Analysis On Reliability Of Crack Control For Concrete Flexural Members

Crack control of the concrete structure is a key factor under serviceability limit design state.In the practice of Chinese code,the approximate probabilistic limit state method based on structure reliability theory is adopted.However,the current reliability analysis for crack control is incompletely considered,mainly in 3 aspects:· Stochastic(or use Random here)variables are adopted in quasi-permanent combination,which is inaccurate in theory.· It is hard to showcase the general reliable crack control level with only a few typical samples.· The anticipated reliability index of the crack control is unclear.Relevant analysis is not implemented precisely.Based on the current situation,it is necessary to improve the reliability analysis method for concrete crack control,and to fully reveal the reliable crack control level.This thesis is aimed at developing a reasonable reliability analysis method for the crack control of the reinforced concrete and prestressed concrete under bending,rectifying the reliability value,providing the crack control reliability index and design advice.Research include:· Drawbacks for the quasi-permanent combination method are discussed with the help of the stochastic theory.The method for combination of actions based on stochastic processes is proposed regarding variable actions appearing with their quasi-permanent values.The reliability analysis model for crack control is built.· Construct a general dimensionless function for reliability analysis of the crack control,through which the accuracy and performance for this issue could be improved.· Based on the rectified results,the reliability index for crack control is advised.Also,by considering important factors for the reliability analysis,design suggestions for crack control are provided.Achievements in this research would enhance the structural reliability theory development as well as lay a solid foundation in the theory of the concrete crack control.