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Yao G.,Shenzhen Municipal Design and Research Institute Co. | Yao G.,Tsinghua University | Li Y.,Fujian Agriculture and forestry University | Liao F.,Fujian Agriculture and forestry University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013

Based on rational constitutive models of steel and concrete, load-deformation relationship curves of concrete-filled steel tube (CFST) reinforced concrete columns subjected to axial compression were calculated by the fiber model method and finite element method to investigate the behavior of composite column subjected to axial compression. The results of theoretical analysis are in good agreement with the experimental ones. Based on the research conclusion mentioned above, behavior analysis of concrete-filled steel tube reinforced concrete columns subjected to axial compression including failure mode, axial load distribution, and the interaction between outer concrete, steel tube and core concrete were carried out. Practical simplified formulae of bearing capacity were proposed, and results calculated using the formulae agreed well with test results. At last, it is suggested that in order to ensure the collaborating between outer concrete and inner concrete filled steel tube, the ratio of stirrup constraint index in outer concrete to constraint effect coefficient in inner concrete filled steel tube should not be less than 0.188. Source

Zheng C.,Jilin University | Zhao D.,Jilin University | Chen C.,Jilin University | Song Z.,Shenzhen Municipal Design and Research Institute Co. | Zheng S.,Jilin Provincial Communication Scientific Research Institute
Construction and Building Materials | Year: 2013

Quantitative test technology on the mesoscopic strength parameters of the mineral aggregate contact surface of bituminous-stabilized macadam was studied. On the basis of the failure mechanism of the mineral aggregate contact surface, the HC-40 hydraulic force measurement device and the self-designed test die were used to apply tensile load on the contact surface of the mineral aggregate. The total tensile strength Rt of the mineral aggregate contact surface was calculated. The total tensile strength Rt was compared with the splitting strength RT of the AM-20 Semi-Open-Graded bituminous-stabilized macadam mixture under different conditions. A corresponding calculation method was used to determine the adhesion strength Ra between the aggregates and bitumen, as well as the cohesion strength Rc of the bitumen binder itself. The results show that despite the small difference in numerical value between the total tensile strength Rt of the mineral aggregate contact surface and the splitting strength RT of the mixture, the variation law is consistent. The method of calculation adopted in the present study can provide the quantitative test for the adhesion strength Ra and the cohesion strength Rc at different states. The mesoscopic parameters of the mineral aggregate contact surface can directly affect the macroscopic strength parameters of the mixture. The test can promote the study on crack resistance and raveling resistance abilities of bituminous-stabilized macadam mixtures. Crown Copyright © 2012 Published by Elsevier Ltd. All rights reserved. Source

Qiao L.-P.,Shenzhen Municipal Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

Based on the engineering application of soil nailing of steel tube in an excavation with deep filling soils, the characteristics of the excavation, the procedures of design and calculation and the attentive aspects are introduced. How to reasonably choose the shear intensity parameters c and ψ of the filling soils and the friction of the nail-soil in the design and calculation and the ways to judge the years of the filling soils, are discussed. At the same time, the production technology of the soil nailing of steel tube and the quality of the jet grouting, which are the key to successful excavation bracings, are emphasized. The ideas of how to choose the design parameters and the requirements of construction technology may offer reference for similar excavation projects. Source

Chen B.,Fuzhou University | Mu T.,Survey and Design Institute | Chen Y.,Shenzhen Municipal Design and Research Institute Co. | Huang J.,Fuzhou University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013

Steel-concrete composite structure is one of the main structures in civil engineering construction. In bridge engineering, composite members can be classified into three types according to the basic bearing behavior, i. e., composite beam, composite column and composite arch. In this paper, the main structure forms and general application of steel-concrete composite bridges in China are described; the research development and engineering application of the new composite structure types presented in recent years are focused on. The traditional steel-concrete composite bridges, such as the shaped steel-concrete slab composite girder, the PC box girder with corrugated steel webs and concrete filled steel tube arch, have been widely used and their specification system has been established by far. In the future, the application experience should be constantly summed up so as to further improve the specifications. At the same time, it is necessary to track closely the latest international trends and carry out innovative research. The research and development of new composite bridge have become very active in our country in recent years. Many new types of steel-concrete composite bridge structures were developed, such as the deck slab with stiffened scaffolding and CFST composite truss, corrugated steel web-CFST composite beam, CFST stiffened scaffolding composite columns, CFST main members with reinforced connection members composite columns and hybrid columns and steel webs (bars)-concrete arch bridge. Some of them have been used in few engineering projects, while others have not been used. In the future, it is important to strengthen their application and popularization, conduct application technology research on the engineering practice requirement, form application guide or technical standards, and make contribution to the development of the composite structures and technical progress of bridge engineering. Source

Zou G.,Shenzhen Municipal Design and Research Institute Co.
Chinese Journal of Environmental Engineering | Year: 2014

The performance of the dual-intake reversed A2/O-MBR System(hereinafter referred to as the "system") processing municipal wastewater was evaluated by inspecting indicators such as COD, NH4 +-N, TN, TP and SS. Results show that the system had high COD and NH4 +-N removal rates, the effluent COD and NH4 +-N confirmed to one-class a permitted criteria of the GB18918-2002. The effluent TN concentration was under 15 mg/L when the mixed liquor reflux ratio reached 200%. The system TP removal rate reached about 83% under normal excess sludge discharge operation. The effluent SS and COD could be affected by damaged flat-sheet membrane. COD, TP and SS can be intercepted directly by the membrane system and due to the nearly 100% solid retention, the system SRT can be controlled properly to in favor of the growth of long life-cycle microorganisms such as nitrifying bacteria and denitrifying bacteria. Thanks to the good solid retention effect, the system effluent can still be good with sludge concentration up to 15000 mg/L even influent increased by 50%. Source

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