• International Journal of Highway Engineering
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• v.14 no.2
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• pp.29-36
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• 2012

In this study, frequently passing vehicles with two, three, four, and five axles were chosen through traffic volume analysis in Kyung-In Expressway in order to analyze how the road roughness and vehicle speed affect on the dynamic loads for roads in various vehicle classes. Dynamic loads according to chosen vehicles are estimated by TruckSim program. Dynamic load amplification factor is ratio between dynamic and static loads, and it is also determined for each vehicle classes. From the result of dynamic loads estimated by the dynamic load amplification factor, it is shown that for three-axles vehicle, when IRI is 3.5 and vehicle speed is 100km/hr, asphalt pavements receive additional 36% of static loads in maximum. The analysis of the amplification factor according to each vehicle classes also indicates that the amplification factor increases as the distance between the axles becomes smaller and each axle receives more loads.

• Computational Structural Engineering
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• v.10 no.4
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• pp.337-347
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• 1997

The dynamic responses of highway bridges are varying depending on the features of either traveling vehicles or bridges. In this study, the probabilistic characteristics of dynamic amplification factors of highway bridges due to traveling heavy vehicles have been examined through analytical simulation processes. The truck with tandem axle and tractor with semitrailer are selected as the representative heavy vehicles, which are modeled with three dimensional 7-DOF and 12-DOF models, respectively. The analytical results have been compared with the experimental results of dynamic loading tests and the validity of the analytical models has been examined. Parametric studies on the means and extreme values of amplification factors have been performed with various traffic conditions such as vehicle types, vehicle weights, surface profiles, number of loading vehicles, loading positions, etc.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.8-14
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• 1997

The dynamic responses of highway bridges are varying depending on the features of either traveling vehicles or bridges. In this study, the probabilistic characteristics of dynamic amplification factors of highway bridges due to traveling heavy vehicles have been examined through analytical simulation processes. The truck with tandem axle and tractor with semitrailer are selected as the representative heavy vehicles, which are modeled with three dimensional 7-DOF and 12-DOF models, respectively. The analytical results have been compared with the experimental results of dynamic loading tests and the validity of the analytical models has been examined. Parametric studies on the means and extreme values of amplification factors have been performed with various traffic conditions such as vehicle types, vehicle weights, surface profiles, vehicle velocity, etc.

• Structural Engineering and Mechanics
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• v.9 no.1
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• pp.17-35
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• 2000

Dynamic response of a three span continuous bridge has been determined by full scale experiments on the bridge. In the experiments, a heavy vehicle was driven across the bridge at different speeds and along different lanes of travel and the strains were recorded at different locations. The bridge was made of reinforced concrete and was asymmetric in plan and in elevation. Frequencies and modes of vibration excited by the vehicle were determined. The dependence of the dynamic amplification on bridge location and vehicle speed was investigated and dynamic amplifications up to 1.5 were recorded, which was higher than values predicted by bridge design codes. It was evident that when this asymmetric bridge was loaded by an asymmetric forcing function, higher modes, which are lateral and/or torsional in nature, were excited. Dynamic modulus of elasticity and the support stiffness influenced the natural frequencies of the bridge, which in turn influenced the dynamic amplifications. Larger than anticipated dynamic amplification factors and the excitation of lateral and/or torsional modes should be of interest and concern to bridge engineers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.3
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• pp.159-169
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• 2020

Acceleration amplification factors, which are variables used in the seismic design of power facilities installed inside substation structures, are presented in the seismic design standards of the United States (US), Japan, and Korea. Unlike the coefficients presented in the design standards of the US and Japan, those presented in domestic design standards can be obtained only by performing dynamic analysis when the substation structure has more than four floors. Because most substation structures in Korea have 4-5 stories, the existing acceleration amplification factor is insufficient to be applied to actual substation structures. To suggest an acceleration amplification factor suitable for domestic substation structure types, the acceleration amplification factor was evaluated for seven representative substation structures. The acceleration amplification factors were evaluated by constructing in-structure response spectra based on a study of far-field and near-fault earthquakes. In general, the acceleration amplification coefficients α_J and α_A according to the US and Japan seismic design criteria tend to be overestimated compared with the acceleration amplification factors obtained through dynamic analysis based on the study of near-fault and far-field earthquakes.

• Steel and Composite Structures
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• v.22 no.1
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• pp.1-12
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• 2016

Severe fatigue and noise problems of modular bridge expansion joints (MBEJs) are often induced by vehicle loads. However, the dynamic characteristics of single-support MBEJs have yet to be further investigated. To better understand the vibration mechanism of single-support MBEJs under vehicle loads, a 3D finite element model of single-support MBEJ with five center beams is built. Successive vehicle loads are given out and the vertical dynamic responses of each center beams are analyzed under the successive loads. Dynamic amplification factors (DAFs) are also calculated along with increasing vehicle velocities from 20 km/h to 120 km/h with an interval 20 km/h. The research reveals the vibration mechanism of the single-support MBEJs considering coupled center beam resonance, which shows that dynamic responses of a given center beam will be influenced by the neighboring center beams due to their rebound after the vehicle wheels depart. Maximal DAF 1.5 appears at 120 km/h on the second center beam. The research results can be utilized for reference in the design, operation and maintenance of single-support MBEJs.

• Earthquakes and Structures
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• v.15 no.1
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• pp.1-8
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• 2018

A new site classification system and site coefficients based on local site conditions in Korea were developed and implemented as a part of minimum design load requirements for general seismic design. The new site classification system adopted bedrock depth and average shear wave velocity of soil above the bedrock as parameters for site classification. These code provisions were passed through a public hearing process before it was enacted. The public hearing process recommended to modify the naming of site classes and adjust the amplification factors so that the level of short-period amplification is suitable for economical seismic design. In this paper, the new code provisions were assessed using dynamic centrifuge tests and by comparing the design response spectra (DRS) with records from 2016 Gyeongju earthquake, the largest earthquake in history of instrumental seismic observation in Korea. The dynamic centrifuge tests were performed to simulate the representative Korean site conditions, such as shallow depth to bedrock and short-period amplification characteristics, and the results corroborated with the new DRS. The Gyeongju earthquake records also showed good agreement with the DRS. In summary, the new code provisions are reliable for representing the site amplification characteristic of shallow bedrock condition in Korea.

• Steel and Composite Structures
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• v.33 no.4
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• pp.525-535
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• 2019

The seismic performance of steel frames equipped with a particular type of bending dissipative braces (BDBs) having U elements, which has recently been introduced and tested by the authors, is investigated. For this purpose, two structural systems, i.e., simple and dual steel building frames, both with diagonal BDBs and different number of stories, are considered. After providing a design method of this new BDB, the detailed structural models are developed in the OpenSees platform to perform nonlinear dynamic analyses. Seismic performance factors like ductility, overstrength, response modification and deflection amplification factors are calculated using incremental dynamic analysis (IDA). In addition, to assess the damage probability of the structural models, their seismic fragilities are developed. The results show high energy dissipation capacity of both structural systems while the number of U elements needed for the bracing system of each story in the moment frames are less than those in the corresponding non-moment (simple) frames. The average response modification and deflection amplification factors for both structural schemes are obtained about 8.6 and 5.4, respectively, which are slightly larger than the corresponding recommended values of ASCE for the typical buckling-restrained braces (BRBs).

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.389-403
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• 2010

Based on the Model Coupled Method (MCM), a case study has been carried out on a Concrete-Filled Steel Tubular (CFST) tied arch bridge to investigate the vibration problem. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements, and the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees-of-freedom. A well-known power spectral density of road pavement profiles defined the road surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated, and the dynamic amplification factors were computed for displacement and internal force. The impact effects of the vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some of the components were analyzed in the frequency domain. From the results some valuable conclusions have been drawn.

• Advances in Computational Design
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• v.8 no.1
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• pp.1-12
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• 2023

To consider the effects of the increasing speed of next-generation high-speed trains, the existing traffic safety code for railway bridges needs to be improved. This study suggests a numerical method of evaluating the new effects of this increasing speed on railway bridges. A prestressed concrete (PSC) box bridge with a 40 m span length on the Gyeongbu track sector is selected as a representative example of high-speed railway bridges in Korea. Numerical models considering the inertial mass forces of a 38-degree-of-freedom train and the interaction forces with the bridge as well as track irregularities are presented in detail. The vertical deflections and accelerations of the deck are calculated and compared to find the new effects on the bridge arising with increasing speed under simply and continuously supported boundary conditions. The ratios between the static and dynamic responses are calculated as the dynamic amplification factors (DAFs) under different running speeds to evaluate the traffic safety. The maximum deflection and acceleration caused by the running speed are indicated, and regression equations for predicting these quantities based on the speed are also proposed.