Papers by Author: Sun Kyu Park

Abstract: For safe and efficient use of the Perfobond Rib shear connector, it is essential to investigate mechanical behaviors and evaluate performance of shear resistance. When the Perforbond Rib shear connectors are to be used for a structure, they show flexural-shear behavior due to external force rather than direct shear behavior. Therefore, this study performed a direct shear test and proposed the equation for the shear resistance assessment. Also, a flexural shear test was conducted. Through the direct shear test, main factors that affect directly shear resistance were found. The flexural shear stress and the direct shear stress were calculated and it is revealed that the flexural shear stress is approximately 6% stronger than the direct shear stress.

Abstract: Modular bridges have structurally weak joints that require a structural safety review. In this study, a static bending test was conducted on a specimen that was prestressed after grouting of its joints with shear keys. The results were compared with those of integral specimens to analyze the structural behavior characteristics of the specimen with grouted joints. Through cyclic loading tests (200,000 and 2,000,000 times), the long-term serviceability was examined in terms of deflections and cracks.

Abstract: With the improvement in the quality of steel materials, the issue of fatigue cracking has become more important for steel bridges than the failure of the material itself. In this study, the Pelikan-Esslinger method was used to determine the fatigue stress of an orthotropic steel deck. A parametric study was then conducted with the steel deck components as the parameters. Based on the results, the effect of the diverse components of the steel deck on the fatigue stress was analyzed.

Abstract: This paper presents the live load distribution in straight prestressed concrete (PSC) girder bridges with curved deck slab utilizing finite element analyses. Numerical modeling methodology was established and calibrated based on field testing results. A parametric study of 73 cases with varying 6 critical parameters was used to determine a trend over each parameter. Through live load girder distribution factor (GDF) comparisons between the AASHTO LRFD, AASHTO Standard factors and finite element analyses results, both AASHTO live load distribution predicted conservatively in most bridges considered in the parametric study. However, in the bridges with curved slab, GDF was underestimated due to curvature influences. This study proposes a new live load distribution formula to predict rational and conservative live load distribution in PSC girder bridges with curved slab for a preliminary design purpose. The proposed live load distribution provides better live load analysis for the PSC girder bridge with curved slab and ensures the GDF is not underestimated.

Abstract: A recently new construction and reconstruction of the bridge have been required to minimize traffic congestion, environmental disadvantage, to reduce the period of construction, and to improve the quality and workability during the construction. For this reason, the application of modular bridge system, which is assembly of the structural members, is necessary to prepare for near future. Fall of girders can occur at the moment to connect between precast girders during the construction, so appropriate cross beams should be installed to solve the mentioned problem. In this study, understanding the structural characteristics and status of cross beam, alternative cross beam system for modular bridge was developed. To inspect the structural characteristics of the alternative system, specimens were built and static loading test was performed. Afterward, the behavior of cross beam in terms of joints and load distribution was observed. Experimental results were analyzed and compared with each data. Therefore, the appropriate cross beam system for modular bridge will be chosen and proposed in this paper.

Abstract: In order to develop a fatigue design method for the actual railroad car body structures using the fatigue data on simulated single spot welded lap joints, firstly, evaluated fatigue strength on the spot welded t-type member which is a component of the actual railroad car body structure. And next, possibility of fatigue design for spot welded T-type member using the fatigue data of single spot welded lap joints was investigated. From the results, it was found that, even though there is some difference in fatigue strength between single spot welded joint and the actual members under the same fatigue life, the fatigue design criterion could be predicted by correction between them.