DESIGN SPECIFICATIONS FOR HIGHWAY BRIDGES - IISEE

simultaneously, shall be verified in such a manner that the sectional forces
occurring in the bearing support and the attached members shall not exceed the
ultimate strength. Here, the ultimate strength can be taken as 1.5 times the
allowable stress.
Furthermore, Type A rubber bearing supports shall be verified in such a way that in
addition to the above the shear strain occurring in the bearing support does not
exceed the allowable value, and also the safety of the bearing support is ensured.
Here, the allowable shear strain shall be properly determined according to the
characteristics of the rubber bearing actually used, in order to protect them from
shear failure.
15.4 Structural Details of Bearing Support System
(1) Type B bearing support shall be positively fixed to the superstructure and
substructure, and therefore be structurally functional.
(2) Sections of the superstructure or substructure connecting with a bearing support
shall be sufficiently strengthened, and therefore be capable of withstanding seismic
forces.
(3) In order to protect a bearing support from brittle failure, highly ductile materials
shall be used in these parts, and stress concentration shall be minimized.
15.5 Excessive Displacement Stopper
(1) Excessive displacement stoppers shall be verified so that the sectional forces due to
design seismic forces obtained from Equation (15.5.1) do not exceed the ultimate
strength. Here, the ultimate strength can be taken as 1.5 times the allowable
stress.
H s = 3 k h R D ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (15.5.1)
where
Hs : Design seismic force used in the design of the excessive displacement stopper
(kN)
kh : Design horizontal seismic coefficient of Level 1 Earthquake Ground Motion,
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