DESIGN SPECIFICATIONS FOR HIGHWAY BRIDGES - IISEE

10.8 Lateral Strength and Ductility Capacity of Reinforced Concrete Two
Column Bents
Lateral strength and ductility capacity of an Reinforced Concretesingle-layer
rigid-frame pier for both out-of-plane and in-plane directions shall be calculated as
follows:
(1) Inertia force resisted by each column member in the out-of-plane direction of an
Reinforced Concrete two column bents shall first be calculated. Then, lateral
strength and ductility capacity of the pier shall be obtained from the provisions of
Sections 10.2 and 10.5, by assuming that each column member is regarded as a
single-column Reinforced Concrete Columns.
(2) Lateral strength and ductility capacity in the in-plane direction of an Reinforced
Concrete two column bents shall be obtained by referring to the following 2),
depending on the evaluation result on failure mode described in 1) below. In
addition, in the case when plastic hinges in a beam member is allowed to be formed,
the requirements as specified in 3) below shall be satisfied, in order to avoid brittle
failure of the beam under the primary loads specified in Section 2.1 of Part I
Common Provisions.
1) Failure mode of an Reinforced Concrete two column bents shall be evaluated
from Equation (10.8.1) using shear force Si, shear strengths Psi and Ps0i, generated at
each plastic hinge when an inertia force equivalent to the lateral strength is applied
to the pier.
Si ≦ Psi : Flexural failure
Psi < Si ≦ Ps0i : Shear failure after flexural yielding ・・・・・・・・・・・・・・・ (10.8.1)
Ps0i < Si
: Shear failure
where
Si : Shear force generated at i-th plastic hinge when an inertia force equivalent to the
lateral strength is applied (N)
Psi: Shear strength at i-th plastic hinge obtained from Section 10.5 (N)
Ps0i : Shear strength at i-th plastic hinge calculated by using a modification factor of
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