Design Parameters
Click Project Parameters on the Analysis to display the Design Parameters. This button allows you modify or review the limiting stresses multipliers, restraining moments,resistance factors/losses and Moment and Shear Provisions. Click OK at any time to accept all changes in all tabs, or click Cancel to discard any changes. Each tab is explained below.
Limiting Stress Tab
Click Design Parameters to activate this screen; it defaults to the Limiting Stress tab, as shown in Figure 1.
You can modify the limiting stress values by typing over the default values. Tensile and compressive stress limits are specified for fully prestressed components for two stages of the Service Limit State -- before and after prestress losses. Tensile stress limit keeps the bridge component from cracking in service, thus minimizing the increased stresses and fatigue of the prestressing strands at the cracks. Fatigue of strands is not a problem in uncracked concrete.
Although the above stress limits are only specified for fully prestressed components and not for reinforced concrete components of composite members, the practice varies in various parts of the country. Precast/Prestressed Girder, by default, only checks the stress limits for the top and bottom fibers of precast, prestressed concrete girders. Optionally, the user may elect to also check the stresses at the top fiber of the cast-in-place, reinforced concrete deck.
