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July 30,2013
Volume 6,Issue 14
Pages -
Subject Area:Hydraulic Structures,Foundation Engineering,Concrete and Reinforced Concrete Structures,Civil and Architectural Engineering Construction,Civil Construction Structure,Architectural Design Method and Theory,Composite Building Materials,Building Materials

Title: Research and design of the water environment monitoring system based on WSN

Authors: CAI Binbin, ZHANG Yun
PP: 1374-1378
Abstract: With the hydrological informatization continuously promoting, a scheme of water environment monitoring system based on the wireless sensor network (WSN) was proposed by further research on the WSN and correlation theory. The scheme made full use of short-range wireless communication technology of WSN, and used tree-topological structure to set up wireless automatic water environment monitoring system. The scheme could carry out remote real-time monitoring for the several important water quality parameters such as water temperature, pH, electrical conductivity and dissolved oxygen. The results showed that the system could operate reliably and had certain popularization and application value. Furthermore, this system could provide technical basis for water resources protection and water pollution prevention.
Keywords: water resources protection; wireless sensor network; tree-topological structure; water environment monitoring

Title: Experimental study and simulated calculation on the formation mechanism of calcium silicate hydrate (C-S-H)

Authors: HE Zhen, WANG Lei, CAI Xinhua
PP: 1368-1373
Abstract: Microstructure of calcium silicate hydrate (C-S-H) from three instars in Portland cement paste was studied by Fourier transform infrared (FTIR) spectroscopy, 29Si magic-angle spinning (MAS), nuclear magnetic resonance (NMR), respectively and from the viewpoints of several main models for the nanostructure of C-S-H. The research showed that the structure of C-S-H in Portland cement paste was different from the crystalline 1.4 nm-tobermorite(T) and jennite(J). C-S-H in cement paste at early age was dimeric and Ca—OH bonds probably occurred in it. Furthermore, the formation of Si—OH resulting from protonation of dimers was critical for increasing the polymerization degree of C-S-H gel. Polymerization between hydrated monomer formed during the hydration process and the protonated dimmers resulted in a few longer silicate chains. The chains of dreierketten with less Ca—OH bonds represented the T-like strutures and the ones with more Ca—OH bonds represented the J-like structures. However, the chains of dreierketten can not exist in a large number in the paste hydrated for 28 d at 20℃.
Keywords: hydraulic structure; calcium silicate hydrate; microstructure; polymerization degree; mechanism; cement

Title: Numerical analysis on effect of seepage control measure for deep overburden

Authors: WEN Lifeng, CHAI Junrui, WANG Xiao
PP: 1359-1367
Abstract: Combining with a project example and using the finite element method, a systematic study which analyzed the impact of anti-seepage wall depth, blanket length and permeability of the overburden on the effect of seepage control was made. The computed result showed that when the permeability coefficient of the overburden was relatively larger (ie. k＞1×10-5 m/s), the overburden became the main seepage channel and it could not achieve good anti-seepage results until the anti-seepage wall was inserted into the relatively impermeable layer. When the hung-upside down imperious wall was used, the relative depth ratio between the anti-seepage wall and overburden was suggested as 0.7. The waterproof blanket was not effective enough to control seepage when the permeability coefficient of the overburden was relatively larger. The permeability of the overburden was a sensitive factor to the effect of seepage control measure for deep overburden whose permeability coefficient and permeability anisotropic both had some impacts on the dam seepage field.
Keywords: hydraulic structure; deep overburden; seepage control; numerical analysis; concrete faced rockfill dam

Title: Numerical simulation of thermal environment in long railway tunnel with shaft

Authors: LEI Bo, YUAN Zhongyuan, MA Guochuan
PP: 1353-1358
Abstract: In this paper, one dimensional unsteady numerical simulation was established to investigate the thermal environment in long railway tunnel with shaft. The air volume rate through shaft was simulated to study the ventilation condition of shaft. In order to investigate the thermal environment characteristics in long railway tunnel with shaft, air temperature distributions that calculated by simulation program were compared between tunnel with shaft and without shaft. Moreover, the effect of train speed on thermal environment in tunnel was researched in the study. The results showed that the maximum air volume flow rate introduced through shaft was 700 m3/s. Those introduced ambient air could be used to cool the high temperature air in tunnel. The air temperature in tunnel increased with the train speed increase.
Keywords: ventilation and air-conditioning project; thermal environment of tunnel; shaft; air temperature; numerical simulation

Title: Research on chlorine decay in water distribution system under secondary chlorination

Authors: LI Cong, YU Chenghan, ZHANG Kejia, BAYIERMINGDA, YU Jieze, MAO Xinwei
PP: 1348-1352
Abstract: The research focused on how chlorine decayed under the first chlorination and the second chlorination in water distribution system. The first-order reaction kinetics model was used to fit the chlorine decay for analyzing the relationship between the decay parameters and chlorine concentration. The experimental results showed that the optimal initial concentration of first chlorination was about 0.60 mg稬-1. The chlorine decay coefficients was inversely proportional to initial concentration and the chlorine decay coefficients was proportional to the water temperature and the pH value. The results also clarified the effect of temperature and pH value on the optimal initial concentration of second chlorination in water distribution system.
Keywords: municipal engineering; water distribution system; residual chlorine decay; second chlorination; first-order reaction model; optimal initial concentration

Title: Calculation analysis on the body frame structure of the Liuhua lake tunnel beneath Kangwang road in Guangzhou city

Authors: DOU Shikang
PP: 1341-1347
Abstract: This paper analyzed the calculation on the main frame structure of Liuhua lake tunnel project beneath Kangwang road in Guangzhou city. The limit state design method based on probability theory, the reliability metric structure member reliability index and the design partial coefficients of the structure expression were used for structural calculations. Structural members should be calculated and checked according to the bearing capacity limit state and serviceability limit state requirements. The waterproof grade was at the first level, the maximum crack width of reinforced concrete structure was obtained under the standard combination of loads and considering the impact of long-term effect of the combination. In the design, the external waterproof was used, the allowed value of the surface and the back surface was 0.2 mm, and there should be no crack. In the calculation of structural load, the condition of the water level and low water level load should be considered. Moreover, this paper introduced the analysis and calculation methods and main results of these frame structure stress, and put forward the problems in the process of the construction, which could provide the references for the similar works in the future.
Keywords: underground construction; tunnel; frame construction; analysis

Title: Dynamic response, deformation and failure mechanism of toppling rock slope with weak interlayer under earthquakes

Authors: SHAO Dongqiao, CHEN Wenwu, HUANG Yunfei
PP: 1333-1340
Abstract: This article established a three-dimensional model of the toppling rock slope with weak interlayer, and the acceleration response regulation of a toppling rock slope under the seismic action was investigated by using the three-dimensional finite difference software FLAC3D. Then the deformation and failure mechanism was analyzed through the investigation on the nature of the plastic zone, the formation of order, the expansion of the plastic zone, and changes of shear strain increment of key elements. The results showed that under the seismic action, the amplification coefficients of the horizontal and vertical peak accelerations of the toppling rock slopes increased with the increasing elevation. The rock mass had vertical amplification effect on the input seismic waves and the wave amplitude came to the maximum at the weak layer and the top of the slope. Furthermore, rock mass amplified the input seismic with low frequency and filtered those with high frequency, but the filtering effect was not obvious. Toppling rock slope deformation and failure occurred mainly in the weak layer. In the plastic zone, the performance presented the upper tensile failure and the lower part of the pull-shear failure with weak layer.
Keywords: ground foundation engineering; toppling rock slope; weak interlayer; earthquake; dynamic response; deformation mechanism

Title: Design and construction for a large-scale seismic model of self-centering reinforced concrete frame

Authors: LIU Jingjing, LV Xilin, ZHOU Ying, LU Wensheng, LU Liang
PP: 1325-1332
Abstract: In this paper, based on similar relation theory, a large-scale model was designed and constructed for shaking table test to study the seismic performance of self-centering reinforced concrete frame. A two-story frame of two specimens was designed and constructed with 3.0 m .5 m dimension, 1.5 m for each layer and 3.0 m in height. The self-centering capacity of columns and short beams were achieved by prestressed tendons respectively, and rubber and angles were used as energy components. The shaking table model design was described in details including model material selection, similitude relationship determination, model simplified design, model construction and other preparation works. Furthermore, the questions in large scale shaking table test model design were discussed. The method applied in model and design of this self-centering frame will be helpful to other relative experimental studies in the future.
Keywords: concrete and reinforced concrete structure; self-centering; shaking table test model; reinforced concrete frame

Title: Implicit precise simplified calculation of the braced frame structure under horizontal loads

Authors: WANG Haibo, LUO Binggui
PP: 1318-1324
Abstract: In this paper, the rigidity matrix of the braced steel frame was deduced by considering the flexural deformation of the pillar and the bending rigidity of the brace. It was applied into the bracing concrete-filled rectangular steel tubular frame by revising it through amendatory contraflexure point method. Analysis was made for the influence of such parameters as width-length ratio and ratio of beam rigidity. Calculation results showed that when the total height of the braced frame was lower, the influence of column’s bending deformation and brace’s stiffness on the structural displacement could not be ignored, while the total height of the braced frame was higher, the influence was very small and could be neglected. In the concrete filled steel tube braced frame, it could take no account of the influence of change of beam-column linear stiffness ratio on the horizontal displacement of braced frame.
Keywords: concrete and reinforced concrete structure; braced frame; concrete filled steel tube; horizontal loads

Title: Comparison and checking calculation of formwork structure scheme based on the current construction specification

Authors: YANG Guoli, LI Ruige
PP: 1313-1317
Abstract: The selection of load standard value, the pressure of young concrete on the side of formwork and others about formwork engineering in the “Code for Construction of Concrete Structures” (GB 50666—2011) are very different from the old specification. According to the new specification, combining with the slab formwork system of a cast-in-situ concrete structure, this paper presents an instance checking calculation. Firstly, the tool-type steel form matching board schemes are selected and compared, the scheme with the minimized number of forms, the arranged staggered joints, and the good rigidity are selected. Secondly, the formwork load standard value per square meter of support surface is calculated, the bending resistance checking, shearing resistance checking and deflection checking of inner steel arris of the formwork structure are carried out. The slenderness ratio checking, axial compressive strength checking and axial compression stability checking of pole are also done. The study provides a new thinking and case model of formwork scheme design for construction organization.
Keywords: civil engineering construction; construction specification; formwork and support; steel form matching board

Title: Experimental study on joints of ring beams and reinforced concrete-concrete filled in steel tube laminated columns

Authors: ZHOU Ying, YU Haiyan, QU Ge, ZHANG Lu, CHEN Yi, HU Kai
PP: 1303-1312
Abstract: This paper presented a type of enlarged joints at the connection between columns and frame beams. To study the mechanical behavior of reinforced concrete-concrete filled in steel tube (RC-CFST), two scaled static tests and five cyclic tests with the two parametric variables of radius-to-width ratio and reinforcement ratio were carried out to obtain the failure modes of the specimens, crack propagation and stress distribution of bars of the joints. The results showed that, under static load, the ultimate capacity of the specimens was higher than the design envelope value; under cyclic load, specimens of different parameter variables, present different failure modes, and rotation angle were large when beam segments were destroyed. These results suggested that the joints of reinforced concrete concrete filled in steel tube laminated columns were feasible in concept, and reasonable design could guarantee the design mechanism of “strong-joint-weak-member”.
Keywords: building and civil engineering structure; reinforced concrete-concrete filled in steel tube laminated columns; ring beam joint; radius-to-width ratio; reinforcement ratio; test

Title: “Great Wall” besides the Great Wall in the Ming dynasty: the military fortress with the Weisuo system

Authors: LI Yan, LI Zhe
PP: 1295-1302
Abstract: This paper firstly introduced the Great Wall of Ming dynasty and Weisuo system, then discussed the rigorous military system and the radiate space position character of the fortresses in detail, and summarized the relationship of the Weisuo system and the military defense system in case of the Yulin town and the Datong town. The analysis revealed that Weisuo system was divided into layers according to the military defense grade up to down, and the order was Zhen—Lu—Wei—Suo—Bao. Accordingly, the fortresses were Zhen town, Lu town, Wei town, Suo town, and Bao town. Therefore, the military fortresses were the basic defense force for the Great Wall in Ming dynasty.
Keywords: architectural design method and theory; Weisuo system; the Great Wall of Ming dynasty; military defense system; military fortress

Title: Experimental study on behavior of concrete columns confined by different strength polyethylene fiber sheets under axial compression

Authors: DENG Zongcai, XU Yongchao
PP: 1288-1294
Abstract: Based on the experiments on concrete columns confined with polyethylene fiber reinforced polymer (PEFRP) sheets under axial compression, this research was emphasized on analyzing failure configuration, bearing capacity, stress-strain curve and ductility. The results showed that: 1) Comparing with the control specimen (without being confined), bearing capacity of concrete quadrate columns confined by two or three layer sheets of high strength polyethylene fiber (PEA-L-2, PEA-L-3), and two or three layer sheets of medium strength polyethylene fiber (PEB-L-2, PEB-L-3) improved 10%, 35%, 27% and 30% respectively. Peak strain improved 195%, 80%, 207% and 182% respectively; 2) Bearing capacity of concrete circular columns confined by two or three layer sheets of high strength polyethylene fiber (PEA-C-2, PEA-C-3), or by two or three layer sheets of medium strength polyethylene fiber (PEB-C-2, PEB-C-3) improved 11%, 21%, 37% and 53% respectively. Peak strain improved 112%, 150%, 159% and 142% respectively. 3) Toughness index was adopted to evaluate the ductility of constraint column. The results showed that PEA was better than PEB in improving column toughness index I1, but PEB which had high elongation rate could improve column late ductility effect more apparently.
Keywords: composite construction materials; polyethylene fiber reinforced polymer; axial compression performance; confined concrete; ductility

Title: Technology and application of hot recycling asphalt concrete of Taiwan district

Authors: MANDULA
PP: 1279-1287
Abstract: Through the study on literature information, this article introduced the status of the development and application of recycling asphalt concrete in Taiwan district and analyzed the historical evolution, policy promotion and technical content of recycling asphalt concrete resources in that area. The aspects such as production review, mix design, construction and management were studied. In Taiwan district, the current specification hot-mix asphalt concrete could not be recycled for use in highway, and requires viscosity-stiffness test indicators were required to be qualified. In addition, the production censorship rules and quality control management were different from those in the domestic. The technical problems existed in excessive aging of asphalt when they were recycled repeatedly.
Keywords: construction materials; Taiwan district; recycling asphalt concrete; construction technology; inspection standard

Title: Normal disaster-prevention planning strategy study of high-density area in city center

Authors: ZENG Jian, WANG Qiao
PP: 1272-1278
Abstract: High density is the inevitable trend in the development of city center. In the view of the current trend of urban disaster prevention plan, this paper puts forward normal disaster prevention as the foundation of central area comprehensive disaster prevention plan. Firstly, this paper summarizes the disaster characteristics of city center in high-density environment from its own properties, in order to build normal disaster-prevention system in macro-, meso-and micro-level. Then it gives the suggestions of central area from the aspects of land using, traffic system, open space and infrastructure layout. The strategies include the land security selection, mixed use and scale control in the aspect of land layout, choosing high-density chessboard type road network in the aspect of traffic system, building open space system corresponding to the urban disaster prevention space, and upgrading the infrastructure fortification criteria and redundancy.
Keywords: urban planning method and theory; high density; city center; disaster-prevention in peacetime; planning strategy

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