• Journal of the Korean Wood Science and Technology
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• 제33권1호통권129호
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• pp.7-16
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• 2005

This study was carried out to evaluate the structural property of double shear bolted connections in Korean Larch. For the main member, sawn lumber and Glulam were used in which thickness of lumber is 39 mm, 89 mm, 139 mm, 189 mm and Glulam 80 mm, 140 mm, 170 mm. For the side member, sawn lumber and steel plate were used in which thickness of lumber is the same of the main member and steel plate is 6mm. And connections were jointed by M12, M16, M20 bolts which were usually used for wood constructions in Korea. Directions of loading to connections were perpendicular and parallel to grain of main and side member. First, through the dowel bearing test, the dowel bearing strength was evaluated and through the bolt bending tests, the bolt bending strength was evaluated. And then experiments for the connection were performed. Obtained results from experiments were compared with calculated values by EYM and analyzed. Strength of double shear bolted connections in Korean Larch was similar or higher than calculated value by EYM. Especially when the side member was made by the sawn lumber, it was similar to the calculated value. In failure mode, the mode was effected by the knot and the dry defect. In the thin main member, it was shown mode I and as the thickness of the main member was thicker, it was changed into mode III.

• Journal of the Korea institute for structural maintenance and inspection
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• 제19권2호
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• pp.170-178
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• 2015

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

• Journal of the Korea Concrete Institute
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• 제17권1호
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• pp.85-94
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• 2005

Post-tensioned Precast concrete System(PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with floor concrete cast on the PC shell beam and post-tensioning. The purpose of this paper is to evaluate the response of PPS interior beam-column joint subjected to cyclic lateral loading. To this end, an experimental investigation was performed with three half-scale specimens of interior connection. The design parameters are the amount of beam reinforcement placed inside the joint core. The test results showed that cracks were distributed well without my significant degradation of strength and ductility. Also, it was found that the prestressing may affect to alter the torsional crack angle. And the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional by ACl of acceptance criteria for concrete special moment frames.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.9-12
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• 2008

The semi-rigid joint is the shape of middle that can supplement the defect of pin joints and accept the good point of rigid joints. Recently, a study on the pin joints is activated in the country, but because the study on semi-rigid joints is not many, this study tried to prove with producing test model of three shape. The test models are rigid joint HI-R, semi-rigid joint HI-S, pin joint HI-P. As a result of the test, respectively HI-R, HI-S, HI-P appeared shear failure of joint, flexure failure of the top fixing, flexure failure of the lower part slipping stair slab, and the maximum strength is measured to 51.74, 51.4, 24.63kN, the stiffness is appeared 1.58, 1.19, 0.37 respectively, The yield strength is respectively kept 44.5, 47.3, 24kN, and ductility ratio is appeared to 3.31, 2.32, 1.54, when is based on KBC code, sag of the acting service load is appeared that HI-P model is over the standard. When is based on distribution of bars strain ratio, HI-S seems similar behavior incipiently, but after the yield, the semi-rigid joint was able to be judged better than pin joint because of the stress allotment of joint internal elements.

• Magazine of the Korea Concrete Institute
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• 제8권6호
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• pp.173-182
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• 1996

An experimental research was carried out to investigate the effect of thc compressive strength of concrete on the stirrup effectiveness in shear behavior of concrete beams. For this purpose. total 24 beams of section dimension of $300{\times}600mm$ were tested: 4 specimens without web reinforcement and 20 specimens with web reinforcement in the form of vertical stirrups. Main variables were two levels(norma1 and high strength) of the compressive strength of concrete and six types of t h e shear rcinfor.cement ratios. Prior to experiment, for given sections and assumed material constants, the reference shear reinforcement ratio(${\rho}_vACI$) which leads to the flexure failure using the provisions of the ACI Building Code(AC1 318-95) was calculated. and the shear reinforcement ratios were relatively selected from the value of ${\rho}_vACI$. From test results, it was shown that thc safety factor of ACI eyuation for p1,ediction of shear strength was decreased with increasing the compressive strength of concrete in beams without stirrups. However. it was observed that as the amount of' stirrup is increased, the safety factor for high strength conci,ete beams with high stirrup ratio is ensured more than that for normal strength concrete beams. Therefore i t appears that the stirrup effectiveness of high strength concrete beams is greater than that of normal strength concrete beams.

• Journal of the Korea Concrete Institute
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• 제24권2호
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• pp.147-156
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• 2012

In recent years, many high-rise buildings have been constructed in irregular structural system with inclined columns, which may have effect on the structural behavior of beam-column joints. Since the external load leads to shear and flexural forces on the inclined columns in different way from those on the conventional vertical columns, failure mode, resistant strength, and ductility capacity of the inclined column-beam joints may be different than those of the perpendicular beam-column joints. In this study, six RC inclined beam-column joint specimens were tested. The main parameter of the specimens was the angle between axes of the column and beam (90, 67.5, and 45 degree). Test results indicated that the structural behavior of conventional perpendicular beam-column joint was different to that of the inclined beam-column joints, due to different loading conditions between inclined and perpendicular beam-column joints. Both upper and lower columns of perpendicular beam-column joints were subjected to compressive force, while the upper and lower columns of the inclined beam-column joints were subjected to tensile and compressive forces, respectively.

• Journal of the Earthquake Engineering Society of Korea
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• 제2권4호
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• pp.155-168
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• 1998

In this paper, the structural properties of the existing reinforced concrete(RC) piers are surveyed and the major factors influencing the member strength and deformation capacity are identified. Also a seismic evaluation procedure of RC piers is presented. The factors controlling the member strength are the applied axial load, the reinforcement ratio and yield strength of longitudinal rebar for flexural strength, and the transverse reinforcement for shear strength. Member deformation capacity largely depends on transverse reinforcement ratio and anchor detail, and splice location of longitudinal reinforcement. The above structural detail should be investigated for the detail seismic evaluation of RC piers. The most of existing RC piers have inadequate transverse reinforcement anchor details and the splices of longitudinal reinforcement in the pier bottom where plastic hinges are formed after yielding. Therefore the deformation capacity is not enough for the ductile flexural behavior of the RC piers. The presented evaluation procedure can be used for the rational decisions as to seismic retrofitting of the existing RC piers.

• Journal of Korean Society of Forest Science
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• 제96권1호
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• pp.54-57
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• 2007

Urea-formaldehyde (UF) resin was formulated similarly to plywood resin in the laboratory. The synthesized UF resin adhesive was mixed with extender, filler and acid catalyst. The mixture contained 56.1% total solids and 43.9% water. The mixes was used to bond five Com-Ply types using Korean wood species. The Com-Ply made were tested for shear strength and wood failure according to KS F 3101 ordinary plywood as well as for bending strength per KS F 3104 particleboard. The performance test results showed good strength properties for all Com-Ply types made in this study. This result represented that the UF resin adhesive mix was adequate for bonding Com-Ply with domestic wood species.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.337-348
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• 2003

본 연구는 8개의 RBS (reduced beam section) 내진 철골모멘트접합부의 실물대 실험결과를 요약한 것이다. 본 실험의 주요변수는 보 웨브 접합법 및 패널존 강도를 택하였다. 균형 패널존 시험체는 접합부의 내진성능을 감소시키지 않으면서, 보와 패널존이 함께 균형적으로 지진에너지를 소산시키도록 설계하여 값비싼 패널존보강판(doubler plates)의 수요를 줄이고자 시도한 것이다. 보 웨브를 용접한 시험체는 모두 특별 연성모멘트골조에서 요구되는 접합부 회전능력을 충분히 발휘하였다. 반면 보 웨브를 볼트접합한 시험체는 조기에 스캘럽을 가로지르는 취성파단이 발생하는 열등한 성능을 보였다. 보 그루브 용접부 자체의 취성파괴가 본 연구에서와 같이 양질의 용접에 의해 방지되면, 스켈럽 부근의 취성파단이 다음에 해결해야 할 문제로 대두되는 경향을 보인다. 보 웨브를 볼팅한 경우에 접합부 취성파단의 빈도가 월등히 높은 이유를 실험 및 해석결과를 토대로 제시하였다 측정된 변형도 데이터에 의할 때, 접합부의 전단력 전달메카니즘은 흔히 가정하는 고전 휨이론에 의한 예측과 전혀 다르다. 이는 전통적 보 웨브 설계법을 재검토할 필요가 있음을 시사하는 것이다. 아울러, 본 연구의 제한된 실험자료 및 접합부에서 요구되는 바람직한 거동기준을 근거로 균형 패널존의 강도범위에 대한 예비적 추정치를 제시하였다.

• Journal of the Korean Wood Science and Technology
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• 제36권4호
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• pp.19-25
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• 2008

This study was carried out to investigate the bending strength properties of the unreinforced glulam beams and the GFRP laminated glulam beams according to the volume ratio of GFRP. The 7-layer glulam beams ($10cm(b){\times}14cm(h){\times}180cm(l)$) were manufactured, using Larch (Larix kaempferi Carr.) laminae ($2cm(h){\times}10cm(b){\times}360cm(l)$), which were dried to the moisture content of 8% and specific gravity of 0.54. GPRP of 0.1 and 0.3 cm was reinforced between the outmost layer of bottom and next layer. When the glulam beams were reinforced with GFRP at the volume ratio of 0.7% and 2.1%, respectively, the bending strength was increased by 12% and 28%, respectively, in the reinforced beams than in control glulam beams. Also, the GFRP reinforced layer of the glulam beams with GFRP laminations blocked the progression of rupture, and the unbroken part held about 90% of the bending strength. In the results of glue joints test, the block shear strength is higher than $7.1N/mm^2$, the standard of KS F3021, and in the result of delamination, the adhesive strength is good as the water soaking and boiling delamination was less than 5%.