• Title, Summary, Keyword: structural design parameters

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A Study on the Uncertainty of Structural Cross-Sectional Area Estimate by using Interval Method for Allowable Stress Design

  • Lee, Dongkyuc;Park, Sungsoo;Shin, Soomi
    • Architectural research
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    • v.9 no.1
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    • pp.31-37
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    • 2007
  • This study presents the so-called Modified Allowable Stress Design (MASD) method for structural designs. The objective of this study is to qualitatively estimate uncertainties of tensile steel member's cross-sectional structural designs and find the optimal resulting design which can resist all uncertainty cases. The design parameters are assumed to be interval associated with lower and upper bounds and consequently interval methods are implemented to non-stochastically produce design results including the structural uncertainties. By seeking optimal uncertainty combinations among interval parameters, engineers can qualitatively describe uncertain design solutions which were not considered in conventional structural designs. Under the assumption that structures have basically uncertainties like displacement responses, the safety range of resulting designs is represented by lower and upper bounds depending on given tolerance error and structural parameters. As a numerical example uncertain cross-sectional areas of members that can resist applied loads are investigated and it demonstrates that the present design method is superior to conventional allowable stress designs (ASD) with respect to a reliably structural safety as well as an economical material.

A Study for Design of Reinforced Concrete Pier Based on Virtual Model (Virtual Modeling 기반의 철근 콘크리트 교각 설계에 관한 연구)

  • Lee, Heon-Min;Park, Jae-Geun;Kim, Min-Hee;Choi, Jung-Ho;Shin, Hyun-Mock
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.96-99
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    • 2008
  • When the design modification is occurred, at present, design process based on 2-D spend more time and effort than that based on 3-D to modify related structural details. To improve and develop these processes, therefore, the design possibility of civil structures based on virtual model of 3-D must be investigated. We designed reinforced concrete pier of 3-D model, containing parameters. The parameters was defined as structural details like area of the section, reinforcement specification for design modification and structural analysis. In this paper, we researched about the processes modeling of reinforced concrete bridge pier based on parameters, the extracting data from the virtual model of 3-D, and the reflection of data to virtual model throughout structural analysis.

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Posterior density estimation for structural parameters using improved differential evolution adaptive Metropolis algorithm

  • Zhou, Jin;Mita, Akira;Mei, Liu
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.735-749
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    • 2015
  • The major difficulty of using Bayesian probabilistic inference for system identification is to obtain the posterior probability density of parameters conditioned by the measured response. The posterior density of structural parameters indicates how plausible each model is when considering the uncertainty of prediction errors. The Markov chain Monte Carlo (MCMC) method is a widespread medium for posterior inference but its convergence is often slow. The differential evolution adaptive Metropolis-Hasting (DREAM) algorithm boasts a population-based mechanism, which nms multiple different Markov chains simultaneously, and a global optimum exploration ability. This paper proposes an improved differential evolution adaptive Metropolis-Hasting algorithm (IDREAM) strategy to estimate the posterior density of structural parameters. The main benefit of IDREAM is its efficient MCMC simulation through its use of the adaptive Metropolis (AM) method with a mutation strategy for ensuring quick convergence and robust solutions. Its effectiveness was demonstrated in simulations on identifying the structural parameters with limited output data and noise polluted measurements.

Development of a Physics-Based Design Framework for Aircraft Design using Parametric Modeling

  • Hong, Danbi;Park, Kook Jin;Kim, Seung Jo
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.3
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    • pp.370-379
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    • 2015
  • Handling constantly evolving configurations of aircraft can be inefficient and frustrating to design engineers, especially true in the early design phase when many design parameters are changeable throughout trade-off studies. In this paper, a physics-based design framework using parametric modeling is introduced, which is designated as DIAMOND/AIRCRAFT and developed for structural design of transport aircraft in the conceptual and preliminary design phase. DIAMOND/AIRCRAFT can relieve the burden of labor-intensive and time-consuming configuration changes with powerful parametric modeling techniques that can manipulate ever-changing geometric parameters for external layout of design alternatives. Furthermore, the design framework is capable of generating FE model in an automated fashion based on the internal structural layout, basically a set of design parameters describing the structural members in terms of their physical properties such as location, spacing and quantities. The design framework performs structural sizing using the FE model including both primary and secondary structural levels. This physics-based approach improves the accuracy of weight estimation significantly as compared with empirical methods. In this study, combining a physics-based model with parameter modeling techniques delivers a high-fidelity design framework, remarkably expediting otherwise slow and tedious design process of the early design phase.

Earthquake performance investigation of R/C residential buildings in Turkey

  • Korkmaz, Kasim Armagan;Demir, Fuat;Yenice, Tugce
    • Computers and Concrete
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    • v.15 no.6
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    • pp.921-933
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    • 2015
  • The aim of this study is to determine the earthquake performances of reinforced concrete (R/C) residential buildings in Turkey and to analyze the parameters that affect the performance. The performance of Turkish residential buildings, determined by their levels of damage, directly relates to their structural systems. Damage parameters observed from previous earthquakes define structural parameters selected to be used in the present study. Five different types of frame R/C buildings were modeled. For the analysis, the model buildings vary according to the number of stories, column sizes, and reinforcement and concrete strength parameters. The analyses consider gravity forces and earthquake loads through 1975 and 2007 Turkish design codes. In a total of 720 different R/C buildings were investigated for the analysis to obtain capacity curves. A performance evaluation was employed by considering the Turkish design code (TDC-2007). The current study ignores irregularities such as soft stories or short columns. The study's analysis considers a comparison of the parameters' influence on the structural performance of the model buildings.

An Investigation on Parameters of a RQP Algorithm for Optimum Structural Design (최적구조물 설계를 위한 RQP 알고리즘의 매개변수 성능평가)

  • 임오강;이병우;변준석
    • Computational Structural Engineering
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    • v.3 no.1
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    • pp.83-95
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    • 1990
  • Many structural optimization problems are solved by numerical algorithms since these are complicated and nonlinear. To provide a wider base and popular it to structual design optimization, reliable, accurate and superlinearly convergent nonlinear programming algorithm with active-set strategy have been developed. One of these is RQP(recursive quadratic programming method). This algorithm has several parameters and its performance is influenced by variations of these key parameters. Therefore, an RQP algorithm is selected to enhance its numerical performances by choosing proper parameters. The paper persents these influences on its numerical performance. For comparison of performances, a structural design software for minimum weight of truss subjected to displacement, stress, and lower and upper bounds on design variables is also implemented.

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Effect of structure configurations and wind characteristics on the design of solar concentrator support structure under dynamic wind action

  • Kaabia, Bassem;Langlois, Sebastien;Maheux, Sebastien
    • Wind and Structures
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    • v.27 no.1
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    • pp.41-57
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    • 2018
  • Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar tracking structures need to be optimized to be competitive against other types of energy production. In particular, the selection of the structural parameters needs to be optimized with regards to the dynamic wind response. This study aims to evaluate the effect of the main structural parameters, as selected in the preliminary design phase, on the wind response and then on the weight of the steel support structure. A parametric study has been performed where parameters influencing dynamic wind response are varied. The study is performed using a semi-deterministic time-domain wind analysis method. Unsteady aerodynamic model is applied for the shape of the CPV structure collector at different configurations in conjunction with a consistent mass-spring-damper model with the corresponding degrees of freedom to describe the dynamic response of the system. It is shown that, unlike the static response analysis, the variation of the peak wind response with many structural parameters is highly nonlinear because of the dynamic wind action. A steel structural optimization process reveals that close attention to structural and site wind parameters could lead to optimal design of CPV steel support structure.

Optimum LCVA for suppressing harmonic vibration of damped structures

  • Shum, K.M.;Xu, Y.L.;Leung, H.Y.
    • Smart Structures and Systems
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    • v.20 no.4
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    • pp.461-472
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    • 2017
  • Explicit design formulae of liquid column vibration absorber (LCVA) for suppressing harmonic vibration of structures with small inherent structural damping are developed in this study. The developed design formulae are also applicable to the design of a tuned mass damper (TMD) and a tuned liquid column damper (TLCD) for damped structures under harmonic force excitation. The optimum parameters of LCVA for suppressing harmonic vibration of undamped structures are first derived. Numerical searching of the optimum parameters of tuned vibration absorber system for suppressing harmonic vibration of damped structure is conducted. Explicit formulae for these optimum parameters are then obtained by a series of curve fitting techniques. The analytical result shows that the control performance of TLCD for reducing harmonic vibration of undamped structure is always better than that of non-uniform LCVA for same mass and length ratios. As for the effects of structural damping on the optimum parameters, it is found that the optimum tuning ratio decreases and the optimum damping ratio increases as the structural damping is increased. Furthermore, the optimum head loss coefficient is inversely proportional to the amplitude of excitation force and increases as the structural damping is increased. Numerical verification of the developed explicit design expressions is also conducted and the developed expressions are demonstrated to be reasonably accurate for design purposes.

Study on sensitivity of modal parameters for suspension bridges

  • Liu, Chunhua;Wang, Ton-Lo;Qin, Quan
    • Structural Engineering and Mechanics
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    • v.8 no.5
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    • pp.453-464
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    • 1999
  • Safety monitoring systems of structures generally resort to detecting possible changes of dynamic system parameters. Sensitivity analysis of these dynamic system parameters may implement these techniques. Conventional structural eigenvalue problems are discussed in the scope of those systems with deterministic parameters. Large and flexible structures, such as suspension bridges, actually possess stochastic material properties and these random properties unavoidably affect the dynamic system parameters. The sensitivity matrix of structural modal parameters to basic design variables has been established in this paper. Moreover, second order statistics of natural frequencies due to the randomness of material properties have been discussed. It is concluded from numerical analysis of a modem suspension bridge that although the second order statistics of frequencies are small relatively to the change of basic design variables, such as density of mass and modulus of elasticity, the sensitivities of modal parameters to these variables at different locations change in magnitude.

A Simplified Procedure for Performance-Based Design

  • Zareian, Farzin;Krawinkler, Helmut
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.4
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    • pp.13-23
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    • 2007
  • This paper focuses on providing a practical approach for decision making in Performance-Based Design (PBD). Satisfactory performance is defined by several performance objectives that place limits on direct (monetary) loss and on a tolerable probability of collapse. No specific limits are placed on conventional engineering parameters such as forces or deformations, although it is assumed that sound capacity design principles are followed in the design process. The proposed design procedure incorporates different performance objectives up front, before the structural system is created, and assists engineers in making informed decisions on the choice of an effective structural system and its stiffness (period), base shear strength, and other important global structural parameters. The tools needed to implement this design process are (1) hazard curves for a specific ground motion intensity measure, (2) mean loss curves for structural and nonstructural subsystems, (3) structural response curves that relate, for different structural systems, a ground motion intensity measure to the engineering demand parameter (e.g., interstory drift or floor acceleration) on which the subsystem loss depends, and (4) collapse fragility curves. Since the proposed procedure facilitates decision making in the conceptual design process, it is referred to as a Design Decision Support System, DDSS. Implementation of the DDSS is illustrated in an example to demonstrate its practicality.