Most of the Preventive maintenance (PM) reliability modeling research has focused on the relationship between two adjacent failure intensity functions, while few real case studies have demonstrated the application of these PM models. Thinking from this vision, a nonlinear PM model with scale and shape adjustment parameters is proposed based on a Weibull distribution, and two adjustment parameters can describe each PM effect. Meanwhile, the proposed model can separate the influence of an environmental factor from the failure intensity function of the new system when it operates under a new condition. The environmental parts in the failure intensity function can be improved or removed after several PM actions. Finally, one real case study is exhibited to illustrate the proposed model. The results indicate that the proposed model exhibits good fitting performance in reliability modeling and can describe the PM effect quantitatively as well as reveal the influence of the environmental factor on the system reliability.

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Introduction:To analyze the basic, mechanical properties of post-tensioned, prestressed concrete, simply supported beams with grouting material of varied porosity under load, a finite element model is established by using ANSYS finite element software. Methods:The mid-span, cracking deflection and the equivalent stress of the prestressed, concrete beams with grouting material of varied porosity are calculated under different load forms. Results and Conclusion:The analysis results show that the cracking deflection of the prestressed, concrete beams increases with the increase in the porosity of the grouting material of the beams under different load forms. By contrast, under the same porosity grouting material, the cracking deflection of the symmetrical loads is larger than that of the uniform and concentrated loads. As the porosity of the grouting material increases, the peak value of equivalent stress decreases. The equivalent, stress-peak value of the concentrated load is always larger than the equivalent, stress-peak value under the uniform and symmetrical loads.

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