LARS LFD Composite Prestressed Concrete Report Information
LARS checks the compression flange and tension for top and bottom for each checkpoint. This is performed because any checkpoint along a beam may be the location at which contraflexure occurs. When the top flange is in compression and the bottom flange is in tension, top fiber +bend and bottom fiber +bend should be considered as a pair. When the top flange is in tension and the bottom flange is in compression, top fiber –bend and bottom fiber –bend should be considered as a pair. Since this is a simple span member, the top flange is in compression and the bottom flange is in tension. Only top fiber +bend and bottom fiber +bend will be examined for inventory and operating ratings.
The purpose of this document is to clarify the values which are output by LARS in the prestressed concrete reports. All formulation for the moment capacities are available in the LARS Specification Analysis Manual.
“U” denotes “Ultimate Moment”. Three codes are used for the moment capacity in prestressed concrete structures. These codes indicate the formulation used by LARS to compute the moment capacity. The codes are: a. “E” = elastic stressb. “L” = low tendonc. “U” = ultimate moment
The ultimate moment is circled on the “Additional Section Data” portion of the detail checkpoint report below.