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Sun J.,Nanjing Southeast University | Qiu H.X.,Nanjing Southeast University | Yang Y.,Nanjing Southeast University | Lu B.,Nanjing Southeast University | Lu B.,Suzhou Institute of Architectural Design Co.
Science China Technological Sciences | Year: 2015

To study the deformability and ductility of an innovative precast shear wall joined by bolted connections, experimental tests were conducted on two test walls under monotonic and cyclic loading, respectively; subsequently, theoretical analysis was performed on the deformation performance of the shear wall assembly. The test results confirmed the favorable deformability and ductility of the specimens. The top displacement of the shear wall assembly was analytically decomposed into several constituent parts, the theoretical formulae of which were subsequently deduced. The compositional analysis demonstrated that the top displacement of the test wall was primarily induced by the elastic deformation of the upper wall panel (UWP), the relative slippages within the bolted connections, and the flexural deformation within the plastic region of the UWP, while the constituent part contributed by the deformation in the connecting steel frame can be neglected. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg.

Li S.,Nanjing Southeast University | Ding J.,Suzhou Institute of Architectural Design Co. | Zhang X.,Nanjing Southeast University | Cheng D.,China Construction | And 2 more authors.
International Journal of Low-Carbon Technologies | Year: 2016

A new CO2 cryogenic capture and liquefaction system has been proposed previously in order to separate CO2 from exhausted gases and make it as a resource for industry. This system combines CO2 cryogenic capture with N2/O2 separation together. Its energy consumption is lower than the traditional amine solution capture process as theoretical analysis. In this study, the simulation of the proposed system with several improvements was carried out aiming to reduce the energy consumption further. Many heat exchangers were introduced and the heat exchanger arrangements were optimized to recycle the refrigeration capacity from the returned N2 after the N2/O2 separation. The discharge pressure of mixture gas from the compressor was reduced from 10 to 3.493 MPa. The simulation results showed that the compression work could be greatly reduced and the energy consumption of CO2 capture in this new system after these improvements reached 2.884 GJ/ton CO2. The new system is promising because not only liquid or solid CO2 could be produced but also N2 and O2 could be separated. © The Author 2013. Published by Oxford University Press.

Li X.-J.,Nanjing Southeast University | Dai G.-L.,Nanjing Southeast University | Gong W.-M.,Nanjing Southeast University | Xu W.-X.,Suzhou Institute of Architectural Design Co. | Wang L.,Nanjing Southeast University
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

In the self-balanced loading test, reasonable determination of conversion factor γ, ratio of downward shaft resistance to upward shaft resistance, is critically important for the accuracy of bearing capacity and final decision of pile loading test. To study the appropriate value of γ in sandy soil, 3 typical construction projects are chosen. All of their main soil layer are sandy soil; and the self-balanced loading test and head-down loading test are conducted at every site. And then a pile from self-balanced loading test and one from head-down loading test are picked as a group. In these groups, the geometrical sizes, geological condition and construction method of the two piles are same or similar. Because the results from traditional loading test are more convincing than ones from self-balanced loading test in general, the results from top-down loading test are taken as references; and then the Matlab is used to find the optimal fitting solution of γ, latterly, returning the value to the simplified capacity equation of the self-balanced loading test, and comparing the result of equivalent top-loaded settlement curve with ones from γ used in actual project and from head-down loading test, γ = 0.6 and 0.7. The results show that: (1) The fitted values of γ from 3 projects are ranged from 0.47 to 0.71, which are rather smaller than that used in actual projects. (2) The accuracy of γ has large effect on the values of Qs (skin friction) and sss (elastic compression from skin friction distribution) of upper piles of the equivalent pile. (3) Compared with the top-loaded settlement curve from traditional loading test, the results from the optimal fitting solution of γ fit much better than of which used in actual project,which means that values of γ used in these projects are overly conservative, which cause overly conservative judgement of bearing capacity. (4) It is suggested that the value of conversion factor γ in sandy soil about 0.6 to 0.7. © 2016, Science Press. All right reserved.

Zheng X.,Nanjing Southeast University | Zhang L.,Suzhou Institute of Architectural Design Co. | Liang W.,Nanjing Southeast University | Qian H.,Nanjing Southeast University
Applied Mechanics and Materials | Year: 2013

This paper developed a heat transfer model of the underground pipe group to study the effect of cooling and heating load imbalance to geothermal field. The results show that, there are the approximate linear relationship between average soil temperature and the total heat flow provided by GSHP system to the soil during the whole running period. The temperature of soil restoration ratio is less than the heat flux ration in the spring and autumn. Simulation results show that when heating/ cooling load equal to 0.5 and the heating flux for the bore hole are 60w/m and -40w/m in the Summer and Winter respectively, after this system run 12 months and 10 hours every day, the average soil temperature around borehole will increase 0.48°C, and the soil close borehole temperature will increase 1.3°C than the initial soil average temperature with the value of 17.6°C, which make GSHP not be efficiently for long term running. The results is hoped to be useful for GSHP design and long term running. © (2013) Trans Tech Publications, Switzerland.

Sun J.,Nanjing Southeast University | Qiu H.,Nanjing Southeast University | Lu B.,Suzhou Institute of Architectural Design Co.
Journal of Southeast University (English Edition) | Year: 2015

To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load bearing capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame (CSF), and relative slippages between the CSF and embedded limbic steel frame (ELSF) were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable. ©, 2015, Southeast University. All right reserved.

Wang Z.,Harbin Institute of Technology | Liu J.-J.,Suzhou Institute of Architectural Design Co. | Wu B.,Harbin Institute of Technology | Xu G.-S.,Harbin Institute of Technology
Zhendong Gongcheng Xuebao/Journal of Vibration Engineering | Year: 2015

Real-time Hybrid Testing (RHT) is a novel hybrid testing method for evaluating structural seismic performance. Even though implicit time-stepping approaches exhibit better stability, their applications to RHT are limited due to their difficulties. This paper firstly analyses limitations of two existing implicit RHT schemes for Multi-Degree of Freedom (MDoF) structures, and then proposes a new implicit RHT based on the nearly-complete delay compensation developed by the authors formerly. Theoretical performance analysis and numerical simulations are performed following that. Numerical simulations show that the proposed scheme is endowed with better convergence speed and accuracy and incorporates delay compensation, which indicate that it is more suitable to RHT for MDoF systems. ©, 2015, Zhendong Gongcheng Xuebao/Journal of Vibration Engineering. All right reserved.

Liu X.,Nanjing University of Science and Technology | Chen Y.,Nanjing University of Science and Technology | Zhang X.,Nanjing University of Science and Technology | Zhang X.,Suzhou Institute of Architectural Design Co. | And 7 more authors.
Journal of Hazardous Materials | Year: 2015

Aerobic granules were successfully cultivated in a sequencing batch reactor (SBR), using a single bacterial strain Rhizobium sp. NJUST18 as the inoculum. NJUST18 presented as both a good pyridine degrader and an efficient autoaggregator. Stable granules with diameter of 0.5-1mm, sludge volume index of 25.6±3.6mL g-1 and settling velocity of 37.2±2.7mh-1, were formed in SBR following 120-day cultivation. These granules exhibited excellent pyridine degradation performance, with maximum volumetric degradation rate (Vmax) varied between 1164.5mgL-1h-1 and 1867.4mgL-1h-1. High-throughput sequencing analysis exhibited a large shift in microbial community structure, since the SBR was operated under open condition. Paracoccus and Comamonas were found to be the most predominant species in the aerobic granule system after the system had stabilized. The initially inoculated Rhizobium sp. lost its dominance during aerobic granulation. However, the inoculation of Rhizobium sp. played a key role in the start-up process of this bioaugmentation system. This study demonstrated that, in addition to the hydraulic selection pressure during settling and effluent discharge, the selection of aggregating bacterial inocula is equally important for the formation of the aerobic granule. © 2015 Elsevier B.V.

Shen J.,Nanjing University of Science and Technology | Zhang X.,Nanjing University of Science and Technology | Zhang X.,Suzhou Institute of Architectural Design Co. | Chen D.,Nanjing University of Science and Technology | And 2 more authors.
Desalination and Water Treatment | Year: 2015

Abstract: Pyridine is one of the most widespread heterocyclic industrial contaminants. Due to rather tough safe level, thorough purification of wastewater containing this eco-toxicant is required. In this study, a novel pyridine-degrading bacterium, strain NJUST18, was isolated from the soil contaminated by pyridine and identified as a member of genus Rhizobium. The biodegradation assays suggested that strain NJUST18 could utilize pyridine as the sole source of carbon and nitrogen, at initial concentration as high as 2600 mg l−1. Pyridine depletion, biomass increase, TOC reduction, pH increase, and (Formula presented.) release during pyridine biodegradation indicated that pyridine could be mineralized by strain NJUST18. Pyridine degradation at high initial concentrations or high initial pH values demonstrated that this biodegradation process was both pH and (Formula presented.) dependent. Release of (Formula presented.) into the alkaline medium led to the formation of free ammonia (NH3) accompanied by the delayed pyridine degradation. High concentration of NH3 generated weakened pyridine biodegradation. A neutral to slightly alkaline pH was crucial for high strength pyridine degradation by NJUST18. Rhizobium sp. NJUST18 could degrade relatively high concentration of pyridine, offering bright prospects for bioremediation of pyridine contaminated environment. © 2014, © 2014 Balaban Desalination Publications. All rights reserved.

Lu W.,Nanjing University of Technology | Sun H.,Nanjing University of Technology | Sun H.,Suzhou Institute of Architectural Design Co. | Liu W.,Nanjing University of Technology
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2016

Nine bolted glulam beam-to-column connections were tested to study their mechanical properties, seven of which were strengthened by self-tapping screws. Results show that glulam beam-to-column connections are easy to tear along wood texture, which can be prevented by the strengthening of self-tapping screws. When the edge/end distances of bolts are less than the limiting values of the 'Technical specification for structural glued laminated timber' (GB/T 50708-2012), the capacity and ductility are increased. The ultimate bearing capacities of joint specimens with 20 mm and 14 mm diameter bolts are improved by 112% and 81% respectively. © 2016, Editorial Office of Journal of Building Structures. All right reserved.

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