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Seismic Response Analysis Of Fully-combined Substation Frame With Lightning Rod

Posted on:2022-02-06Degree:MasterType:Thesis
Country:ChinaCandidate:H LouFull Text:PDF
GTID:2492306323991659Subject:Architecture and Civil Engineering
Abstract/Summary:PDF Full Text Request
Steel structure fully combined transformer frame with lightning rod in service will be subjected to wind or earthquake and other dynamic load,especially in the structure of seismic fortification area,when rare or more than the fortification intensity of the earthquake,the structure may be damaged.Previous researches mainly focus on the mechanical performance of a single trussed substation frame structure under static force and wind load.There are few researches on the dynamic response,spatial action mechanism and dynamic response of the fully combined substation frame structure under earthquake action.In this paper,ANSYS finite element software is used to establish finite element models of full combined substation frame before and after damage and single substation frame with or without lightning rods,to analyze the response of the structure under earthquake action.The main research contents and conclusions of this paper are as follows:(1)Based on the actual engineering background,the finite element model of the substation frame is established,and the modal analysis and dynamic response analysis of the structure under earthquake action are carried out.The results show that the lightning rod on the upper part of the substation frame has a great influence on the structure,which reduces the natural frequency of the whole structure.Under the action of earthquake,lightning rod produces "whiplash effect",which is a weak link in the structure of full combined substation structure,and should be paid more attention to in the design and construction.If the design allows,it is recommended to set the lightning rod in the middle of the substation frame,and avoid setting it in the side span,so as to reduce the dynamic response of the lightning rod.From the absolute value and average value of the structural stress,the seismic performance of the steel structure transformer frame lightning rod is better.(2)The spatial action coefficient is introduced and calculated to analyze the effect of spatial action on the structure of the substation frame.The results show that for the substation frame with lightning rods under unidirectional and tridirectional earthquake action,the dynamic response of all the lightning rods decreases in X direction(horizontal direction with greater structural stiffness)due to space action.In the Y direction(horizontal direction with less structural stiffness),the dynamic response of No.1 and No.3 lightning rods(outside of side span)is amplified,and No.2 lightning rods(middle of side span)are reduced.The dynamic response of the frame column is amplified in both X and Y directions.For the substation frame without lightning rods,the dynamic response of the ground column is reduced in both X and Y directions by space action,while the frame column is enlarged in both X and Y directions.Under the action of three-direction earthquake,the spatial action makes the substation frame reduced in Z direction(vertical direction of structure).(3)Based on the equivalent stiffness simulation method,the finite element model of the damaged substation frame is established,and the modal analysis and dynamic response analysis of the structure under earthquake action are carried out.The results show that with the linear increase of the damage coefficient β,the natural frequencies of the first few order of the structure decrease linearly,so the damage degree of the structure can be judged by analyzing the change degree of the modal frequency of the substation frame.Under the earthquake action,the dynamic response of the substation frame increases with the increase of the damage degree.When the structure is slightly damaged(β =4.26%)and moderately damaged(β =17.02%),the structure still has a certain seismic safety reserve.When structure to severe injuries(β =30.00%),under severe earthquake,lightning rod at the bottom and the bottom of the frame column stress reached 240.90 MPa and 236.06 MPa,exceed the material yield strength,can not guarantee the reliability of the whole structure,it shows that if the substation structure in earthquake or exceeds the region seismic fortification intensity of earthquake,the structure is likely to happen,must be replaced or repair the damaged components at this time.
Keywords/Search Tags:Steel structure, Substation frame, Lightning rod, Seismic action, Spatial effect, Damage
PDF Full Text Request
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