| Steel has the disadvantage of poor corrosion resistance,and it is prone to corrosion damage in humid or water environments.The proportion of steel in building materials has increased,and the proportion of steel structures in building structures has increased.The shortcomings of steel being easy to corrode cause the load-bearing capacity of components to decrease,thereby affecting the safety of the structure.According to incomplete statistics,the loss caused by steel corrosion accounts for an increasing proportion of the national economy every year,and the research on the relative force performance of steel structural members after corrosion is particularly important.This paper mainly studies the influence of local pitting corrosion damage on the mechanical properties of circular pipe string members,and analyzes the influence of the occurrence range of pitting corrosion on the bearing capacity of the members.The local pitting damage component is applied to a foreign derrick engineering practice,and its related mechanical properties under earthquake action are analyzed.The specific conclusions are as follows:(1)The ANSYS finite element software was used to establish a numerical model and the Euler formula was used to theoretically verify the rationality of the model design;a local damage numerical model was established and the improved standard formula was used to theoretically verify the rationality of the damage model design.(2)The damage intensity(DOP)and the wall thickness damage(α)are used as the control parameters for the amount of pitting corrosion.As the damage intensity(DOP)increases,the reduction factor R decreases,and the bearing capacity of the steel pipe member gradually decreases.When the DOP is small,the reduction factor R declines more gently;the increase in wall thickness damage(α),the reduction factor R decreases,and the ultimate load-bearing capacity of the steel pipe member decreases,and a has a significant impact on the decline factor R.When DOP is 23.61%,with the increase of α,the decreasing trend of the reduction factor R approximates a quadratic curve.(3)Divide the steel pipe into five equal parts in the longitudinal direction,and study the influence of pitting corrosion damage on the ultimate bearing capacity at the distance from the column foot L/5,L/5-2L/5,2L/5～3L/5(in the column)The study found that changes in the extent of local pitting have a significant impact on the reduction factor R.Among them,the bearing factor R is 0.973 of the member with local pitting corrosion damage at the column foot has the least impact on the bearing capacity of the member,and the bearing factor R is 0.730 of the pitting damage member at the center of the column has the greatest impact on the ultimate bearing capacity.(4)Selects the weightlessness rate of 0,5%,10%and 15%respectively,20%,five kinds of working condition of earthquake excitation is calculated,and the selection of more severe earthquake 35 gal(peak acceleration)is studied,with the increase of weightlessness rate,maximum displacement increases the overall trend,heavy rate of 20%maximum interlayer displacement is small,still do not meet the elastic-plastic deformation,in the elastic state.9 degrees of rare seismic waves with peak acceleration of 620gal were selected to study the limit conditions of the damaged derrick.It was found that the damaged derrick with a weight loss rate of 22%began to enter the stage of elastic-plastic deformation due to seismic excitation,and the maximum interlayer displacement was 0.023m,exceeding the standard limit.Figure[36]table[13]reference[58]... |
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