Diego State University San Diego CA 92182-1324 United States

This study focused on pre-fabricated wooden doors and their supply chain, which have all of its components pre-assembled by the supplier. The literature indicates that supply chain management in construction has four roles. One concerns the transfer of activities from the site to the supply chain to take advantage of better conditions at the fabricator's end. This role assumes that fabricators are in a better environment to perform certain tasks and deliver better products that can be quickly installed on site, as the product is pre-assembled. This is the first working hypothesis tested in study. A second working hypothesis is that off-site prefabricated doors have short lead times for fabrication and on-site installation and present fewer problems during installation when compared to traditional doors. The two-phase research comprised a preliminary study and two in-depth case studies about pre-fabricated wooden doors. Wooden doors presented problems related to the installation and final product quality regardless of the type of project. Some advantages of prefabricated elements were lost due lack of trust between contractors and suppliers, lack of consideration of preconditions necessary for successful site installation, and lack of standardization and tolerance management resulted in suboptimal solutions during the installation phase.

关键词： Fabrication

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Finite element modelling of steel beams with web openings

Finite element modelling of steel beams with web openings

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11th International Conference on Civil, structural and Environmental engineering Computing, Civil-Comp 2007

作者： Rodrigues, F. Da Vellasco, P.C.G.S. De Lima, L.R.O. De Andrade, S.A.L. Da Silva, J.G.S. Post-Graduate Program in Civil Engineering State University of Rio de Janeiro Brazil Structural Engineering Department State University of Rio de Janeiro Brazil Mechanical Engineering Department State University of Rio de Janeiro Brazil

ISBN: (纸本)9781905088157

Height limitations are frequent in multi-storey buildings due to zoning regulations, economic requirements and esthetical considerations. On the other hand, substantial spaces are normally required to enable the passage of large pipes and ducts beneath steel beams leading to uneconomic floor heights. The most adopted solution is the use of holes at the steel beam webs in order to enable the passage of services. Chung et al. [1], [3] state that nowadays services that require web openings up to 75% of the beam height are not uncommon. These openings could lead to a significant decrease of the beam load carrying capacity depending on the adopted holes shape, size and location. This motivated the present study that used finite elements simulations to quantitative and qualitative evaluates the structural behaviour of steel beams with web openings. This paper presents the developed finite element models using the ANSYS [6] program to investigate the structural response of steel beams with web openings. The analysis incorporated geometric and material non-linearities and were calibrated against numerical and test results to validate the proposed finite element models. The investigation also contemplated the simulations of beams with a series of holes distributed all over their length known as cellular beams. The imulations were centred at the evaluation of the different steel beams with web penings failure mechanisms and the main reasons for yours collapse modes. © 2007 Civil-Comp Press.

关键词： Finite element method

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WITHDRAWN: A finite element/generalized finite element code-coupling approach for linear elastic fracture mechanics problems

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engineering Analysis with Boundary Elements 2016年 73卷 200-207页

作者： Mohammad Malekan Felício B. Barros Roque L.S. Pitangueira Graduate Program in Structural Engineering (PROPEEs) School of Engineering Federal University of Minas Gerais (UFMG) Belo Horizonte MG Brazil

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