• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.4
• /
• pp.401-408
• /
• 2015

Conventional model updating methods for the structures have used global structural responses which are modal parameters obtained through vibration measurements. Although models updated by modal parameters estimate global structural responses accurately, they have difficulties to predict local responses for safety assesment of structural members. The safety of structural members in the structures has been evaluated through the stress estimation based on strain measurements. Thus, this study additionally uses measured strain responses of structural members to perform model updating besides modal parameters. In the proposed method, the objective functions are set to the differences of the global and local responses obtained from updated model and measurement and those functions are minimized by NSGA-II, one of the multi-objective optimization techniques. The strain responses predicted from updated model are used for safety assessment of the steel frame structures. The proposed method are verified by numerical and experimental studies through the impact hammer tests for a steel frame specimen.

• Computers and Concrete
• /
• v.2 no.1
• /
• pp.31-53
• /
• 2005

In the present structural codes the safety verification is based on a linear analysis of the structure and the satisfaction of ultimate and serviceability limit states, using a semi-probabilistic security format through the consideration of partial safety factors, which affect the action values and the characteristic values of the material properties. In this context, if a non-linear structural analysis is wanted a difficulty arises, because the global safety coefficient, which could be obtained in a straightforward way from the non-linear analysis, is not directly relatable to the different safety coefficient values usually used for the different materials, as is the case for reinforced concrete structures. The work here presented aims to overcome this difficulty by proposing a methodology that generalises the format of safety verification based on partial safety factors, well established in structural codes within the scope of linear analysis, for cases where non-linear analysis is needed. The methodology preserves the principal assumptions made in the codes as well as a reasonable simplicity in its use, including a realistic definition of the material properties and the structural behaviour, and it is based on the evaluation of a global safety coefficient. Some examples are presented aiming to clarify and synthesise all the options that were taken in the application of the proposed methodology, namely how to transpose the force distributions obtained with a non-linear analysis into design force distributions. One of the most important features of the proposed methodology, the ability for comparing the simplified procedures for second order effects evaluation prescribed in the structural codes, is also presented in a simple and systematic way. The potential of the methodology for the development and assessment of alternative and more accurate procedures to those already established in codes of practice, where non-linear effects must be considered, is also indicated.

• Journal of the Society of Naval Architects of Korea
• /
• v.42 no.6 s.144
• /
• pp.644-653
• /
• 2005

In general the loads due to ocean wave are considered as main design parameters governing the global structural safety of VLFS (Very Large Floating Structure). In order to predict design wave loads accurately, hydro-elastic analysis must be conducted considering the initial global flexural rigidity of VLFS. However, in order to determine the structural scantling of major members (deck, bottom, side panels and longitudinal / transverse BHD etc.), static load and design wave loads must be given as explicit form generally. Therefore in order to determine a proper structural arrangement and scantlings of VLFS at initial design stage, both calculations of structural scantling and hydro-elastic analysis for wave conditions must be conducted iteratively and the convergence of their results must be checked. On this paper, based on the case design of a 500×300 m size's floating marina resort, the details of structural design technique using hydro-elastic analysis are explained and discussed. At first, the environmental conditions and the system requirements of the design of marina resort are described. The scantling formulas for the major members of pontoon type VLFS are proposed from the local and global design points of view. Considering the design wave loads as well as static design loads, the structural safety is checked iteratively.

• Journal of the Korean Society of Safety
• /
• v.12 no.3
• /
• pp.120-131
• /
• 1997

This paper presents an approximate reanalysis methods of structures based on substructuring for an effective optimization of large-scale structural systems. In most optimal design procedures the analysis of the structure must be repeated many times. In particular, one of the main obstacles in the optimization of structural systems are involved high computational cost and expended long time in the optimization of large-scale structures. The purpose of this paper is to evaluate efficiently the structural behavior of new designs using information from previous ones, without solving basic equations for successive modification in the optimal design. The proposed reanalysis procedure is combined Taylor series expansions which is a local approximation and reduced basis method which is a global approximation based on substructuring. This technique is to choose each of the terms of Taylor series expansions as the basis vector of reduced basis method in substructuring system which is one of the most effective analysis of large -scale structures. Several numerical examples illustrate the effectiveness of the solution process.

• Korean Journal of Geomatics
• /
• v.4 no.1
• /
• pp.17-22
• /
• 2004

It is very important to manage efficient data for safety and maintenance of those constructs. Estimation for structural safety can be evaluated by using data that surveys various structural durability and safety elements. so, it should be based on synthetic and efficient data that includes a variety of related safety elements obtained from a structure. It will subsequently be managed properly and economically. Accordingly, we will approach efficient maintenance management using a Geographic Information System (GIS) with data from structural-safety diagnosis and a Global Positioning System (GPS). In this study, we noted that by using the data that measures the factors (crack, incline, settlement etc.) of various structures as evaluate safety degree. And the horizontal coordinate variation/time of structure was monitored using the GPS easily.

• Journal of the Korean Society of Mechanical Technology
• /
• v.20 no.6
• /
• pp.947-956
• /
• 2018

This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.10a
• /
• pp.354-361
• /
• 2002

This paper propose section properties factor to generate stress history for fatigue analysis and safety inspection of steel bridge. A methodology is described for the computation of numerical stress histories in the steel truss bridge, caused by the vehicles using section properties factor. The global 3-D beam model of bridge is combined with the local shell model of selected details. Joint geometry is introduced by the local shell model. The global beam model takes the effects of joint rigidity and interaction of structural elements into account. Connection nodes in the global beam model correspond to the end cross-section centroids of the local shell model. Their displacements are interpreted as imposed deformations on the local shell model. The load cases fur the global model simulate the vertical unit force along the stringers. The load cases fer the local model are imposed unit deformations. Combining these, and applying vehicle loads, numerical stress histories are obtained. The method is illustrated by test load results of an existing bridge.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.2_2
• /
• pp.343-349
• /
• 2020

As global warming accelerates due to global climate change, the International Maritime Organization(IMO) has set up Emission Control Area(ECA) and encourages the use of Liquefied Natural Gas(LNG). For this reason, as the demand for LNG increases, the demand and research of related equipment also increases. In this study, one of them, the vent mast for the discharge of LNG was studied. In general, vent mast receives various loads such as wind load, earthquake load and dead load during operation. Accordingly, consideration of these loads is essential for structural design and safety evaluation of the vent mast. In this study, the structural safety of the vent mast is evaluated by performing finite element analysis. As a result, the structural safety evaluation results were analyzed based on the database of materials of the vent mast, and the stress level was analyzed to provide a design guide.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.1
• /
• pp.175-180
• /
• 2008

Due to the global environment problems and the consumer's need for higher vehicle performance, it becomes very important for the global car makers to reduce vehicle weight. To reduce vehicle weight, many car makers have tried to use lightweight materials, for example, aluminum, magnesium, and plastics, for the vehicle structures and components. Especially, the ASF(aluminum space frame) is known for the excellent concept of the vehicle to satisfy structural rigidity, safety performance and weight reduction. In this research, the design of experiments and the multi-disciplinary optimization technique were utilized to meet the weight and structural rigidity target of the ASF. For the structural performance of the ASF, the locations and the size of aluminum extruded frames, aluminum cast nodes, and the aluminum sheets were optimized. As a result, the optimization design procedure has been set up to meet both structural and weight target of the ASF, and the assembled ASF showed good structural performance and weight reduction.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.544-551
• /
• 2011

As the cargo tank size and configuration of Liquefied Natural Gas carriers(LNGC) grows in response to the global increase in demands for LNG and the necessities of its economical transportation, impact loading from sloshing may become one of the most important factors in the structural safety of LNG Cargo Containment Systems(CCS). The objective of this study is to demonstrate the procedure of the structural safety assessment of MARK III membrane type CCS under sloshing impact loading using local zooming analysis technique of LS-DYNA code.