Reliability Analysis On Deflection Control Of Concrete Flexural Members

Deflection control is an important item in serviceability limit states design of concrete flexural members.The approximate probability limit state design method based on structural reliability theory is adopted on the approximate probability limit state design method in our country.In the process of creating and using it,the deflection control of concrete flexural members of reliability level are analyzed and validated.But the action probability combination method taken in these jobs is unreasonable on theory,because the practical use of the maximum value of the random variable combination method rather than random process combination method for the frequency value and quasi-permanent value in a variable role,which lead to an unreasonable results.And the results are not comprehensive because that reliability of deflection control is checked mostly based on individual special cases.In order to reveal the reliability level on deflection control of the concrete flexural members comprehensively and accurately in our country,firstly analyze the problems existing in the current analysis method by comparison,use the form of dimensionless system to analyze the various cases of concrete flexural member deflection control reliability level in our country,according to the random process in function ordinal value of a combination method and reliability analysis model.In accordance with the structures of the reliability index of the serviceability limit state control given by national standard "reliability standard for the design of building structures"(GB50068-2001),our country at present,requirements of reinforced concrete flexural members appearing no cracks of prestressed concrete flexural members reliability control is relatively modest,and the control of allowing cracks of prestressed concrete flexural members is slightly conservative.In order to control the reliability level on deflection control of the concrete flexural members,the quantitative analysis of the main influence factors of the deflection control reliability level concrete flexural members is carried on,specifying the importance of each influence factor,thus providing a more effective way for deflection control of concrete flexural members.