AD.2007-1001.1.9 Section Property Reduction in Analysis to Account for Cracking
In STAAD.Pro this approach has been simplified as per the recommendations in the ACI-318: 2005 standard which suggests a user input of reduction factors for the individual members. Section 10.11.1 of ACI-318 has provided a list of suggested reduction factors of section properties dependant upon the nature of stresses the member is subjected to.
An additional sheet has been added to the Beam Specifications dialog to allow the reduction of section properties for analysis to be created and assigned. The method is identical to that for creating any other beam specification.
The Specifications dialog can be accessed from the General | Specifications Page in the Modeling Mode:
The reduction factor should be a fraction of unity; hence a factor of 0.5 defined for RAX will reduce a defined cross sectional area of 0.5 ft2 to 0.25 ft2.
The format of the command that is generated in the STAAD.Pro STD file is:
MEMBER CRACKED
<Member List> REDUCTION { RAX | RIX | RIY | RIZ} factor
Multiple factors can be assigned on the same line