Applied Mechanics and Materials Vols. 90-93

Abstract: By using of the approximate value of T proposed in FEMA450, the equations of the approximate effective fundamental period are derived for circular mat foundations supported at the surface, embedded foundations of circular shape and embedded foundations of arbitrary shapes, respectively. It is found that the limit values of of Veletsos are not uniform, and excessive for structures with h/r > 9, but too small for embedded deeply foundations. In this paper the uniform limit value of is 1.10 for all structures, and the conditions of consideration of SSI are given for ordinary reinforced concrete frame structures with circular mat foundations supported at the surface, embedded foundations of circular shape, and embedded foundations of arbitrary shapes, respectively.

Abstract: A large scale centrifugal shaker is the most effective testing facility for dynamic problems in geotechnical earthquake engineering. There are only two worldwide nowadays, whereas, no one has been established in China. As the most advanced testing facility, almost every aspect in the construction of a large scale centrifugal shaker encounters new challenges. Meanwhile, the facility layout and construction design face many new difficulties. In this paper, the general layout of laboratory and some relevant key technologies in construction are investigated and the scheme of facility general layout is proposed. The composition and variation of total power of centrifuges is analyzed, simultaneously the advantages and limitations of different cooling systems in the operation hall are compared. Also basic requirements and difficulties of foundation design are discussed, which can provide reference and guidance to construction of large scale centrifugal shakers.

Abstract: Through the indoor resonance column and dynamic tri-axial test of liquefaction on diversion dike soil of a nuclear power plant, its got the curves of dynamic shear modulus-dynamic shear strain and damping ratio-dynamic shear strain, analyzed the dynamic deformation characteristics of diversion dike soil, studied the exponentiation function between liquefaction resistance strength and liquefaction shake times of sand soil, confirmed the indexes of liquefaction resistance strength, providing the relevant parameters for evaluating seismic stability and liquefaction analysis of diversion dike, and reference value for the seismic safety evaluation and liquefied evaluation of the dam project site.

Abstract: With the continuous research in earthquake engineering, great advances have been made in the theoretical research of ground motion attenuation. A lot of new achievements and views [1,2,3] provide the theoretical basis for the improvement of the ground motion attenuation experience models and the parameter estimation. Additionally, it provides a good environment for deeper study on the ground motion attenuation by the increase of strong motion records and the improvement of pertinent information. In this paper, the improved two-step method is put forward, and the regressed ground motion attenuation coefficients are obtained by the improved models and analysis method. This method not only considers the correlation of magnitude and distance, but also makes the regression coefficients more stable. The results can better show the characteristics of the ground motion attenuation.

Abstract: The article considers the two horizontal components of ground motion and torsional component, to do nonlinear time history analysis both on regular and irregular shaped column frame structure models. The results show that torsional component of ground motion haves some impact on torsion reaction of structures, stiffness of irregular shaped column frame structure is uneven, and angle of columns are greater than that of the regular structure; torsion haves some impact on the torque of structure, the torque increases of corner columns is maximum, so corner columns are weak links in shaped column structure, considered fully during the seismic design.

Abstract: In this paper, March 11, 2011 East-Japan Earthquake was introduced briefly, including main shock, aftershock and tsunami resulted from this earthquake. After that, the situation about bridge damage was focused; involving the bridge damage resulted from earthquake and tsunami, then some reason and preliminary findings were further suggested.

Abstract: A Ms=8.0 earthquake striked the most of the China on May 12th, 2008, and brought about near 90,000 deaths and about 700 billion dollars of direct economic losses. This earthquake impacted all kind of transportation system including highway, railway, airline and water carriage systems in a huge area. This paper provides many records of observed damage to transportation system by site investigation. The seismic performances related to transportation system in meizoseismal zonation were described in details in this paper. Occurring in a mountainous region, this earthquake severely damaged the transportation system because of strong earthquake motion, near the active faults, trigged landslides and debris, rock and soil collapses, and large ground deformation. Transportation system performance degradation was due to not only physical damages of equipments and buildings, but also the shortage of the electric powers and supporting from other lifeline systems. some statitical laws among transportation system , slope failure and fault distance, and some valuable measures for resisting strong earthquake motion, secondary earthquake-induced geological disaster and lessons learned for damage prevention and system recovery to lifeline system were also discussed in this paper.

Abstract: Experiments have been performed to observe flow pattern and investigate convective heat transfer for air-water vertical flow in a forced circulation system. The bubbles motion was recorded by a high-speed CCD camera. For the bubble and slug flow pattern, the temperature fluctuation signals and local heat transfer coefficients were obtained in a short heated tube. The probability density function classical was applied to analyze the temperature. The results qualitatively reflected characteristics of local heat transfer in two phase flow comparing with that in single-phase liquid. The comparison revealed that the gas phase could enhance the heat transfer.

Abstract: In this paper, based on the analysis of strata soil temperature variation, the DeST software is used to simulate changes of outdoor air parameters under typical meteorological year in Jinan. One-dimensional unsteady state soil air heat transfer model is regarded as the research object, this paper theoretically studies export air temperature change rules for the whole year under tunnel intermittent running condition. The results show that the tunnel plays a preheating role for outdoor air in winter and the cold role in summer, which provides a good cold、heat source conditions for the application of air source system based on the tunnel wind, especially the most hot and cold day throughout the year, the system has a remarkable effect.

Abstract: In case of tunnel fire at congest traffic, central smoke extraction by controlling the longitudinal flow velocity can confine and extract the fire-induced smoke in a short time, and retain the natural stratification as well as possible for obvious reason of safety. With respect to three vents located on both sides of the fire in an asymmetrical arrangement, a series of experimental tests are carried out in a 1/14 reduced scale model tunnel. For the experimental simulations, fire induced smoke is simulated by a heated air release using the model proposed by Mégret et al. Detailed temperature distributions in the tunnel have been carried out. According to the test results, it is difficult to give consideration to the smoke control both upstream and downstream the fire. At critical ventilation, until the exhaust rate Ge is more than 519m3/s, air temperature in the respiratory region can decrease to 322K for people survival.