• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.11 no.4
• /
• pp.1-8
• /
• 1991

Recently the use of steel fibers has been increased in flexural members and columns of concrete structures subjected to cyclic loadings; such as bridge decks, highway roads, runway of airport, buildings, etc.. However only a few experimental tests have been carried out under fatigue loading. In the present study, the reinforced concrete beams with 1% and 2% steel fiber volume fraction are investigated with and without stirrups. It has been found that in fatigue tests, the failure of the beam is usually due to breaking of fibers rather than fiber pull-out. A comparison of experiments and numerical analysis using the nonlinear F.E.M. program (ADINA) is also presented herein.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.11c
• /
• pp.95-104
• /
• 1999

In this study, laboratory pull-out tests and finite element modeling are carried out focused on the grid effects of geogrid and the analyses of friction characteristics associated with interaction behaviors of the composite reinforcement composed of geogrid with a superior function in tensile resistance and geotextile with sufficient drainage effects. In addition, drainage effects of the geotextile below geogrid are examined based on the analysis of finite difference numerical modeling. From the present investigation, it is concluded that the geosynthetic composite reinforcement in the weathered granite backfills may possibly be used to achieve effects on both a reduction of deformations and an increase of the tensile resistance, together with drainage effects due to the geotextile.

• Structural Engineering and Mechanics
• /
• v.7 no.1
• /
• pp.35-52
• /
• 1999

Realistic steel-concrete bond/slip relationships proposed in the literature are usually uniaxial. They are based on phenomenological theories of deformation and degradation mechanisms, and various pull-out tests. These relationships are usually implemented using different analytical methods for solving the differential equations of bond along the anchored portion, for particular situations. This paper justifies the concepts, and points out the assumptions underlying the construction and use of uniaxial bond laws. A finite element implementation is proposed using 2-D membrane elements. An application example on an interior beam-column joint illustrates the possibilities of this approach.

• Structural Engineering and Mechanics
• /
• v.17 no.2
• /
• pp.141-152
• /
• 2004

The bonding behaviors of Lightweight Aggregate Concrete (LWAC) and normal weight concrete were investigated experimentally. Pull-out tests were carried out to measure the bond strengths of three groups of specimens with compressive strength levels of 60, 40, and 20 MPa, respectively. Test results showed that the difference in the bond failure pattern between LWAC and normal weight concrete was significant as the concrete compressive strength became lower than 40 MPa. The corresponding bond strengths of LWAC were lower than that for normal weight concrete. As the compressive strength of concrete became relatively high (> 40 MPa), a bond failure pattern in normal weight concrete occurred that was similar to that in LWAC. The bond strength of LWAC is higher than that for normal weight concrete because it possesses higher mortar strength. Stirrup use leads to an increase of approximately 20% in nominal bond strength for both types of concrete at any strength level.

• Computers and Concrete
• /
• v.19 no.4
• /
• pp.375-385
• /
• 2017

In the present paper experimental and numerical analysis of hook-ended steel fiber reinforced concrete is carried out. The experimental tests are performed on notched beams loaded in 3-point bending using fiber volume fractions up to 1.5%. The numerical analysis of fiber reinforced concrete beams is performed at meso scale. The concrete is discretized with 3D solid finite elements and microplane model is used as a constitutive law. The fibers are modelled by randomly generated 1D truss finite elements, which are connected with concrete matrix by discrete bond-slip relationship. It is demonstrated that the presented approach, which is based on the modelling of concrete matrix using microplane model, able to realistically replicate experimental results. In all investigated cases failure is due to the pull-out of fibers. It is shown that with increase of volume content of fibers the effective bond strength and slip capacity of fibers decreases.

• Computers and Concrete
• /
• v.15 no.6
• /
• pp.951-972
• /
• 2015

The focus of the present study is to investigate both local and global behaviour of a precast concrete sandwich panel. The selected prototype consists of two reinforced concrete layers coupled by a system of cold-drawn steel profiles and one intermediate layer of insulating material. High-definition nonlinear finite element (FE) models, based on 3D brick and 2D interface elements, are used to assess the capacity of this technology under shear, tension and compression. Geometrical nonlinearities are accounted via large displacement-large strain formulation, whilst material nonlinearities are included, in the series of simulations, by means of Von Mises yielding criterion for steel elements and a classical total strain crack model for concrete; a bond-slip constitutive law is additionally adopted to reproduce steel profile-concrete layer interaction. First, constitutive models are calibrated on the basis of preliminary pull and pull-out tests for steel and concrete, respectively. Geometrically and materially nonlinear FE simulations are performed, in compliance with experimental tests, to validate the proposed modeling approach and characterize shear, compressive and tensile response of this system, in terms of global capacity curves and local stress/strain distributions. Based on these experimental and numerical data, the structural performance is then quantified under various loading conditions, aimed to reproduce the behaviour of this solution during production, transport, construction and service conditions.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.2
• /
• pp.101-107
• /
• 2016

The main target in this paper is the localization of VME Type EPSM in Generator Exciter(EX2100) System. Developed EPSM has the compatibility with the existing product in the structure and shape and electrical feature and so on, but it has a much improved capacity and reliability in comparison with origin company product. this paper, to improve these functions, put emphasis on protection, monitoring, power capacity increase(over 120%), an enlarged scale of input voltage supply, AC/DC dual voltage use and so on. After manufacturing product localization, it was carried out several tests for the performance and reliability verification of developed product. These tests were performed in Authorized Inspection Agency(KTL) and field application test and maker self-test were additionally performed. Finally, the results of all tests were "success".

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.1
• /
• pp.64-70
• /
• 2023

In this study, reliability tests of torsion control expansion anchors according to drill bit diameters were performed. The standard deviation and coefficient of variation of the anchor were reviewed through the tests for each variable, and the results were compared and evaluated with the standard test results. As a result of the reliability test of the M12 and M16 anchors with 1.04 times the drill bit diameter, they were within 20% of the ultimate tensile load permissible standard coefficient of variation. It was found that the pulling-out performance of the anchor installed in the large hole was sufficiently secured. However, it was found to be about 253% and 210% of the design strength, indicating that the pulling performance of the anchor installed in 1.04 times the drill bit diameter was sufficiently secured. As a result of the reliability test of the M12 and M16 anchors with 1.02 times the drill bit diameter, the value of the coefficient of variation of the ultimate tensile load limit was within 20%, which satisfies the test standard. It was shown to be about 136% and 168% of the design strength, indicating that the pulling-out performance of the anchor installed in 1.02 times the drill bit diameter is sufficiently secured.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.6
• /
• pp.709-719
• /
• 2023

In general, most of the electrical equipment responsible for control within power plants is housed in self-standing cabinets. These cabinets are typically fixed to a slab using post-installed anchors. Although the fixation method of using post-installed anchors provides stability, there is a risk of conductor failure due to external forces, including moments. However, the performance assessment of current anchors is only evaluated through uniaxial material tests. Therefore, the primary purpose of this study is to compare the static performance of post-installed anchors, considering on-site installation conditions, with their performance in material tests and to analyze the behavioral characteristics of the anchors. While conducting experiments using actual cabinets would be ideal, practical and spatial constraints make this approach difficult. As an alternative, experiments were conducted using a test specimen consisting of a steel column and a support. As a result, the pull-out performance of anchors reflecting on-site installation conditions was measured to be about 10% higher than that observed in material tests. The trends in load reduction and the point of maximum performance for the anchors also differed. To verify the reliability of the experimental study, a 3D FEM analysis was performed, which will provide predictive information on the loads transferred to the post-installed anchors for structural performance evaluations of electrical cabinets using shaking table test in the future.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.3
• /
• pp.17-28
• /
• 2017

We performed laboratory spudcan penetration and extraction tests considering various geometries. Jumunjin sand, representative standard sand in South Korea, and kaolinite were used for uniform sand and clay layers, respectively. The measured vertical bearing and pull-out capacities were compared to empirical equations for shallow foundations. The results showed good agreement between measured and calculated bearing capacity from laboratory test and previous study at shallow depths. The effect of spudcan geometry is shown to depend on site condition. The influence of a sharp spigot is not significant in clays. The slope of the spudcan surface is shown to influence the pull-out capacity. The characteristics of spudcan penetration and extraction behavior considering various geometries can be a useful reference for determining spudcan geometries.