Investigation of material partial factors for assessing structural safety and bearing capacity
In the safety assessment of existing structures,the evaluation of structural bearing capacity must rely on on-site measured data to accurately represent the structure's actual condition.To address uncertainties in material properties due to testing errors,the coefficient of variation for material strength is classified into five levels:0,0.05,0.1,0.15,and 0.2.This classification aligns predominantly with the control standards for testing data variability outlined in current domestic testing protocols.Given that the current domestic standard has revised certain resistance calculation models,adjustments have been made to the calculation model uncertainty.Statistical parameters for resistance at various coefficient of variation levels were derived using the resistance uncertainty analysis method.With the recent updates to domestic standards elevating the characteristic value of variable loads and extending the reproduction period of wind load characteristic values,revised statistical parameters for variable loads are now employed to refine the material partial factors.However,the statistical parameters for dead loads continue to align with the design-specific statistical parameters.The analysis results reveal that the load partial factors and material partial factors,optimized based on the methodologies outlined in the current domestic standards,are not suitable for the structural safety assessment of existing structures.This discrepancy arises from the less distinct pattern of variation observed between the derived partial factors and the coefficient of variation of material strength,failing to align with intuitive judgment.Hence,an approach is employed to determine material partial factors based on the load partial factors,yielding appropriate material partial factor values corresponding to the 5 levels of material strength variation coefficients.Notably,as load partial factors are established,the material partial factors exhibit a reduction in tandem with decreasing material strength variation coefficients.This alignment with intuitive judgment makes it easily acceptable for structural safety assessment professionals.Through evaluating the bearing capacity of components in real-world engineering scenarios,it was found that employing the material partial factor established in this study can lead to an enhancement in the calculated resistance of concrete structural components by 12％to 22％.Similarly,the ratio of resistance to load effect for masonry structural components can see an increase of 10％to 18％.
safety engineeringsafety assessmentpartial factorsbearing capacitycoefficient of variation
万方数据
维普
