Experimental Study on Breakage Characteristics and Energy Dissipation of the Crushed Rock Grains

Luzhen Wang,Minggan Yin,Hailing Kong,Hualei Zhang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

Water inrush disasters are mostly related to the permeability of broken rock mass, which is associated with the deformation of rock mass, the particles migration and loss in seepage process and the breakage behavior. In this paper, samples’ breakage characteristics, grain size distribution and gradation were discussed, as well as their fractal behavior and energy dissipation. It shows that compaction has an obvious effect on breakage and the fractal behavior of samples, which are inapparently affected by loading speed. The rock grains’ breakage categories are related to their sharps, which affect the grain size distribution after compaction. Samples of different sizes have different optimal loading speeds and main breakage stages during compaction. It proposed two kinds of intuitive methods to judge the breakage behavior qualitatively through the grain size distribution (GSD) curves. Strain energy densities in samples mostly increase with compaction and loading speed, except for few special cases. Strain energy densities in samples are linearly correlated with the breakage index and fractal dimension, regardless of the compactions and the loading speeds. This study can provide a reference for further analysis of the permeability of the broken rock mass and even to solve the water inrush problem in the coal mines or tunnels.

복합단면성능을 갖는 슬릿형 강재댐퍼의 이력특성

김민철,김동건 대한건축학회지회연합회 2020 대한건축학회연합논문집 Vol.22 No.1

Recently, a steel damper is widely used among energy dissipation devices for seismic retrofit, a steel damper has many advantages than other types of seismic control devices. It can be easily manufactured based on the design specification, and it can dissipate a lot of seismic energy through the stable hysteresis behavior of steel. In this study, in order to obtain more effective energy dissipation capacity than general types of steel dampers, the yield strength of steel with different section properties were used as variables. For this purpose, steel dampers were manufactured using two types of steel dampers with relatively different section properties. As a result, the steel with relatively low section property first yielded and the steel with high section property progressively yielded. Finally, it effectively responded to various range of lateral load and showed good performance with respect to the ductility.

보강재에 따른 방호패널의 에너지 소산능력에 대한 실험적 연구

이예찬 ( Lee Yae-chan ),김규용 ( Kim Gyu-yong ),석원균 ( Seok Won-kyun ),최병철 ( Choi Byung-cheol ),사수이 ( Sasui Sasui ),남정수 ( Nam Jeongsoo ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.1

The purpose of this study is to identify the rear energy transfer amount and time delay capability of the protection panel that has been impated by a projectile and the protection panel reinforced the foam polypropylene on the rear of the fiber reinforced cement itious composites, and compared and analyzed the load resistance capacity, energy dissipation capacity, and impact delay capacity when dynamic extreme load were applied to the specimen.

고연성-저항복강을 사용한 복합강재댐퍼의 최적형상 도출을 위한 해석적 연구

김건호(Kim, Geon-Ho),김민성(Kim, Min-Seong),조용현(Cho, Young-Hyun),김동건(Kim, Dong-Keon) 대한건축학회 2021 대한건축학회 학술발표대회 논문집 Vol.41 No.2

In this study, carbon steel(SS275) and low-yield-point steel(HSA80) were used to develop the CSD(carbon steel damper), the LSD(low-yield-point steel damper), and the HSD(hybrid steel damper). Finite element analysis of the HSD was performed by setting the ratio of the yield strength of the CSD to the yield strength of the LSD to 1, 1.5 and 2, and also by GSD(the general type of the steel damper) with the same yield strength as HSD. Finally, the HSD gave better energy dissipation capability than the general type of the steel damper with the same yield strength. At the yield strength ratio of the LSD was 1.5, it was shown that the HSD gave sequential yield characteristics and higher energy dissipation capacity rather than other types of dampers.

Reliability evaluation of water distribution network considering mechanical characteristics using informational entropy

Mostafa Ghanbari Kashani,Mahmood Hosseini,Armin Aziminejad 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.1

Many studies have been carried out to investigate the important factors in calculating the realistic entropy amount of water distribution networks, but none of them have considered both mechanical and hydraulic characteristics of the networks. Also, the entropy difference in various networks has not been calculated exactly. Therefore, this study suggested a modified entropy function to calculate the informational entropy of water distribution networks so that the order of demand nodes and entropy difference among various networks could be calculated by taking into account both mechanical and hydraulic characteristics of the network. This modification was performed through defining a coefficient in the entropy function as the amount of outflow at each node to all dissipated power in the network. Hence, a more realistic method for calculating entropy was presented by considering both mechanical and hydraulic characteristics of network while keeping simplicity. The efficiency of the suggested method was evaluated by calculating the entropy of some sample water networks using the modified function.

돌입전류 제한용 $Mn_3$$O_4$-NiO-CuO-$Co_3$$O_4$-ZnO계 NTC 써미스터에서 ZnO/$Mn_3$$O_4$비에 따른 전기적 특성

윤중락,김지균,권정렬,이현용,이석원 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.6

Oxides of the form Mn$_{4}$/O$_{4}$-CuO-Co$_{3}$/O$_{4}$-NiO-ZnO present properties that make them useful as power NTC thermistor for current limited. Electrical properties of Mn$_{3}$/O$_{4}$-CuO-Co$_{3}$/O$_{4}$-CuO-Co$_{3}$/O$_{4}$-NiO-ZnO power NTC thermistor such as I-V characteristics tim constant activation energy and heat dissipation coefficient measured as a function of temperature and composition. In Mn$_{4}$/O$_{4}$-CuO-Co$_{3}$/O$_{4}$-NiO-ZnO system with the 5wt% addition of Co$_{3}$/O$_{4}$ it can be seen that resistivity and B-constant were increased as the ratio of ZnO/Mn$_{3}$/O$_{4}$ was increased. Heat dissipation constant, I-V characteristics and time constant showed similar behaviour compared with those of conventional thermistors. In particular resistance change ratio ($\Delta$R) the important factor for reliability varied within $\pm$5% indicating the compositions of these products could be available for power thermistor.

Test Study on Axial Compression Behavior of GCFST Columns Under Unidirectional Repeated Load

Cun Hui,Yongbo Zhang,Yangguang Wang,Ran Hai 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.4

Geopolymer concrete is one of the directions of green development in the construction industry, and casting geopolymer concrete inside steel tubes can effectively play the respective advantages of both. In order to study the axial compression performance and failure mechanism of geopolymer concrete-filled steel tubular (GCFST) columns, two hollow steel tubular columns were designed as the control group and eight geopolymer concrete-filled steel tubular columns were tested in axial compression with concrete strength grade, length-to-diameter ratio, and steel tube wall thickness as parameters. The load–displacement curve, skeleton curve, and stiffness degradation curve of each specimen were obtained by observing the force process and failure mode of each specimen, analyzing the characteristic load, and characteristic displacement, stiffness degradation, ductility, and energy dissipation capacity, and deriving the method of calculating the axial compression load-bearing capacity of GCFST columns, and comparing with several codes commonly used in the world. The results show that the length-diameter ratio has a significant effect on the failure mode of GCFST columns. The peak load and initial stiffness of each group of specimens are different, but their load–displacement curves, skeleton curves, and stiffness degradation trend are the same. The increase of geopolymer concrete strength and steel tube wall thickness can improve the ultimate load-bearing capacity, average compression capacity, and energy dissipation capacity of GCFST columns. The axial compression load-bearing capacity calculation formula proposed in this paper is in good agreement with the test results, and the calculated values of the formula are compared with the calculation results of the international codes to verify the accuracy and applicability of the axial compression load calculation formula proposed in this paper, and the results of the study can provide reference for the theoretical research and engineering application of geopolymer concrete-filled steel tube composite structure.

마찰진자형 지진격리받침의 설계 특성 전산 해석 방법 비교

홍동의 ( Hong Dong Uie ),이재석 ( Lee Jae Seok ) 충북대학교 건설기술연구소 2020 建設技術論文集 Vol.39 No.2

이 논문에서는 교량의 내진설계에 사용되는 마찰진자형 지진격리 받침의 설계 특성치에 대하여 해석모델과 해석 방법을 달리하여 유한요소해석을 기반으로 한 전산해석을 수행하고 결과를 비교함으로써 해석모델과 해석방법의 타당성과 효율성을 검토하였다. 해석모델을 교량에 설치되는 형상과 유사한 경우, 실물시험에서의 시험기 받침들까지 같이 고려한 경우 그리고 실물시험과 배치형상은 같지만 시험기 받침들을 고려하지 않은 경우들에 대하여 실제 교량에서의 거동을 모사할 수 있도록 경계조건을 부과한 후 해석을 수행한 결과 유효강성 및 EDC의 경우 유사하게 발생됨을 확인할 수 있었고 주요 부재의 최대발생응력도 모두 허용응력 이내로 나타나 어느 해석 모델이라도 실물시험에 대한 대안으로 활용될 수 있음을 확인하였다. 해석모델을 교량에 설치되는 형상과 유사하게 모사한 경우가 다른 해석 모델에 비해 마찰판의 응력을 상대적으로 크게 예측하므로 안전여유 측면에서 유리하고 또한 해석 모델이 단순해 해석 효율성이 높으며 해석 모델의 형상과 구속 방법이 실제 교량과 유사하므로 상대적으로 효율적이라고 판단된다. A comparative study on the enhancement of the computational method for the evaluation of the design characteristics of the friction pendulum bearings is presented. The computational method is based on the finite element approach and the commercial finite element analysis package, MIDAS is used in this study. Friction pendulum bearings are widely used in the bridge and building structures to mitigate the structural response due to earthquake. Typically, the performance of the friction pendulum bearing is evaluated through the full-scale test which is time-consuming and expensive. Recently, the computer simulation based on finite element analysis method is regarded as an alternative of the full-scale test to evaluate the performance of the friction pendulum bearings. Through the computer simulations, not only the energy dissipation characteristics but also the stresses and strains at the crucial points of the friction pendulum bearings which can not be available in the full-scale test can be traced. In this paper, a comparative study is presented to enhance the computational method for the evaluation of the design characteristics of the friction pendulum bearings. Three relatively realistic modeling cases are compared to finalize the reasonable computational method for the evaluation of the design characteristics of the friction pendulum bearings.

울돌목 조류발전의 연안물리적 관점에서의 고찰

염기대(Yum, Ki-Dai),이광수(Lee, Kwang Soo),박진순(Park, Jin Soon),강석구(Kang, Sok Kuh) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

The pilot tidal current power plant is to be constructed at the Uldolmok between Chindo and Haenam, during next year. and extensive coastal engineering research works have been carried out. In this paper we describes some observation results of the tide and tidal current. as well as modeling work in order to investigate the tide and tidal current regime change in relation to the tidal current power plant (TCPP) construction. The special modeling skill in order to consider the turbine operation in the TCPP is developed and applied to the estimation for the flow regime change by the simple layout of the tidal current power plant.

울돌목 조류발전의 연안물리적 관점에서의 고찰

강석구(Kang, Sok Kuh),염기대(Yum, Ki-Dai),이광수(Lee, Kwang Soo),박진순(Park, Jin Soon) 한국신재생에너지학회 2005 신재생에너지 Vol.1 No.2

The pilot tidal current power plant is to be constructed at the Uldolmok between Chindo and Haenam, during next year, and extensive coastal engineering research works have been carried out. In this paper we describes some observation results of the tide and tidal current, as well as modeling work in order to investigate the tide and tidal current regime change In relation to the tidal current power plant [TCPP] construction. The special modeling skill in order to consider the turbine operation in the TCPP is developed and applied to the estimation for the flow regime change by the simple layout of the tidal current power plant.