• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.1
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• pp.21-32
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• 2021

Concrete masonry prisms are strengthened with steel fiber-reinforced mortar (SFRM) overlay and tested for compressive and diagonal tension strength. Masonry prisms are produced in poor condition considering standard workmanship for masonry buildings in Korea. Amorphous steel fibers are adopted for SFRM, and appropriate mixing ratios of SFRM are derived considering constructability and strength. Masonry prisms are strengthened with different fiber volume ratios, while numerous strengthened faces and additional reinforcing meshes are produced for compression and diagonal tension tests. Compression and diagonal tension strength are increased by up to 122% and 856%, respectively, and the enhancement effect for diagonal tension strength was superior compared to compression strength. Finally, the test results and strength prediction equations based on existing literature and regression analysis are compared.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.139-147
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• 1999

Six reinforced concrete shear wall, constructured with fully rigid, slit, and infilled types, were tested under both vertical and cyclic loadings. Experimental programs were carried out to evaluate the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility, under load reversals. All the specimens were modeled in one-third scale size. Based on the test results, the following conclusions can be made. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crushing due to slippage prevention of boundary region and reduction of diagonal tension rathar than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by l.14 times and l.49 times in comparison with the standard fully rigid shear wall frame.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.178-185
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• 2000

A set of tests were accomplished in order to get better insight of the basic material properties of masonry made of normal concrete brick and different type of mortar compositions. Three different types of test were performed. Masonry unit and prism were tested by compressive strength test, Masonry wallets were tested by compressive strength test. Masonry wallets were tested in diagonally under tension. A significant influence of different mortar compositions on compression strength of masonry prism was observed, The tests have shown that for diagonal compression three different mode of failure were possible : tension crack along the loaded diagonal sliding along a mortar joint and combined sliding and diagonal crack according to the adhesive strength of a mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.187-192
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• 1995

Four types of experiments were performed to check the similitude of member behavior between prototype and 1/10 scale models:(1) Test of slender columns with P- effect, (2)Test of short columns with and without confinement steel, (3)Test of simple beams without stirrups, and (4)T-beam test. Based on the results of experiments, the conclusions were made as follows : (1) The P- effect of slender columns can be almost exactly represented by 1/10 acale model. (2)The effect of confinement on short columns by the hoop steel can also roughly simulated by 1/10 scale model. (3)The failure modes of simple beams models were the yielding of tension steel followed by large diagonal tension cracking+compressive concrete failure. (4)The behaviors of prototype and 1/10 scale model in T-beams appear very similar.

• Structural Engineering and Mechanics
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• v.57 no.4
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• pp.641-656
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• 2016

Reinforced concrete frame buildings with masonry infill walls are one of the most popular structural systems in the world. In most cases, the effects of masonry infill walls are not considered in structural models. The results of earthquakes show that infill walls have a significant effect on the seismic response of buildings. In some cases, the buildings collapsed as a result of the formation of a soft story. This study developed a simple method, called corner opening, by replacing the corner of infill walls with a very flexible material to enhance the structural behavior of walls. To evaluate the proposed method a series of experiments were conducted on masonry infill wall and reinforced concrete frames with and without corner openings. Two 1:4 scale masonry infill walls with and without corner openings were tested under diagonal tension or shear strength and two RC frames with full infill walls and with corner opening infill walls were tested under monotonic horizontal loading up to a drift level of 2.5%. The experimental results revealed that the proposed method reduced the strength of infill wall specimens but considerably enhanced the ductility of infill wall specimens in the diagonal tension test. Moreover, the corner opening in infill walls prevented the slid shear failure of the infill wall in RC frames with infill walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.89-92
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• 2008

This study investigates the shear behavior of architectural masonry veneer wall reinforced with specific reinforcement details proposed by this study. For this purpose, experimental tests were conducted using one un-reinforced masonry(URM) wall specimen and three reinforced masonry(RM) wall specimens under quasi static cyclic loads. Un-reinforced(plain) masonry wall is expressed that behavior and failure mode are different for aspect ratio(L/H) and axial compressive force. The test variables are wall aspect ratio and presence of reinforcement. These specimens are masonry structure for architectural clading that is not to exist the axial compressive force. thus the axial compressive force is excepted from test variable. Test result, Behavior of specimens are dominated over rocking mode, but final failure modes are combined with different behaviors. And FEMA273 has proposed the equation of shear strength of masonry pier subjected to in-plane loading. Shear strength equations are classified four types of failure mode that is Rocking, and Toe-Crushing, Bed-Joint-Sliding and Diagonal-Tension. FEMA273 equations predict the behavior modes well, but shear strength is shown in different result.

• Earthquakes and Structures
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• v.13 no.5
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• pp.473-484
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• 2017

The objective of this paper is to report on a study of the use of unstiffened thin steel plate shear walls (SPSWs) for the seismic performance improvement of reinforced concrete frames with deficient lateral rigidity. The behaviour of reinforced concrete frames during seismic activities was rehabilitated with an alternative and occupant-friendly retrofitting scheme. The study involved tests of eight 1/3 scale, one bay, two storey test specimens under cyclic quasi-static lateral loadings. The first specimen, tested in previous test program, was a reference specimen, and in seven other specimens, steel infill plates were used to replace the conventional infill brick or the concrete panels. The identification of the load-deformation characteristics, the determination of the level of improvement in the overall strength, and the elastic post-buckling stiffness were the main issues investigated during the quasi-static test program. With the introduction of the SPSWs, it was observed that the strength, stiffness and energy absorption capacities were significantly improved. It was also observed that the experimental hysteresis curves were stable, and the composite systems showed excellent energy dissipation capacities due to the formation of a diagonal tension field action along with a diagonal compression buckling of the infill plates.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.6 s.46
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• pp.31-39
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• 2005

The purpose of this study was to investigate the nonlinear behavior of a cold-formed steel (CFS) shear panel, which was composed of built-up columns and tension-only diagonal straps for bracing, when excited by earthquake motions. For the purpose, shaketable tests of a full-scale two-story cold-formed steel (CFS) shear panel were conducted. in the shear panel, the diagonal strap is a major lateral force resisting system, which is a very ductile member, and the columns, which are gravity resisting members, are fabricated by wooing studs, which can't develop their full flexural strength because they may buckle locally. The test results showed that the straps dissipate most of energy of the shear panel in a tension-only and pinched way and the columns dissipate it relatively smaller than the straps but they still contribute to overall dissipation. As a result of this study, investigating real nonlinear behavior of a structure in earthquakes is a very important process by shaketable tests even though it is simple.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.601-608
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• 2000

Steel fiber and Polymer are used widely for the reinforcement material of RC structures because of its excellence of durability, serviceability as well as mechanical properties. Polymer-Steel fibrous high strength concrete beam's input ratio are 1.0%. The shear span-to-depth ratio are 1.5, 2.8 and 3.6, compressive strength of specimens 320kg/㎠, 436kgf/㎠ and 520kgf/㎠ in 28 days. The static test was carried out to measure the ultimate load, the initial load of flexural crack and of diagonal crack, from which crack patte군 and fracture modes are earned. Also, stress-strain, load-strain and load-deflection are examined during the test cracks(shear crack, flexural crack, and diagonal tension crack), when the load values are sketched according to the growth of crack. Result are as follows; (1) The failure modes of the specimens increase in rigidity and durability in accordance with the increase of mixing steel fiber and polymer. (2) The load of initial crack was the same as the theory of shear-crack strength (3) Polymer-Steel fibrous high strength concrete beams have increased the deflection and strain at failure load, improving the brittleness of the high strength concrete. (4) In this result of study, an additional study need to make a need formular because the study is different from ACI formular and Zsutty formular.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.139-146
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• 2002

A analysis of crack behavior in RC member was performed by nonlinear finite element method. Two crack models were used in F.E.M.(finite element method): one was FCM (the fixed crack model) and the other was RCM (the rotated crack model). Based on parametric study, the ratio of shear steel, strength of concrete, and a/d(shear span/effective depth) were compared with test results of references. According to the test results, when the member behavior was affected by the shear or diagonal tension, RCM was reasonable. However, when the behavior was affected by the flexibility, FCM was more appropriate. In addition, each crack model behavior for the change of shear steel ratio, the increase of strain energy was constant in FCM, but it was different in RCM because of diagonal crack distribution and crack width. Since the strength of concrete is affected not only by shear but also by flexural strength, each crack model behavior yields similar results.