• Earthquakes and Structures
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• 제12권1호
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• pp.47-54
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• 2017

Introduction of robustness index in the structure is done in three ways: deterministic robustness index, probabilistic robustness index, and risk-based robustness index. In past decades, there have been numerous researches to evaluate robustness index in both deterministic and probabilistic ways. In this research, by using a risk analysis, a risk-based robustness index has been defined for the structure. By creating scenarios in accordance with uncertainty parameters of critical and unexpected gas blast accident, a new method has been suggested for evaluating risk-based robustness index. Finally, a numerical example for the evaluation of risk-based robustness index of a four-storey reinforced concrete moment frame, designed and built based on Eurocode 8 code, has been presented with results showing a lower risk of robustness.

• Smart Structures and Systems
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• 제20권5호
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• pp.637-640
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• 2017

The adoption of cladding panels as dissipation device is a sort of passive control "ante litteram" for residential and commercial buildings. This paper gives details on the current technology outlining the difference between buffer panels and cladding panels. The discussion of robustness and resilience of the resulting system is afforded. It is shown that the strength of such solution, originally related to economy and light weight, is mainly associated with the respect of the main robustness requisites, as well as the short time it requires for removal and replacement (resilience).

• 한국군사과학기술학회지
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• 제18권1호
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• pp.8-14
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• 2015

Transmission of a tracked vehicle designed for multiple functions such as steering, gear-shifting, and braking is a core component of heavy vehicle to which the power is transferred based on combined technology of various gears, bearing, and fluid machineries. Robustness and durability of transmission, however, have been issued due to a large number of driving units and sub-components inside its body. Particularly, transmission housing is important structure which supports the transmission, and is made of aluminum alloy. Thus, structural robustness against such mechanical loading or vibration must be attained. Structural reliability evaluation through FEM analysis can save time and cost of the actual tests. In this study, structural evaluation is conducted on output housing of transmission, which is core component of tracked vehicle, using the simulation program. In addition, transmission dynamo test is performed to evaluate structural robustness of the output housing against the vibration which can be produced during the transmission operation.

• Structural Engineering and Mechanics
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• 제82권2호
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• pp.245-258
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• 2022

Many Structural Health Monitoring (SHM) methods have been proposed for structural damage diagnosis and prognosis. However, SHM for pinched hysteretic structures can be problematic due to the high level of nonlinearity. The model-free hysteresis loop analysis (HLA) has displayed notable robustness and accuracy in identifying damage for full-scaled and scaled test buildings. In this paper, the performance of HLA is compared with seven other SHM methods in identifying lateral elastic stiffness for a six-story numerical building with highly nonlinear pinching behavior. Two successive earthquakes are employed to compare the accuracy and consistency of methods within and between events. Robustness is assessed across sampling rates 50-1000 Hz in noise-free condition and then assessed with 10% root mean square (RMS) noise added to responses at 250 Hz sampling rate. Results confirm HLA is the most robust method to sampling rate and noise. HLA preserves high accuracy even when the sampling rate drops to 50 Hz, where the performance of other methods deteriorates considerably. In noisy conditions, the maximum absolute estimation error is less than 4% for HLA. The overall results show HLA has high robustness and accuracy for an extremely nonlinear, but realistic case compared to a range of leading and recent model-based and model-free methods.

• Structural Engineering and Mechanics
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• 제16권3호
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• pp.327-340
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• 2003

Variations in system parameters due to uncertainties of parameters may result in system performance deterioration and create system internal stability problems. Uncertainties in structural modeling of structures are often considered to ensure that the control system is robust with respect to response errors. So the uncertain concept plays an important role in the analysis and design of the engineering structures. In this paper, the active control of the intelligent structures with the uncertainties is studied and a new method for analyzing the robustness of systems with the uncertainties is presented. Firstly, the system with uncertain parameters is considered as the perturbation of the system with deterministic parameters. Secondly, the feedback control law is designed on the basis of deterministic system. Thirdly, perturbation analysis and robustness analysis of intelligent structures with uncertainties are discussed when the feedback control law is applied to the original system and perturbed system. Combining the convex model of uncertainties with the finite element method, the analysis theory of the robustness of intelligent structures with the uncertainties can be developed. The description and computation of the robustness of intelligent structures with uncertain parameters is obtained. Finally, a numerical example of the application of the present method is given to show the validity of the method.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.168-173
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• 2000

Design of experiments is utilized for exploring the design space and for building response surface models in order to facilitate the effective solution of multi-objective optimization problems. Response surface models provide an efficient means to rapidly model the trade-off among many conflicting goals. In robust design, it is important not only to achieve robust design objectives but also to maintain the robustness of design feasibility under the effects of variations, called uncertainties. However, the evaluation of feasibility robustness often needs a computationally intensive process. To reduce the computational burden associated with the probabilistic feasibility evaluation, the first-order Taylor series expansions are used to derive individual mean and variance of constraints. For robust design applications, these constraint response surface models are used efficiently and effectively to calculate variances of constraints due to uncertainties. Robust optimization of automotive seat is used to illustrate the approach.

• Structural Engineering and Mechanics
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• 제65권4호
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• pp.415-422
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• 2018

The Conjugate Finite-Step Length" (CFSL) algorithm is proposed to improve the efficiency and robustness of first order reliability method (FORM) for reliability analysis of highly nonlinear problems. The conjugate FORM-based CFSL is formulated using the adaptive conjugate search direction based on the finite-step size with simple adjusting condition, gradient vector of performance function and previous iterative results including the conjugate gradient vector and converged point. The efficiency and robustness of the CFSL algorithm are compared through several nonlinear mathematical and structural/mechanical examples with the HL-RF and "Finite-Step-Length" (FSL) algorithms. Numerical results illustrated that the CFSL algorithm performs better than the HL-RF for both robust and efficient results while the CFLS is as robust as the FSL for structural reliability analysis but is more efficient.

• Structural Engineering and Mechanics
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• 제45권2호
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• pp.159-168
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• 2013

The effect of structural uncertainties or measurement errors on damage detection results makes the robustness become one of the most important features during identification. Due to the wide use of vibration signatures on damage detection, the development of vibration-based techniques has attracted a great interest. In this work, a review on vibration-based robust detection techniques is presented, in which the robustness is considerably improved through modeling error compensation, environmental variation reduction, denoising, or proper sensing system design. It is hoped that this study can give help on structural health monitoring or damage mitigation control.

• Ecology and Resilient Infrastructure
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• 제3권3호
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• pp.182-188
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• 2016

본 연구는 도시 홍수문제의 구조적 해결방안을 도출하기 위하여 내구성-비용지수 (robustness cost index, RCI)를 수질오염 문제 사례에 재해석 및 적용하였다. 처리기준 산정방식이 다른 하수 처리수 내 내생호르몬 오염과 취수원 원생동물 번성을 대표 사례로 선정하여 기존시설과 대안시설 (구조적 대안)의 내구성 지수 (RI) 값이 1 이상인 경우를 내구성을 확보한 대안으로 판정하고 내구성 지수와 비용지수 (CI)를 결합한 RCI 값을 산정하였다. 하수 처리수 내 내생호르몬 오염은 인체로부터 기인하는 $17{\beta}$-estradiol 을 대상 오염물질로 하여 현재 하수처리시설과 대안시설 (고도처리공정 증축)을 비교하였고, 고도처리공정을 증축한 사례에서 RI뿐만 아니라 RCI 값이 큰 결과가 나타났다. 취수원 원생동물 번성의 경우 크립토스포리디움을 처리하기 위한 소독방안으로 자외선 소독과 오존 소독을 대상으로 RCI를 산정하였고 오존 소독시설이 RCI값이 더 높은 것을 확인하였다. 처리기준이 다른 수질오염사례의 RCI 산정과정과 도출한 값을 바탕으로 재해 발생 시 피해 복구와 피해 방지를 위한 구조적 대안 수립과정의 방향을 제시하고 그 구축전략을 제안하였다.

• Structural Engineering and Mechanics
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• 제60권1호
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• pp.31-50
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• 2016

During the recent years, resistance mechanisms of reinforced concrete (RC) buildings against progressive collapse are investigated extensively. Although a general agreement is observed about their qualitative behavior in technical literature, there is not such a comprehensive point of view regarding the quantitative methods for predicting collapse resistance of RC members. Therefore, in the present study a simplified theoretical method is developed in order to predict general behavior of RC frames under the column removal scenario. In the introduced method, the robustness of the frame is extracted based on the capacity of the beams. The proposed method expresses ultimate arching and catenary capacities of the beams and also obtains the corresponding vertical displacements. Based on the calculated capacities, the introduced method also provides a quantitative assessment of structural robustness and determines whether or not the collapse occurs. The capability of the method is evaluated using experimental results in the literature. The evaluation study indicates that the proposed theoretical procedure can establish a reliable foundation for progressive collapse assessment of RC frame structures.