Why the bearing reactions for SAP2000/Bridge spine model look incorrect?
Extended Question: The bearing reactions for my spine SAP2000/Bridge model do not seem to be correct. The loads taken by each bearing are not in the anticipated proportion to each other and I am even getting unexpected uplift forces for some bearings. Answer: The spine bridge model uses a single Body constraint to connect a joint of the superstructure frame element with all the joints representing the top of bearing links at a given substructure unit. While this modeling approach is adequate to obtain global response of the structure, it does not fully capture the distribution of the superstructure load to the individual bearings. You would need to update the Linked Bridge Model as Area Model to get more meaningful bearing forces for the design of bearings and the pier caps.
