ai	the height of main crack at the ith cycle
As	cross-sectional area of tensile steel bar
A′s	cross-sectional area of compressive steel bar
Af	cross-sectional area of CFRP
b	the width of the RC beam
c	the depth of the concrete cover(measured from bottom surface of section)
c′	the depth of the concrete cover(measured from top surface of section)
D	accumulation of fatigue damage
Eci	effective elastic modulus of concrete at the ith cycle
Ec	initial elastic modulus of concrete
Es	elastic modulus of the tensile steel bar
E′s	elastic modulus of the compressive steel bar
Ef	elastic modulus of the CFRP
fc	uniaxial compressive strength of concrete
fy	yield strength of the tensile steel bar
ft	uniaxial tensile strength of the concrete
h	the height of the RC beam
hci	the height of the tension zone for the concrete at the ith cycle at the main cracked section
k1, k2, k3, k4	parameters determined by the tensile steel bar
M	bending moment at the main cracked section
ni	the cycle number for the specified stress amplitude of tensile steel bars
N	cycle number to fatigue failure
Nf	fatigue lives
Ni	the final cycle number to failure for the specified stress amplitude of tensile steel bars
Nci	the number of loading cycles to failure for concrete
Pmax	peak load
Pmin	minimum load
R	the stress ratio
Ssi	stress range applied at steel
Sci	maximum stress level at the ith cycle for concrete
yci	height of the compression zone for the concrete at the ith cycle at the main cracked section
${\sigma }_{si}$	maximum tensile stress of steel
${\sigma }_{ci}$	maximum compressive stress of concrete
${\epsilon }_{ci}$	maximum strain of the compressive concrete at the ith cycle
${\epsilon }_t$	uniaxial tensile strain of the concrete
${\epsilon }_{si}$	longitudinal strain of the tensile steel bar at the ith cycle
${\epsilon }^{\prime }{}_{si}$	longitudinal strain of the compressive steel bar at the ith cycle
${\epsilon }_{pe}$	initial strain of prestressed CFRP
${\epsilon }_{si}$	longitudinal strain of CFL at the ith cycle