Trends in Civil Engineering

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Authors: Yi Fang Feng, Hua Zhi Zhang
Abstract: Based on the deep foundation pit works of Wuhan Metro Line 2 Gold Garden station, orthogonal test method, finite difference method and BP neural network method are synthetically used to do the inverse analysis study of mechanical parameters of foundation pit. The mechanical parameters are substituted in the finite difference process of deep foundation pit to simulate and calculate. The deformation and bearing situation of building enclosure and soil in the construction process of foundation pit is acquired, which is returned to the design and construction management to provide reference for design modification, construction optimization and engineering prediction, to ensure the security and stability of foundation pit and to greatly reduce investment outlay.
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Authors: Fa Hai Yang, Wei Jun Liu, Xiao Ling Yang
Abstract: Ground failure caused by liquefaction is a major cause of earthquake damage and casualties during many history earthquakes. The gravels liquefaction extensively occurred following the 2008 Wenchuan Ms8.0 Earthquake, and 70-80% liquefied sites generated lots of 100 meter to hundreds kilometer long and 5 centimeter to 50 centimeter wide ground fissures, which intersected house, farmland, etc. and caused serous damage. The mechanism of the building damage and ground fissures were investigated by borehole drilling and Multi-Channels Electricity Resistance Test. The detailed in-situ tests and comparison show that: (1) The building, whose foundation intersected by liquefaction, suffered more severe damages than its surrounding buildings; (2) The abundant ground fissures were generated by gravels liquefaction rather than the raptures or secondary faults; (3)The fundamental conditions for the generation of ground fissures by liquefaction are: flat ground surface (slop less than 3%), horizontal non uniform distribution of liquefiable soils.
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Authors: Kao Zhong Zhao, Feng Wang, Xiao Feng Bian
Abstract: The concrete-filled glass fiber reinforced gypsum wall panel is a kind of panel that the inside cavums of the glass fiber hollow gypsum panel are filled with concrete, which can be used as the bearing wall of a building. The influences of eccentricity distance and height to thickness ratio on the bearing capacity of the compression wall panels were studied, and the failure mechanism and bearing capacity of compression wall panels were gained through the experiments of twenty-seven(nine groups) axial compression wall panel specimens and twenty-seven(nine groups) eccentric compression wall panel specimens. The analysis results indicate that the bearing capacity of compression wall panels is obviously affected by the eccentricity distance and height to thickness ratio, and there is a linear relation between bearing capacity and eccentricity distance. The bearing capacity calculation formula of the concrete-filled glass fiber reinforced gypsum wall panel is obtained by regression analysis, which provides reliable gist for structural design of concrete-filled glass fiber reinforced gypsum wall panel buildings.
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Authors: Gang Wu, De Yong Wang
Abstract: The mechanical properties and acoustic emission evolution process of limestone under the action of high temperature load were investigated by combining methods of uniaxial compression test and acoustic emission (AE) technique. The temperature varies in the range of 100, 200, 400, 600 and 800°C. By analysis of AE parameters and the mechanical parameter, the relations of stress-time (strain)-accumulative counts of AE, stress-time (strain)-AE rates under different temperatures are analyzed. The results show that the temperature does not obviously affect the mechanical properties of limestone at the temperature ranging from 100 to 400°C, the accumulative ring-down counts and accumulative energy increase with the rise of temperature. However, when the temperature is above 400°C, the mechanical properties of limestone deteriorate rapidly with the increase of temperature, and also the peak stress of limestone decrease in different extents. In the meantime, the accumulative ring-down counts decrease coupled with the change of mechanical parameter. The brittle fracture is main failure mode of limestone when the temperature is below 800°C and the change of peak strain of limestone is unobvious. The stress-strain curve conforms to the acoustic emission curve which shows that changes of minerals formation and microstructure due to high temperature result in the changes of mechanical and acoustic emission characteristic of limestone.
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Authors: Wei Ming Xiang, Zhou Huang, Wen Wei Gao, Xian Chang Zheng
Abstract: This report is about the spatial stress analysis of a large underground civil air defense projects in Guangdong province. Aiming at the problems of plane stress models, spatial calculation models are built and the results are compared to those of plane stress calculation models, revealing how internal force of the spatial structure models change in different conditions.
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Authors: Jing Jing Li, Guang Ying Gao, Yu Fei Wang, Lin Guo
Abstract: In order to obtain functional polymer latex with surface carboxyl groups which can enhance colloidal stability and alkali viscosity, a molecular design was carried out and novel latex for building sealant was synthesized by using the technology of soap-free emulsion and core-shell polymerization. The monomer component, initiator, reaction temperature, adding mode of raw materials, carboxylation of colloidal particle and application of cross-linking reaction in molecular design were investigated. The suitable formula and process conditions were defined.
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Authors: Rong Guo, Shuang Guo, Rong Xia Wang
Abstract: Abstract. In order to establish damage model of concrete-filled rectangular tubular (CFRT) column, the paper utilized the cumulative dissipated hysteretic energy through 7 CFRT columns’pseudo static test. Moreover, the earthquake damage model based on CFRT columns has been set up by regression analysis. The damage model offers references for reinforcing the damaged structures caused by earthquakes and evaluating the ability of aseismatic of structures.
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Authors: Zhi Xiang Cao, Xiu Li Cao
Abstract: Transmission tower line system dynamic response and failure mechanism are very complex under seismic load, the dynamic response and cooperation mechanism of the upper structure, pile and soil of transmission tower line system under seismic load based on the MATLAB numerical calculation method in this paper, and the displacement, acceleration velocity and displacement of axial force distribution of different positions of transmission tower line system are calculated by building transmission tower line of the stiffness matrix, equivalent load node, system quality matrix, motion equation and the upper structure of whole pile of model and with the help of the solution of the MATLAB function. The numerical calculation results show that the soil-consider the upper structure of pile-coordination effects for displacement and acceleration amplification effect are obvious, but the truss of axial force amplification effect is relatively small. Meanwhile, the earthquake action soil pile-between the upper structure are strong dynamic interaction, which provides certain theoretical guidance for recognizing transmission tower line system dynamic response mechanism under earthquake and adopting efficient anti-seismic measures.
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Authors: Qing Sheng Guo, Qing Shan Yang
Abstract: For steel staggered-truss (SST) system, RC slabs are the main structure members to make the whole building work together beside to take the vertical load. There are openings in the RC slabs due to requirement of staircases、lift wells and other services, these openings will reduce the stiffness of RC slab and make stress concentration. Usually, the RC slab is designed under vertical load only, this will lead to the design defect and building calapse for SST structure. There are few research for SST RC slab are presented untill now. In the paper, based on two different 3D models considering or ignoring the stiffness of infilled walls (SIW), a numerical investigation is presented on the structural behaviors of the SST system utilizing the soft ware ETABS. As a finite element analysis method, the shell element is adopted for RC slab & infilled wall, the beam element is adopted for beam、colum and truss members. The structure is asymmetrical due to the SIW, it causes the torsional forces in the building and the extra stresses in the RC slabs, the additional reinforcement need to be provided to strengthen the high stress areas. Comparing with the results of response spectrum analysis under the combination with earth quake load, we make some conclusions, including the capacity of anti-seismic and the effect of the SIW for SST system RC slab,that could be a reference for SST structure design.
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