• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.1-14
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• 2004

The seismic behavior of a 1/3-scale model of a two-story unreinforced masonry (URM) structure typically used in constructing low-rise residential buildings in Korea is studied through a shaking table test. The purposes of this study are to investigate seismic behavior and damage patterns of the URM structure that was not engineered against seismic loading and to provide its experimental test results. The test structure was symmetric about the transverse axis but asymmetric to some degrees about longitudinal axis and had a relatively strong diaphragm of concrete slab. The test structure was subjected to a series of differentlevels of earthquake shakings that were applied along the longitudinal direction. The measured dynamic response of the test structure was analyzed in terms of various global parameters (i.e., floor accelerations, base shear, floor displacements and storydrift, and torsional displacements) and correlated with the input table motion. Moreover, different levels of seismic performance were suggested for performance-based design approach. The results of the shaking table test revealed that the shear failure was dominant on a weak side of the 1stfloor while the upper part of the test model remained as a rigid body. Also, it was found that substantial strength and deformation capacity existed after cracking.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.305-313
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• 2012

Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.

• Tunnel and Underground Space
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• v.9 no.1
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• pp.72-77
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• 1999

New criteria to evaluate blasting damage to structure is proposed considering environmental caused daily deformation of cracks in structures. Results from 3 brick houses in fishing village shows that more than 10 times higher vibration level than design criteria of 0.5 kine is required to cause structural damage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.3
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• pp.3-13
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• 2001

The behavior of the masonry lining is studied to gain basic information on how to reinforce the masonry tunnels. Apart from the previous works on the masonry structures, the multi-course masonry structure, realistic in field condition, is considered and the constitutive relationship of the masonry is, therefore, established. The design charts of the orthotropic material properties are proposed according to the stiffness ratio and the crack initiation and subsequent propagation model is also considered to model the brittle nature of the masonry. A numerical analysis on the masonry panel is investigated to verify the proposed model and future works of the masonry lining are briefly explained.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.535-542
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• 2006

In Seoul, more than 80 percent of residential buildings are constructed with unreinforced masonry(URM) buildings in early 1970 to 1990. In general, URM buildings have the advantages of reducing the construction time and easy to construction. However, URM buildings do not have enough strength against the lateral force. Moreover, low rise buildings have not adopted seismic designs, and for that reason a critical damage is expected with an earthquake. And also, the necessity of the seismic performance evaluation of existing building structures is raised through the Taiwan earthquake in 1999. The purpose of this study is to provide basic information for unreinforced masonry building in Korea by application of the proposed seismic evaluation method. In this study, seismic capacities of 50 existing unreinforced masonry buildings are evaluated based on the proposed method. Also, relationships of seismic capacities between Korean earthquake damage ratios of korean unreinforced masonry buildings are estimated. Results of this study were as follows; 1)Seismic retrofit was needed $8{\sim}48%$ in Korean unreinforced masonry buildings. 2)Korean unreinforced masonry buildings were expected to have severe damage under the earthquake intensity level experienced in Japan.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.13-20
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• 2017

Unreinforced masonry buildings are vulnerable to lateral forces, such as earthquakes, owing to the nature of the building materials, yet numerous masonry buildings remain in South Korea. Since the majority of the existing masonry buildings were constructed more than 20 years ago, it is necessary to develop economical reinforcement methods for disaster reduction. In this study, external reinforcement of masonry walls using adhesive stiffeners was proposed as a reinforcement method for such age-old masonry buildings. Six specimens were fabricated with different aspect ratios (L/H = 1.0, 1.3, and 2.0) and used in static load tests to verify the reinforcement effect. The experimental results showed that the masonry walls before and after reinforcement were ruptured by rigid body rotation and slip. In addition, the maximum strength, maximum displacement, and dissipated energy of the walls were shown to increase after applying the adhesive stiffeners, thereby verifying the excellent reinforcement effect. Furthermore, an adhesive stiffener design for unreinforced masonry walls was proposed based on the increased shear strength achieved by using conventional glass fibers. The proposed design can be used as a basis for the application of adhesive stiffeners for unreinforced masonry walls.

• Korean Journal of Construction Engineering and Management
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• v.21 no.6
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• pp.66-74
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• 2020

To prevent incident of demolition work the Building Management Act was implemented to manage demolition work. According to this law, buildings with the scale upper than 500㎡ of floor area are classified as permission to conduct the demolition work, however it may be hard to perform safety management at demolition work. In addition, the risk level of demolition work is varied with related to the structure type. So, the purpose of this study is to suggest the improvements of criteria on demolition work considering building structure types including small-scale structures such as masonry, wooden, and other structure. The research process was conducted by three steps. (I) Application of Building Management Act; (II) Analysis of demolition work by structure types; and (III) Subdivision of permission targets by building structure types. The result of this study, permission ratio was only 10% for total demolition work and 2.43% for masonry. Because the masonry, wooden, and other structure types are concentrated on a floor area of small-scale, the separate criteria of demolition work is need to prevent the accident and fatal incident. Through the results, the decision maker can be utilized (1) For the special building structure types, the criteria of enhanced safety management are applied by referring to the overseas law ; and (2) The demolition work can be considered by the criteria of separate permission in terms of structure types.

• Journal of the Korean Institute of Rural Architecture
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• v.15 no.4
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• pp.51-58
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• 2013

This study Masonry Buildings in rural areas, due to the lateral load resistance for seismic reinforcement method is proposed. Some of the proposed methods for reinforcement directly through finite element analysis to evaluate the change in frequency. The results for the following: This paper has the object of investigating natural frequencies of opening thick plates on Pasternak foundation by means of finite element method and providing Kinematic design data for mat of building structures. In this paper, vibration analysis of rectangular opening thick plate is done by use of Serendipity finite element with 8 nodes by considering shearing strain of plate. It is shown that natrural frequencies depend on not only Winkler foundation parameter but also shear foundation parameter, opening position.

• Computational Structural Engineering
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• v.2 no.3
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• pp.37-39
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• 1989

본 고에서는 선진 각국의 해체공법에 대한 연구동향을 고찰하기 위한 일환으로 1988.11.7-11 일본 동경에서 개최된 콘크리트와 조적조의 해체 또는 폐재의 재이용에 관한 제2회 심포지움에서 발표된 논문을 기초로 해체공법에 관한 연구동향을 살피고자 한다. 해체공법에 대하여 발표된 논문을 주제별로 살펴보았다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.28-39
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• 2013

The most common housing type in Korea is low-rise buildings with unreinforced masonry walls (UMWs) that have been known as a vulnerable seismic-force-resisting system (SFRS) due to the lack of ductility capacities compared to high lateral stiffness of an UMW. However, there are still a little experimental investigation on the shear strength and stiffness of UMWs and on the seismic performance of buildings using UMWs as a SFRS. In Korea, the shear strength and stiffness of UMWs have been evaluated with the equations suggested in FEMA 356 which can not reflect the structural and material characteristics, and workmanship of domestic UMW construction. First of all, this study demonstrates the differences in shear strength and stiffness of UMWs obtained from between FEMA 356 and test results. The influence of these differences on the seismic performance of UMW buildings is then discussed with incremental dynamic analyses results of a prototype UMW building that were selected by the site survey of more than 200 UMW buildings and existing test results of UMWs. The seismic performance assessment of the prototype UMW building are analyzed based on collapse margin ratios and beta values repesenting uncertainty of seismic capacity. Analysis results show that the seismic performance of the UMW building estimated using the equations in FEMA 356 underestimates both a collapse margin ratio and a beta value compared to that estimated by test results. Whatever the estimation is carried out two cases, the seismic performance of the prototype building does not meet the criteria prescribed in a current Korean seismic code and about 90% collapse probability presents for more than 30-year-old UMW buildings under earthquakes with 2400 return years.