콘크리트에 표면매입 보강된 FRP판의 전단키 및 연단거리 효과

서수연 한국구조물진단유지관리공학회 2016 한국구조물진단유지관리공학회 논문집 Vol.20 No.1

본 연구에서는 콘크리트에 표면매입된 FRP판의 부착거동에서, 전단키와 연단거리의 효과를 관찰하기 위한 부착시험을 실시하였 다. 실험에서의 주요변수는 전단키의 위치, 형태 그리고 연단길이이다. 규격 3.6 ㎜×16 ㎜의 FRP를 400 ㎜×200(300) ㎜×400 ㎜ 규격의 콘크리 트 블록에 매입하고 에폭시로 고정시켜서 실험변수에 따라 총 10개의 부착실험체를 제작하였다. FRP의 연단에 인장력을 가한 뒤 파괴시까지 실험을 실시하고 하중을 기록하였으며, 미끄러짐과 FRP의 인장변형량을 기록하였다. 실험으로부터, 전단키의 위치는 가력부에서 멀리 떨어 질수록 전단강도가 상승하는 것으로 나타났으며, 전단키의 직경이 커질수록 내력이 저하되는 것으로 나타났다. 특히 전단키가 일정 이상의 규 격이 되면 전단키가 없는 경우에 비하여 내력이 저하되어 오히려 부착강도에 부정적인 영향을 미칠 수 있는 것으로 나타났다. NSM FRP에서 응력장용방향의 연단거리가 길어짐에 따라 동일 부착길이임에도 불구하고 내력이 일부 증가하는 것으로 나타났다. 표면매입 보강된 FRP의 부착실험에서, FRP와 콘크리트사이의 부착-미끄러짐은 전체거동을 지배하는 것으로 나타나므로 이에 따른 과도한 미끄러짐은 설계에 반드시 고려될 필요가 있다. This paper presents a bond test to find the effect of shear key and edge length from the bonded FRP in near surface-mounted(NSM) retrofit using FRP plate. Main parameters in the test are the location and size of shear key and the edge length. For the test, 10 specimens were made by embedding FRP plate of 3.6 ㎜×16 ㎜ into 400 ㎜×200(300) ㎜×400 ㎜ concrete block and fixing it by using epoxy. Tensile load was applied to the FRP of the specimens until failure and was recorded at each load increase. In addition, the bond slip and elongation of FRP were measured during the test. From the test, it was found that the further the shear key located from the loading, the higher strength we could get. The bond strength inversely depended on the size of shear key. Especially, when the size of shear key was to be lagger than certain size, the bond strength decreased to very low value; even less than that of the case without shear key. The bond strength somewhat increased corresponding to the increase of edge length from the bonded end of FRP to loading in spite of same bond length. The bond-slip between FRP and concrete governed overall deformation in the bond test of NSM FRP so that the effect of excessive slip is necessary to be considered in the design.

보-기둥 접합부 Rigidity에 따른 PC 골조건물의 응답저감계수 변화에 관한 연구

서수연 忠州大學校 2003 한국교통대학교 논문집 Vol.38 No.2

Current design codes(1997 UBC, 1997 NEHRP Provisions) for precast concrete frame structures require the use of strong connections, unless the strength of the connectors at the required ductilities are demonstrated to be adequate by both suitable experimental and analytical methods. Then the response modification factors(RMF) appropriate for precast concrete frame buildings are to be the same as those for monolithic concrete frame buildings. However, where plastic hinging occurs in a connection , the expected response of the precast concrete frame building will differ from that of the monolithic frame building and depend on the characteristics of the connection. For that condition, estimates of the appropriate RMF for the precast concrete frame buildings are required because the response of such buildings may differ from those for monolithic frame concrete buildings. This study evaluates the nonlinear response characteristics of precast concrete frame buildings where plastic hinging occurs in the precast connection. Designs were developed for buildings 5, 10, and 15 stories in height for moderate seismic risk region of the U.S. The response of the buildings were analyzed using DRAIN-2DX(1992) and following the Nonlinear Static Analysis procedure. The main variables of the analysis are the strength and stiffness of the connection. Also, for the analysis, the bi-linear response model developed and inserted into the DRAIN-2DX program by Shan Shi and D. Fouch(1997), are used. It was shown that the strength of the buildings as well as their displacement capacities decreased with decrease of either the strength or stiffness in the connections. Therefore such changes also require reductions in RMF values for the buildings. The decreasing ratio of RMF of precast concrete frame buildings in accordance with reduced stiffness and strength of connection is proposed.

가무백희의 전승양상 연구

서수연 成均館大學校 大學院 1996 首善論集 Vol.21 No.-

H-pile과 콘크리트로 합성된 철근콘크리트 지하벽 접합부의 전단성능에 관한 연구

서수연 忠州大學校 2007 한국교통대학교 논문집 Vol.42 No.-

In general, conventional sheeting H-pile is often used as a temporary member installed upon construction of outer retaining wall at basement floors. However, it is noted that H-pile and reinforced concrete wall with certain thickness can be effectively composited by shear connectors. Hence, in order to acquire possible higher resistances from composite behaviors of H-pile and concrete wall structure, this study intends to investigate the behavior of joint in composite wall structure under shear stress, and know the effects of additional U or C type reinforcement. Push out test is performed for four specimens and their resistances are analyzed. From the test, the shear resistance was increased by using U or closed C type connectors.

합성지하벽의 휨거동에 있어서 폼타이의 기여도에 대한 실험 연구

서수연 忠州大學校 2008 한국교통대학교 논문집 Vol.43 No.-

Recently, the construction demand for a large underground space has been increased so that the excavation technology for the underground construction of building has been being developed. Sheet pile is for resisting lateral pressure of soil during the excavation and generally used as a temporary member. In CBW (Composite Basement Wall), R/C basement wall is combined with H-Pile and resists lateral soil pressure together. The overall behavior of this composite wall depends on the composite ratio between those two members. Several research works have been performed to verify the composite behavior by Seo et. all. In constructing the underground basement wall, a new construction method which doesn't use supports to resist the form was developed. The form in the developed system is hanged by ties which are linked from H-pile to the form. These tie can be used for hanging the form in the construction of basement wall as well as reinforcement or shear connector after construction. This study is to investigate the contribution of the form tie in the composite basement wall, especially under flexural stress. For this, a total of five specimens with simple-ends are designed and tested. Main parameters are the depth of basement wall and arrangement of shear connectors. Test result shows the tie contributes in improving the stiffness of the composite wall after peak load.

합성지하벽 철골부재 설치를 위한 앵커볼트의 인발내력에 관한 연구

서수연 충주대학교 2006 한국교통대학교 논문집 Vol.41 No.-

This paper presents the evaluation on the tensile strength of anchors embedded in concrete that can cause a brittle failure of the concrete. The pull-out test for set anchor and set strong anchor, domestically manufactured and installed in plain concrete member is conducted. Test parameters in the test, are anchor type, diameter, and embedded length. Also, design of post-installed steel anchors by the Concrete Capacity Design(CCD) approach, is presented. This approach is compared with the well-known provision ACI 318-05. In addition, these two process are evaluated by comparing with the test results. Test results showed that set anchor made of stainless had 10% lower strength than normal one. For all specimens, the calculated strength by ACI code was almost two times higher than test result. But similar calculation strength to test result can be given when CCD process is adopted.

철근콘크리트 기둥에서 반복횡력에 대한 헤드형 횡보강근의 구속효과에 대한 실험연구

서수연,함주호 한국구조물진단유지관리공학회 2012 한국구조물진단유지관리공학회 논문집 Vol.16 No.5

본 연구는 철근콘크리트 기둥 횡보강근의 형태 특히 크로스타이의 유무 및 단부 정착형태에 따른 내진성능을 평가하기 위한 실험연구이다. 계획된 실험변수인 크로스타이의 유무, 크로스타이의 단부 정착형태(헤드형 또는 갈고리형), 그리고 기둥 축응력의 크기에 따라 총 5개의 기둥 실험체를 제작한 뒤 일정 축력하에 횡방향 반복가력 실험을 수행한 후, 크로스타이가 철근콘크리트 기둥의 구조성능에 미치는 영향을 평가하였다. 실험으로부터, 크로스타이가 없이 띠철근만으로 횡보강된 기둥은, 낮은 횡력에서 균열과 함께 띠철근이 휨변형한 뒤 코아 콘크리트가 탈락되는 파괴양상을 보인 반면에 크로스타이가 있는 기둥은 균열이 발생한 이후에도 띠철근이 휨변형과 주근좌굴을 억제하고 코아 콘크리트를 효과적으로 구속하여 내력 및 연성을 증진시키는 것으로 나타났다. 횡방향 대변형시, 갈고리형 크로스타이는 90˚ 갈고리 부분이 펴지면서 코아 콘크리트가 탈락되는 양상을 보이지만 헤드형 크로스타이는 대변형 시에도 헤드가 매우 효과적으로 띠철근과 주근을 구속하여 높은 내력과 연성능력을 발휘하는 것으로 나타났다. This paper presents an experimental result and suggests the confinement effect of headed cross tie in reinforced concrete(RC) columns subjected to cycling horizontal loads under constant axial load. Five RC columns specimens were manufactured, taking confined type of transverse reinforcement, whether or not using cross tie, end detail of cross tie (hooked or headed), and axial stress in column as major variables, Cyclic horizontal load applied to the columns under constant axial stress and the effect of cross tie to structural capacity of column was evaluated from the test. The column without cross tie failed showing bending deformation of hoop with crack in core concrete at low horizontal load while the column with cross tie showed quite improved strength and ductility by suppressing bending deformation of hoop as well as buckling of longitudinal bar at once even after crack in core concrete. At high lateral displacement, the column with hooked cross tie showed the failure pattern loosing the confining force of cross tie since the 90˚ hooked part of cross tie was stretched out and the cracked core concrete lumps were came off. However, the column with headed cross tie showed very stable behavior since the head of cross tie effectively confined the hoop and longitudinal bars even at high lateral displacement.

FRP판으로 휨 보강된 철근콘크리트 보의 장기거동

서수연,트랜 하이반,김강수,윤현도,이건철 대한건축학회 2023 대한건축학회논문집 Vol.39 No.3

The purpose of this study is to evaluate the long-term behavior of RC beams reinforced by fiber reinforced polymer (FRP) strip such asnear-surface mounted retrofit (NSMR) and externally bonded retrofit (EBR). The 30% loads of nominal strength of the RC beams wereapplied and continued for up to 49 days. The loads were increased up to 55% of the nominal strengths of RC beams at 50 days afterperforming flexural retrofit by using FRP with the planned retrofit methods and have been kept for almost one year. During all loadingperiods, the deflections and the strains of rebars and FRPs were measured at least once every week. The long-term behavior of all specimenswas evaluated and the deflection variations were predicted by considering the long-term effect on the nonlinear sectional analysis result of thereinforced RC beams. As a result, in the specimen reinforced with partially de-bonded NSM FRP, the strains of the FRP strip were notconcentrated on the center of the beam and the magnitude at the center was less than that with the fully bonded FRP. In addition, it ispossible to properly simulate the deflections of the beams strengthened with FRP exposed to a long-term load by considering the long-termeffect on the sectional analysis result. 본 연구에서는 FRP판으로 표면매립과 표면부착 보강된 RC 보들의 장기거동을 평가하고자 한다. RC 보에 공칭강도의 30%에 해당하는 하중을 가력하여 42일을 지속시킨 후, 하중 작용상태에서 계획된 보강방법에 따라 FRP 판으로 휨보강하고 1주일의 양생기간을 거쳐 50일째에는 보강후 공칭강도의 55%로 하중을 증대시키고 약 1년동안 하중을 유지시켰다. 모든 가력기간동안의 처짐과 인장철근 및 FRP의 변형률을 1주일에 최소 1회이상 계측하였다. 모든 실험체의 장기거동을 평가하였고 단면해석결과에 장기재하 효과를 고려하여 처짐의 변화를 평가하였다. 그 결과, 부분 비부착 FRP로 표면매립보강된 실험체는 비부착구간에서 FRP 변형률이 보의 중앙에 집중되지 않음에 따라, 중앙부 변형률이 완전부착인 경우에 비하여 낮게 나타났다. 또한 단면해석결과에 장기거동 효과를 고려함으로써 장기하중에 노출된 FRP 보강 RC 보의 처짐을 적절하게 예측할 수 있는 것으로 나타났다.

A mechanical acupuncture instrument mitigates the endoplasmic reticulum stress and oxidative stress of ovariectomized rats

서수연,Suk Yun Kang,권오상,Se kyun Bang,Soo Phil Kim,Kwang-Ho Choi,Ji Young Moon,Yeonhee Ryu 한국한의학연구원 2019 Integrative Medicine Research Vol.8 No.3

Background: Acupuncture has become a common complementary and alternative treatment approach for anxiety and depression. However, there is little research on the detailed mechanism of acupuncture therapy relieving depression. Previously, 17β-estradiol (E2) was shown to prevent oxidative stress and endoplasmic reticulum (ER) stress in ovariectomized (OVX) rats. This study investigated whether stimulation of Sanyinjiao (SP6) using a mechanical acupuncture instrument can alleviate depression-like behavior caused by estrogen deficiency in OVX rats. Furthermore, we found that acupuncture reduced ER stress and oxidative stress-related proteins expression. Methods: The OVX operation was performed on female SD rats that were separated into four groups: The E2 (2.5 μg/kg, i.p.) injection group (OVX + E2), the OVX group (OVX), and the OVX with acupuncture stimulation group (OVX + SP6). Non-acupoint stimulation group (OVX + NonAcu). The acupuncture point stimulation began three weeks after surgery. The depressive behavior was analyzed by the forced swim test and open field test. The 8-OHDG, BiP, Sigma receptor 1, pJNK, PDI, Ero1-Iα and Calnexin protein levels were evaluated by immunoreactivity in the amygdala. Results: Acupuncture stimulation reduced depressive behavior and altered depression-related proteins. Stimulation of SP6 decreased the immobility time of the FST and altered the ER stress and oxidative stress marker proteins, such as 8-OHDG, BiP, pJNK, PDI, Ero1-Ia and Calnexin. Conclusion: Our results indicated that acupuncture at SP6 showed a significant antidepressant-like effect on an OVX-induced depression rat model by mitigation of ER stress and oxidative stress in amygdala.

기둥형상과 보 깊이 변화에 따른 외부 기둥-넓은 보 접합부의 이력거동에 관한 연구

서수연,윤승조,윤용대 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.3

In wide beam, how the effective width is decided is very important since the calculation of stiffness and strength of the beam is based on it. Several research works have been conducted by previous researcher to find the effective width of wide beam. And also New zealand code prescribes a formula to calculate it. However these didn't consider the effectiveness of spandrel beam in exterior joint, which affects the behavior of wide beam. In this study, therefore, an evaluation on seismic resistance capacity of the exterior column-wide beam joint with spandrel beam is performed. Five specimens are designed to have variable test parameters; that are column width, column depth and the beam depth. Cyclic loads are applied to the beam end of test specimen according to the test procedure suggested by ACI committee. Before the test, previous formula to calculate the effective of wide beam were reviewed and the strength of specimens was predicted by using these. From the test, it was found that the ultimate strength of specimen linearly increased when the beam or column depth increased; the variation of column depth was more sensitive to the strength of specimens. The comparison result by using previous formula in predicting the strength of specimen shows that most close prediction can be possible when uses Wight's one. Other two formula codified in ACI or New zealand code underestimate test results.