http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Rujin Ma (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Haocheng Chang,Rujin Ma 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.6
A new 3D finite element model is presented to analyze creep in reinforced concrete (RC) and prestressed concrete (PC) bridges. The proposed hybrid model uses a 12-node solid element to simulate concrete and a 2-node truss element to simulate rebars, the volume occupied by rebars in concrete and ducts. Structures are meshed with a special meshing technique and truss element connects with solid element through non-nodal connection. In this study, an additional two-node spatial truss element with a negative area is introduced to consider the non-negligible influence of rebar ducts in concrete and obtain a more precise and efficient simulation of RC and PC bridges. Different uses of the truss element with a negative area in both RC and PC structures are also explained, and two drop-frame cases and associated construction stages are investigated to validate the applicability of this model. The construction process analysis of a simplified PC continuous rigid frame bridge is also conducted in this study to further demonstrate the ability of the newly developed program to capture shear lag effect. The results show that the proposed model with negative-area truss elements enables the long-term behavior of RC and PC structures to be effectively predicted.
-
Zhiyong Zhou,Rujin Ma 한국풍공학회 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4
Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number (St), pressure distribution and Reynolds number (Re) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from 105 to 106, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.
-
Zhou, Zhiyong,Ma, Rujin Techno-Press 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4
Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number ($S_t$), pressure distribution and Reynolds number ($R_e$) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from $10^5$ to $10^6$, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.
-
A study on ITZ percolation threshold in mortar with ellipsoidal aggregate particles
Zichao Pan,Dalei Wang,Rujin Ma,Airong Chen 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.6
The percolation of interfacial transition zone (ITZ) in cementitious materials is of great importance to the transport properties and durability issues. This paper presents numerical simulation research on the ITZ percolation threshold of mortar specimens at meso-scale. To simulate the meso-scale model of mortar as realistically as possible, the aggregates are simplified as ellipsoids with arbitrary orientations. Major and minor aspect ratios are defined to represent the global shape characteristics of aggregates. Some algorithms such as the burning algorithm, Dijkstra’s algorithm and Connected-Component Labeling (CCL) algorithm are adopted for identification of connected ITZ clusters and percolation detection. The effects of gradation and aspect ratios of aggregates on ITZ percolation threshold are quantitatively studied. The results show that (1) the ITZ percolation threshold is mainly affected by the specific surface area (SSA) of aggregates and shows a global decreasing tendency with an increasing SSA; (2) elongated ellipsoidal particles can effectively bridge isolated ITZ clusters and thus lower the ITZ percolation threshold; (3) as ITZ volume fraction increases, the bridging effect of elongated particles will be less significant, and has only a minor effect on ITZ percolation threshold; (4) it is the ITZ connectivity that is essentially responsible for ITZ percolation threshold, while other factors such as SSA and ITZ volume fraction are only the superficial reasons.
-
Research on the probability model of basic wind speed estimation in China
Cheng Xiang,Airong Chen,Qiheng Li,Rujin Ma 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.32 No.6
Wind speed is one of the most critical parameters in predicting structural performance under wind effects. In most of the current standards and codes, the design reference wind speed is usually determined by fitting a typical probability distribution model based on the historical wind speed data. However, a single distribution model is generally insufficient to reflect the regional differences in wind characteristics. Therefore, in this research, the optimal probability is selected to determine the extreme wind speed in different regions in China based on the fourth-order linear moment method (FLMM). Firstly, several probability models for estimating extreme wind speed distribution are introduced. Then, the optimal model, as well as the relative parameters, are determined by the linear moments (L-moments) method, and the one with the minimum value of the fourth-order linear moment between the probability model and the sample is taken as the optimal distribution. Finally, the extreme wind speed of each meteorological station is estimated according to the obtained optimal distribution, and the results are compared with the recorded extreme wind speed of typical metrological stations as well as that in the previous version of specification (JTG/T D60-01-2004). Compared with the traditional method that adopting a single distribution model-based wind speed estimation, the extreme wind speed obtained by the proposed method possessed higher accuracy.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
