US 12,492,480 B2 · Smart carbon fiber reinforced polymer-shape memory alloy bar reinforced concrete structure integrating cathodic protection, force sensing, and bearing capacity self-adjustment

Abstract

A smart carbon fiber reinforced polymer (CFRP)-shape memory alloy (SMA) bar reinforced concrete structure integrating cathodic protection, force sensing, and bearing capacity self-adjustment is provided. A CFRP-wrapped composite bar with SMA embedded with an optical fiber in the smart CFRP-SMA bar reinforced concrete structure is both a concrete reinforced bar and an auxiliary anode for ICCP to prevent steel bars from being rusted. In addition, the SMA has an ability to adjust stress after excitation, and the embedded optical fiber can perceive a force condition of the composite bar. This structure system significantly improves durability of a concrete structure in a coastal environment, solves problems of in-service real-time bar sensing and bearing capacity control of the structure, and provides a new solution to performance degradation caused by deterioration of a CFRP anode in a traditional ICCP process.

An enhancement method for a deterioration of an impressed current cathodic protection (ICCP) system, comprising:

applying an excitation current to a plain round Fe-shape memory alloy (SMA) bar of a carbon fiber reinforced polymer (CFRP)-wrapped composite bar with an SMA embedded with an optical fiber in a smart CFRP-SMA bar reinforced concrete structure integrating cathodic protection, force sensing and bearing capacity self-adjustment, such that the CFRP-wrapped composite bar with the SMA embedded with the optical fiber generates a pretightening force, wherein the pretightening force generates a contribution ΔM to a bearing capacity of the smart CFRP-SMA bar reinforced concrete structure, thereby enhancing the deterioration of the ICCP system;
wherein
applying the excitation current comprises:
applying the excitation current to the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber after a CFRP winding layer deteriorates when the ICCP system is turned on, or directly applying the excitation current to the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber when the CFRP winding layer does not deteriorate before the ICCP system is turned on, wherein
when a strain εf of the CFRP winding layer after a normal service load is applied is greater than a strain εfa of the CFRP winding layer when the excitation current is applied, and a power-on time T of the ICCP system is less than or equal to a service life tlife of the smart CFRP-SMA bar reinforced concrete structure, the excitation current is applied to the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber after the CFRP winding layer deteriorates when the ICCP system is turned on;
a strain of the CFRP winding layer is continuously monitored when εf≤εfa;
and a process is ended because a requirement for a safe use is not met when εf>εfa and T>tlife;
or
when the excitation current is directly applied to the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber when the CFRP winding layer does not deteriorate before the ICCP system is turned on, a bearing capacity Mi1 of the smart CFRP-SMA bar reinforced concrete structure after the pretightening force is applied in an initial design stage is calculated, wherein Mi1 is equal to a sum of the contribution ΔM generated by the pretightening force to the bearing capacity and an initial bearing capacity Mi of the smart CFRP-SMA bar reinforced concrete structure;
after the excitation current is applied, the ICCP system is turned on;
and when Mi1>Ma, the strain of the CFRP winding layer is continuously monitored;
or when Mi1<Ma, the strain of the CFRP winding layer is monitored, and if εf>εfa and T≤tlife, the excitation current is continuously applied to the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber;
and
a value of the excitation current satisfies:
an average strain Δεsp of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber after the excitation current is applied is greater than or equal to a difference between the strain εfa of the CFRP winding layer when the excitation current is applied and a strain εfi of the CFRP winding layer when the normal service load is initially applied, and the contribution ΔM generated by the pretightening force to the bearing capacity is greater than or equal to a difference between the initial bearing capacity Mi of the smart CFRP-SMA bar reinforced concrete structure and a designed bearing capacity Ma of the smart CFRP-SMA bar reinforced concrete structure for normal use;
wherein a calculation formula for the service life of the smart CFRP-SMA bar reinforced concrete structure is obtained according to a formula I:
t
life
=
A
a
⁢
q
anode
/
(
i
p
⁢
4
⁢
π
⁢
nA
c
⁢
ρ
)
Formula
⁢
I
wherein in the formula I, tlife represents the service life of the smart CFRP-SMA bar reinforced concrete structure;
Aa represents a surface area per unit length of the CFRP winding layer of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber;
qanode represents a density of an electric quantity passing through the CFRP winding layer with a value of 1.6×107 C/m2, wherein under the value of 1.6×107 C/m2, an anode reaction system is stable and a residual strength efficiency of an anode material of the CFRP winding layer is 68%;
ip represents a density of an applied cathodic protection current, wherein ip ranges from 2 mA/m2 to 20 mA/m2 and is taken as 20 mA/m2;
ρ represents a reinforcement ratio of a tensile steel bar;
Ac represents a cross-sectional area perpendicular to the CFRP-wrapped composite bar with the SMA embedded with the optical fiber in the smart CFRP-SMA bar reinforced concrete structure;
and n represents a quantity of tensile steel bars;
wherein a calculation formula for the initial bearing capacity of the smart CFRP-SMA bar reinforced concrete structure is shown in a formula II:
M
i
=
(
d
-
A
s
⁢
f
y
+
A
f
⁢
E
f
⁢
ε
fi
1.7
f
c
′
⁢
b
)
⁢
(
A
s
⁢
f
y
+
A
f
⁢
E
f
⁢
ε
fi
)
Formula
⁢
II
wherein in the formula II, assuming that the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber and the steel bars have a same yield strength of fy, As represents a total area of the steel bars and the plain round Fe-SMA bar, d represents an effective height of the smart CFRP-SMA bar reinforced concrete structure, Af represents a cross-sectional area of the CFRP winding layer, Ef represents an elastic modulus of the CFRP winding layer, εfi represents the strain of the CFRP winding layer when the normal service load is initially applied, fc′ represents a strength of a concrete, b represents a width of the smart CFRP-SMA bar reinforced concrete structure, and Mi represents the initial bearing capacity of the smart CFRP-SMA bar reinforced concrete structure;
wherein a calculation formula for the contribution ΔM generated by the pretightening force to the bearing capacity is shown in a formula III:
Δ
⁢
M
=
(
σ
pc
-
γ
⁢
f
tk
)
⁢
W
0
Formula
⁢
III
γ
=
(
0.7
-
120
/
h
)
⁢
γ
m
Formula
⁢
IV
σ
pc
=
E
sp
⁢
Δε
sp
=
E
sp
(
Δ
⁢
l
⁢
∑
i
=
1
u
ε
sp
,
i
)
/
l
Formula
⁢
V
wherein in the formula III, ΔM represents the contribution generated by the pretightening force to the bearing capacity, ftk represents a standard value of a tensile strength of the concrete, W0 represents an elastic resistance moment of a tensile edge of a transformed cross-section, γm represents a basic value of a plastic influence coefficient of a cross-section resistance moment of the smart CFRP-SMA bar reinforced concrete structure, wherein γm is taken as 1.15 for a rectangular cross-section, γ represents the plastic influence coefficient of the cross-section resistance moment of the smart CFRP-SMA bar reinforced concrete structure, wherein γ is calculated according to the formula IV, σpc represents a pre-stress of the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber, wherein σpc is calculated according to the formula V, Esp represents an elastic modulus of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber, Δl represents a spatial resolution of a distributed optical fiber sensing acquisition, u represents a total quantity of measurement points for the distributed optical fiber sensing acquisition, i represents a measurement point for the distributed optical fiber sensing acquisition, εsp,i represents a strain at an ith measurement point after the excitation current is applied, l represents a total length of a distributed optical fiber sensing measurement section, and Δεsp represents the average strain of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber after the excitation current is applied;
wherein a calculation formula for the strain εfa of the CFRP winding layer when the excitation current is applied is shown in a formula VI:
ε
fa
=
(
-
B
+
B
2
-
4
⁢
AC
)
/
2
⁢
A
Formula
⁢
VI
wherein
⁢
A
=
-
A
f
2
⁢
E
f
2
,
B
=
2
⁢
A
s
⁢
f
y
⁢
A
f
⁢
E
f
-
1.7
f
c
′
⁢
bdE
f
,
and
C
=
1.7
f
c
′
⁢
f
y
⁢
bdA
s
-
1.7
f
c
′
⁢
bM
a
-
A
s
2
⁢
A
f
2
;
wherein the smart CFRP-SMA bar reinforced concrete structure integrating the cathodic protection, the force sensing and the bearing capacity self-adjustment comprises the ICCP system and an ICCP system deterioration enhancement system;
wherein the ICCP system comprises a reinforcing cage, the concrete, the CFRP-wrapped composite bar with the SMA embedded with the optical fiber, the steel bars, and a first external power supply, wherein the reinforcing cage is placed in the concrete, the CFRP-wrapped composite bar with the SMA embedded with the optical fiber and the steel bars are dispersed in the concrete, the CFRP winding layer of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber is connected to a positive terminal of the first external power supply through a first wire, and the steel bars are connected to a negative terminal of the first external power supply through second wires;
the ICCP system deterioration enhancement system comprises a second external power supply;
a positive terminal and a negative terminal of the second external power supply are respectively connected to two ends of the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber through third wires;
the first external power supply is configured to provide a direct current (DC) power for the ICCP system;
and
the second external power supply is an excitation device for the plain round Fe-SMA bar;
wherein a voltage of the first external power supply ranges from 5 V to 20 V;
wherein a current of the first external power supply ranges from 200 mA to 3 A;
wherein the reinforcing cage is made of ribbed bars
the smart CFRP-SMA bar reinforced concrete structure is prepared by:
placing the reinforcing cage with a built-in CFRP-wrapped composite bar with the SMA embedded with the optical fiber and built-in steel bars in a mold, pouring the concrete, and performing curing;
connecting the CFRP winding layer of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber to the positive terminal of the first external power supply through the first wire, and connecting the steel bars to the negative terminal of the first external power supply through the second wires;
and
respectively connecting the two ends of the plain round Fe-SMA bar of the CFRP-wrapped composite bar with the SMA embedded with the optical fiber to the positive terminal and the negative terminal of the second external power supply through the third wires.

265 more elements

Smart carbon fiber reinforced polymer-shape memory alloy bar reinforced concrete structure integrating cathodic protection, force sensing, and bearing capacity self-adjustment

Life of this patent

Smart carbon fiber reinforced polymer-shape memory alloy bar reinforced concrete structure integrating cathodic protection, force sensing, and bearing capacity self-adjustment

Life of this patent

Abstract

Claims1