Applied Mechanics and Materials Vols. 94-96

Abstract: The bolt-ball joints and welded hollow spherical joints are used frequently in the reticulated structures. Many researches on the influence of the bolt-ball joints stiffness on dynamic and static mechanical behavior of these structures are carried out by far. This paper reviews these researches, and points out the limitation as well, then the future work of which has been put forward. In addition, the progress made in our work team in this filed is illustrated.

Abstract: Based on a certain super deep building foundation pit of Tianjin railway station, according to analysis of measured data and numerical analysis, it get the changing regular of horizontal displacement of retaining and protecting for foundation excavation——diaphragm wall, and surrounding soil around foundation pit. The conclusion would be helpful for the future similar projects.

Abstract: Genetic algorithms (GA) are very effective at finding optimal solutions to a variety of problems. This innovative technique performs especially well when solving complicated real-world problems. Therefore, this paper aims to use the fuzzy analytical hierarchy process (AHP) GA approach to optimize SRC beam. In the process of optimization, the matlab toolbox with GA is used. To increase the performance of the genetic-based approach for optimization problems, the design constraints related to member stress, bending moment etc are described by using fuzzy set theory. Finally, a example for beam optimization is presented. The example shows that the approach is flexible enough to deal with optimization of SRC beam.

Abstract: Abstract. The characteristic frequency was generated when blasting seismic wave propagate in rock mass. The characteristic frequency played an important role in the amplitude attenuation of seismic wave with time and propagation distance. Rock mass was simplified as visco-elastic media. The time attenuation model of seismic wave amplitude was studied by wave equation and the complex number theory. Theoretical analysis demonstrates that attenuation coefficient of seismic wave amplitude with time is mainly affected by rock viscosity coefficient and elastic modulus. The attenuation coefficient decreases with increase of elastic modulus. The attenuation coefficient increases with increase of viscosity coefficient. The test method of equivalent elastic modulus of rock mass was analyzed according to model of time attenuation of seismic wave amplitude in situ. The wave velocity test verified effectiveness of the method. A new method of determining rock mass mechanical parameter was put forward.

Abstract: Long-span hybrid structures have been widely used in recent years. Composition and working mechanism of cable-strut-supported rigid shell structure of a gymnasium roof are analyzed in this paper. Influences of different type of supports and bracing members on the spatial working property of this hybrid structure and factors that influence stiffness of the structure are analyzed too. Analysis results identify the formation mechanism of spatial stiffness of the hybrid structure. The research results can shed light on study and designing of the same kind of structure.

Abstract: A parametric study of an foundation on soft soils reinforced with stone columns is performed using Phase2D. The real foundation is modeled and its bearing capacity is decided by the columns and their surrounding soft soil. The following parameters are analysed: the replacement area ratio, the deformability, mean stress, absolute horizontal (vertical) displacement, volumetric strain, maximum shear strain of the foundation. Based on the results of this study, a new design method is proposed: for decreasing the settlement and satisfying bearing capacity, increasing the replacement area ratio is good idea.

Abstract: Based on the nonlinear finite element software, the mechanical properties of polyurethane filled double skin steel tubular (PFDSST) members with different hoop coefficients and slenderness ratios under axial compression have been studied by nonlinear finite element software. On the basis of the researches on the numerical simulation results, it was summarized that the influences on stability, ductility and properties of the PFDSST members under axial compression, and then the work processes of the PFDSST members have been revealed deeply, the theoretical basis for the designs of the PFDSST members was established.

Abstract: The elasto-plastic dynamic response on the steel-pipe arch truss with 120 m span and 0.2 rise-span ratio is analyzed in this paper under earthquake wave with SAP2000, the geometric and material nonlinear effects are considered during the analysis simultaneously based on the plastic hinge theory. Under the action of EL-Centro waves with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL-Centro waves when applied in horizontal direction is 644 gal and is 375 gal when applied in vertical direction; The ratio of its maximal node horizontal displacement and its rise-height is 1/538, and its displacement ductility coefficient is 1.3 and the ratio of its bars with plastic hinge appearing when buckling is 3.28% when EL-Centro waves applied on structure in horizontal direction; The ratio of its maximal node vertical displacement and its structural rise-height is 1/1136, and its displacement ductility coefficient is 1.03 and the ratio of its bars with plastic hinge appearing when buckling is 1.5% when EL-Centro waves applied in vertical direction.

Abstract: The conventional advanced analyses assume the sections to be compact, and do not account for the degradation of the flexural strength caused by local buckling. Since the sections of real structures are not always compact, the analysis should be improved to consider local buckling. Based on the finite element model, using flexural tangent and axial tangent modulus to consider the effect of local buckling, a concentrated plasticity method suitable for practical advanced analysis of planer steel frame structures comprising non-compact sections is presented in the paper. The accuracy and precision of the method is established by comparison with steel frame tests.

Abstract: Based on the design of general layout and transportation optimization of a variety of factors, established a program evaluation system, the theory of fuzzy mathematics general layout and transportation design a comprehensive evaluation. For the fuzzy weight of each factor to determine the application of an objective method of empowerment from the perspective of information entropy to determine the factors enabling the weight of each evaluation index, fuzzy comprehensive evaluation of the results obtained. To detail with an example.