EARTHQUAKE RESISTANT BEAM OF RIGID FRAME BRIDGE

摘要

PROBLEM TO BE SOLVED: To improve earthquake resistance of a moment resisting frame type bridge pier to prevent a large damage in the pier itself by providing an earthquake resistant beam having a side board element for a side board part of the beam, easily generating plastical distorsion when subjected to shearing force. ;SOLUTION: A portal rigid frame bridge 1 is composed of legs, cross beam 9. The beam 9 is composed of structural steel. An earthquake resistant beam 5 is positioned at the midway of the height of the leg 3, and a side board element 6 easily generating plastical distorsion when applied with external force upon earthquake is used in the vicinity of the center of a side board of the beam 5df. The element 6 is composed of very soft steel whose yielding point is about half the normal steel and whose rigidity is the same as the normal steel. With this constitution, bending moment caused by earthquake force is shared by the beam 5, and thereby the beam 5 reduces benging moment of the legs 17 and corners 15. Accordingly, earthquake energy can be absorbed by the plastical deformation of beam 1 after the shearing yielding.;COPYRIGHT: (C)1999,JPO