DESIGN SPECIFICATIONS FOR HIGHWAY BRIDGES - IISEE

10.3 Calculation of Lateral Strength and Displacement
Lateral strength Pc at cracking, yielding lateral strength Py, the lateral strength Pu,
yield displacementδy, and ultimate displacement δu of a single-column Reinforced
Concrete Columns shall be calculated for both Type I and Type II Earthquake Ground
Motions defined in Section 2.2, with the following conditions:
(1) Fiber strain is proportional to the distance from the neutral axis.
(2) Skeleton curve between horizontal force and horizontal displacement shall be
expressed by an ideal elasto-plastic model shown in Fig. 10.3.1.
(3) Stress-strain curve and ultimate strain of concrete shall conform to Section 10.4.
(4) Stress-strain curve of a reinforcing bar shall conform to Fig. 10.3.2.
(5) Lateral strength Pc at cracking shall be calculated by Equation (10.3.1)
P
c
W N
( bt
) ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (10.3.1)
h A
where
W : Section modulus of a pier with consideration of axial reinforcement at the pier
bottom section (mm 3 )
σbt : Flexural tensile strength of concrete (N/mm 2 ) to be calculated by Equation
(10.3.2)
σ bt = 0.23
2 3
ck ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (10.3.2)
N : Axial force acting on the pier bottom section (N)
A : Sectional area of a pier, with consideration of axial reinforcement at the pier
bottom section (mm 2 )
h : Height from the pier bottom to the height of superstructural inertial force (mm)
σck : Design strength of concrete (N/mm 2 )
(6) Yield limit state denotes the elastic limit state in the skeleton curve of an ideal
elasto-plastic model. Yield lateral strength and yield displacement shall be calculated
by Equations (10.3.3) and (10.3.4), respectively.
M
u
Py ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (10.3.3)
h
52