• Structural Monitoring and Maintenance
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• v.7 no.4
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• pp.283-294
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• 2020

In this paper, an adaptive MEMD based modal identification technique for linear time-invariant systems is proposed employing multiple vibration measurements. Traditional empirical mode decomposition (EMD) suffers from mode-mixing during sifting operations to identify intrinsic mode functions (IMF). MEMD performs better in this context as it considers multi-channel data and projects them into a n-dimensional hypercube to evaluate the IMFs. Using this technique, modal parameters of the structural system are identified. It is observed that MEMD has superior performance compared to its traditional counterpart. However, it still suffers from mild mode-mixing in higher modes where the energy contents are low. To avoid this problem, an adaptive filtering scheme is proposed to decompose the interfering modes. The Proposed modified scheme is then applied to vibrations of a reinforced concrete road bridge. Results presented in this study show that the proposed MEMD based approach coupled with the filtering technique can effectively identify the parameters of the dominant modes present in the structural response with a significant level of accuracy.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1166-1169
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• 2009

Bridges are exposed to very severe environment and experience, as service life increased, elevated traffic load and traffic flow, in addition to natural disasters. In comparing to other road structures, bridges may cause more significant damage, such as human-involved accidents, to the society in the event of collapse. A certain level of service shall be necessarily secured to assure the minimum safety of users. The cost for manage and preserve bridges will increase gradually and more restrictions will be loaded to efficiently distribute the limited resources, such as monetary budget and human resource etc. In order to enhance performance and serviceability of bridges with the limited resource, asset management technique has been applied into the bridge management system, which capitalizes the road infrastructures including bridges and assess them in accordance with the government finance report. In the application of asset management, there must be a tool for assess the performance of bridges and this study introduces the basic information on the definition and role of performance measures for asset management for bridges. This research suggests future development direction of performance measure for asset management for bridges in Korea.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.713-718
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• 2005

A methodology is developed to evaluate the vulnerability of bridge piers to scour and to help establish effective disaster measures, taking into account the locality and scour characteristics in Korea. Based on the bearing capacity of bridge foundation-ground integrating system changed by scour, this methodology is able to prioritize bridge foundations reflecting on the geotechnical factors as well as hydraulic ones. The bridge foundation vulnerability to scour is categorized into 7 groups considering the concise information of the bridge foundation-ground integrating system. A case study of implementing this method which includes the analysis of the scour depth and evaluation, and categorizing the scour vulnerability of bridge foundation is presented.

• Earthquakes and Structures
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• v.18 no.1
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• pp.1-14
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• 2020

The vehicle-bridge interaction (VBI) analysis might be cumbersome and computationally expensive in bridge engineering due to the necessity of solving large number of coupled system of equations. However, VBI analysis can provide valuable insights into the dynamic behavior of highway bridges under specific loading conditions. Hence, this paper presents a numerical study on the dynamic behavior of a conventional highway bridge under strong near-field and far-field earthquake motions considering the VBI effects. A recursive substructuring method, which enables solving bridge and vehicle equations of motion separately and suitable to be adapted to general purpose finite element softwares, was used. A thorough analysis that provides valuable information about the effect of various traffic conditions, vehicle velocity, road roughness and effect of soil conditions under far-field and near-field strong earthquake motions has been presented. A real-life concrete highway bridge was chosen for numerical demonstrations. In addition, sprung mass models of vehicles consist of conventional truck and car models were created using physical and dynamic properties adopted from literature. Various scenarios, of which the results may help to highlight the different aspects of the dynamic response of concrete highway bridges under strong earthquakes, have been considered.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.103-110
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• 2013

PURPOSES: The objective of this study is to analyze and evaluate the behavior of orthotropic steel bridge deck pavement using three-dimensional finite element analysis and full-scale wheel load testing. METHODS: Since the layer thickness and material properties used in the bridge deck pavement are different from its condition, it is very difficult to measure and access the behavior of bridge deck pavement in the field. To solve this problem, the full-scale wheel load testing was conducted on the PSMA/Mastic bridge deck pavement and the deflection of bridge deck and horizontal tensile strain on top of pavement were measured under the loading condition. Three-dimensional finite element analysis was conducted to predict the behavior of bridge deck pavement and the predicted deflection and tensile strain values are compared with measured values from the wheel loading testing. RESULTS: Test results showed that the predicted deflections are 10% lower than measured ones and the error between predicted and measured horizontal tensile strain values is less than 2% in the critical location. CONCLUSIONS: The fact indicates that the proposed the analysis is found to be accurate for estimating the behavior of bridge deck pavements.

• Structural Engineering and Mechanics
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• v.61 no.1
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• pp.117-124
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• 2017

Load testing is one of the important tests to determine if the structural elements can be used at the intended locations for which they have been designed. It is nothing but gradually applying the loads and measuring the deflections and other parameters. It is usually carried out to determine the behaviour of the system under service/ultimate loads. It helps to identify the maximum load that the structural element can withstand without much deflection/deformation. It will also help find out which part of the element causes failure first. The load-deflection behaviour of the road bridge girder has been studied by carrying out the load test after simulating the field conditions to the extent possible. The actual vertical displacement of the beam at mid span due to the imposed load was compared with the theoretical deflection of the beam. Further, the recovery of deflection at mid span was also observed on removal of the test load. Finally, the beam was checked for any cracks to assert if the beam was capable of carrying the intended live loads and that it could be used with confidence.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.321-326
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• 2008

Recently the large sea bridge's construction crossing harbor and main ship's route have been propelled in the domestic so that it is active for the smoothly traffic flow of inland transportation and road user's convenience. However, it can bring about the trouble to ensure marine traffic safety if it is built that sea bridge's construction sets to an economy principle in the extension of the land road system. We're adopting Ship Handling Simulation in representative method for the influence assessment of marine traffic safety and danger elements beforehand. This research attempts to show the problems through the comparison and analysis of the reports relating to the sea bridge construction for 4 organization possessing Ship Handling Simulation. Finally, We offer the necessity of standardization on performing and assessment method of simulations.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.700-706
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• 2009

Bridges are vital components of any road network which demand crucial and timely decision-making for Maintenance, Repair and Rehabilitation (MR&R) activities. Bridge Management Systems (BMSs) as a decision support system (DSS), have been developed since the early 1990's to assist in the management of a large bridge network. Historical condition ratings obtained from biennial bridge inspections are major resources for predicting future bridge deteriorations via BMSs. Available historical condition ratings in most bridge agencies, however, are very limited, and thus posing a major barrier for obtaining reliable future structural performances. To alleviate this problem, the verified Backward Prediction Model (BPM) technique has been developed to help generate missing historical condition ratings. This is achieved through establishing the correlation between known condition ratings and such non-bridge factors as climate and environmental conditions, traffic volumes and population growth. Such correlations can then be used to obtain the bridge condition ratings of the missing years. With the help of these generated datasets, the currently available bridge deterioration model can be utilized to more reliably forecast future bridge conditions. In this paper, the prediction accuracy based on 4 and 9 BPM-generated historical condition ratings as input data are compared, using deterministic and stochastic bridge deterioration models. The comparison outcomes indicate that the prediction error decreases as more historical condition ratings obtained. This implies that the BPM can be utilised to generate unavailable historical data, which is crucial for bridge deterioration models to achieve more accurate prediction results. Nevertheless, there are considerable limitations in the existing bridge deterioration models. Thus, further research is essential to improve the prediction accuracy of bridge deterioration models.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.485-498
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• 2014

In this paper, vehicle-bridge interaction analysis under a series of moving vehicles to simulate a lane load was performed to estimate impact factor of the main cable, hanger and girder for the selected suspension bridges with 404m and 1545m main span. Korea Bridge Design Code(Limit State Design) was selected for the live model in which KL-510 truck was modeled 6-d.o.f. vehicle and a lane load was simulated by a series of single-axle vehicles. For the 404m main span bridge, hinge-type and floating-type girders at the tower were considered to examine the impact factor according to the connection and supporting type of the girders. The parameters considered herein are the types of live load-a truck only and a truck plus lane load, eccentricity of moving vehicles, road surface roughness and vehicle speed. The road surface roughness was randomly generated based on ISO 8608 and it was applied to the truck only. The impact factors were also evaluated by using the influence line method that is commonly used in cable-supported bridges and compared with those from vehicle-bridge interaction analysis.

• 한국도로학회:학술대회논문집
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• 2008.03a
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• pp.47-58
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• 2008