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Simplified Footing design with Interaction Diagrams

PRACTICE PERIODICAL ON STRUCTURAL design AND CONSTRUCTION 2023年第1期28卷 06022004-06022004页

作者： Fargier-Gabaldon, Luis B. Univ Notre Dame Practice Heavy Civil Engn Notre Dame IN 46556 USA

Two interaction diagrams for proportioning rigid rectangular or wall footings on soil or rock are presented in this technical note. A new alternative approach to an old problem, based on simplicity and versatility. The content is derived from standard bridge specifications. It covers bearing resistance at the strength limit state of wall foundations on soil and rock, while the loading pattern that has been adopted allows checking against uplift. A unique feature of the proposed design methodology is that the interaction diagrams are derived in a dimensionless form and thus any rectangular shallow foundation on any soil classification can be proportioned with the aid of a single plot.

关键词： Soil-structure interaction Bearing pressures Interaction diagrams Footings substructure design

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Influence of structural design variations on economic viability of offshore wind turbines: An interdisciplinary analysis

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RENEWABLE ENERGY 2020年 145卷 1348-1360页

作者： Huebler, Clemens Piel, Jan-Hendrik Stetter, Chris Gebhardt, Cristian G. Breitner, Michael H. Rolfes, Raimund Leibniz Univ Hannover Inst Struct Anal ForWind Appelstr 9a D-30167 Hannover Germany Leibniz Univ Hannover Inst Informat Syst Konigsworther Pl 1 D-30167 Hannover Germany

Offshore wind energy is a seminal technology to achieve the goals set for renewable energy deployment. However, today's offshore wind energy projects are mostly not yet sufficiently competitive. The optimization of offshore wind turbine substructures with regard to costs and reliability is a promising approach to increase competitiveness. Today, interdisciplinary analyses considering sophisticated engineering models and their complex economic effects are not widespread. Existing approaches are deterministic. This research gap is addressed by combining an aero-elastic wind turbine model with an economic viability model for probabilistic investment analyses. The impact of different monopile designs on the stochastic cost-efficiency of an offshore wind farm is investigated. Monopiles are varied with regard to diameters and wall thicknesses creating designs with increased lifetimes but higher capital expenditures (durable designs) and vice versa (cheaper designs). For each substructure, the aero-elastic wind turbine model yields distributions for the fatigue lifetime and electricity yield and different capital expenditures, which are applied to the economic viability model. For other components, e.g. blades, constant lifetimes and costs are assumed. The results indicate that the gain of increased stochastic lifetimes exceeds the benefit of reduced initial costs, if the overall lifetime is not governed by other turbine components' lifetimes. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Offshore wind energy substructure design Economic viability Stochastic cost-efficiency Lifetime distribution

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Efficient topology optimization of multicomponent structure using substructuring-based model order reduction method

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COMPUTERS & STRUCTURES 2020年 228卷 1页

作者： Koh, Hyeong Seok Kim, Jun Hwan Yoon, Gil Ho Hanyang Univ Mech Engn Seoul South Korea

This study develops a novel model reduction (MR) scheme called the multi-substructure multi-frequency quasi-static Ritz vector (MMQSRV) method to compute dynamic responses and sensitivity values with adequate efficiency and accuracy for topology optimization (TO) of dynamic systems with multiple substructures. The calculation of structural responses of dynamic excitation using the framework of the finite element (FE) procedure usually requires a significant amount of computation time. The ever-increasingly complex phenomena of FE models with many degrees of freedom make it difficult to calculate FE responses in the time or frequency domain. To overcome this difficulty, model reduction schemes can be utilized to reduce the size of the dynamic stiffness matrix. This paper presents a new model order reduction method called MMQSRV, based on the quasi-static Ritz vector method, with Krylov subspaces spanned at multiple angular velocities for efficient TO. Through several analysis and design examples, we validate the efficiency and reliability of the model reduction schemes for TO. (C) 2019 Published by Elsevier Ltd.

关键词： Topology optimization Model reduction schemes substructure design Krylov subspace Ritz vector method

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Influence of substructure design, veneer application technique, and firing regime on the in vitro performance of molar zirconia crowns

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DENTAL MATERIALS 2013年第7期29卷 E113-E121页

作者： Preis, Verena Letsch, Christoph Handel, Gerhard Behr, Michael Schneider-Feyrer, Sibylle Rosentritt, Martin Univ Med Ctr Regensburg Dept Prosthet Dent D-93042 Regensburg Germany

Objectives. The aim of this in vitro study was to evaluate the influence of substructure design, veneer application technique, and firing regime on the failure and fracture resistance of molar zirconia crowns. Methods. Six groups (n = 8/group) of zirconia crowns were fabricated in simple core (SC) or anatomically reduced (AR) design, veneered with different feldspathic or glass ceramic materials, and defined according to the application technique and firing regime (LT: layering technique;LT L: LT with long-term cooling;PT: press technique;DV: digital veneering technique). The following groups were investigated: SCLT, ARLT, SCLT_L, SCPT, ARPT, ARDV. Crowns were adhesively bonded to polymethylmethacrylate abutment teeth and subjected to thermal cycling (TC: 2 x 3000 x 5 degrees/55 degrees) and mechanical loading (ML: 1.2 x 10(6);50 N;1.6 Hz) in a chewing simulator with metal-ceramic molar crowns as antagonists. Failures were monitored and fracture resistance determined after aging. Data were statistically analyzed (one-way analysis of variance, ANOVA;post hoc Bonferroni, alpha = 0.05). Crowns were subjected to scanning electron microscopy for fractographic failure analysis. Results. Failures (chipping, cracks) during TCML were observed in groups SCLT (2x), ARDV (2x) and SCLT_L (1x). Defect sizes varied between 3.5 mm (SCLT: crack) and 30.0 mm(2) (SCLT_L: chipping). Mean (SD) fracture forces ranged between 1529.0 (405.2) N for SCPT and 2372.3 (351.8) N for ARDV. Significance. The failure frequency of veneered zirconia crowns could be reduced by using anatomically reduced substructures, the press veneering technique, and an adapted cooling protocol. Fracture resistance increased with use of anatomically reduced substructures and the digital veneering technique. (C) 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

关键词： Zirconia Ceramics Veneering substructure design Chipping Fracture resistance

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Fracture resistance of different metal substructure designs for implant-supported porcelain-fused-to-metal (PFM) crowns

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JOURNAL OF DENTAL SCIENCES 2013年第3期8卷 314-320页

作者： Wang, Chau-Hsiang Wu, Ju-hui Li, Hung-Yuan Wang, Ping-Ping Lee, Huey-Er Du, Je-Kang Kaohsiung Med Univ Hosp Dept Dent Kaohsiung 80708 Taiwan Kaohsiung Med Univ Coll Dent Med Sch Dent Kaohsiung Taiwan Natl Kaohsiung Univ Appl Sci Dept Mold & Die Engn Kaohsiung 807 Taiwan Kaohsiung Med Univ Coll Dent Med Grad Inst Dent Sci Kaohsiung Taiwan

Background/purpose: This study evaluated the fracture resistance of different metal substructure designs for implant-supported porcelain-fused-to-metal (PFM) crowns. Materials and methods: Eighteen PFM crowns were fabricated using different metal substructure designs and were conventionally cemented on an implant abutment analog. The crowns were divided according to the metal substructure design for manufacturing the metal framework into three groups of six specimens each: Group A had a minimum required thickness;Group B had a conventional design;and Group C had a wrinkled design. After applying a load of 200 N at a frequency of 2 Hz with 300,000 cycles of dynamic loading, all specimens were tested for fracture resistance using compression loading on the buccal functional cusp. Results: Among these three groups, Groups A and B, respectively, had the minimum and maximum fracture resistance strengths. Respective data for Groups A, B, and C were 111.13 +/- 27.15 kg, 236.13 +/- 39.21 kg, and 188.63 +/- 12.10 kg. Statistically significant differences were observed among the three groups (P < 0.05). Conclusion: These results confirm that the conventional design had the best fracture resistance, and an excessively thick porcelain layer can cause crown fracture. However, there was no obvious proof that the wrinkled design had better fracture resistance than the conventional design. Therefore, the theory that PFM can provide better support requires further corroboration. Copyright (C) 2013, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.

关键词： cyclic loading fracture resistance implant support porcelain-fused-to-metal substructure design wrinkled design

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Recommendations for Numerical Rail substructure Modeling Considering Nonlinear Elastic Behavior

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JOURNAL OF TRANSPORTATION ENGINEERING 2013年第8期139卷 848-858页

作者： Gallego, Inmaculada Munoz, Jorge Sanchez-Cambronero, Santos Rivas, Ana Univ Castilla La Mancha Dept Civil Engn E-13071 Ciudad Real Spain

This paper considers the problem of modeling railway track substructure. The most commonly used methodology for designing the railway substructure cross section does not considerably differ from that proposed in the 1980s. For the bearing capacity of the subgrade, the currently used design methodology implicitly meets one objective: the stresses transmitted to the subgrade must be compatible with its bearing capacity. The bearing capacity depends on the qualities and thicknesses of the soils that compose the subgrade, from the formation layer to the lower layers. In addition, railway administrations have included additional recommendations based on their experience. During the last decade, finite-element models (FEM) have been shown to be a very useful tool for designing cross sections. These models are often very complex and require a very high computational time to be solved. To reduce this complexity and computational time while remaining faithful to the reality to be modeled, this paper proposes some recommendations to develop a parameterized numerical model in three dimensions within the elastic nonlinear range under the static load of a given railway section. To adequately reproduce the real behavior of materials (elastoplastic) and the contact surfaces between very different materials adequately, artifices to use the model in the elastic range are propsed. In addition, the goodness of this design is analyzed using multilayer numerical models. This model may be a very useful tool for analyzing the behavior of different types of railway cross sections. (C) 2013 American Society of Civil Engineers.

关键词： Finite-element numerical model Railway track design Railway track modeling Nonlinear elastic behavior Parameterized geometry substructure design

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Mechanical characterization of railway structures based on vertical stiffness analysis and railway substructure stress state

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART F-JOURNAL OF RAIL AND RAPID TRANSIT 2013年第F1期227卷 74-85页

作者： Montalban, Laura Real, Julia Real, Teresa Univ Politecn Valencia Dept Ingn & Infraestruct Transportes Valencia 46022 Spain Univ Alicante Dept Ingn Construcc Alicante Spain

This paper uses the finite element method to analyse the mechanical behaviour of different track types by considering the different conditions to which they may be subjected: superstructure, height, embankment and foundation quality. The values of the stress and deformation as a function of depth are obtained at each point of the cross-section of the considered track. These values allow quantification of the basic design parameters for railway structures: track stiffness and stress supported by the railway platform. Optimal combinations of superstructure, height, embankment and foundation materials are presented for various specific operation conditions. The presented information can be used to improve the design of railway structures.

关键词： Railway stiffness stress substructure design ballast track slab track

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Study of the influence of geometrical and mechanical parameters on ballasted railway tracks design

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2012年第9期26卷 2837-2844页

作者： Real, Julia I. Gomez, Laura Montalban, Laura Real, Teresa Univ Politecn Valencia Escuela Tecn Super Ingenieros Caminos Canales & P Dept Ingn & Infraestruct Transportes Valencia 46022 Spain Univ Alicante Dept Ingn Construcc Obras Publ & Infraestruct Urb E-03080 Alicante Spain

This paper investigates the vertical deflection on ballasted railway tracks from a set of cases of railway track typologies which differ in six track parameters: embankment height, ballast thickness, sleeper spacing, rail pad stiffness, Young's modulus of the embankment material and the load applied to the structure. Finite element method has been the tool to assess the structural combinations and the results provided by linear and nonlinear analyses have been contrasted. Then, a new formulation for the deflection estimation in terms of the aforementioned parameters is presented based on a multiple regression model. The results provided by this formulation have been compared to those obtained from the classic Zimmermann theory. Finally, a stress analysis has been performed to complete the study and better understand the global behaviour of the railway structure. This article pretends to improve the design process and construction of ballasted railway tracks by means of proposing a formulation which estimates the track deflection to obtain the optimum track stiffness.

关键词： Railway Stiffness Stress substructure design Ballast track Finite elements

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Analysis of various designs of the stationary platform substructures for the Pechora Sea shelf

Analysis of various designs of the stationary platform subst...

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10th International Offshore and Polar Engineering Conference (ISOPE-2000)

作者： Bellendir, EN Toropov, EE BE Vedeneev VNIIG St Petersburg Russia

ISBN: (纸本)1880653478

Arctic shelf of Russia is a region rich in production of hydrocarbon materials. The nearest prospect is the development of oil and gas fields in the Pechora Sea. Intensive surveying of this region including hydrometeorological, geological, geotechnical and ice studies for deployment of prosperous fields were carried out during the last years. Analysis of possible types of permanent platform substructures (caisson, monocone, multicolumn and truss types) applicable for hydrocarbon extraction in Pechora Sea was carried out accounting for the influence of soil conditions on the design. Qualitative comparison of technical parameters is given for various substructure types.

关键词： offshore oil field development substructure design gravity based structures pile foundation substructure installation soil conditions Pechora Sea

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THE DEVELOPMENT OF AESTHETIC GUIDELINES FOR SHORT AND MEDIUM SPAN TEXAS BRIDGE SYSTEMS

THE DEVELOPMENT OF AESTHETIC GUIDELINES FOR SHORT AND MEDIUM...

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作者： SCOT THOMAS LISTAVICH The University of Texas at Austin

学位级别：硕士

The Texas Department of Transportation (TxDOT) has been building successful bridges for many years In addition to their proven economy, safety, and durability, their use of precast pretensioned girders alleviates construction congestion which is typical of cast-in-place construction It can be said that Texas pretensioned girder bridges represent the state of the art in ways such as economy, constructability, safety, and durability The only area not extensively explored by the Department of Transportation is the area of aesthetics Recent strides in bridge aesthetics has shown that improvements in the appearance of bridges not only need not be costly, but can result in beneficial public acceptance of state and federal bridge projects TxDOT has recognized these benefits and initiated Project 1410 to explore methods of enhancing the appearance of substructures, and bridge systems as a whole This thesis describes the preliminary work done on the development of the Aesthetic Guidelines, a manual of techniques for enhancing the appearance of Texas bridge systems Relevant information was gathered in four main ways: a literature review of bridge aesthetics, building of a photographic database of existing Texas systems, an informal survey of Texan public opinion, and experience gained through work on an example project This thesis describes the origins and evolution of the Aesthetic Guidelines through the above mentioned major topics and other relevant minor topics A version of the preliminary draft of the Aesthetic Guidelines is included

关键词： thank Suggestions produce proud DEVELOPMENT OF AESTHETIC GUIDELINES FOR SHORT MEDIUM SPAN TEXAS BRIDGE Andrew Vernooy substructure design

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