Applied Mechanics and Materials Vols. 256-259

Abstract: Finite element analysis have been carried out in order to study the mechanical properties of the joints between elevated columns and truss column in substation frame. Firstly, the numerical results and the experimental ones were compared to verify the efficiency of the FEM model. Then, the whole process of elastic-plastic analysis was carried out to the prototype structure. The results show that when the bottom of the elevated column was yielding, the stress of the stiffeners at the joint is small, which can meet the design principle of “strong joint - weak member” criterion. Furthermore, when the structure enters into the elastic-plastic stage, the stress in the upper stiffeners at the horizontal load direction is large and most of them yield, but the stress in the plane gusset plate of the joint is still small.

Abstract: Based on elastic wave theory, the characteristics for axisymmetric longitudinal wave propagation in double layered hollow cylindrical shell structure with a continuous contact interface are investigated. According to free boundary conditions and interfacial contact continuity condition, the first mode non-dimension dispersion equations for longitudinal wave is derived and validated by calculation data of existing literature. The non-dimension expressions of stress and displacement are deduced and the stress and displacement distribution in cylindrical shell are obtained by calculation examples. Under the fixed outside radius condition, the shell thickness influence on dispersion relation of axisymmetric longitudinal wave and stress and displacement fields in cylindrical shell are discussed. The results show that the thickness of inner shell or outer shell has little influence on dispersion characteristics when the value of wave number is small. As wave number increased, the effect of shell thickness also increased. The stress and displacement in shell increase with the increase of the thickness of inner or outer layer shell when the wave number value is large.

Abstract: In order to analyze the mechanical properties of the steel truss roof burst in the case of defective within, the use of non-linear display dynamic finite element analysis software ANSYS / LS-DYNA to study the different effects of different random defect structure. The measured defect data is obtained by a construction tube truss roof structure .To accord to the random sampling method, defects randomly distributed and the parametric statistical information is to establish. Defect structure antiknock performance is derived, considering the tube truss structure roofing layer, and unconsidering the two simulation models for pipe truss structure roofing layer, and taking into account the rod defects affect the dynamic characteristics of tube truss structure to explosivesposition, explosives equivalent parameters by analyzing and comparing the different parameters of the explosion of the power of the tube truss structure response. Roof layer, the location of the explosion, explosives equivalent with tube truss structure antiknock performance relationship and the weak position of the structure is determined to ensure that the building security to provide a theoretical basis . The results show that the tube truss structure system when the explosion shock wave loads, its dynamic response is a very complex process, the role of the explosion shock wave loading, pipe truss the plastic development process and the structure of the internal location of the explosion, explosivesweight, defects, and consider whether the the roofing layer has relationship.

Abstract: This paper deals with dynamic analysis of a multi-span continuous beam with an arbitrary number of cracks. This problem is solved by a hybrid analytical/ numerical method that is the basis for applying to a method of damage detection in the multi-span continuous beam later. In this paper, we calculate in detail about vibration frequencies, vibration mode shape of beam structure with cracks. The proposed method is the method that improved the transfer matrix method combined with the mode-superposition method. Only need to use two unknowns, this method can solve the problem of multi-span continuous beam with an arbitrary number of cracks. Calculation cases of beam with cracks and beam without cracks are compared with previous studies.

Abstract: To ascertain the dynamic performance of recycled aggregate concrete (RAC) shear walls, four 1/3 scale models, including three mid-rise shear walls with reinforcement ratio 0.25% but different recycled aggregate replacement rate, and one with reinforcement ratio 0.46% and 100% recycled coarse and fine aggregate, were tested on the shaking table. The testing process included elastic, cracking, and failure stage of the models. Dynamic characteristic and dynamic response of models at different stages were studied and the comparison between failure patterns of 4 models was also made. The shaking table test results show that the seismic performance of RAC mid-rise shear wall becomes worse with the increase of the recycled aggregate replacement. And the seismic performance of 100% recycled aggregate concrete shear wall gets a little higher with the increase of the reinforcement ratio.

Abstract: A general formulation of constitutive relations in non-smooth elastoplasticity is presented. The treatment applies to general non-smooth plasticity problems and to problems characterized by non-smooth yield criteria or dealing with non-differentiable functions. The mathematical tools and instruments of convex analysis and subdifferential calculus are suitably applied since they provide the proper mathematical instruments for dealing with non-smooth problems and non-differentiable functions. General formulations of constitutive relations and evolutive laws in non-smooth elastoplasticity are illustrated within the presented theoretical framework. Connections between the proposed mathematical treatment and the classical relations in elastoplasticity are illustrated and discussed in detail. The presented generalized treatment is equipped with considerable advantages since it shows to be ideally suited for the development of variational formulations of structural problems in non-smooth elastoplasticity.

Abstract: In a certain steelmaking plant, there were many steel beams to be strengthened by CFRP because the fatigue stress range could not satisfy the requirement of the standard. According to the project condition of high temperature and dust, and the strict construct cycle in construction, we would make sure the reasonable construction technology and the control of construction process after choosing the proper strengthening materials. The whole construction process including: 1.surface disposed, burnish area pasted, and reveal the component; 2.orientation, make sure the pasted area based on the drawing; 3. paste CFRP by the drawing; 4. paste up the defend dope; 5. quality check up; 6.long range supervise. Practice testify, CFRP strengthens is feasible for FRP strengthens appliance and development, and develop the domain of FRP strengthens. It makes progress for engineering appliance of FRP in our country.

Abstract: By the method of plane charge on the tested beams, this paper studied 5 groups 15 pieces of beams， dynamic performance by 14 times loadings, displayed the deflection waveform curves, measured the bearing ability of beams, analyzed the effects of the deformed performance and the ductility of the test beams with different adhering forms.

Abstract: The constitutive models of plasticity and viscoplasticity are formulated in a unified framework by taking advantage of the appropriate mathematical tools of convex analysis and subdifferential calculus. Two viscoplastic constitutive models frequently adopted in viscoplasticity are analyzed, the Duvaut and Lions viscoplastic constitutive model and the Perzyna viscoplastic constitutive model. In literature these two models are frequently adopted as alternatives. In the present paper it is discussed on the relation between the two models and it is shown that, under certain conditions and assumptions, the Duvaut-Lions model may be considered as derived from the Perzyna model.

Abstract: The joint domain of beam-to-column connection is very complex parts under loading, which plays an important role in transferring internal forces in light steel structure, such as moment, shear, axial force and so on. Considering the influence of its shear deformation in the structure calculation can help us to reflect the actual mechanics performance and evaluate precisely practical bearing capacity of the structure. According to the actual characteristics of beam-to-column connection, the author established some models of its joint domain, and used the finite element method to analyze and calculate shear deformation of these models. Meanwhile, the author researched the influence of the changes of various parameters to its shear deformation, and provided beneficial suggestions for revising the current design method of light steel structure finally.