• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.661-668
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• 2015

Coupled shear walls are effective lateral force resisting system in which coupling beams link individual walls. For improving the energy dissipation capacity of coupling beams, diagonal reinforcement details were developed. However, it is difficult to construct diagonal reinforced coupling beams due to the congestion of reinforcement in the beam. For resolving the problem, this study developed precast coupling beams with bundled diagonal reinforcement. To reduce the reinforcement congestion, bundled diagonal reinforcement were placed in the coupling beam. To evaluate the cyclic performance of coupling beams with bundled diagonal reinforcement, experimental test were conducted. For this purpose, two slender specimens with an aspect ratio of 3.5 were made and tested. It was observed that the cyclic performance of the coupling beam with bundled diagonal reinforcement was similar with that of the coupling beam with normal diagonal reinforcement placed according to design code to ACI 318-11.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.345-349
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• 2019

In Korea, the mountainous area occupies more than 70% of the whole country, cutting of earth slope that cuts a part of the ground surface is widely used when building infrastructures such as road, railroad, and industrial complex construction. In recent years, regulations on environmental damage have become more strict, and various methods have been developed and applied. Among them, Concrete-Panel Retaining Wall technique is actively applied. Concrete-Panel Retaining Wall is a method to resist horizontal earth pressure by forming a wall by attaching a precast retaining wall to the front of the support material and increasing the shear strength of the disk through reinforcement of the support material. Soil nailing, earth bolt, and ground anchor are used as support material. Among them, ground anchor is a more aggressive reinforcement type that introduces tensile load in advance to the steel wire, and a large concentrated load acts on the front panel. This concentrated load is a factor that creates cracks in the concrete panel and reduces the durability of the retaining wall itself. In this study, steel pipe sleeves and reinforcements were purchased at the anchorage of the panel to prevent cracks, and by applying bumpy shear keys to the end of the panel, the weakness of the individual behavior of the existing grout anchors was improved. The problem of degraded landscape by exposure to front concrete of retaining wall and protrusion of anchorage was solved by the production of natural stone patterns and the construction of sections that do not protrude the anchorage. In order to verify the effectiveness of anti-crack sleeves and reinforcements used in the null, indoor testing and three-dimensional numerical analysis have been performed, and the use of steel pipe sleeves and reinforcements has demonstrated the overall strength increase and crack suppression effect of panels.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.2
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• pp.55-62
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• 2015

Shear wall systems behave as individual wall because of openings like window and elevator cage. When coupling beams are installed in shear walls, they will have high strength and stiffness so that be less damaged by lateral loads like earthquake. However, coupling beam is difficult construction method. And arranging reinforcement of slender coupling beams are especially hard. It is because the details of coupling beam provided by ACI 318 are complex. In this paper, experiments were conducted using coupling beams with 3.5 aspect ratio to improve the details of slender coupling beams provided by ACI 318. Two specimens were proposed for this study. One specimen applied with bundled diagonally reinforcement only. Another specimen applied both bundled diagonally reinforcement and High-Performance Fiber Reinforced Cementitious Composite (HPFRCC) so that coupling beams have half of transverse reinforcement. All specimen were compared with a coupling beam designed according to ACI 318 and were evaluated with hysteretic behaviors. Test results showed that the performance of two specimen suggested in this study were similar to that of coupling beam designed according to current criteria. And it was considered that simplification of the details of reinforcement would be available if transverse reinforcement was reduced by using bundled diagonally reinforcement and HPFRCC.

• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.23-36
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• 2008

Soil nailing system can be mentioned to a method of supporting as the shear strength of in-situ soils is increased by passive inclusions. In the general soil nailing system, facing walls are used in two kind of a lattice concrete block or a cast in placed concrete wall. A case of lattice concrete blocks is used in slow slopes greater than 1(V):0.7(H). Also, a case of a cast in placed concrete wall is used in steep slopes less than 1(V):0.5(H). The cast in placed concrete walls are constructed to 30 cm thick together with a shotcrete facing. In this study, the assembling soil nailing method as a new soil nailing system will be proposed. This method is assembly construction using precast concrete panels with 20 cm thick. So, the ability of construction and the quality of facings can be improved more than a conventional soil nailing system. This method can be obtained the effects that a global slope stability increase, as precast concrete panels are immediately put on cutting face after excavating a slope. In this study, confining effects of concrete panels using the assembling soil nailing system were found out by large scaled load tests. In the tests, the load-settlement relationship to an assembling soil nailing system due to the stiff facings as concrete panels appeared to be better than a typical soil nailing system with shotcrete facings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.209-216
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• 2009

Flexible frames on their own offer little resistance to lateral forces, resulting often in large deflections and rotations at the joints. On the other hand, walls subjected to lateral loads fail mainly in shear at relatively small displacements. Therefore, when the nonductile frames and wall act together, the combined action of the composite system differs significantly from that of the frame or wall alone. The objective of the study is to evaluate seismic response of infill walls with notched midsection. Reinforcement detail of wall was main variable in the experiment. Also SHCC was used in order to prevent damage concentration into notched midsection of walls. Test results, SHCC infill walls show the multiple crack patterns as expected. However, PIW-ND specimen exhibits less story drift, stiffness and energy dissipation capacity than those of PIW-NC specimen.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.549-556
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• 2009

This research analyzed the structural efficiency and application by improving the 100 mm width vertical joint to 150 mm and developing three connection methods to reduce the difficulty in assembling and handling PC walls. Moreover, nonlinear finite analysis was used for analyzing. From the analysis results, when double width connection was applied, the PC wall showed larger load capacity and ductility due to the steel bar sharing loads efficiently. Moreover, as the dimension of loops and the number of bars increased, the maximum load capacity increased as well. Also, among the double width connections, the largest capacity showed in the order of welding, ring and C type loop. However, in case of welding type loop connection, the ring type loop is more stable due to changes in different site conditions. Therefore, thorough quality control of welding is necessary.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.327-335
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• 2009

In the seismic region, non-ductile structures often form soft story and exhibit brittle collapse. However, structure demolition and new structure construction strategies have serious problems, as construction waste, environmental pollution and popular complain. And these methods can be uneconomical. Therefore, to satisfy seismic performance, so many seismic retrofit methods have been investigated. There are some retrofit methods as infill walls, steel brace, continuous walls, buttress, wing walls, jacketing of column or beam. Among them, the infilled frames exhibit complex behavior as follows: flexible frames experiment large deflection and rotations at the joints, and infilled shear walls fail mainly in shear at relatively small displacements. Therefore, the combined action of the composite system differs significantly from that of the frame or wall alone. Purpose of research is evaluation on the seismic performance of infill walls, and improvement concept of this paper is use of SHCCs (strain-hardening cementitious composites) to absorb damage energy effectively. The experimental investigation consisted of cyclic loading tests on 1/3-scale models of infill walls. The experimental results, as expected, show that the multiple crack pattern, strength, and energy dissipation capacity are superior for SHCC infill wall due to bridging of fibers and stress redistribution in cement matrix.