(1) For abutment pier to be assigned as fixed pier at the same time as bridge is quite long, longitudinal loads since earthquake are quite large. As earthquake loads are resisted by fixed piers, size of fixed piers will be huge and enormous. In this relation, for better aesthetic appearance, selection of abutment as fixed piers can accommodate large size and massiveness of piers. On the whole abutments are relatively little in height and for same horizontal force; bending moment induced is smaller.
(2) For central pier to be selected as a fixed pier, bridge deck is allowed to move starting from central pier to end of the bridge. However, if a fixed pier is located at abutment, an amount of movement to be incorporated in each bearing because of temperature variation, shrinkage, etc. is additional than that when a fixed pier is located at central pier. Therefore, size of movement joints is able to be condensed significantly.