The Bearing Capacity Reliability Analysis Of RC Frame Column Considering Biaxial Random Eccentricity Under Strong Wind

Wind load is one of the most common external horizontal loads on buildings.RC eccentrically loaded column is one of the most important load-bearing components in buildings,under wind load,it often presents a biaxial bending and axial compression state.Unsafe design may occur if the bearing capacity calculation is still carried out according to the uniaxial bending and axial compression member.At present,the research on the reliability of the bearing capacity of RC biaxial bending and axial compression members is relatively few,and the relevant laws have not been fully revealed.So,this article considering the random characteristics of biaxial eccentricity and the uncertainty of the resistance calculation model,the reliability of eccentric columns in the common RC regular frame model is calculated and analyzed by Monte Carlo method.The main works completed are as follows:(1)By collecting the test data of the biaxial bending and axial compression members at home and abroad,the uncertainty of the resistance calculation mode of the biaxial bending and axial compression is statistically analyzed,and the mean and coefficient of variation are obtained.The analysis shows that the mean value of the uncertain variables corresponding to the Chinese code resistance calculation model is 0.945,the coefficient of variation is 0.12,the mean value of the uncertain variables corresponding to the American code resistance calculation model is 1.090,and the coefficient of variation is 0.10,which all have great uncertainty.(2)Due to the horizontal(wind)load and the vertical load(dead load and live load)have certain random characteristics and obey different distributions,the eccentricity will also have certain random characteristics.Based on the example RC frame structure model,the random characteristics of biaxial eccentricities in practical engineering are analyzed in detail in this paper,the analysis shows that the biaxial random eccentricity does not simply obey the normal distribution,and its distribution has certain complexity.(3)The resistance of RC column considering the uncertainty of resistance calculation model and the random characteristics of biaxial eccentricity and the resistance of RC column without considering the uncertainty of resistance calculation model and the random characteristics of biaxial eccentricity are calculated,respectively.The analysis shows that the uncertainty of resistance calculation model and the random characteristics of biaxial eccentricity have great influence on the resistance.(4)Two regular RC framework structure models are established by ETABS,the wind bearing capacity reliability is calculated,not only in uniaxial bending and axial compression case,but also in biaxial bending and axial compression case.Among them,the biaxial bending and axial compression case adopts the fixed eccentricity criterion and the random eccentricity criterion,respectively.Through analysis,it is found that the reliability of RC column bearing capacity considering biaxial fixed eccentricity is overestimated in varying degrees compared with that considering biaxial random eccentricity,Overestimation ranges up to 28%;and the column reliability with uniaxial random eccentricity is significantly higher than that with biaxial random eccentricity,the maximum is 30%.(5)Considering the biaxial random eccentricity,the Monte Carlo method is used to parameters analyze of bearing capacity reliability of the model columns.The analysis shows that the bearing capacity reliability of RC columns varies obviously with the characteristic parameters,especially with the axial load.When the ratio of axial load to load is-0.5,the bearing capacity of RC columns under eccentric compression will decrease seriously.