• Title/Summary/Keyword: unreinforced masonry

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Out-of-plane performance of infill masonry walls reinforced with post-compressed wedges under lateral-concentrated push load

  • Sanghee Kim;Ju-Hyun Mun;Jun-Ryeol Park;Keun-Hyeok Yang;Jae-Il Sim
    • Earthquakes and Structures
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    • v.26 no.6
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    • pp.489-499
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    • 2024
  • Infill masonry walls are vulnerable to lateral loads, including seismic, wind, and concentrated push loads. Various strengthening metal fittings have been proposed to improve lateral load resistance, particularly against seismic loads. This study introduces the use of post-compressed wedges as a novel reinforcement method for infill masonry walls to enhance lateral load resistance. The resistance of the infill masonry wall against lateral-concentrated push loads was assessed using an out-of-plane push-over test on specimens sized 2,300×2,410×190 mm3. The presence or absence of wedges and wedge spacing were set as variables. The push-over test results showed that both the unreinforced specimen and the specimen reinforced with 300 mm spaced wedges toppled, while the specimen reinforced with 100 mm spaced wedges remained upright. Peak loads were measured to be 0.74, 29.77, and 5.88 kN for unreinforced specimens and specimens reinforced with 100 mm and 300 mm spaced wedges, respectively. Notably, a tighter reinforcement spacing yielded a similar strength, as expected, which was attributed to the increased friction force between the masonry wall and steel frame. The W-series specimens exhibited a trend comparable to that of the displacement ductility ratio. Overall, the findings validate that post-compressed wedges improve the out-of-plane strength of infill masonry walls.

Experimental Study on the Material Properties of Unreinforced Masonry Considering Earthquake Load (지진하중을 고려한 비보강 조적조의 재료특성 평가에 관한 실험연구)

  • 김희철;김관중;박진호;홍원기
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.2
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    • pp.93-101
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    • 2001
  • 본 논문은 국내의 비보강 조적조에 대해 내진성능을 조사하기 위하여 재료측성 평가를 위한 실험연구를 수행하였다. 실험결과를 바탕으로 조적용 모르터의 압축강도식을 제안하였다. 또한 조적용 모르터의 배합비에 따른 조적조 프리즘의 압축강도 특성을 비교하였다. 조적조 프리즘의 압축강도로써 조적조의 탄성계수를 구할 수 있는 약산식을 제시하였으며, 약산식을 사인장 조적조 실험을 통하여 구한 전단탄성계수값과 비교하여 볼 때 타당성을 가지고 있다고 판단된다. 실험결과로써 나온 재료특성 값을 바탕으로 2층 조적조 다세대 주택에 대한 유사동적해석을 수행하였다. 해석결과로 얻은 전단응력과 전단파괴가 나타난 사인장 조적조의 허용전단응력은 유사한 것으로 확인되었다.

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A study on out-of-plane strengthening of masonry-infilled wall (조적채움벽의 면외보강에 관한 연구)

  • Jang, Hye-Sook;Eun, Hee-Chang
    • Journal of Industrial Technology
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    • v.41 no.1
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    • pp.7-13
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    • 2021
  • Fiber-reinforced polymer reinforcement or polyurea reinforcement techniques are applied to strengthen unreinforced masonry walls (UMWs). The out-of-plane reinforcing effect of sprayed glass fiber-reinforced polyurea (GFRPU), which is a composite elastomer made of polyurea and milled glass fibers on UMW, is experimentally verified. The out-of-plane strengths and ductile behaviors based on various coating shapes are compared in this study. An empirical formula to describe the degree of reinforcement on the out-of-plane strength of the UMW is derived based on the experimental results. It is reported that the peak load-carrying capacity, ductility, and energy absorption capacity gradually improve with an increase in the strengthening degree or area. Compared with the existing masonry wall reinforcement method, the GFRPU technique is a construction method that can help improve the safety performance along with ease of construction and economic efficiency.

Seismic Performance Evaluation of a 2 Story Unreinforced Masonry Building (2층 비보강 조적조 건물의 내진 거동 평가)

  • 김홍범;이준석;한상환
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.10a
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    • pp.531-536
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    • 2001
  • URM buildings have been damaged seriously during earthquake since they were not designed to resist lateral loads. It has led to the importance of studying the behavior and capacity for URM building. The objective of this study is to evaluate seismic performance of URM (Unreinforced Masonry) building. For this purpose, this paper discuss the response of 2 story reduced-scale building subjected to earthquake motion and compare them using existing guidelines to provide improved knowledge for URM building.

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Seismic Performance Evaluation of Unreinforced Masonry Buildings By Using a Three-Step Procedure (3단계 절차를 이용한 비보강 조적조 건물의 내진성능평가)

  • Kim, Tae-Wan;Min, Chan-Gi;Lee, Hui-Man
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.3
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    • pp.57-64
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    • 2011
  • In this study, a seismic performance evaluation of unreinforced masonry buildings was conducted based on a revised draft of the outline of the seismic performance evaluation of existing buildings. The procedure of the performance evaluation is composed of three-steps, which are a preliminary evaluation, a first-level detailed evaluation, and a second-level detailed evaluation, where evaluation is conservatively conducted in the beginning and then more detailed evaluations are gradually conducted. For the study, ten two-story unreinforced masonry buildings were selected and evaluated using the three-step evaluation. The result showed that the performance levels between the preliminary and the first-level detailed evaluations were reversed, which is different from the intent of the procedure. Therefore, in the near future, the problems in each evaluation step that are presented in the results of this study need to be refined.

Evaluation of Shear Strength of Unreinforced Masonry Walls Retrofitted by Fiber Reinforced Polymer Sheet (FRP로 보강한 비보강 조적 벽체의 전단강도 산정)

  • Bae, Baek-Il;Yun, Hyo-Jin;Choi, Chang-Sik;Choi, Hyun-Ki
    • 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.

Modeling of unreinforced brick walls under in-plane shear & compression loading

  • Kalali, Arsalan;Kabir, Mohammad Zaman
    • Structural Engineering and Mechanics
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    • v.36 no.3
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    • pp.247-278
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    • 2010
  • The study of the seismic vulnerability of masonry buildings requires structural properties of walls such as stiffness, ultimate load capacity, etc. In this article, a method is suggested for modeling the masonry walls under in-plane loading. At the outset, a set of analytical equations was established for determining the elastic properties of an equivalent homogeneous material of masonry. The results for homogenized unreinforced brick walls through detailed modeling were compared in different manners such as solid and perforated walls, in-plane and out-of-plane loading, etc, and it was found that this method provides suitable accuracy in estimation of the wall linear properties. Furthermore, comparison of the results of proposed modeling with experimental out coming indicated that this model considers the non linear properties of the wall such as failure pattern, performance curve and ultimate strength, and would be appropriate to establish a parametric study on those prone factors. The proposed model is complicated; therefore, efforts need to be made in order to overcome the convergency problems which will be included in this study. The nonlinear model is basically semi-macro but through a series of actions, it can be simplified to a macro model.

A methodology for development of seismic fragility curves for URBM buildings

  • Balasubramanian, S.R.;Balaji, Rao K.;Meher, Prasad A.;Rupen, Goswami;Anoop, M.B.
    • Earthquakes and Structures
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    • v.6 no.6
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    • pp.611-625
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    • 2014
  • This paper presents a simple methodology that integrates an improved storey shear modelling, Incremental Dynamic Analysis and Monte Carlo Simulation in order to carryout vulnerability analysis towards development of fragility curves for Unreinforced Brick Masonry buildings. The methodology is demonstrated by developing fragility curves of a single storey Unreinforced Brick Masonry building for which results of experiment under lateral load is available in the literature. In the study presented, both uncertainties in mechanical properties of masonry and uncertainties in the characteristics of earthquake ground motion are included. The research significance of the methodology proposed is that, it accommodates a new method of damage grade classification which is based on 'structural performance characteristics' instead of 'fixed limiting values'. The usefulness of such definition is discussed as against the existing practice.

Experimental Study on Seismic Resistance of A Unreinforced Cement Brick Building (비보강 시멘트벽돌 건물의 내진성능 실험연구)

  • 김장훈
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2000.04a
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    • pp.298-307
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    • 2000
  • The behavior of a unreinforced cement brick building structure subjected to earthquake loading was experimentally investigated. for this four full size wall specimens were tested under quasi-static in-plane cyclic loading. Experimental observations indicate that the failure modes of unreinforced masonry walls are principally governed by sliding or/and rocking depending on the aspect ration and magnitude of axial loading. Also found was the flexure or shear mode resulting from the degraded strength of brick and/or mortar due to the cyclic loading effect.

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A Study on the Response Modification Factor of Unreinforced masonry Buildings (비보강 조적조 건물의 반응 수정 계수에 관한 연구)

  • 정상훈
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.10a
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    • pp.265-272
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    • 1999
  • there is no earthquake resistant design code for the unreinforced masonary(URM) buildings in Korea. But it does not mean that all URM buldings in Korea is safe under the possible extent of an earthquake. The purpose of this study is in the inelastic analysis of unreinforced masonary walls with many different types of openings and carry out their ductilities an strengths, response modification factor of each wall has been compared and the most appropriate response modification factor for URM building in Korea has been proposed.

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