| A large number of steel structure industrial plants have been built with the development of China’s industrialization process in recent years.To meet the ventilation and emission requirements of the super-large indoor space,the fan equipment is usually mounted on the roof structure of the factory,this type of equipment will generate reciprocating loads during operation and have a long operating time,which may lead to fatigue damage of the roof structure.Therefore,it is of theoretical and engineering significance that analyze the vibration effect caused by the suspension vibration equipment,explore the fatigue effect of the fan vibration on the roof structure and propose the countermeasure of vibration reduction.This paper has a study on Single layer 3-span steel plant,the eigenvalues of the single-portal rigid frame is analyzed,the vibration response of different number of suspension fans and operating conditions has been explored,the fatigue effect is evaluated,The vibration reduction measures and the verification analysis have been put forward for the conditions and structures that do not meet the requirements of fatigue damage code.Concrete research content based on four aspects is as follows:(1)Classical fatigue analysis theory and methods are organized by making a summary on the importance and research progress of fatigue problem of steel structure plant.With comparing various fatigue evaluation methods,the allowable stress amplitude method of ’Code for design of steel structure’(GB50017-2003)would be adopted as the evaluation method for fatigue damage in this paper.(2)using numerical simulation,a typical portal frame with two,six,and eight fans is arranged for single trusses,prospectively.Besides,Establish a finite element model and perform eigenvalue analysis to reveal the basic dynamic characteristics of the rigid frame structure.(3)Considering the influence of 2~8 fans synchronous booting,the dynamic response of the roof frame was analyzed.Considering the influence of average stress,the stress amplitude of the key crosssection is calculated,and the fatigue characteristics of the rigid frame roof is evaluated.The calculation results show that the reduced stress amplitude of the control section of the rigid roof exceeds the allowable stress amplitude,and the fatigue damage may occur when 6-8 fans are turned on at the same time.(4)In view of the fatigue damage of the roof frame,a three-layer rubber damper consisting of a WJ type rubber cushion is used as a vibration reduction measure to study the effect of vibration damping on the vibration of the roof frame fan.It shows that the vibration response of the roof frame can be controlled within the allowable range after using the rubber vibration damping pad,when 3 layers of laminated rubber are adopted,the vibration damping amount reaches more than 37.14%,which can effectively improve the vibration of the roof fan and meet the fatigue requirements. |
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