• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.579-585
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• 2018

Masonry walls are of a complex (anisotropic) structure in terms of their mechanical properties. The mechanical properties of the walls are affected by the properties of the materials used in wall construction, joint thickness and the type of masonry bond. The carried-out studies, particularly in the seismic zones, have revealed that the most of the conventional masonry walls were constructed without considering any engineering approach. Along with that, large-scale damages were detected on such structural elements after major earthquake(s), and such damages were commonly occurred at the brick-joint interfaces. The aim of this study was to investigate the effect of joint thickness and also type of mortar on the mechanical behavior of the masonry walls. For this aim, the brick masonry walls were constructed through examination of both the literature and the conventional masonry walls. In the construction process, a single-type of brick was combined with two different types of mortar: cement mortar and hydraulic lime mortar. Three different joint thicknesses were used for each mortar type; thus, a total of six masonry walls were constructed in the laboratory. The mechanical properties of brick and mortars, and also of the constructed walls were determined. As a conclusion, it can be stated that the failure mechanism of the brick masonry walls differed due to the mechanical properties of the mortars. The use of bed joint thickness not less than 20 mm is recommended in construction of conventional masonry walls in order to maintain the act of brick in conjunction with mortar under load.

• Journal of Korean Association for Spatial Structures
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• v.20 no.3
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• pp.107-116
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• 2020

In this paper, the displacement response to seismic loads was analyzed after installing TMD in spatial structures and high-rise buildings. In the case of a spatial structures, since it exhibits complex dynamic behavior under the influence of various vibration modes, it is not possible to effectively control the seismic response by installing only one TMD, unlike ordinary structures. Therefore, after installing eight TMDs in the structure, the correlation between displacement response and mass ratio was examined while changing the mass. The TMD must be designed to have the same frequency as the structure frequency so that the maximum response reduction effect can be exhibited. It can be confirmed that the most important variable is to select the optimal TMD mass in order to install the TMD on the structure and secure excellent control performance against the earthquake load. As a result of analyzing the TMD mass ratio, in the case of high-rise buildings, a mass ratio of 0.4% to 0.6% is preferable. In spatial structures, it is desirable to select a mass ratio of 0.1% to 0.2%. Because this study is based on the theoretical study based on numerical analysis, in order to design a TMD for a real structure, it is necessary to select within a range that does not affect the safety of the structure.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.69-76
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• 2009

In this study, design method for debris flow and drift wood dams used in Japan was evaluated to develop currently available design method practiced in Korea. In Japan, represented a similarity in the aspects of topography and the climate compared with Korea, casualties due to debris flow, landslide, and collapse of cliff as well as earthquake, have been reported every year. Especially, debris flow had often occurred during heavy rainy season rather than due to Typhoons or localized torrential thunderstorms. Since the characteristic of the debris flow reveals in the middle of water flow and soil behaviors, the behavior of debris flow associated with drift wood was not fully understood at this moment and therefore empirical design method to design debris flow dam is adopted in the practice and currently used in Japan. Based on the result of this study, modification of debris flow design method used in Korea are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.744-751
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• 2006

In case of the Soil Nail System applied to a slope, effects of vibrations from blasting, earthquake and creep of long term behaviors cause reductions of adhesion between grout and soil-nail. There are some reports of nail's pull-out failure by those reasons. In this paper it is suggested that the Cone Nailing System is enable to diminish effects of vibrations and creep. In this study on Cone Nailing System, the cones are installed to each nail by 2m. By such installing cones, the adhesion between nail and grout will increase and the long term creep behavior will decrease. In this study, the centrifuge test is performed to understand the behaviors of the Cone Nail System. For the centrifuge test, the soil tank is 52cm in width, 17cm in length and 35cm in height. In comparison with general soil nail, the centrifuge test of general soil nail(without cone) is performed equally. Additionally, the interface between cone nail and soil through the pull-out test is applied to FLAC 2D version 3.3. and the evaluation of application for the Cone Nail System in slope is performed.

• Journal of the Korea Concrete Institute
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• v.14 no.2
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• pp.180-189
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• 2002

The objective of this experimental research is to assess the seismic performance of circular RC bridge pier specimens retrofitted with fibers which were designed as a prototype of Hagal bridge in the city of Suwon, Korea. Pseudo dynamic test has been done for four(4) test specimens which were nonseismically or seismically designed by the related provisions of the Korea roadway bridge design specification, and four nonseisemic test specimens retrofitted with fibers in the plastic hinge region. Glass and carbon fiber sheets were used for the seismic capacity enhancement of circular test specimens. Important test parameters were confinement steel ratio, load pattern, and retrofitting. The seismic behavior has been analyzed through the displacement ductility, energy analysis, and capacity spectrum. Approximate 7.7 ∼8.7 displacement ductility was observed for nonseismic test specimens retrofitted with fibers subjected to Korea Highway Cooperation artificial earthquake motions. It is concluded that these retrofitted test specimens could have sufficient seismic capacity in the region of moderate seismic zone.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.441-448
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• 2007

The beam-column assembly in a ductile reinforced concrete (RC) frames subjected to seismic loading are generally controlled by shear and bond mechanisms, both of which exhibit poor hysteretic properties. Hence the response of joints is restricted essentially to the elastic domain. The usual earthquake resistant design philosophy of ductile frame buildings allows the beams to form plastic hinges adjacent to beam-column assembly. Increased strain in these plastic hinge regions affect on joint strain to be increased. Thus bond and shear joint strength are decreased. The research reported in this paper presents the test results of five RC beam-column assembly after developing plastic hinges in beams. Main parameter of the test Joints was the amount of the longitudinal tensile reinforcement of the beams. Test results indicted that the ductile capacity of joints increased as the longitudinal tensile reinforcement of the beams decreased. In addition, both the tensile strain of the longitudinal reinforcement bars in the joint and the ductile ratio of the beam-column assemblages increased due to the yielding of steel bars in the plastic hinge regions.

• Steel and Composite Structures
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• v.16 no.4
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• pp.417-436
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• 2014

During an earthquake, steel frame columns can be subjected to high axial forces combined with inelastic rotation demand resulting from story drift. Generally, the whole beam or component can be represented with one element. In elasto-plastic analysis, subdivision is necessary if the plastic deformation occurs within two ends of beams. If effects of the joint panel are necessarily considered in the analysis, the joint panel should be represented with an independent element. It is a special element to represent the shear deformation of the joint panel in the beam-column connection zone. Several analytical models for panel zone (PZ) behavior exist, in terms of shear force-shear distortion relationships. Among these models, the Krawinkler PZ model is the most popular one which is used in the AISC code. Some studies have pointed out that Krawinkler's model gives good results for the range of thin to medium column flanges thickness. This paper, introduces a new model to estimate the response of shear force-shear distortion for the PZ including column axial force. The model is applicable to both thin and thick column flange. To achieve an appropriate PZ mathematical model first, the effects of PZ strength and stiffness on connection response are parametrically studied using finite element models. More than one thousand and four-hundred beam-column connections are included in the parametric study, with varied parameters; then based on analytical results a simple mathematical model is presented. A comparison between the results of proposed method herein with FE analyses shows the average error especially in thick column flange is significantly reduced which demonstrates the accuracy, efficiency, and simplicity of the proposed model.

• Journal of Korean Society of societal Security
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• v.2 no.4
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• pp.35-41
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• 2009

If any bridge has the monitoring system, the bridge manager can check the history of bridge behavior and the progress of the damage more exactly. When the unexpected event (ex: earthquake and flood) happens, the manager can check the safety condition of the bridge and make the pertinent action for bridge management which is reduction of vehicle speed or traffic control through the system. Additionary the manager can make the well-timed repair or reinforcement through the system, so he can save the management cost or the life cycle cost. This study presents the method of setting the criteria by FEM analysis in bridge monitoring system, and the standard progress for setting the criteria about measurement items of monitoring system for the steel box type bridge.

• The Journal of Engineering Geology
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• v.21 no.1
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• pp.87-95
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• 2011

To provide regulatory standards and technical guides that are likely to be required for the Fault Monitoring System (FMS), soon to be installed and operated at the Shin-Wolsong NPP #1, 2 site, technical trend analysis was performed for currently operating geodetic and/or earthquake monitoring systems and activities worldwide, resulting in the identification of several items of concern regarding the design, installation, and operation of FMS at Korean sites. The items are as follows: 1) characterization of site-specific properties (including local noise), 2) selection of measuring instruments/design of appropriate sensitivity for the tectonic behavior of the target, 3) data/electricity backup system, 4) cross-checking and/or cross-referencing system to enhance data quality and credibility, 5) transparent data operation and open-to-the-public policy, and 6) long-term operation in a stable environment.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.585-596
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• 2006

This study focuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors), i.e., 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for 20 ground motions representing the hazard level, which is equal to a 2% probability in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. the 20-story buildings, which were designed without using the minimum requirement of spectral acceleration CS prescribed in IBC 2000, did not satisfy the seismic performance for Collapse Prevention performance.