Steel Structure Damage Accumulated To Fracture And The Long Term Effect Of Damage Passive Encouragement

In many structure-engineering accidents, each kind of loading and the structural material flaw is the objective existence. This paper embarks from the mathematics methodology, and makes use of the multi-subjects overlapping research technique. On the base of widespread synthesis of the domain about solid mechanics, hydromechanics, mathematics, physics, material science, heat transfer science, using the theory of differential equation of similarity transformation, function analysis, integral equation, generalized function, stochastic process, stochastic vibration and optimized design. Based on the theory of the mathematics simulation and the value simulation, the paper concerned with the conventional and the non-conventional boundary condition about the steel structures of inter-damage, the damage process of energy inter-transmission, the expansion of damage domain, the energy dissipation and the destruction, which is the problems of the analytical solutions, the solution condition and the behavior of corresponding comparison under the system of research in every way. The goal is thoroughly revealing the problems of intrinsic essence about the steel structures damage, the destruction, the reliability, the service deadline and so on, and provided the method basis and the rationale for the solution of actual project.The great span, the high level steel structure (steel bridge) is one of ingredient in national economy, their huge investment, the vital role in national economy, which links security to the people life and the property. The great span of steel structures have some characteristics in the security, the durability and the normal using function, which become more and more to be valued.The researches is steel structures damage accumulated to fracture and the long-term effect of damage passive encouragement, which establish a series of practical, effective solution for the steel structures engineering, and provided the rich theory for further development and application of the system of security defense.First, the numerical simulation method that is based on the dynamic damage responses of initially flawed steel structures is proposed. It is pointed out that the critical step is to solve the fractures of steel structures with working stress lower than yield stress. In order to analyze the developing process from damaging to fracturing of steel structure, the sensitivity of the initially flawed structures used to predict the damage accumulation is presented. The initial crack is regarded as the sensitivity parameters, and the mathematical models are provided for the fatigue damage of steel structures. Numerical examples are presented to demonstrate the feasibility and effectiveness of the proposed method for the fracture toughness and fatigue life of steel structures with different initial flaws. The conclusions can offer guidelines for the security design of steel structures.Second, for the behavior of structure fracture, the dissipation of energy and the damage of passive encourage should be taken into consideration in the course of dynamic damage. The paper presents a comprehensive assessment method which combines the theory of energy transmission and loss (TETL) and the mechanism of the damage of passive encouragement (MDPE). The comprehensive assessment standard has been applied to the case of steel bridge, which defined the relation between the mechanism of the damage of passive encourage and welded structure parameters. These tremendously improve the combination of TETL and MDPE. The results are compared with the method of CD and target reliability, numerical simulation about steel bridge demonstrates that method the paper presented is reasonable and effective. There are certain application prospects in the security design of the steel bridge.Besides, the network of damage exists in the process of energy dissipation. The optimizes of energy delivery can be make use of the time difference in the process of damage accumulation mainly, adjusts the damage accumulation about the beginning of loss and end of time section, to reaching the amounts of consumption and cutting down peak-hour, the delivery increases the amounts of dissipation that lowers the point of expectation, making every part of energy tends to balance.In actual problem of interconnection damage, it can be seen, damage amounts have obvious two requests. One is that the damage amounts on every way cannot exceed the maximal of the capacity. Two is that the amounts of delivery in the process are zero. The time region of damage stable is a kind of time region that not following time to develop. This kind of time region is comparatively common in the engineering. Article introduce that the time region of damage stable about a few concepts and project applies, include time region and their relevance function, every state of time, spectral density, spectral decomposition, the time region of damage stable in the energy system and so on.Meanwhile, the behavior of structure fracture because of dynamic damage, which need appraise correctly, is the key to realizing the security defense of steel structures. The paper concerned with the damage of steel structures in engineering application and put forward some new thought, such as, energy transmission and its dissipation, the speculation of time region of damage stable, Runge-Kutta crack development, the network of damage transmission, durability and life assessment, and considered the model of comprehensive assessment for the service deadline of steel structures. Based on the damage of constitutive relations and the energy criterion of Irwin—Orowan, expounded the inherent laws of multi-dimensional damage and energy dissipation between the synchronized change and the coordination development, and set the method of the model of parameters. The case of comparative computation demonstrates that the precision and numerical efficiency that the paper given is parallel to the traditional assessment, which offers some value applications in the multi-security defenses of steel structures.At last, the researches of the mechanism of steel structural destroys under the function of the traffic loading, wind loading, earthquake loading, waves loading is an enhancement for the ability of security defense and service deadline of the building. At the same time, the mutually studies among the material flaw, the damage, the destruction, the fracture, the residual stress, the energy criterion, the optimized plan and the reliability appraises, which will promote structural building to the development of the economy, safety and suitability, launches the broaden prospect for the steel structures of project applications.