• Journal of the Korean Geophysical Society
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• v.7 no.1
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• pp.31-40
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• 2004

When surveying the cultural heritages especially in the case of stone structures, preserving their original state is of primary importance. For the effective assessment of survey results of stone structure, the dynamic characteristics of that system should be considered. Dynamic characteristics of stone masonry structures depend on several factors such as coefficients of friction, contact conditions, and number of layers of bonding stones. These factors can be estimated by using the dynamic analysis results. This paper describes a method for natural frequency determination of traditional stone arch bridge subjected to compressive force. For this purpose, multi-layered granite brick models of for arch bridge were made and fundamental frequencies corresponding increasing axial forces were measured.

• Journal of the Korean Society of Safety
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• v.21 no.6 s.78
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• pp.74-81
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• 2006

Probabilistic Risk Assessment considering statistically random variables is performed for the preliminary design of a Arch Bridge. Component reliabilities of girders have been evaluated using the response surfaces of the design variables at the selected critical sections based on the maximum shear and negative moment locations. Response Surface Method(RSM) is successfully applied for reliability analyses for this relatively small probability of failure of the complex structure, which is hard to be obtained by Monte-Carlo Simulations or by First Order Second Moment Method that can not easily calculate the derivative terms of implicit limit state functions. For the analysis of system reliability, parallel resistance system composed of girders is changed into parallel series connection system. The upper and lower probabilities of failure for the structural system have been evaluated and compared with the suggested prediction method for the combination of failure modes. The suggested prediction method for the combination of failure modes reveals the unexpected combinations of element failures in significantly reduced time and efforts compared with the previous permutation method or system reliability analysis method.

• Advances in concrete construction
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• v.7 no.1
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• pp.11-22
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• 2019

A comprehensive assessing approach for durability of reinforced concrete structures dealing with the corrosion process of rebar subjected to the attack of aggressive agent from environment was proposed in this paper. Corrosion of rebar was suggested in the form of combination of global corrosion and pitting. Firstly, for the purposed of considering the influence of rebar's radius, a type of Plane Corrosion Model (PCM) based on uniform corrosion of rebar was introduced. By means of FE simulation approach, global corrosion process of rebar regarding PCM and LCM (Linear Corrosion Model) was regressed and compared according to the data from Laboratoire $Mat{\acute{e}}riaux$ et $Durabilit{\acute{e}}$ des Constructions (LMDC). Secondly, pitting factor model of rebar in general descend law with corrosion degree was introduced in terms of existing experimental data. Finally, with the comprehensive numerical simulation, the durability of an existing arch bridge was studied in depth in deterministic way, including diffusion process and sectional strength of typical cross section of arch, crossbeam and deck slab. Evolution of structural capacity considering life-cycle rehabilitation strategy indicated the degradation law of durability of reinforced arch bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.685-693
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• 2002

This bridge was planed to be located in Geuk-rak river at south of Kwangju city. And it is very important to emphasis the beauty of bridge appearance. So Ive adopted unbraced tube arch type those linear beauty is elegance and simple. Actually, foreign bridges similar to this won various prizes for excellence of design. But there is no similar precedent in domestic highway bridge. therefore we intended to certify the security of this bridge through computational analysis. In this paper, approximate introduction of this bridge, design procedure and principal examination item is mentioned.

• Steel and Composite Structures
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• v.45 no.2
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• pp.263-279
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• 2022

With the span and arch rib size of concrete-filled steel tube (CFST) arch bridges increase, the hydration heat of pumped mass concrete inside large-size steel tube causes a significant temperature variation, leading to a risk of thermal stress-induced cracking during construction. In order to tackle this phenomenon, a hydration heat conduction model based on hydration degree was established through a nonlinear temperature analysis incorporating an exothermic hydration process to obtain the temperature field of large-size CFST. Subsequently, based on the evolution of elastic modulus based on hydration degree and early-age creep rectification, the finite element model (FEM) model and analytical study were respectively adopted to investigate the variation of the thermal stress of CFST during hydration heat release, and reasonable agreement between the results of two methods is found. Finally, a comparative study of the thermal stress with and without considering early-age creep was conducted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.113-120
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• 2010

Recently, various evaluations concerning structural stability under construction step and completely constructed step have been executed during a Long-span Arch Bridge designing procedure. However, the breakage of cable-hangers of arched bridge in unexpected accident or periodic cable-replacement has not been considered. Therefore, the purpose of this study is that analyzing structural safety of arched bridge when the cable-hangers being fractured by that reasons. Dynamic analysis are performed by idealizing impact load to three types of impact functions as fracturing the cables. Consequently, when the hangers are fractured, the maximum tensile force by dynamic analysis is larger than those by static analysis. Therefore, the dynamic analysis is demanded to accurately obtain the responses for the structural stability with a realistic impact loading model in the breakage and replacement of cable hangers of long-span arched bride. Moreover, the analysis method and results in this study can be used to basic criteria in design.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.12 no.1
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• pp.61-63
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• 2001

The mucosal bridge of the vocal fold is an arch of mucosa, formed by some portion of the vocal fold mucosa which is detached in various extension and length. The etiology is uncertain but some is related to vocal sulcus. Because it affects the voice with variable impact, it must be differentiated from functional voice disorder. We report a case of a mucosal bridge of vocal fold with a vocal polyp treated by microlaryngeal surgery and voice therapy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.29-47
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• 2014

The masonry stone arch bridge, due to its superior durability and aesthetics, has been one of the oldest and popular types of short span bridges. In Europe, this type of bridges have been continuously constructed, and numerous related researches have been conducted until recently. However, there are few construction cases in Korea since the economic efficiency and the construction effectiveness is not contentable. Therefore, this study proposed the reinforced joint to improve structural performance of the conventional arch systems which is proposed by previous researchers. The structural performance of the proposed reinforced joint, which consists of the transverse loop joint and the longitudinal reinforcement, is validated by experimental test of an arch bridge which is constructed using precast concrete segments. Based on this results of the experimental test, it is concluded that the strength of arch bridges can be enhanced by applying the proposed reinforced joints since the reinforced joint restrains hinge behavior and relative displacement between segments with a little reinforcement.

• Steel and Composite Structures
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• v.32 no.4
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• pp.479-495
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• 2019

In tied-arch bridges, the way the arch and the deck are connected may become crucial. The deck is usually suspended from hangers made out of steel pinned cables capable of resisting axial forces only. However, a proper structural response may be ensured by fixing and stiffening the hangers in order to resist, additionally, shear forces and bending moments. Thus, this paper studies the effect of different pinned and stiffened hanger arrangements on the structural behavior of the tied-arch bridges, with the intention of providing designers with useful tools at the early steps of design. Longitudinally and transversally stiffened hangers (and the effect of hinges at the hangers and their locations) are studied separately because the in-plane and the out-of-plane behavior of the bridge are uncoupled due to its symmetry. As a major conclusion, regarding the in-plane behavior, hangers composed of cables (either with vertical, $Nielsen-L\ddot{o}hse$ or network arrangements) are recommended due to its low cost and ease of erection. Alternatively, longitudinally stiffened hangers, fixed at both ends, can be used. Regarding the out-of-plane behavior, and in addition to three-dimensional arrangements of cables, of limited effectiveness, transversally stiffened hangers fixed at both ends are the most efficient arrangement. A configuration almost as efficient and, additionally, cheaper and easier to build can be achieved by locating a hinge at the end corresponding to the most flexible structural element (normally the arch). Its efficiency is further improved if the cross-section tapers from the fixed end to the pinned end.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.319-327
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• 2002

Development of high-strength and light-weight structural steel as well as advancement in steel structure analysis enable construction of long span steel arch bridge. In an economic viewpoint, however, the design values of long span steel arch bridge needs to be optimized to reduce construction cost and achieve proper levels of structural safety. This study investigated the girder depth and the rise-span ratio for optimum design values, as well as the spectral analysis for protection against earthquake. The relationship between rise-span ratio and girder depth was derived based on the parametric studies of the basic span lengths of 60, 70, 80, 90, and 100m using a commercial Cis SAP2000. The equation relating the two variables was derived using linear regression.