FAQ

Why do I need to assign bearing property to integral bent cap?

Extended Question: The bearing assignments do not seem to be relevant for integral bents and abutment with integral girder support condition (the bearing property should be always fixed and the elevation does not seem to carry any useful information since there are no bearings at integral bents). How is the bearing assignment used for bents and abutments with integral girder support condition?

Answer: A truly integral bent would be fully fixed, so the statement about irrelevant bearing assignments makes sense. However, we are allowing the option that the connection may not fixed be for all DOF. Really, what SAP2000 is doing for the integral bent/abutment is connecting the bearing to the girder top and bottom. So to define a fully integral bent, you should use fixed bearing. If you choose a different bearing, you will get different behavior that may apply in some special situations, such as when steel box cross girder is connected to superstructure girders by a shear-only connection and hence the longitudinal girders are allowed to rotate relative to the cross girder.

The figure below shows the links utilized in modeling integral girder support condition for a bridge with "Steel Girders" deck section and girders modeled by shell elements: