Performance-Based Seismic Fragility and Risk Assessment of Five-Span Continuous Rigid Frame Bridges

Table 1

Characteristics of curvature ductility index.

Damage degree	Damage characteristics	Specific parameter index
Nondamaged	The outermost longitudinal reinforcement is not yielded
Slightly damaged	The yield strain of the outermost longitudinal bars is less than initial strain, and the compressive strain of unconstrained concrete is less than 0.004	,
Moderately damaged	The longitudinal reinforcement strain is less than 0.55 times of the ultimate tensile strain, and the constrained concrete is less than 0.75 times of the ultimate compressive strain	,
Severely damaged	The longitudinal reinforcement strain is less than the ultimate tensile strain, and the constrained concrete is not larger than the ultimate compressive strain	,
Completely damaged	The longitudinal reinforcement strain is greater than the ultimate tensile strain and the restrained concrete cracks	,

Note: φ_s represents the tensile strain of the outermost longitudinal reinforcement of the section; φ_c represents the compressive strain of unconstrained concrete on the outermost side of the cross section; φ_y represents the theoretical yield strain of longitudinal reinforcement; φ_cc represents the compression strain of the outermost constrained concrete of the section; φ_co represents the strain corresponding to the peak compressive stress of unconstrained concrete; φ_sh represents the tensile strain when the longitudinal reinforcement is initially hardened; φ_ccu represents the tensile strain of the outermost constrained concrete of the section.