• Structural Engineering and Mechanics
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• v.52 no.2
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• pp.261-274
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• 2014

An accurate finite element (FE) model of a structure is essential for predicting reliably its dynamic characteristics. Such a model is used to predict the effects of structural modifications for dynamic design of the structure. These modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can't be used for accurate prediction of vibration amplitudes. This paper deals with the basic formulation of damped finite element model updating method and its use for structural dynamic modifications. In this damped damped finite element model updating method, damping matrices are updated along with mass and stiffness matrices. The damping matrices are updated by updating the damping coefficients. A case involving actual measured data for the case of F-shaped test structure, which resembles the skeleton of a drilling machine is used to evaluate the effectiveness of damped FE model updating method for accurate prediction of the vibration levels and thus its use for structural dynamic modifications. It can be concluded from the study that damped updated FE model updating can be used for structural dynamic modifications with confidence.

• Structural Engineering and Mechanics
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• v.43 no.3
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• pp.371-394
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• 2012

Accurate finite element (FE) models are needed in many applications of Civil Engineering such as health monitoring, damage detection, structural control, structural evaluation and assessment. Model accuracy depends on both the model structure (the form of the equations) and the model parameters (the coefficients of the equations), and can be generally improved through that process of experimental reconciliation known as model updating. However, modelling errors, including (i) errors in the model structure and (ii) errors in parameters excluded from adjustment, may bias the solution, leading to an updated model which replicates measurements but lacks physical meaning. In this paper, an application of ambient-vibration-based model updating to a large-scale benchmark prototype of a building structure is reported in which both types of error are met. The error in the model structure, originating from unmodelled secondary structural elements unexpectedly working as resonant appendages, is faced through a reduction of the experimental modal model. The error in the model parameters, due to the inevitable constraints imposed on parameters to avoid ill-conditioning and under-determinacy, is faced through a multi-model parameterization approach consisting in the generation and solution of a multitude of models, each characterized by a different set of updating parameters. Results show that modelling errors may significantly impair updating even in the case of seemingly simple systems and that multi-model reasoning, supported by physical insight, may effectively improve the accuracy and robustness of calibration.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.821-826
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• 2001

This paper presents four types of strut-tie model design approaches of structural concrete through the anchorage zone design of a post-tensioned concrete I-beam. The differences and distinctive feature of each approach in terms of structural type of selected strut-tie model, external force acting on strut-tie model, effective strength of concrete strut, and strut-tie model design procedure are analyzed and compared. The outcomes of present study enable structural designers to understand the merits and demerits of each strut-tie model design approach, and thus to conduct reasonable and accurate design of structural concrete.

• Computational Structural Engineering
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• v.8 no.3
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• pp.123-133
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• 1995

This study presents an application of object-oriented methodology for structural design process. A prototype of integrated structural design system is developed by introducing a structural analysis object model(SAOM) and structural design object model (SDOM). This SAOM module, which models structural member, performs structural analysis using FEM approach and the SDOM module checks structural members based on Korea steel design standard. The abstraction, encapsulation and reusability properties of the proposed models are in establishing the integrated structural design system.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.246-257
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• 2006

In the ship building industry, the generation of a structural analysis model, that is, a finite element model of a hull structure, has been manually performed by a designer and thus has required lots of time as compared with that of a mechanical part, because of many constraints, the complexity, and the huge size of the hull structure. To make this task automatic, a generation method of the structural analysis model is proposed through the reconstruction of the topological information of a hull structural model in this study. The applicability of the proposed method is demonstrated by applying it to the generation of the structural analysis model of a deadweight 300,000ton VLCC(Very Large Crude oil Carrier).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.713-718
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• 2007

Structural tests often involve a large amount of complicated information. Data models can be used to efficiently organize the information. This paper briefly describes a data model for structural tests including hybrid tests, performed by the Real-Time Multi-Directional (RTMD) facility at the ATLSS Center of Lehigh University in America. The RTMD facility is an equipment site within the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES). The data model is called the Lehigh Model. An overview of classes and attributes of the Lehigh Model is presented, and the Lehigh Model is compared with other data models to show its benefits for structural testing.

• Structural Engineering and Mechanics
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• v.30 no.5
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• pp.619-645
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• 2008

This study presents the efficiency of simulating structural systems using a method that combines a simplified component model (SCM) and rigorous component model (RCM). To achieve a realistic simulation of structural systems, a numerical model must be adequately capturing the detailed behaviors of real systems at various scales. However, capturing all details represented within an entire structural system by very fine meshes is practically impossible due to technological limitations on computational engineering. Therefore, this research develops an approach to simulate large-scale structural systems that combines a simplified global model with multiple detailed component models adjusted to various scales. Each correlated multi-scale simulation model is linked to others using a multi-level hierarchical modeling simulation method. Simulations are performed using nonlinear finite element analysis. The proposed method is applied in an analysis of a simple reinforced concrete structure and the Reuipu Elementary School (an existing structure), with analysis results then compared to actual onsite observations. The proposed method obtained results very close to onsite observations, indicating the efficiency of the proposed model in simulating structural system behavior.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.680-687
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• 2005

This study presents a schema matching technique which can be applied to XML semantic model of structural calculation reports of steel-box bridges. The semantic model of structural calculation documents was developed by extracting the optimized common elements from the analyses of various existing structural calculation documents, and the standardized semantic model was schematized by using XML Schema. In addition, the similarity measure technique and the relaxation labeling technique were employed to develop the schema matching algorithm. The former takes into account the element categories and their features, and the latter considers the structural constraints in the semantic model. The standardized XML semantic model of steel-box bridge's structural calculation documents called target schema was compared with existing nonstandardized structural calculation documents called primitive schema by the developed schema matching algorithm Some application examples show the importance of the development of standardized target schema for structural calculation documents and the effectiveness and efficiency of schema matching technique in the examination of the degree of document standardization in structural calculation reports.

• ETRI Journal
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• v.33 no.5
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• pp.712-719
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• 2011

In this paper, we study the problem of domain adaptation for structural support vector machines (SVMs). We consider a number of domain adaptation approaches for structural SVMs and evaluate them on named entity recognition, part-of-speech tagging, and sentiment classification problems. Finally, we show that a prior model for structural SVMs outperforms other domain adaptation approaches in most cases. Moreover, the training time for this prior model is reduced compared to other domain adaptation methods with improvements in performance.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.389-403
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• 2004

This study presents the structural model modification based on the modal data such as natural frequencies and mode shapes. Preliminary structural model can be obtained using design drawings and field measurement, and therefore the deteriorated stiffness of a structure and the effect of the boundary conditions are difficult to be evaluated in preliminary analysis model, and the preliminary model can be modified using structural response data including static and/or dynamic characteristics. In this study, the structural model is modified based on the structural modal data using genetic algorithm. Modal testing were carried out for Imjin River Bridge and Hangjoo Bridge, the modal properties were estimated using modal identification techniques, and finally the structural models were updated using genetic algorithm. The modified structural model could give us more reliable structural analysis results and therefore those can be used for structural performance evaluation such as load carrying capacity and seismic capacity.