• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.175-176
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• 2023

The masonry structure is constructed by cement mortar binding material of brick objects and uses reinforced hardware(connected hardware or wall tie) together when building. However, over time, the corrosion of reinforced steel and the deterioration of joint mortar as well as bricks cause the risk of collapse. In particular, when the externally decorated brick wall is installed on the concrete girder for each floor, the angle bracket is not constructed or corroded, the full-layer weight load is applied to the wall of 0.5B, which is an example of full-scale or collapse. As a result of the evaluation, it was confirmed that the performance was improved compared to the existing bracket, and we plan to carry out a real-life test and long-term performance review of the building using the bracket in the future.

• 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 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.

• 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.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.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.4
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• pp.59-66
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• 2014

This paper deals with vibration of plates with concentrated mass on elastic foundation. The object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Free vibration analysis that tapered thick plate in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. The Winkler parameter is varied with 10, $10^2$, $10^3$ and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0. And the Concentrated Mass is applied as P1, Pc, P2 respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.205-214
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• 2010

Masonry structures have been used throughout the world for the construction of residential buildings. However, from a structural point of view, the masonry material is characterized by a very low tensile strength. Moreover, the bearing and shear capacity of masonry walls have been found to be vulnerable to earthquakes. In this study, to improve the seismic performance of masonry walls, hexagonal blocks were developed and six masonry walls made with hexagonal block were tested to failure under reversed cyclic lateral loading. This paper focuses on an experimental investigation of different types of wall with hexagonal blocks, i.e. walls with different hexagonal blocks and with different reinforcing bar arrangements, subjected to applied cyclic loads. The cracking, damage patterns and hysteretic feature were evaluated. Results from the hexagonal masonry wall were shown more damage reduction and less brittle failure in comparison to the existing rectangular masonry walls.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.495-496
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• 2012

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.399-406
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• 2001

Most unreinforced masonry buildings have a lot of structural faults under the lateral load. Therefore, considering the heavy damage of URM buildings caused by the earthquakes, it may be necessary for the effective seismic code and reinforcing method. This paper describes the research-in-progress on an experiment program fur the investigation of the relatively simple and reliable analytical model to estimate dynamic response of URM buildings and briefly reviews the concept of the reinforcement fur damaged URM buildings.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.1 s.24
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• pp.1-9
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• 2007

This study does by purpose that propose shear resisting force equation of reinforced masonry wall that is reinforced by GFRP(glass fiber reinforced polymer) based on result that is noted through cyclic loading of masonry wall and a shaking table experiment of mock that reflect identifying marks of masonry building which is constructed in domestic. It was Rocking mode to dominate failure of masonry wall in the experiment results, and the equations of UBC show the most resemblant value with experiment results. Through this study, propose the shear force equation of GFRP strengthened masonry wall as following. $$V_n=0.02A_n{\sqrt{f'_m}}+0.022b_gh_g(1+2{\alpha})^3{\sqrt{f_g}}(N/mm^2)$$.