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Behavior of concrete-filled steel tubular column at large axial deformation

STRUCTURES 2024年 70卷

作者： Qi, Hong-Hui Li, Guo-Qiang Lou, Guo-Biao Tongji Univ Coll Civil Engn Shanghai 200092 Peoples R China State Key Lab Disaster Reduct Civil Engn Shanghai 200092 Peoples R China

This paper develops a three-stage load-bearing capacity formulation for concrete-filled steel tubular (CFST) columns throughout the entire deformation process, comprising three stages: prior to buckling, buckling, and large deformation, each characterized by distinct load-bearing mechanisms. The concept of vaulting pole action is introduced to describe the column behavior with large axial deformation. An analytical method is proposed to determine the load-bearing capacity of CFST columns at large axial deformation. To validate the theoretical approach, the axial load test was conducted on the CFST column until large deformation, measuring both the structural force and deformation responses. The experimental results confirmed the substantial load-bearing capacity at large axial deformation, retaining 57 % of its maximum load-bearing capacity when the axial deformation reached one twenty-fifth of the column length. Additionally, a numerical approach using the Newton-Raphson method in displacement control mode was also presented to analyze CFST column behavior under large deformation. The numerical results demonstrate that geometric dimensions and the constraining factor significantly affect the column behavior at large deformation, with the relative load-bearing capacity factor (eta lb) decreasing as the effective length increases and increasing as the constraining factor rises. The parametric study using the analytical method demonstrates that reducing the slenderness and enhancing the material strength can increase the load-bearing capacity of CFST columns under large axial deformation. The considerable load-bearing capacity retained at large deformation highlights the importance of vaulting pole action and suggests that columns should not be simply removed when evaluating the structural collapse of buildings.

关键词： Concrete-filled steel tubular column Large axial deformation Vaulting pole action Relative load-bearing capacity factor solution algorithm

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A study of mixed discrete bilevel programs using semidefinite and semi-infinite programming

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OPERATIONS RESEARCH LETTERS 2023年第1期51卷 84-91页

作者： Kue, Floriane Mefo Dempe, Stephan Univ Yaounde I Higher Training Coll Dept Math POB 812 Yaounde Cameroon AIMS Cameroon Res Ctr POB 608 Limbe Cameroon TU Bergakad Freiberg Dept Math & Comp Sci Akad str 6 D-09596 Freiberg Germany

In this paper, we study the bilevel programming problem with discrete polynomial lower level problem. We start by transforming the problem into a bilevel problem comprising a semidefinite program (SDP for short) in the lower level problem. Then, we are able to deduce some conditions of existence of solutions for the original problem. After that, we again change the bilevel problem with SDP in the lower level problem into a semi-infinite program. With the aid of the exchange technique, for simple bilevel programs, an algorithm for computing a global optimal solution is suggested, the convergence is shown, and a numerical example is given.(c) 2022 Elsevier B.V. All rights reserved.

关键词： Bilevel programming Semidefinite programming Semi -infinite programming solution algorithm

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Adjustable robust optimization with decision-dependent uncertainty for power system problems: A review

ENERGY CONVERSION AND ECONOMICS

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ENERGY CONVERSION AND ECONOMICS 2025年

作者： Tan, Tao Yang, Meng Xie, Rui Cao, Yuji Chen, Yue Chinese Univ Hong Kong Dept Mech & Automat Engn Hong Kong Peoples R China

The increasing uncertainty caused by volatile renewable generation and random electricity demand has always been a critical challenge in power system operations. Robust optimization (RO) is a powerful tool for effectively addressing this uncertainty. As the interplay between uncertain factors and decision-making becomes more prevalent, RO with decision-dependent uncertainty (DDU) has attracted increasing attention. DDU significantly changes how the uncertainty set in RO is modelled and how the problems are solved. This study provides a comprehensive overview of the recent developments in RO with DDU for power system problems. We begin by introducing various models of DDU, classified according to their underlying causes. Next, we summarize the state-of-the-art solution algorithms for RO with DDU, such as variants of the column-and-constraint generation (C&CG) algorithm, variants of Benders decomposition, and multiparametric programming. Furthermore, we explore the application of RO with DDU in power systems. Based on our findings, we propose several research directions that may be valuable for future studies.

关键词： application decision-dependent uncertainty power system robust optimization solution algorithm

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Optimal Design of eVTOLs for Urban Mobility using Analytical Target Cascading (ATC)

Optimal Design of eVTOLs for Urban Mobility using Analytical...

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AIAA SciTech Forum

作者： Chinthoju, Prajwal K. Lee, Yong Hoon Das, Ghanendra K. James, Kai A. Allison, James T. Univ Illinois Ind & Enterprise Syst Engn 104 S Mathews Ave406 TB Urbana IL 61801 USA Univ Memphis Dept Mech Engn 3815 Cent Ave322D ES Memphis TN 38152 USA Georgia Inst Technol Sch Aerosp Engn 275 Ferst Dr NW212 Weber Atlanta GA 30332 USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

Over the past few decades, multidisciplinary design optimization (MDO) techniques have shown great potential in generating optimal designs for complex system of systems. Monolithic MDO methods that formulate the design problem as a single optimization problem are effective, but present challenges in coordination. On the other hand, distributed MDO methods decompose the design problem into different optimization problems and hence offer more modularity and flexibility, especially when implemented by teams of optimization specialists. In this article, one such distributed MDO method, Analytical Target Cascading (ATC), is investigated as a candidate for the design of electric Vertical Take Off and Landing aircraft (eVTOL). Design of eVTOLs for urban mobility has been a subject of immense interest over the past decade. eVTOLs offer many advantages over conventional modes of urban transport such as reduced environmental impact, utilization of vertical space for transportation, and competitive cost of transportation. Most current efforts for eVTOL design are in relatively early stages. Hence, distributed MDO methods that can effectively consider complex interactions between different subsystems and disciplines can help support eVTOL design efforts. In this study, ATC is implemented to optimize the total cost per flight for a simple mission, involving take-off to a set altitude, cruising at constant velocity for a range of 50-150 km, and landing, all while carrying a given payload. The key design parameters that are optimized as a part of this study are the mass of aircraft and individual subsystems, cruise velocity, wingspan, and radius of the propeller. Furthermore, a comparison of the resulting optimal solutions using ATC and monolithic MDO methods is presented. General observations are also articulated regarding potential computational advantages, such as parallelism and tailored solution algorithms, as well as organizational considerations, such as distributed iterati

关键词： Multidisciplinary Design and Optimization Electric Vertical Take off and Landing Propeller Blades solution algorithm Maximum Takeoff Weight Lift Coefficient Electric Motors Helicopters Drag Coefficient Blade Element Momentum Theory

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Optimal Deployment of Flood Emergency Response Materials under Stochastic Demands

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JOURNAL OF MARINE SCIENCE AND TECHNOLOGY 2022年第2期30卷 86-101页

作者： Yan, Shangyao Lin, Jenn-Rong Ku, Chia-Fu Natl Cent Univ Dept Civil Engn Taoyuan 32001 Taiwan Natl Taiwan Ocean Univ Dept Transportat Sci Keelung 20224 Taiwan

This study aims to develop a planning model for the deployment of flood emergency response materials under stochastic demands. For ease of modeling, a deterministic demand model is first proposed, from which the stochastic model is further extended. These models are used to determine the allocation of materials the transport truck routes and distribution of the stockpiled materials to emergency sites. The models are formulated as multiple integer network flow problems with special side constraints which are characterized as NP-hard in terms of optimization. To solve the complicated stochastic model efficiently, we also develop a solution algorithm based on a problem decomposition technique coupled with a variable fixing technique. Finally, to preliminarily evaluate the proposed models and solution algorithm, we perform numerical tests using data related to a Taiwan flood emergency response system. The test results are good, indicating the potential usefulness of the models and solution algorithm in practice.

关键词： Flood emergency response Material deployment Time-space network Stochastic demand solution algorithm

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A new solution approach for the twin yard crane scheduling problem in automated container terminals

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ADVANCED ENGINEERING INFORMATICS 2023年第1期57卷

作者： Oladugba, Andrew Omoniyi Gheith, Mohamed Eltawil, Amr Egypt Japan Univ Sci & Technol Dept Ind & Mfg Engn Alexandria Egypt Alexandria Univ Fac Engn Prod Engn Dept Alexandria Egypt

The Twin-Automated Stacking Crane (Twin-ASC) system is a special configuration of Yard Crane (YC) that is common in most of the Automated Container Terminals (ACTs) used for stacking and retrieving containers on the yard side of a Container Terminal (CT). The usual objective when scheduling the Twin-ASC to perform a given set of transport jobs is the minimization of the schedule length (makespan). The problem is NP-hard, which means that problem of realistic size cannot be solved within a reasonable time limit by default solvers or conventional methods, necessitating the use of an efficient algorithm. Thus, this work proposes a novel algorithm based on the modified Johnson algorithm (JA) to a formulated Mixed Integer Programming (MIP) model for solving the TwinASC scheduling problem to minimize the makespan of the schedule. Differ from the existing heuristics, the proposed algorithm has the flexibility of varying the handshake area, and the system utilization can be investigated. The handshake area is a temporary storage location in the Twin-ASC system where an ASC can leave a job for the other to complete since the crossing of the cranes is not possible, and it greatly affects the makespan of completing the given set of jobs. An extensive computational study was carried out and results were compared with (two) existing heuristics to evaluate the effectiveness of the proposed solution approach.

关键词： Automated container terminals Stacking crane Handshake area solution algorithm Makespan

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A Review of Models and Methods for Precise Load Control Strategies

A Review of Models and Methods for Precise Load Control Stra...

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2024 Boao New Power System International Forum - Power System and New Energy Technology Innovation Forum, NPSIF 2024

作者： Wei, Aoqiu Wang, Shengli Xie, Li Luo, Cheng Xu, Lihui Maimaitituxun, Alimire Zheng, Hua School of Electrical and Electronic Engineering North China Electric Power University Beijing China Kashgar Power Supply Company State Grid Xinjiang Electric Power Co. Ltd. Kashgar China

ISBN: (纸本)9798331504557

With the advancement of China's "dual carbon"goals, renewable energy represented by wind and solar power is set to become the main source of the future power system. However, the uncertainty of renewable energy output significantly affects the supply-demand balance of the system. In this context, This paper provides a review of precise load control technologies based on the actual scheduling needs of the power grid. It categorizes controllable loads into traditional controllable loads and new controllable loads, explaining the application scenarios of load control in peak shaving, frequency regulation, and emergency load shedding. It also analyzes the models of various controllable loads and presents solution methods based on physical models as well as data-driven models. Finally, it looks ahead to the future development of precise load control technology. © 2024 IEEE.

关键词： control model load classification objective function solution algorithm

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Acoustic analysis of a rotor in forward flight with deformable blades through a boundary integral formulation

Acoustic analysis of a rotor in forward flight with deformab...

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AIAA Aviation Forum

作者： Gennaretti, M. de Rubeis, B. Poggi, C. Bernardini, G. Roma Tre Univ Dept Engn I-00146 Rome Italy

ISBN: (数字)9781624107047

ISBN: (纸本)9781624107047

This paper presents the results of the development of a novel boundary integral formulations suitable for the aerodynamic and aeroacoustic analysis of deformable bodies in arbitrary motion. The starting point is the most general form of the wave equation governing the propagation of perturbations in a fluid medium of aerodynamic and aeroacoustic interest. Therefore, the derived formulation represents the most general integral form solution allowing for the study of aerodynamics and aeroacoustics of rigid or deformable bodies, able to handle both solid and porous boundary surfaces. Two versions of the boundary integral formulation are developed, which differ in terms of the frame of reference in which they are expressed. First, the validation of the corresponding implemented numerical solution algorithms is obtained by confirming through cross-comparison between the predictions their theoretical equivalence. Then, the noise radiated by the blades of an advancing rotor subject to aeroelastic bending and torsion is examined, with particular attention on the aeroacoustic effect of blade deformations. The correlations with the available experimental measurements show an overall good quality of the obtained numerical predictions.

关键词： Ffowcs Williams Hawkings Equation Rotor Aerodynamics solution algorithm Green's Function Aeroelastic Analysis Flexible Structures Acoustic Emission Structural Dynamics Rotor Blades Aviation

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Development of an interval quadratic programming water quality management model and its solution algorithms

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JOURNAL OF CLEANER PRODUCTION 2020年 249卷 119319-000页

作者： Zhang, Qianqian Li, Zhong Chengdu Univ Informat Technol Sch Management Chengdu 610225 Peoples R China McMaster Univ Dept Civil Engn 1280 Main St West Hamilton ON L8S 4L7 Canada

Interval quadratic programming (IQP) is one of the most popular programming techniques for addressing the uncertainties associated with nonlinear environmental management problems. However, efficient algorithms for solving IQP problems in water quality management (WQM) have not been well studied. In this study, an IQP model is developed for WQM under uncertainty. Three solution algorithms, including a piecewise linear approximation (PLA) method, a derivative algorithm (DEA) and a duality-based algorithm (DUA) are proposed for solving the IQP-WQM problem. The developed model and the corresponding solution algorithms are applied to a hypothetic WQM problem to demonstrate their applicability. The results show the lower bounds of the total cost obtained by three algorithms have a relationship of f(DUA)(-) = f(DEA)(-) <= f(PLA)(-), while that of the upper bounds is f(DEA)(+) <= f(PLA)(+) <= f(DUA)(+). Moreover, the sensitivity analysis shows that no matter how the IQP-WQM model is solved, the model response from the three solution algorithms is consistent. The results indicate that all of the three algorithms can efficiently deal with quadratic programming problems under uncertainties in the format of intervals. Comparison among the three algorithms shows that DUA provides interval solutions with wider ranges than the other two methods, and it requires less computational efforts than DEA. It is also found that PLA is more flexible and might require lower computational efforts for large scale problems. This study can provide useful technical support for effective WQM. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Interval quadratic programming Piecewise linear approximation Derivative algorithm Duality-based algorithm Water quality management solution algorithm

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The Influence of External Heat Exposure on the Stress State of Shell Molds by Smelting Models

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Mathematical Models and Computer Simulations 2022年第6期14卷 995-1001页

作者： Evstigneev, A.I. Dmitriev, E.A. Chernyshova, D.V. Odinokov, V.I. Evstigneeva, A.A. Ivankova, E.P. Komsomolsk-na-Amure State University Komsomolsk-on-Amur 681013 Russian Federation

Abstract: The problem of determining the force effect of the support filler on the resistance of the shell mold (SM) during the crystallization of liquid metal (steel) in it is formulated and solved. The tensile normal stress that occurs in the outer layers of the mold in the initial time moments when liquid metal is poured into it is taken as the leading physical quantity that affects the crack resistance of the SM. The force factor affecting the stress-strain state (SSS) of the SM is the friction between the SM and the supporting filler (SuFi), which appears during the elastic expansion of the outer layer in the SM as a result of the temperature exposure from the crystallizing liquid metal. The problem of mathematical programming (minmax function) is formulated to determine the coefficient of friction between the SM and SuFi to obtain the smallest value of the normal tensile stress in the SM over the area under consideration in the presence of a system of constraints. An axisymmetric body of rotation is considered, which has four regions: liquid metal, solid metal, SM, and SuFi, which is considered to be a solid body that creates friction at the contact point with the outer layer of the SM. To solve the problem, equations of the linear theory of elasticity, the equation of thermal conductivity and a proven numerical method are used, according to which the area under study is divided into elements by a system of orthogonal surfaces. For each element, the formulated system of equations is written in a difference form. An algorithm for solving the problem is developed and the results of the solution are presented, stress diagrams in the SuFi are constructed using the found value of the friction coefficient. The analysis of the received results is given. © 2022, Pleiades Publishing, Ltd.

关键词： casting by smelting models crack resistance displacement force action numerical method shell mold software solution algorithm stress stress state support filler

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