Advanced Materials Research Vols. 368-373

Abstract: This study concentrates on investigating the tensile strength of fresh concrete after the occurrence of an earthquake. The experiments have been carried out through the simulated earthquakes that were generated by a high-performance vibrating platform with a size of 6m×6m, provided by the Nuclear Power Institute of China. There are three types of ground acceleration (0.05g, 0.10g, 0.25g) acting on 10 kinds the fresh concrete (C30 and C50) with five ages (12hours,24hours,48hours,72hours,168hours) respectively. The modified E1 centro was used to take the recordings of the time series of parameters. The results show that the tensile strength of the fresh concrete undergoing the simulated earthquake can be well recovered after 28 days.

Abstract: Micro-crack defects in concrete can affect the Chloride ion permeability of concrete in a certain extent. In the paper, the splitting experiments of concrete specimens from the four different dimensions are carried out in order to build the even damage fields. The displacements of the concrete specimens’ surface are analyzed through DSCM (Digital Speckle Correlation Method). Therefore damage parameters are determined that are damage area based on the MCOD (Micro-Crack Opening Displacement) and damage variable DE based on the weighting-damping elastic modulus. At the same time, Clˉ permeation of concrete specimens before and after the splitting test are studied by NEL method, and Clˉ diffusion coefficients D are recorded in detail. Further relationships between damage parameters and diffusion coefficients of Clˉ are discussed.

Abstract: This paper analyzes the fire hazard of logistics centers, puts forward to prevent the spread of fire has important significance on study the horizontal spread of fire performance under different fire scene of a project example by using the methods of calculation and numerical simulation. Provide a reference on the spray system and shelf location settings for such construction.

Abstract: This paper took a large store building from Xi'an city which was on fire in 2008 to be the research object, simulating fire smoke, temperature and flame situation with FDS computer numerical simulation, and performed a comparative analysis with its real fire scene pictures. The research shows that during the early 12 minutes, the flamed area is small, the simulated temperature, smoke are highly coherent with the real scene; In the mean time, when considering the whole spreading tendency of building fire in a period of time from macro angle, large eddy simulation can truly reflect fire transient turbulence properties, but the volumetric heat source method has some limitations in fire spreading simulation, thereby it will have a certain affect on smoke flowing simulation.

Abstract: To a large comprehensive convention center as an example, this paper analyses the flow characteristics of fire smoke of the main hall and the feasibility for sharing space as "Quasi safety zone". First, the fire scenario was identified through the fire hazard analysis, then, set a model and take a simulation analysis by fire simulation software FDS, based on this fire scenario which have been established. At last, draw conclusions according to the smoke flow properties.

Abstract: On the basis of the simplified model of lateral-torsional coupling isolated structure, dynamic equations of non-proportional damping isolated system of lateral-torsional coupling is established, and the influence of the isolated layer and the superstructure damping dynamic parameters on earthquake response is calculated and analyzed. The results show that, by reasonable adjustment of the damping distribution of the isolated layer, the torsion effect of the superstructure can be significantly reduced, and the basis displacement as well as rotation can be better suppressed, providing a basis for the design of the isolated layer damper reasonable distribution.

Abstract: Rockburst is a common dynamic failure phenomenon in deep-buried underground construction process, which greatly threatened the safety of equipment and person. In the paper, combined with the engineering of Xinjiang Xiabandi hydraulic and the Russense’s rockburst criteria, the finite element analysis are employed to study the effect of advance dig-hole and softening of surrounding rock. The results of the study indicate that the two measures can effectively reduce the intensity of rockburst level in the construction of deep-buried tunnel.

Abstract: Decreasing the temperature of fire field is one of the most important technologies of metro fire emergency rescue. It is calculated that the total heat is released in metro fire and the mass of ice, liquid nitrogen and dry ice are needed when the temperature is decreased to 60°C. Ice is the best option among the three through comprehensive analysis from mass, volume, transportation, storage and so on. Research on cooling technology of emergency rescue in metro fire can do contribution to reduce metro fire casualties.

Abstract: Arch type on an empty stomach type arch bridge and push culvert in the disease that can arise different level under temperature role. The reason that article produces for disease is analysed , push , Dao act on without the foot arch of circular arc in permanent year and temperature power calculation formula, have pointed out the theoretical source that the arch sky belly arch and arch culvert crack disease of arch bridge produce , and have made to administer the measure of this kind of disease.

Abstract: As a new type of section, central-open box sections are more and more popular. Some existed bridges of central-open box section can not to be used because of vortex-excited resonance. Based on this situation, the paper taking the Hongkong-Zhuhai-Macao River-sea ship canal Bridge for example, takes measures of taking the central bottom plate opening hole, changing the angle of web, and setting baffle, according the experimental study and CFD analysis, it is obtained that different aerodynamic sections are various in the character of vortex-excited, although taking the central bottom plate opening hole is effective, it only refers to the best opening ratio, changing the angle of web can not improve the vortex-excited effectively, setting baffle on the lateral sides is the most effective measure to forbid the vortex-excited resonance.