Papers by Author: Jin Sheng Han

Abstract: The fire resistance of concrete filled steel tubular column is usually obtained by the numerical analysis method, which is difficult to operate and not convenient in the actual civil engineering. So it is necessary to study the simplified calculation method. A large number of numerical simulation results of the temperature distribution of the section and the bearing capacity at high temperature of the concrete filled steel tubular columns are analyzed. The influences of secondary parameters are simplified. The simplified calculation method at 150 min and 180 min for the bearing capacity at high temperature of concrete filled steel tubular columns subjected to axial compression and fire is presented on the basis of comprehensive analysis of the numerical calculation results. The calculation results can be used as the basis to judge the fire resistance. It is shown by the comparison with the experimental results that the precision of the simplified calculation method can meet the requirements of engineering application.

Abstract: The fire resistance ability of load-bearing column of building structure under fire is an important aspect affecting the safety of the structure. Although a large number of research results have been achieved in this respect, the researches on the numerical analysis of the bearing capacity and deformation process at high temperature are still not sufficient. The numerical simulation of the bearing capacity and deformation process at high temperature is hard to carry out and complex to operate, and not practical as well. Therefore, simplified analysis method is adopted to analyze the deformation and internal force of the controlling section of the load-bearing column subjected to fire. Besides, taking the concrete filled circular steel tubular column as example, the basic analysis theory of the fire resistance and the deformation performance of columns subjected to constant load is presented. The numerical calculation program which is developed on the basis of this theory can well simulate the process of deformation and the fire resistance of the columns subjected to fire. The simulation results are in good agreement with the experimental results.

Abstract: At present, many analysis methods and calculation formulas of the bearing capacity of concrete filled steel tubular columns have been researched. But these numerous calculation formulas of the bearing capacity have varied forms, and the application scope and the calculation precision of them are also quite different, which makes it difficult and confused for engineering designer to choose a suitable formula. Primary calculation formulas of the bearing capacity of concrete filled steel tubular columns are summarized. The calculation results of these formulas are compared with some test results of the concrete filled steel tubular columns with a large diameter. The applicability and the accuracy of these formulas are analyzed. Based on these comparisons and analyses, reasonable suggestion is given to select the suitable formula. Finally, one formula is provided to calculate the ultimate bearing capacity of concrete filled steel tubular columns reinforced with steel bars.

Abstract: Finite element model was built in order to study the section temperature field of concrete-filled double steel tubular columns through the software of ANSYS. Moisture of concrete and thermal contact resistance were considered in the model. Based on the Eurocode 2, specific heat of concrete was modified in order to consider the effect of moisture. Contact elements were created in the interface between steel tube and concrete in order to consider the effect of thermal contact resistance. The effects of diameter of steel tube and type of aggregate to section temperature field were studied. Distribution of section temperature field is given on the concrete-filled double steel tubular columns, which provides the basis for the analysis of fire resistance capability.

Abstract: The water separated from concrete and the thermal contact resistance between steel tube and concrete have important effects on the temperature field of concrete filled steel tubular columns subjected to fire. Therefore, it is necessary to consider these effects in many cases to obtain accurate results of temperature field. The actual influences of water and thermal contact resistance on the temperature field of concrete filled steel tubular columns are analyzed in this paper, and the corresponding simplified methods are presented to take into account these effects in numerical analysis. A numerical program using these simplified methods is developed to calculate the temperature field of concrete filled steel tubular columns under fire. It can be shown by the comparison with the test results that the methods adopted in this paper have good accuracy and feasibility, and can obviously improve the calculation precision of temperature field.

Abstract: The structural form of a kind of cellular hollow flat slab floor using thin wall plastic boxes was introduced. The equivalent frame method, which was used to analyze the internal force of this kind of cellular hollow flat slab floor, was discussed. Finally, the method to calculate the deflection of cellular hollow flat slab was investigated and some improvements in this method were presented. The effects of the cracks on the stiffness and deflection of hollow flat slabs were taken into account in this method to decrease the error of elasticity calculation results.

Abstract: Load-carrying system of reinforced concrete structure on construction is different from load-carrying system on service life. This temporary load-carrying system is composed of shores and concrete members of early age on construction. Geometrical model and material property of structure are time-varying on construction. Through secondary development of ANSYS, the processes of placing concrete and removing shore are simulated on construction. Critical effect factors are determined through the analysis on mechanical property of temporary load-carrying system, such as shore stiffness, foundation stiffness and diurnal temperature difference. Results of analog calculation to temporary load-carrying system will provide basis for shoring system design and structure reliability analysis on construction.

Abstract: The glassy alloy rods of Cu₅₀Zr₄₃Al₇, (Cu₅₀Zr₄₃Al₇)_100-xY_x(x=2,5) and (Cu₅₀Zr₄₃Al₇)_100-xAg_x(x=6,7) with diameters of 3.0 mm were prepared by copper mold suction casting method. The influence of adding Ag and Y to Cu₅₀Zr₄₃Al₇ metallic glass on glass formation ability (GFA) and thermal stability was studied by means of X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC). The results show that Ag and Y appropriate micro-addition enhance the glass formation ability and thermal stability of the Cu-Zr-Al metallic glass. The effect of Ag is better than that of Y. The addition of Ag causes a increase of the reduced glass transition temperature (T_rg) of (Cu₅₀Zr₄₃Al₇)_100-xAg_x alloy from 0.618 at 0 at.% Ag to 0.628 at 7 at.% Ag. The width of the supercooled liquid region of Cu₄₃Zr₄₃Al₇Ag₇ glassy alloy increases about 25K compared with that of Cu₅₀Zr₄₃Al₇, and the γ value of Cu₄₃Zr₄₃Al₇Ag₇ reaches 0.433. The electrochemical corrosion behaviors of Cu₅₀Zr₄₃Al₇, (Cu₅₀Zr₄₃Al₇)_100-xY_x(x=2,5) and (Cu₅₀Zr₄₃Al₇)_100-xAg_x(x=6,7) metallic glasses in 3.5% NaCl solution were investigated by potentiodynamic polarization method. It is found that corrosion resistance of all amorphous alloys is better than that of the corresponding crystalline alloys. The Ag and Y micro-addition improve corrosion resistance of Cu₅₀Zr₄₃Al₇ metallic glass. The corrosion current density of Cu₄₃Zr₄₃Al₇Ag₇ metallic glass decreases 1~2 orders of magnitude compared with that of Cu₅₀Zr₄₃Al₇.

Abstract: Mechanical properties of high-rise building on construction and on service life are different. Geometrical model of structure and material property are time-varying on construction, so mechanical property analysis of high-rise building on construction is complex. The software of ANSYS is selected as the analysis tool. Construction process of high-rise building is simulated through the element “life and death” function of ANSYS. Results of analog calculation are close to the actual values of structure because of considering the construction process. It is beneficial to the safety of high-rise building on construction.

Abstract: The simplified calculation method of the temperature field of concrete filled steel tubular columns under fire conditions was studied for convenience. Firstly, a numerical program of finite difference method was developed to calculate the temperature field of concrete filled steel tubular columns subjected to fire, and the calculation results of the program have good agreement with the experimental results. Secondly, the effects of the steel tube thickness, the steel tube diameter and the type of concrete aggregate were analyzed on the base of plentiful experimental and numerical results. Finally, the effects of some major factors on the temperature field were simplified, and the simplified calculation method was presented to calculate the temperature field of concrete filled steel tubular columns based on data fitting. The precision of the simplified calculation method can satisfy the accuracy requirement of engineering practices.