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Cheng B.,Shanghai JiaoTong University | Qian Q.,China Shanghai Architectural Design and Research Institute Co. | Zhao X.-L.,Monash University
Thin-Walled Structures

This paper presents a numerical study on stress concentration square bird-beak square hollow section (SHS) welded joints. Both conventional and square bird-beak SHS joints considered have T-shapes and are simply supported at their chord ends. Refined finite element models are developed to obtain the strain/stress concentration factors (SNCFs/SCFs) of square bird-beak joints with various dimensions. The FE models are validated by comparing with the experimental data. The SNCF differences among considered hot spots are analyzed for the identification of critical locations. The influences of three major non-dimensional parameters, i.e., brace/chord width ratio β, chord wall slenderness ratio 2γ, and brace/chord wall thickness ratio τ, on the stress concentration factors (SCFs) of square bird-beak T-joints are revealed on the basis of numerous parametric studies. Comparisons of joint types are finally made. The results indicate that, in case of identical non-dimensional parameters, square bird-beak SHS T-joints provide SCFs smaller than conventional SHS T-joints in most occasions, especially when β is small; and SCFs of square bird-beak T-joints are expected to be lower than CHS T-joints with small β and large 2γ and τ. © 2015 Elsevier Ltd. All rights reserved. Source

Zheng H.,Hohai University | Zheng H.,China Shanghai Architectural Design and Research Institute Co. | Liu H.-L.,Hohai University | Lei Y.-H.,Tianjin Huazheng Geotechnical Co. | Ren L.-W.,Hohai University
Yantu Lixue/Rock and Soil Mechanics

JG(jet grouting) soil-cement-pile strengthened pile, simply called JPP pile, is a new sort of composite pile used in soft foundation. It may improve the vertical bearing capacity effectively; and it has been practically used in a considerable scale. In order to study the behaviors under lateral load, large-scale model test is carried out, using large test room made by Hohai University. It is shown that the JPP pile could improve horizontal bearing capacity by about 15% compared with bored concrete pile; and the biggest bending moment of JPP pile is located in the place 2 m below the pile tip; and lateral earth pressure is concentrated in the top 2 m soil. Meanwhile, with a cap added, JPP pile has a much higher horizontal bearing capacity. According to the formula for bored concrete pile based on m method, which standard remmends, horizontal bearing capacity of JPP pile has been calculated; and calculation results basically coincide with the experimental results. The results may be useful for the practical engineering and analysis of JPP pile in the similar soil layer. Source

Zhou C.,Shanghai JiaoTong University | Zhou C.,China Shanghai Architectural Design and Research Institute Co. | Kou X.-J.,Shanghai JiaoTong University
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology

In order to study the partial safety coefficient concerned the effect of human error in construction. The contaminated distribution model was employed to obtain the realistic mean value and standard variance of variable X of structural parameters which coexisted with random error and human error. The reasonable partial safety coefficient can be calculated based on the realistic value of structural parameters concerned the effects of random error and gross error. The results show that the current studies of partial safety factors do not consider human error in construction for structural reliability. It is not comply with the real situation. Partial safety factors must be evaluated precisely for the given target β to ensure the certain level of structural reliability due to uncertain factors. Source

Huang L.,Hunan University | He D.,Hunan University | Wu Z.,Hunan University | Wu Z.,China Shanghai Architectural Design and Research Institute Co.
Tumu Gongcheng Xuebao/China Civil Engineering Journal

Sufficient redundancy may provide shear wall with multiple seismic fortification lines, and enhance its ability to resist seismic actions. To investigate the seismic performance of redundant shear wall, two under-reinforced specimens with joint are designed in this work, one is combined with single-layer reinforced RC wall, and the other is combined with reinforced concrete masonry wall. The failure pattern and failure mechanism, hysteretic property, attenuation process, stiffness degradation and energy dissipation are analyzed through low-cycle loading test. Test results show that there is an obvious hierarchical characteristic in the failure process for both specimens, and the residual structure can still bear additional loads after weak portion of wall fails, reflecting their good redundancy performances. The seismic performance of the specimen combined with single-layer reinforced RC wall may outperform the specimen combined with reinforced concrete masonry wall, due to its better energy dissipation and post bearing capacity. Source

Luan W.,China Electric Power Research Institute | Wang B.,China Shanghai Architectural Design and Research Institute Co. | Zhou N.,Henan Electric Power Research Institute | Guo Z.,Henan Electric Power Research Institute
Dianwang Jishu/Power System Technology

For a long time, due to various reasons, power utilities don't have full or accurate mastering of information of LV distribution network. This is one of the cases for distribution network parameters. Accurate circuit parameters of LV distribution network are basis of power flow calculation, loss analysis and energy theft detection. Electrical parameters are important, but research on them is far from sufficient mainly because of absence of measured data in LV distribution network. Implementation of advanced metering infrastructure (AMI) provides new ways for solving this problem. This paper researches approaches on accurate electrical circuit parameter calculation in LV distribution network using smart meter measurements, so as to obtain accurate model of LV distribution network. Provided distribution network topology is known, the method leverages a series of smart meter measurements at end nodes of distribution network, mainly voltage, active power and reactive power at customer sides. It calculates voltage of the most upstream node or source node in radial network with bottom up approach and builds an optimization model to minimize source node voltage variance derived from different meter node measurements, or the differences between estimated source node voltage from different smart meter measurements and actual voltage measurement in source node over a period of time. Then the best estimates for branch impedances are obtained. Validity of the proposed method is verified with a practical distribution network with 17 metering nodes and 21 branches. ©, 2015, Power System Technology Press. All right reserved. Source

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