Search

The present study established a numerical investigation on the behavior of concrete filled steel tube reinforced concrete (CFSTRC) columns subjected to fire. A finite element analysis (FEA) model was built to simulate the performance of CFSTRC columns under combined loading and fire. The FEA model was verified by the experimental results of CFSTRC columns subjected to fire. The comparison demonstrated an acceptable accuracy for the proposed FEA model. Afterwards, the FEA model was used to analyze the failure modes, the redistribution of internal force, the changes and development of the stress and strain, and the contact stress between the tube and concrete of CFSTRC columns subjected to fire. Influencing factors that may affect the bearing capacity of the CFSTRC columns subjected to fire were analyzed. The bearing capacity and stiffness of the CFSTRC columns gradually decreased in the fire; the parameters such as the fire duration time, sectional dimension, slenderness ratio, and sectional core area ratio significantly influenced the bearing capacity of the CFSTRC columns. Finally, a simplified calculating formula was proposed to calculate the influence factors of the bearing capacity of the CFSTRC columns subjected to ISO-834 standard fire. The formula-calculated results were well in agreement with the finite element analysis results, which provide a simple and feasible method for evaluating the fire-resistance design of these types of components in practical engineering. [ABSTRACT FROM AUTHOR]

To provide a theoretical and technical basis for base isolation of LNG storage tanks, based on the shear beam theory for the outer-concrete-tank and the velocity potential theory for the inner-steel tank, and by introducing isolation stiffness and damping, the equivalent mechanical model of LNG storage tank base isolation system was established, the movement equations of LNG storage tank base isolation system were derived according to Hamilton's principle and the theoretical expression of seismic response were given. To 160 000 m³ large LNG storage tank, the numerical analysis results showed that, in addition to wave height, the base shear and overturning moment damping effect was obvious, the foundation design of LNG storage tank was necessary to consider the impact of outer-tank, however, when designing the inner-steel tanks, the impact of outer-tank could be ignored. It was necessary to optimize the design considering the influence of isolation on the sloshing of base isolation of LNG storage tanks. [ABSTRACT FROM AUTHOR]

To reduce the vertical seismic response of vertical storage tanks with fluid-structure coupling motion, according to the boundary conditions and potential theory, the hydrodynamic was given by selecting reasonable velocity potential. Considering hydrodynamic and soil-structure interaction, the control equation of vertical isolation storage tanks was established and the theoretical expression of wall shear, bending moment and stress were given. Seismic response analysis was carried out with Wilson-θ method selecting 150 000 m³ storage tanks. The results showed that: a vertical base isolation system storage tank could reduce the seismic response of radius, axial and hoop stress. It is necessary to take various factors into account to select the best site, isolation period, damping ratio and height-radius ratio in design of different storage tanks. [ABSTRACT FROM AUTHOR]

To study vertical steel storage tank isolation design and analysis methods, three-stage design method is used as the optimal design of base isolated for the vertical steel storage tank. In the first stage, from rigidity theory, the wave height amplification effect caused by the base isolated is considered firstly, and the wave amplification is limited to the boundaries of isolation design to adjust the frequency. In the second stage, from elasticity theory, the base shear of isolation is analyzed, and the damping effect of the base isolated is studied. In the third stage, the square and square root results of the base shear obtained by the rigid theory and the theory of elasticity are used as a design basis. In theory, the only guarantee the effect of the two effects, but also for engineering design and analysis provides a easy to understand method of analysis. The results showed that this approach to design can not only achieve the right base shear reduction, but also be capable of controlling the amplification effect of wave height. [ABSTRACT FROM AUTHOR]

Based on the seismic isolation study of the storage tanks, starting with sloshing, rigid motion and fluid -- structure coupling motion of the tanks, the dynamic response theory of hydrodynamic pressure, sloshing wave, base shear and overturning moment of the storage tanks was studied. Rational potential function was selected according to the velocity potential and boundary conditions that the structure of storage tanks satisfied. The equivalent mass and the relative height of mass center were given by using the same base shear and overturning moment of the liquid tank system and equivalent mechanical model when subjected to the same ground motion, and a three centralized particles mechanics analysis model was established. The simplified expressions of sloshing wave, base shear and overturning moment were given as well. The motion equation of the seismic system was established according to Harmilton principle. The earthquake responses of 2 x 104 m⊃3 and 15 x l04 m⊃3 isolated and non-isolated tanks were analyzed by adopting the time history method. The numerical result shows that the base isolation seismic system exhibits good performance of seismic isolation. [ABSTRACT FROM AUTHOR]

In order to reduce the seismic response of storage tanks under the earthquake, the base of ring beam structure is designed as a parallel isolation structure system with the slipping and the rubber isolation support. The convection and liquid -- solid coupling vibration are considered as a non -- coupled multi -- particle system. Depending on the judgment boundary whether the base shearing force is bigger than the yield shearing force or not, the seismic response of the tanks with the slipping and the rubber isolation support is analyzed by the Newmark-β method, considering the parameters of different seismic intensities, different friction coefficients, different total load ratios of the parallel isolation support structure, different locations, different ratios of height to diameter, different isolation periods and equivalent damping ratios. Results indicate that the base shearing forces of the tank are decreased obviously, and the rocking wave height is increased lightly under definite design parameters after isolation. Different parameters result in different isolation effects, thus the parameter design needs to be optimized. [ABSTRACT FROM AUTHOR]

• Depth prediction methods are used during cooling time in square-heating thermography. • Depth prediction methods suit materials with lower thermal diffusivity and deeper defects. • The logarithmic characteristic time and logarithmic depth show a linear relationship. • Two of the four depth prediction methods do not require a reference area. Square-heating thermography was used to predict the depth of glass fiber reinforced plastic (GFRP) flat-bottom holes during its cooling period. Four methods were proposed for depth prediction using a specified characteristic peak time. Square-heating thermography cooling theory was analyzed using numerical methods, the linear relationship between the logarithmic characteristic time and logarithmic depth of the GFRP's flat-bottom holes was obtained, and the slope and intercept of the linear curve were mainly related to the thermal diffusivity and the heating time. Finally, the flat-bottom hole depth was predicted using experimental cooling data from GFRP samples. [ABSTRACT FROM AUTHOR]

Laparoscopic D2 radical surgery for gastric cancer is minimally invasive but complex. In this path: (1) Repeated operation of lesser curvature side; (2) The gastrohepatic ligament is relatively fixed. Hence, it is not easy to expose the suprapancreatic area; and (3) It is not easy to dissect No. 1, 12 lymph nodes. This area may not be sufficiently cleaned or surrounding vessels may be injured during a resection. So it is critical to choose position fixing, and a clear, fast and convenient operation path. The author, based on his experience, has established a set of procedural steps called "Gao's double-way", lesser omentum approach and traditional greater omentum approach, which are described in detail in this article. The path of this first approach is described as a "W" type of dissection. The second way is the traditional greater omentum approach, whose path is described as a "M" type of dissection. This will enable laparoscopic surgeons to select a suitable path. This new approach not only simplifies the surgery but also provides more space for the subsequent operation, thereby making the surgery more simple, safe and easy.

Objective: To investigate the expression of recombination activating gene-1 (RAG-1) and its localization in the mouse brain during the embryonic development., Methods: The brain tissues of E (embryonic day) 11, E13, E15, E17, E19, P0 (the birth day) and adult mice were taken, the total RNA of brains were extracted and the changes of RAG-1 expression were detected with the method of RT-PCR. The freeze sections of brain tissues from each group were stained with immunohistochemistry method., Result: The expression of RAG-1 persisted from E11 to P0 brain and was steadily increased from E11 to E19; the results of RT-PCR were similar to that of immunohistochemistry. The positive-cells mainly appeared in the nucleus amygdalae, hypothalamus, thalamus and hippocampus at developmental stage. The expression began to appear in ventricular zone (VZ) and intermediate zone (IZ) of telecephalic vesicle, then gradually increased in subventricular zone (SVZ), corticle plate (CP) and subcorticle plate (SP)., Conclusion: The expression of RAG-1 in mouse embryonic brain tissue is higher than that in the adult mouse, which may be related to the process of neuron development.