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Locally Corroded Stiffener Effect on Shear Buckling Behaviors of Web Panel in the Plate Girder
Huh, Jungwon,Kim, In-Tae,Ahn, Jin-Hee Hindawi Limited 2015 Advances In Materials Science And Engineering Vol.2015 No.-
<P>The shear buckling failure and strength of a web panel stiffened by stiffeners with corrosion damage were examined according to the degree of corrosion of the stiffeners, using the finite element analysis method. For this purpose, a plate girder with a four-panel web girder stiffened by vertical and longitudinal stiffeners was selected, and its deformable behaviors and the principal stress distribution of the web panel at the shear buckling strength of the web were compared after their post-shear buckling behaviors, as well as their out-of-plane displacement, to evaluate the effect of the stiffener in the web panel on the shear buckling failure. Their critical shear buckling load and shear buckling strength were also examined. The FE analyses showed that their typical shear buckling failures were affected by the structural relationship between the web panel and each stiffener in the plate girder, to resist shear buckling of the web panel. Their critical shear buckling loads decreased from 82% to 59%, and their shear buckling strength decreased from 88% to 76%, due to the effect of corrosion of the stiffeners on their shear buckling behavior. Thus, especially in cases with over 40% corrosion damage of the vertical stiffener, they can have lower shear buckling strength than their design level.</P>
A Novel Risk Assessment for Complex Structural Systems
Jungwon Huh,Haldar, A IEEE 2011 IEEE transactions on reliability Vol.60 No.1
<P>Risk management is an essential tool for safe, economical, and efficient design, operation, and maintenance of complex engineering systems. Seismic risk assessment of structures, particularly in nuclear power plants, needs special attention from the reliability community. Available risk assessment methods may not be sufficient to estimate the risk of complex systems made with different materials, numerous ways elements are connected to each other, and excited by dynamic loadings including seismic loading applied in the time domain. A hybrid risk assessment approach is proposed by intelligently integrating the stochastic finite element method, and the response surface method. It is capable of estimating the probability just before failure considering all major sources of nonlinearity and uncertainty, eliminating the deficiencies of the currently available reliability methods. With the help of the illustrative examples, it is shown that the method is robust, accurate, and efficient in estimating risk of complex systems excited by dynamic loadings applied in the time domain.</P>
Jungwon Huh(허정원),Nhu Son Doan(도안누손),Van Ha Mac(맥반하),Van Phu Dang(당반푸),Dong Hyawn Kim(김동현) 한국해안해양공학회 2021 한국해안해양공학회 논문집 Vol.33 No.6
하중·저항계수 설계는 일관된 시스템적 설계해를 제공하는 효율적인 설계 방식이다. 이 연구는 확률론적 프레임워크 내에서 방파제의 지반기초(foundation) 설계에 필요한 하중계수 및 저항계수를 결정하는 것을 목표로 하여 한국형 방파제의 대표적인 4가지 유형인 경사식 방파제, 무공케이슨 혼성식방파제, 유공케이슨 혼성식방파제, 소파블록 피복제를 대상으로 조사하였다. 파랑하중조건에서 방파제 기초의 지지력을 면밀히 조사하였다. 100,000회 샘플에 의한 Monte Carlo 시뮬레이션을 사용하여, 목표신뢰도지수(RI) 2.5와 3.0의 두 가지 수준을 선택하여 하중·저항계수의 보정을 수행하였다. 예상대로 더 높은 RI에 대해 정규화된 저항계수는 더 낮은 값을 갖는 것으로 확인되었다. 그 범위는 목표 RI 2.5의 경우 0.668~0.687이며, 목표 RI 3.0의 경우 0.576~0.634이다. Load and resistance factor design is an efficient design approach that provides a system of consistent design solutions. This study aims to determine the load and resistance factors needed for the design of breakwater foundations within a probabilistic framework. In the study, four typical types of Korean breakwaters, namely, rubble mound breakwaters, vertical composite caisson breakwaters, perforated caisson breakwaters, and horizontal composite breakwaters, are investigated. The bearing capacity of breakwater foundations under wave loading conditions is thoroughly examined. Two levels of the target reliability index (RI) of 2.5 and 3.0 are selected to implement the load and resistance factors calibration using Monte Carlo simulations with 100,000 cycles. The normalized resistance factors are found to be lower for the higher target RI as expected. Their ranges are from 0.668 to 0.687 for the target RI of 2.5 and from 0.576 to 0.634 for the target RI of 3.0.