Advanced Materials Research Vols. 163-167

Abstract: A specimen for a static model test was designed to simulate a steel anchor box on the arch pylon of a cable-supported bridge. In order to reflect mechanical behavior of the prototype of the real structure, appropriate boundary conditions were determined by the comparison of FE analysis results from the real structure and the specimen. The design of the specimen successfully dealt with the difficulties in loading irregular structures. The FE analysis results show: the stress distribution on specimen was in good accordance with the real structure; the specimen can well represent the mechanical behavior of the anchor box on arch pylon.

Abstract: The nucleation and crystallographic characteristics of acicular ferrite in the as-rolled and tempered steel were investigated by using an optical microscopy (OM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD). The results showed that acicular ferrite forms at nucleation sites such as dislocations within austenite grains under the heavy reduction in the austensite non-recrystallization region and accelerated cooling conditions, and the inclusions such as Al2O3•MnS may have promotion effect for the formation of acicular ferrite. Acicular ferrite has high misorientation angle boundaries and a number of sub-boundaries or high density of dislocations inside, which contributes to an excellent combination of high strength and toughness. And the morphology of acicular ferrite does not show obvious change in tempering microstructure due to high temperature thermal stability, which plays an important part in keeping good mechanical properties for tempered specimens.

Abstract: The effect of fire is the most important factor in steel design, in this paper, the existing steel structure fire resistant design methods are analyzed, and pointed out the shortcomings of various methods, through the research of fire resistance properties of steel and reference to European standards, the stress - strain properties of common steel under high temperature were analyzed and calculated, and the ease to use of stress - strain relations were obtained.

Abstract: In calculating the reliable capacity of carrying load of cold-formed thin-walled steel members, there has not yet been a proper method which directly takes into account the impact of the residual stress. Through the research of residual stress, models close to the actual situation are established. Based on the ultimate load criterion, considering both cold-formed residual stress and initial out-of-straightness, the whole stability of axially loaded compression member of cold-formed thin-walled crimping angle steel and channel steel are analyzed using FEM. Based on a lot of FEA numerical results obtained, the φ-λ curves of different kinds of sections and size are obtained. Finally, φ-λ curve that reflects the fact can be obtained. By comparing the curve with the code and results of experience, it is proposed that the stability coefficient φ of small slenderness member of the code should be increased appropriately.

Abstract: To analyze the flexural and torsional buckling of H-beams with corrugated webs, the stress characteristics were compared with beams with plat webs firstly, then, the previous methods calculating warping constant of the H-beams with corrugated webs was discussed. Based on such works, a new calculation method was put forward. This method is simple in shape, by which the warping constant can be calculated easily. To test the accuracy of the method, plenty of numerical simulation models of beams under uniform bending was used to compare the difference between each method. The results proved that the method in this paper was successful and convenient.

Abstract: Under most cases, the non-liner energy dissipation is approximately replaced with Rayleigh damping model which belongs to Maxwell-Kelvin type, the method is a fuzzy evaluation method of damping. Based on complex damping theory, equivalent dynamics equation of complex damping model is derived and loss factor is discussed, the accuracy of the equation is theoretically confirmed in this paper. Based on the existing damping theories, a new damping model is proposed, which is a zero amplitude damping model combing with stress dependent complex damping model. The model is used in seismic resistance analysis. Taking a steel beam for an example, the relationship between response amplitude and damping ratio is analyzed with the new damping model. It shows that the method of stress-dependent damping with consideration of zero amplitude damping can precisely describe the energy input and energy dissipation principles and the dynamic response under seismic loads can be precisely obtained. A solid foundation is laid for the further study of complex damping theory, its equivalent viscous damping model and engineering application.

Abstract: The dynamic pile driving process is so complex that till now the analysis on the process had been focusing on the filed test or laboratory test. However, the past study about the dynamic process is a time consuming one; with the computational method development, the numerical simulation on this process is possible. In this paper, explicit dynamical analysis method is adopted, the pile is simulated using the elastic solid element, two computational cases are considered and finally the pile driving process dynamical stress is studied.

Abstract: The theory of performance-based seismic design (PBSD) is the key issue for the modern earthquake engineering research. With comparison of the traditional prescriptive seismic design code based on the bearing capacity design, the PBSD method presents the specific performance object for the buildings. On the base of the background and development of the PBSD about reinforced concrete (RC) structures, some researches and design approaches of PBSD were proposed for the concrete-filled steel tubular (CFST) structures based on the research results on PBSD of RC structures and the mechanical behavior of CFST structures. Some theory analysis was performed to investigate the PBSD performance of CFST structures. This is referred to further study on PBSD for CFST structures.

Abstract: Energy conservation in Building is becoming the most important topic for energy conservation and environmental conservation. In order to explain the relationship between building exterior-protected construction and energy conservation .We choose Wenyuan Building as an example, using DOE program and Air-Pak software to study, to prove the importance of exterior-protected construction to building conservation.

Abstract: Space steel structure stability has been a focused problem in the engineering field, in the past the study mainly concentrated on the single layer dome structure stability and elastic stability analysis, but with the structure shape complex, new type structure emerges continually, it needs more accurate stability analysis method. In this paper the linear and nonlinear buckling theory and analysis method are introduced firstly, and then a new type steel space structure with partially double layer dome structure is chosen as the computational model. The structure self vibration mode, linear buckling analysis and nonlinear buckling process and buckling characteristics are studied by the FEM commercial code ANSYS; the nonlinear load-deflection curves at the different points are gotten and some conclusions about this kind of structure are drawn.