• Title/Summary/Keyword: Full-scale testing

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Comparison of numerical and analytical solutions for reinforced soil wall shaking table tests

  • Zarnani, Saman;El-Emam, Magdi M.;Bathurst, Richard J.
    • Geomechanics and Engineering
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    • v.3 no.4
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    • pp.291-321
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    • 2011
  • The paper describes a simple numerical FLAC model that was developed to simulate the dynamic response of two instrumented reduced-scale model reinforced soil walls constructed on a 1-g shaking table. The models were 1 m high by 1.4 m wide by 2.4 m long and were constructed with a uniform size sand backfill, a polymeric geogrid reinforcement material with appropriately scaled stiffness, and a structural full-height rigid panel facing. The wall toe was constructed to simulate a perfectly hinged toe (i.e. toe allowed to rotate only) in one model and an idealized sliding toe (i.e. toe allowed to rotate and slide horizontally) in the other. Physical and numerical models were subjected to the same stepped amplitude sinusoidal base acceleration record. The material properties of the component materials (e.g. backfill and reinforcement) were determined from independent laboratory testing (reinforcement) and by back-fitting results of a numerical FLAC model for direct shear box testing to the corresponding physical test results. A simple elastic-plastic model with Mohr-Coulomb failure criterion for the sand was judged to give satisfactory agreement with measured wall results. The numerical results are also compared to closed-form solutions for reinforcement loads. In most cases predicted and closed-form solutions fall within the accuracy of measured loads based on ${\pm}1$ standard deviation applied to physical measurements. The paper summarizes important lessons learned and implications to the seismic design and performance of geosynthetic reinforced soil walls.

Cyclic testing of weak-axis column-tree connections with formation of plastic hinge at beam splice

  • Oh, Keunyeong;Chen, Liuyi;Hong, Sungbin;Yang, Yang;Lee, Kangmin
    • Earthquakes and Structures
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    • v.8 no.5
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    • pp.1039-1054
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    • 2015
  • The purpose of this study was to evaluate the seismic performance of weak-axis column-tree type connections used in steel moment frames. These connections are composed of a shop-welded and fieldbolted steel structure and can improve welding quality. On this basis, column-tree type connections are widely used in steel moment resisting frames in Korea and Japan. In this study, splices designed with a semirigid concept regarding the seismic performance of column-tree connections were experimentally evaluated. The structures can absorb energy in an inelastic state rather than the elastic state of the structures by the capacity design method. For this reason, the plastic hinge might be located at the splice connection at the weak-axis column-tree connection by reducing the splice plate thickness. The main variable was the distance from the edge of the column flange to the beam splice. CTY series specimens having column-tree connections with splice length of 600 mm and 900 mm were designed, respectively. For comparison with two specimens with the main variable, a base specimen with a weak-axis column-tree connection was fabricated and tested. The test results of three full-scale test specimens showed that the CTY series specimens successfully developed ductile behavior without brittle fracture until 5% story drift ratio. Although the base specimen reached a 5% story drift ratio, brittle fracture was detected at the backing bar near the beam-to-column connection. Comparing the energy dissipation capacity for each specimen, the CTY series specimens dissipated more energy than the base specimen.

A Study on the Critical Speed of 1/5 Scaled Bogie Model (1/5 스케일 축소대차 모델 임계속도에 관한 연구)

  • Hur, Hyun-Moo;Park, Joon-Hyuk;Kim, Min-Soo;You, Won-Hee;Park, Tae-Won
    • Journal of the Korean Society for Railway
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    • v.10 no.6
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    • pp.800-805
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    • 2007
  • The critical speed of railway bogie is very important in terms of the verification of the vehicle design procedure and safety. The dynamic performance of bogie is tested on the railway roller rig in a laboratory in place of field testing on track. But, the testing on the full scale roller rig caused many problems relating to test costs, test time and has the difficulty in test condition setup. To overcome these problems, scaled models were used in the filed of railway vehicle design and test. In this paper, we have studied the critical speed of scaled bogie model. We have made the 1/5 scaled bogie, the scaled roller rig and analyzed the critical speed of the scaled bogie through the numerical simulation and running test of the scaled bogie. We have confirmed that the analysis results of the critical speed correspond with the test results.

Experimental Study on the Damping Estimation of the 5×5 Partial Fuel Assembly (5×5 부분핵연료 집합체의 감쇠추정을 위한 실험적 연구)

  • Lee, Kang-Hee;Yoon, Kyung-Ho;Song, Kee-Nam
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.2 s.107
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    • pp.163-168
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    • 2006
  • The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle $(5\times5)$ which is called partial fuel assembly is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid to obtain the Flow-Induced Vibration (FIV) characteristics of the scaled fuel assembly over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the assembly prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the scaled test assembly. For the damping factor of the partial fuel assembly and the grid cage at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the partial fuel assembly is about $0.7\%$ with reasonable error of $2\%$ for the previous results. Nonlinear behavior of the partial fuel assembly might be stem mainly from the rod-grid support configuration.

Effects of PZ Strength on Cyclic Seismic Performance of RBS Steel Moment Connections (RBS 철골모멘트접합부의 내진성능에 대한 패널존 강도의 영향)

  • Lee, Cheol-Ho;Kim, Jae-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.3 s.49
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    • pp.149-158
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    • 2006
  • The reduced beam section (RBS) steel moment connection has performed well in past numerous tests. However there still remain several design issues that should be further examined. One such issue on RBS connection performance is the panel zone strength. Although a significant amount of test data are available, a specific recommendation for a desirable range of panel zone strength versus beam strength has yet to be proposed. In this paper, the effects of panel zone strength on the cyclic performance of RBS connection are investigated based on the available test database from comprehensive independent testing programs. A criterion for a balanced panel zone strength that assures sufficient plastic rotation capacity while reducing the amount of beam buckling is proposed. Numerical studies to supplement the test results are then presented based on the validated finite element analysis. Satisfactory numerical simulation achieved in this study also indicates that numerical analysis based on quality finite element modeling can supplement or replace, at least in part, the costly full-scale cyclic testing of steel moment connections.

Small-Sample Inspection Plans for the New Product Quality Level Evaluation of Finite Population : Focused on Guided Weapons in Development Stage (생산수량이 한정된 신제품의 품질수준 평가를 위한 샘플링검사 방법 : 개발단계 유도무기를 중심으로)

  • Shin, Byung-Cheol;Byun, Jai-Hyun;Lee, Chang-Woo;Lee, Ki-Yong;Choi, Jong-Soo;Woo, Hee-Sung;Seo, Bo-Gil
    • Journal of Korean Institute of Industrial Engineers
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    • v.41 no.5
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    • pp.481-487
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    • 2015
  • In the product development stage, it is very important to ensure demanded quality level before moving to the full-scale manufacturing. For example, in developing guided weapons, live-fire tests are required to verify the final performance of the weapons which are very expensive. The quality evaluation of the guided weapons needs destructive testing, which makes it necessary to test as small number of samples as possible. This paper presents sampling inspection plans and calculating system for finite population guided weapons, which can meet the demanded quality level and confidence level with the minimum number of performance tests. The result of this paper can be useful for any kind of costly destructive testing.

A STUDY ON THE SHEAR BOND STRENGTH OF THE COMPOSITE RESIN TO AMALGAM ACCORDING TO AMALGAM SURFACE TREATMENT METHODS (아말감의 표면처리에 따른 복합레진과의 전단결합 강도에 관한 연구)

  • Park, Mun-Hee;Cho, Young-Gon;Hwang, Ho-Keel
    • Restorative Dentistry and Endodontics
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    • v.18 no.1
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    • pp.114-121
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    • 1993
  • The purpose of this study was to evaluate the effect on treatment methods to shear bond strength between composite resin and amalgam when the alloy surface was finished with a diamond wheel or an sandblaster. Forty round acrylic cylinders were fabricated with a diameter of 33mm and a height of 20mm to fit into the device used during shear bond strength testing. A round undercut cavity (diameter, 8mm: depth, 2.5mm) was prepared in the center of the acrylic surface and the cavity was restored using a amalgam. A total of 40 acrylic cylinders with amalgam were divided into 4 groups according to treatment method. The group treatment were as follows : Group 1 : acid etching after finishing the amalgam with diamond wheel Group 2 : no acid etching after finishing the amalgam with diamond wheel Group 3 : acid etching after sandblasting the amalgam Group 4 : no acid etching after sandblasting the amalgam The shear bond strength of composite resin bonded to amalgam of each specimen was tested with a universal testing machine at a crosshead speed of 0.5mm/min and 500kg in full scale. The results were as follow: 1. After diamond finishing, the non-acid etching group had highest shear bond strength with 7.29kg/$cm^2$ and after sandblasting, the acidetching group had lowest shear bond strength with 4.49kg/$cm^2$. 2. In both diamond finishing and sandblasting group, acid etching of the roughened amalgam surface decreased the shear bond strength. 3. The group treated with a diamond wheel had higher shear bond strength those treated with an sandblaster but there was not significanat.

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A STUDY ON THE SHEAR BOND STRENGTH OF THE PORCELAIN LAMINATE ACCORDING TO SURFACE ROUGHNESS OF THE CUT ENAMEL (삭제된 법랑질의 표면거칠기에 따른 도재 라미네이트의 전단결합강도에 관한 연구)

  • Park, Bong-Seok;Cho, Young-Gon
    • Restorative Dentistry and Endodontics
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    • v.19 no.1
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    • pp.159-168
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    • 1994
  • The purpose of this study was to evaluate the shear bond strength of the porcelain laminate specimens according to the surface roughness of the cut enamel of human anterior teeth. Flat enamel surfaces were prepared in 30 extracted human anterior teeth with diamond disc which were divided into two groups. Group 1 Coarse enamel surface group prepared with LVS-3 bur. Group 2 Fine enamel surface group prepared with superfine diamond bur. 30 teeth specimens of two group were stored in normal saline during 24 hours. 30 disk - type porcelain laminate specimens with diameter 4mm and thickness 1mm were made and sand - blasted on internal surface which were to cemented on enamel surface. Porcelain laminate specimens were cemented on enamel surface with Choice Veneer System (Bisco Dental, U.S.A) according to manufacture's instructions. All teeth specimens of two groups were manipulated with same method and stored In normal saline before testing. An Universal Testing machine (Model No.UTM-4206,Instron, U.S.A) was used to apply shear loads in the vertical directed, and the force required for separation was recorded with a cross head speed of 3mm/min and 500kg in full scale. The results were as follow ; 1. The mean shear bond strength of coarse surface group was 36.30kg and that of fine surface group was 44.39 kg, but there was no significant difference in breaking strength of two groups(p>0.05).

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A STUDY ON THE TENSILE BOND STRENGTH OF COMPOSITE RESIN INLAYS ACCORDING TO THEIR INTERNAL SURFACE TREATMENT AND TYPES OF LUTING CEMENT (복합레진 인레이의 내면처리와 합착용 시멘트의 종류에 따른 인장접합강도에 관한 연구)

  • Kim, Jin-Cheol;Cho, Young-Gon;Hwang, Ho-Keel
    • Restorative Dentistry and Endodontics
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    • v.18 no.1
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    • pp.103-113
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    • 1993
  • The purpose of this study was to evaluate the tensile bond strength of composite resin inlays according to the their internal surface treatment and types of luting cement and compared them with the conventional direct resin filling thchnique. Class II cavities were prepared in 50 extracted human molar teeth, and then equally divided into five groups. Group 1 : Cavities of control group were directly filled with P-50. Group 2 : Cavities of resin inlay group were luted with resin cement. Group 3 : Cavities of resin inlay group were luted with luting G-I cement. Group 4 : Cavities of resin inlay group were luted with resin cement after sandblasting. Group 5 : Cavities of resin inlay group were luted with luting G-I cement after sandblasting. All specimens were polished with same method and stored in normal saline for 24 hours before testing. An Universal Testing machine(Model No. AGS-100A, Shimadzu, Japan) was used to apply tensile loads in the vertical direction, and the force required for separation was recorded with a cross-head speed of 5mm/min and 100kg in full scale. The results were as follows : 1. The mean tensile bond strength was lowest in group luted with luting G-I cement, with measurements of $14.45{\pm}0.78(kg/cm^2)$ and highest in group luted with resin cement after sandblasting, with measurements of $49.6{\pm}2.74(kg/cm^2)$. 2. The tensile bond strength was greater in resin inlay groups luted with resin cement than in control group and resin inlay groups luted with luting G-I cement(P<0.05). 3. The tensile bond strength was lower in resin inlay groups luted with luting G-I cement than in control group(P<0.05). 4. The tensile bond strength was greater in resin inlay groups luted with resin cement or luting G-I cement after sandblasting than without that(P<0.05).

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Evaluation of 4.75-mm Nominal Maximum Aggregate Size (NMAS) Mixture Performance Characteristics to Effectively Implement Asphalt Pavement System (4.75 mm 공칭 최대 골재 치수 아스팔트 혼합물의 효과적인 포장 시스템 적용을 위한 공용성 특성 평가 연구)

  • Chun, Sanghyun;Kim, Kukjoo;Park, Bongsuk
    • International Journal of Highway Engineering
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    • v.18 no.1
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    • pp.33-41
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    • 2016
  • PURPOSES : This study primarily focused on evaluating the performance characteristics of 4.75-mm nominal maximum aggregate size (NMAS) asphalt mixtures for their more effective implementation to a layered flexible pavement system. METHODS : The full-scale pavements in the FDOT's accelerated pavement testing (APT) program, including 4.75-mm mixtures at the top with different thicknesses and asphalt binder types, were considered for the faster and more realistic evaluation of the rutting performance. The results of superpave indirect tensile (IDT) tests and hot-mix asphalt fracture mechanics (HMA-FM) based model predictions were used for cracking performance assessments. RESULTS : The results indicated that the rutting performance of pavement structures with 4.75-mm mixtures may not be as good as to those with the typical 12.5-mm mixtures, and pavement rutting was primarily confined to the top layer of 4.75-mm mixtures. This was likely due to the relatively higher mixture instability and lower shear resistance compared to 12.5-mm mixtures. The energy ratio (ER) and HMA-FM based model performance prediction results showed a potential benefit of 4.75-mm mixtures in enhanced cracking resistance. CONCLUSIONS : In relation to their implementation, the best use of 4.75-mm mixtures seem to be as a surface course for low-traffic-volume applications. These mixtures can also be properly used as a preservation treatment that does not necessarily last as long as 12.5-mm NMAS structural mixes. It is recommended that adequate thicknesses and binder types be considered for the proper application of a 4.75-mm mixture in asphalt pavements to effectively resist both rutting and cracking.