• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.27-40
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• 2007

Stratigraphy has been renewedly set up and the evolution of tectonic events related to basin formation has been exam-ined on the basis of fault-slip data analysis in the Tertiary Eoil and Waeup basins of the southeastern part of Korea. First of all, field mapping was carried out in detail for Tertiary formations and then paleostress analysis were peformed with more than 400 fault slip data collected from 11 sites in the Tertiary formations and the Yucheon Group. It is judged that both the Eoil and Waeup basins filled up with Tertiary deposits might be simultaneously formed in separate locations. The Janggi Group in the Eoil basin is divided into following stratigraphic units in ascending order: Gampo Conglomerte, Hongdeok Basalt, Nodongri Conglomerate and Yeondang Basalt, and the Bomkori Group in the Waeup basin: Waeupri Tuff; Andongri Conglomerate, Yongdongri Tuff and Hoamri Volcanic Breccia. Paleostress analysis by using striated faults reveals five sequential tectonic events: (1) NW-SE transtension (event I), (2) NW-SE transpression (event IIl), (3) NE-SW pure extension (event III), (4) N-S transpression (event IV) and (5) E-W pure compression (event V). Therefore, five sequential tectonic movements are closely associated with the formation and evolution of the Tertiary basins in the study area: tectonic event I of NW-SE extension is related to formation of the Tertiary basins during the late Oligocene to the Early Miocene, tectonic events II, III and IV caused the termination of the Tertiary basin opening and the crustal uplift in the study area, and tectonic event V upheaved the east coast or Korean Peninsula with compressive stress due to intense subduction of the Pacific plate into Asian continent since the Early Pliocene.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.199-210
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• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.