• Structural Engineering and Mechanics
• /
• v.45 no.4
• /
• pp.455-470
• /
• 2013

RC flat plates that have no flexural stiffness by boundary beams may be governed by a serviceability as well as a strength condition. A construction sequence and its impact on the distributions of construction loads among slabs tied by shores are decisive factors influencing immediate and long term performances of flat plate. Over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction. A reshoring work may be helpful in reducing slab deflections by controlling the vertical distributions of construction loads in a multi-shored flat plate system. In this study, a change of construction loads by reshoring works and its effects on deflections of flat plate systems under construction are analyzed. The slab construction loads with various reshoring schemes are defined by a simplified method, and the practical calculation of slab deflections with considering construction sequences and concrete cracking effects is applied. From parametric studies, the reshoring works are verified to reduce construction loads and slab deflections.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.05a
• /
• pp.5-8
• /
• 2002

The use of the co-cured joining method for composite structures is attractive due to several benefits. However, since the design stress level in cyclic loads is often smaller than the joint strength obtained from the static tensile load test, it is important to establish proper fatigue design criteria. Although some researchers have reported on co-cured joints, there are only a few papers published on the fatigue characteristics of co-cured joints. In this paper, the effect of bond parameters on the fatigue characteristics of a steel-composite co-cured double lap joint under cyclic tensile loads was experimentally investigated. We considered the surface roughness of the steel adherend and the stacking sequence of the composite adherend as bond parameters. A fatigue failure mechanism of the co-cured double lap joint was explained systematically by investigating the surfaces of failed specimens.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.135-140
• /
• 1999

The size effect of axial compressive strength of concrete in notched specimens was experimentally investigated. Based on the concept of the fracture mechanics and size effect law, theoretical studies for axial compressive failure of concrete were reviewed, and two failure modes of concrete specimen under compression were discussed. In this study, experiment of axial compressive failure, which is one of the two failure modes, was carried out by using double cantilever fracture specimens. By varying the slenderness of cantilevers and the eccentricity of applied loads with respect to the axis of each cantilever, the size effect of axial compressive strength of concrete was investigated, and predicted by Bazant's size effect law. The test results show that size effect appears conspicuously for all series of specimens. For the eccentricity of loads, the influence of tensile and compressive stress at the notch tip are significant and so that the size effect is varied. In other words, if the influence of tensile stress at the notch tip grows up, the size effect of concrete increases. And the fact that the fracture process zone must be sufficiently secured for more accurate experiment was affirmed.

• Journal of Industrial Technology
• /
• v.26 no.B
• /
• pp.127-134
• /
• 2006

As material needs have been increasing with recent economic growth, it is a current tendency that the magnitude of load applied to structure has been rising. With improved technique of product materials, steel and concrete have been stranger than ever so the danger of fatigue damage increases as permanent action of repeated loads. In case of deformed steel bars widely used in reinforced concrete structure, when they are product in factory, there will exist same parts connecting the steels. Such connections are easy to be weakened by permanent action of repeated loads. It is a real condition in Korea that there is lack of research of it. As a result of estimating fatigue characteristic of Pressure Welded joints with the steels that are oftenly used and producted in domestic it is showed that there are no remarkable difference in fatigue strength. Because there is no detail which is refered in Civil Specification, this paper will be the basic data being added in later Specification.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.10a
• /
• pp.569-576
• /
• 2003

Fundamental issues in static finite element analysis of reinforced concrete panel subjected to biaxial tensile loads are discussed. This paper is trying to bring our attention to the appropriate use of concrete material models such as cracking criteria, tension stiffening model and the steel models which are basically used in the nonlinear finite element analysis of reinforced concrete panels. We mainly investigate the sensitivity of available material models and finite element technologies to the finite element analysis result using our recent reinforced concrete panel experiment result. Throughout this study, we found that the judicious use of the material models and finite element technologies with the sound understanding of structural characteristics can only guarantee the accurate prediction of panel behaviour.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2002.10a
• /
• pp.267-272
• /
• 2002

Pitting corrosion is a very common occurrence in marine structures. Therefore, the 3-D finite element analysis is carried out to determine the stress intensity factors at the pit depth and also at the surface of the pit. The pits are modeled as a part of sphere, based on the pit depth and the pit diameter as specified by the Ship Structural Committee. The pit depth and pit diameter are function of the percentage of pitting that the plate is subjected to. A dog-bone shaped specimen is subjected to different intensities of pitting and the stress intensity factors are determined under axial tensile loads.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.3 no.3
• /
• pp.195-202
• /
• 1999

This study present the stability of middle slabs directly supporting train loads in the subway station. According to results of Quality confirmation, mixing and curing conditions are good. But, when effects of hydration heat are analyzed, cracks seems to take place because tensile stress is higher than tensile strength in several points of middle slabs. It is found that vibration by train running don't have an effect on cracks in the structure. The structural analysis shows that there is no problem on the stability of structural body, but the design through 3-dimensional analysis is need to consider columns and opening specially in the subway station structures.

• Geomechanics and Engineering
• /
• v.13 no.3
• /
• pp.431-446
• /
• 2017

Rock bridges in rock masses would increase the bearing capacity of Non-persistent discontinuities. In this paper the effect of ratio of rock bridge surface to joint surface, rock bridge shape and normal load on failure behaviour of intermittent rock joint were investigated. A total of 42 various models with dimensions of $15cm{\times}15cm{\times}15cm$ of plaster specimens were fabricated simulating the open joints possessing rock bridge. The introduced rock bridges have various continuities in shear surface. The area of the rock bridge was $45cm^2$ and $90cm^2$ out of the total fixed area of $225cm^2$ respectively. The fabricated specimens were subjected to shear tests under normal loads of 0.5 MPa, 2 MPa and 4 MPa in order to investigate the shear mechanism of rock bridge. The results indicated that the failure pattern and the failure mechanism were affected by two parameters; i.e., the ratio of joint surface to rock bridge surface and normal load. So that increasing in joint area in front of the rock bridge changes the shear failure mode to tensile failure mode. Also the tensile failure change to shear failure by increasing the normal load.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6D
• /
• pp.951-960
• /
• 2006

Structural pavement analysis considering lateral loads of moving vehicle was carried out in order to simulate passing vehicle loads under various interface conditions. To verify of existing multi-layer elastic analysis of layer interface effect parameters, this study compared outputs by using ABAQUS, a three dimensional finite element program and KENLAYER, multi-layer elastic analysis as vertical load was applied to the surface of asphalt pavements. Pavement performance depending on interface conditions was quantitatively evaluated and fundamental study of layer interface effect parameters was performed in this study. As results of the study, if only vertical loads of moving vehicle is applied, subdivision of either fully bonded or fully unbonded is enough to indicate interface effect parameters. On the other hand, when lateral loads are applied with vertical loads, pavement behavior and performance are greatly changed with respect to layer interface conditions. The thinner thickness of the asphalt layer is and the smaller elastic moduli of the asphalt layer is, the more pavement behavior is influenced by interface conditions. In addition, regression analysis equation analytically computing tensile strain which was considered thicknesses and elastic moduli of the asphalt layer and layer interface effect parameters at the bottom of the asphalt layer was presented using database from numerical analyses on national pavement model sections.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.6
• /
• pp.715-724
• /
• 2011

A turn buckle inserted between tension members that sustain the structural loads in a suspension structure system is a device that is capable of adjusting the tensile force. The tension member is an important element of a tension structure, but no simple and economical method of measuring a tensile force applied to members has been proposed yet. Thus, a turn buckle for measuring the tensile force in a tension member was developed in this study. The turn buckles of the measurement limit loads of 100kN, 200kN, and 300kN were tested through a theoretical analysis and a finite element analysis. There was no significant difference in the results of the theoretical analysis, FEA, and the test. In addition, the ultimate strength of the turn buckle using FEA showed that a new turn buckle is sufficiently safe to use even when there is a five-times overload in the measurement limit load.