Applied Mechanics and Materials Vols. 105-107

Abstract: Liquid filled double bottom structure is a usual type for large surface vessel, so the optimal design of which has important significance for viability of vessels in war. Appling a FEM process of MSC.Dytan, and changing the depth of liquid cabins, the thickness of bottoms and the thickness of stiffening, the response of different double bottom structures to underwater explosion were studied. After comparing and analyzing the deformation, the optimal design method of double bottom structures filled with liquid resisting underwater explosion was achieved. The best depth of water in water cabins is 90%, the best ratio of thickness of inner bottom and outer bottom is 11/9, and the stiffening should be thicker than outer bottom and thinner than inner bottom.

Abstract: This paper presents a method that using inner transverse prestressing bars to enhance the shear capacity of concrete beams, which can be used in new transformer beams to decrease the sectional dimensions. Four transversely prestressed concrete beams and one ordinary reinforced concrete beam were tested. The nonlinear finite element method was applied to analyze them, parametric study was carried out to analyze the behavior of transversely prestressed concrete beam, and the following conclusions can be drawn: (a) With the increase of the prestressing force level, the shear capacity of transversely prestressed concrete beam increase rapidly, which means that prestressing force level has a significant effect to the shear capacity of transversely prestressed concrete beam. (b) If the area of transversely prestressing bars is almost same, the transverse bars with smaller diameter and smaller spacing can enhance shear capacity of transversely prestressed concrete beam more efficiently. (c) If steel plate of 100 mm×350 mm×16 mm being changed to steel padding of 100mm×100mm×16 mm the shear capacity of transversely prestressed concrete beam will decrease little. It means in the actual engineering the steel plate can be changed to steel padding, and then the amount of steel will be reduced.

Abstract: Three support structures with different configurations have been selected to be presented in this paper. Through numerical simulations of structures subjected to current loads, wave hydrodynamic loads and inertia loads, some useful results are gained. The results show that first scheme is simple but stress is largest of all, and second scheme is reasonable for the loads are transferred effectively, and third scheme is less stable. Thus research work provides a valuable reference for harnessing of tidal energy.

Abstract: To discuss the effect of energy saving of heat-reflective insulation coating on exterior walls of building, the wall temperature change of two test rooms with heat insulation or not in Hangzhou has been monitored in summer, and the heat flux data of east, south and west walls were analyzed. The results indicate that the temperature of outside wall surface with the heat reflective insulation coating is reduced effectively, and the maximum temperature change was about 9, 10°C. There is a positive proportional between the mean daily air temperature and heat gain that the heat gain increases with the mean daily air temperature. By calculating, the higher the air temperature, the more the cooling effect of coating in summer. But the higher the mean daily temperature do not mean that the more heat gain in summer. The result shows the energy saving effect of the heat insulation coating on building wall was very obvious in summer in Hangzhou.

Abstract: In recent years, a new type of frame consisting of steel beam and concrete-filled square steel tubular special-shaped column is increasingly widespread. Compared with the joint of ordinary reinforced concrete special shaped frame, the joint between concrete-filled square steel tubular special-shaped columns and steel beams has the advantage of better ductility, higher loading capacity, uncomplicated reinforcement disposing and convenience in construction. This paper indicates that the joint has strong energy dissipation capacity and high loading capacity, and the use of diaphragm is effective to enhance the structural performance of the joints. Stress transferring mechanism in the joints is discussed, and the calculating model of the shear strength of panel zone is established. This study is helpful for further study of the design and use of the joint between concrete-filled square steel tubular special-shaped columns and steel beams.

Abstract: Choosing scaled stiffened cylindrical shell model as simulation object, the simulation model of stiffened cylindrical shell subjected to underwater explosion load is built by using MSC-DYTRAN finite element analysis software, the typical test conditions which shock factor is 1.1 is simulated, the damage properties of stiffened cylindrical Shell is analyzed, numerical results are compared with experimental data, it is proved that the simulation method is effective and feasible. By performing a series of numerical experiments, the influence of attack angle of explosive and submergence depth of model on the elastic-plastic dynamic response were investigated. It is shown that angle of 90 degrees is the most serious attack angle, angle of 0 degrees is less serious than other angle, the submergence depth of stiffened cylindrical shell has obvious influence on dynamic response, the more deep cylindrical shell is, the more serious cylindrical shell is damaged.

Abstract: This paper is focused on the evaluation of the structural influencing coefficient in multi-story moment-resisting steel frames involving local bucking effect, with due consideration to both their ductility and overstrength. Ductility and overstrength play an important role in keeping satisfactory performance of structures during strong earthquake. Firstly, moment-resisting steel frames of are designed according to Chinese seismic code. Based on the non-linear shell element method, both inelastic time history and pushover analyses has been performed on these steel frames to get the global capacity envelopes. The results show that number of stores and spans have effect on the behaviour factor values, and that the local buckling affects the ductility capacity of steel frames. Finally, based on the findings presented in the article, tentative influencing coefficient values are proposed for moment-resisting steel frames.

Abstract: This study introduces the theory of asphalt aging with infrared adsorption spectrum. Qualitative and quantificational comparisons are carried out between Karamay asphalt ultraviolet radiation aging, after which asphalt turns from sol-type to gel-type and other aging types. The variance ratio of absorbance A at 1700 cm^-1 in infrared spectrum chart is consistent with the tendency of asphalt’s three general indexes, including penetration, ductility and softening point. The oxidation speed of ultraviolet radiation aging is 1.80~6.23 times that of thermal aging. In addition,the process of photo-oxidation, the order of carbonyl content in different asphalt samples, the influence of ultraviolet radiation on long term aging of asphalt and other useful information has been gained for better and further researches in this field.

Abstract: An experiment on shear capacity for HRB500 grade R/C frame columns within yield hinge regions is studied. The different failure modes for specimens within yield hinge regions are classified, and the hysteretic curves are studied. The shear contributions of stirrups and concrete for columns are analyzed in detail. Based on the experimental study, formulas for the shear capacity of reinforced concrete columns are supposed under seismic loading, and the different formulas are adopted to estimate the shear capacity for columns at different seismic levels, Both security and economy of structural design are all considered.

Abstract: In prestressed plane structures, tensioning prestressing tendons in one direction will bring primary moment in another direction, so the method of calculating secondary moment by removing the primary moment from the resultant moment is not applicable for plane structures, in which the primary moment is calculated by prestressing force multiplying the distance from prestressing force to neutral axis of section. The reason for this method can not be used for calculating secondary moment in plane structures is analyzed. The method for calculating secondary moment in plane structures is presented.