1. A method for the estimation of damage zones in prestressed girders comprising:
selecting a prestressed girder for identification of damage zones; and
estimating damage zones by taking account cracking moment of the girder, ultimate load of the girder, fully cracked inertia of the girder, and elastic stiffness of the girder.
2. A method as in claim 1, wherein the cracking moment is defined as:
M
Cr
=
S
b
\ue8a0
P
O
A
C
\ue89e
(
1
+
e
\xd7
C
b
r
2
)
+
7.5
\ue89e
\ue89e
\u03bb
\ue89e
f
\u2032
c
where Sb is the modulus of the composite section at the bottom fibers of the girder, Cb is the distance from the center of gravity of the girder section to the extreme tension fibers of the girder, Pe is the effective prestress force, Ac is the gross sectional area of the girder, e is the eccentricity of the tendons of the girder from the girder section center of gravity, r is the radius of gyration of the girder, and \u03bb is equal to 1.0 for normal weight and 0.75 for lightweight concrete.
3. A method as in claim 1, wherein fully cracked inertia is defined as:
I
Cr
=
n
p
\ue89e
A
p
\ue89e
\ue89e
s
\ue89e
d
p
\ue8a0
(
1
–
1.6
\ue89e
n
p
\xd7
\u03c1
p
)
where np is the young modulus ratio, Aps is the area of prestressing steel, dp is the distance from the top of the section to the centroid of prestress, and \u03c1p is the prestress reinforcing ratio.
4. A method as in claim 1, further comprising taking into account deviation from linearity at ultimate.
5. A method as in claim 4, wherein deviation from linearity at ultimate is defined as:
I
DLU
=
(
1
–
I
e
I
O
)
\xd7
10
0
6. A method as in claim 5, further comprising estimating damage zones based, in part, on the following thresholds:
damage zones can be estimated as follows,
IDL-MINOR\u22660.2\xd7IDLU
0.2\xd7IDLU<IDL-INTERMEDIATE\u22660.45\xd7IDLU
0.45\xd7IDLU<IDL-HEAVY
7. A method as in claim 1, wherein the girder is formed from self-consolidating lightweight concrete.
8. A method as in claim 1, wherein the girder is formed from self-consolidating concrete.
9. A method as in claim 1, wherein the girder is formed from high-early-strength concrete.
10. A method for the estimation of damage zones in prestressed girders comprising estimating damage zones by using a global integrity parameter (GIP).
11. A method as in claim 10, wherein GIP is defined as:
G
\ue89e
\ue89e
I
\ue89e
\ue89e
P
=
(
I
DL
0.2
\ue89e
I
DLU
)
\u2264
1.0
where IDLU is the theoretical deviation from linearity at ultimate and the IDL is the experimental deviation from linearity experienced by the girder at any load level during testing.
12. A method as in claim 10, wherein GIP is defined as:
GIP=An\u03b2\u22121\u22661.0
where for lightweight,
\u03b2
=
0.001
+
0.2
\ue89e
(
P
T
–
P
O
P
mt
–
P
O
)
and
P
O
=
P
CR
+
0.1
\ue89e
(
P
mt
–
P
CR
)
while for normal weight,
\u03b2
=
0.0001
+
0.035
\ue89e
(
P
T
–
P
O
P
mt
–
P
O
)
and
P
O
=
P
CR
+
0.31
\ue89e
(
P
mt
–
P
CR
)
and further where AD is the arch of damage from the plot for any loadset, PT is the target load at which the damage criterion should reach unity and which must be greater than Po, PCR is the cracking load, and Pmi is the load at the theoretical minor-intermediate threshold.
13. A method as in claim 10, wherein the girder is formed from self-consolidating lightweight concrete.
14. A method as in claim 10, wherein the girder is formed from self-consolidating concrete.
15. A method as in claim 10, wherein the girder is formed from high-early-strength concrete.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An imaging lidar system aboard an aircraft or a spacecraft comprising:
a light source transmitting a first beam of light;
a scanner for scanning both the first beam of light transmitted to the surface of the ground and a second beam of light received from the surface of the ground, wherein transmission scanning of the field of view of the surface is ahead of reception scanning of the field of view of the surface;
a detector for detecting the second beam of light received from the scanner and generating signals responsive to the light, wherein the detector comprises a photon detector that includes an array of two-dimensional pixellated detectors for detecting the second beam of light received from the scanner and generating signals responsive to the light;
a processor system for processing signals from the detector; and,
a multi-channel timing receiver wherein the number of channels is equal to the number of pixels in the array detectors.
2. The imaging lidar system as in claim 1, wherein the light source includes a laser.
3. The imaging lidar system as in claim 2, wherein the laser is pumped by diode laser arrays operating in CW mode and passively Q-switched by a saturable absorber.
4. The imaging lidar system as in claim 1 further comprising:
means for angularly displacing the transmitter beam in the forward direction of the lidar system motion at the input to the scanner.
5. The imaging lidar system as in claim 4, wherein the angularly displacing means include a prism or a mirror.
6. An imaging lidar system aboard an aircraft or a spacecraft comprising:
a light source transmitting a first beam of light;
means for scanning both the first beam of light transmitted to the surface of the ground and a second beam of light received from the surface of the ground, wherein transmission scanning of the field of view of the surface is ahead of reception scanning of the field of view of the surface;
means for detecting the second beam of light received from the scanning means and generating signals responsive to the light wherein the detector means comprises a photon detector that includes an array of two-dimensional pixellated detectors for detecting the second beam of light received from the scanning means and generating signals responsive to the light;
a processor system for processing signals from the detector means; and,
a multi-channel timing receiver wherein the number of channels is equal to the number of pixels in the array detectors.
7. The imaging lidar system as in claim 6, wherein the means for scanning includes a dual wedge scanner comprising:
a first optical wedge, with a first cone half-angle, comprising a central portion and an annular portion;
a second optical wedge, with a second cone half-angle, comprising a central portion and an annular portion wherein phases of the central portions of the first and the second optical wedges are advanced relative to phases of the annular portions of the first and the second optical wedges, respectively; and
means for counter-rotating the first and the second optical wedges whereby the rotation of one of the optical wedges is in one direction while the rotation of the other optical wedge is in the opposite direction.
8. The imaging lidar system as in claim 7, wherein the instantaneous position of the receiver field of view on the surface at time t is determined by the following equations:
x(t)=\u03bdgt+R tan \u03b1 cos \u03c9+cos(\u2212\u03c9t+\u0394\u03c6.)
y(t)=R tan \u03b1 sin \u03c9t+sin(\u2212\u03c9t+\u0394\u03c6)
wherein \u03bdg is the ground velocity of an aircraft or a spacecraft in the positive x-direction;
\u03c9 is the angular velocity of the counter-rotating optical wedges; \u03b1 is the cone half-angle of optical wedges; R is the perpendicular distance from the scanner to the surface; and
\u0394\u03c6 is the relative starting phase of the optical wedges.
9. The imaging lidar system as in claim 7, wherein the means for counter-rotating the first and second optical wedges comprises in combination:
a first annular bevel gear connected relative to the first optical wedge;
a second annular bevel gear connected relative to the second optical wedge;
a bevel miter gear rotatably journaled between the first annular bevel gear and the second annular bevel gear for engagement therewith;
a motor; and
means for operatively connecting said motor to the first optical wedge, the second optical wedge or the bevel miter gear whereby rotation of one of the wedges in one direction will rotate the other of the wedges in the opposite direction.
10. The imaging lidar system as in claim 7, wherein the means for counter-rotating the first and second optical wedges comprises in combination:
a first annular bevel gear connected relative to the first optical wedge;
a second annular bevel gear connected relative to the second optical wedge;
a first motor means for rotating the first annular bevel gear;
a second motor means for rotating the second annular bevel gear; and,
means for driving said first motor means and said second motor means in the opposite directions at the angular velocity of \u03c9 and with a fixed phase offset \u0394\u03c6.
11. The imaging lidar system as in claim 7, wherein the first and the second wedges are in a constant rotating motion.
12. The imaging lidar system as in claim 6, further comprising means for determining and controlling scan frequency of the scanning means.
13. The imaging lidar system as in claim 6, further comprising a telescope that transmit the first beam and receives and collimates the second light beam returned from the surface prior to the scanning means.
14. An imaging lidar system aboard an aircraft or a spacecraft comprising:
a light source transmitting a first beam of light;
means for scanning both the first beam of light transmitted to surface of the ground and a second beam of light received from the surface of the ground, wherein transmission scanning of field of view of the surface is ahead of reception scanning of field of view of the surface;
an array of two-dimensional pixellated detectors for detecting the second beam of light received from the scanning means and generating signals responsive to the light; and
a processor system for processing signals from the detectors wherein said processor system includes a multi-channel timing receiver wherein the number of channels is equal to the number of pixels in the array detectors.
15. An imaging lidar system aboard an aircraft or a spacecraft comprising:
a light source transmitting a first beam of light;
a optical scanner comprising:
a first optical wedge, with a first cone half-angle, comprising a central portion and an annular portion;
a second optical wedge, with a second cone half-angle, comprising a central portion and an annular portion;
wherein phases of the central portions of the first and the second optical wedges are advanced relative to phases of the annular portions of the first and the second optical wedges, respectively; and
means for counter-rotating the first and the second optical wedges whereby rotation of one of the optical wedges is in one direction while rotation of the other optical wedge is in the opposite direction and with a fixed phase offset \u0394\u03c6; and
means for detecting the second beam of light received from the scanning means and generating signals responsive to the light; and
a processor system for processing signals from the detecting means.
16. An imaging lidar system aboard an aircraft or a spacecraft comprising:
a light source transmitting a first beam of light;
a optical scanner comprising:
a first optical wedge, with a first cone half-angle, comprising a central portion and an annular portion;
a second optical wedge, with a second cone half-angle, comprising a central portion and an annular portion;
wherein phases of the central portions of the first and the second optical wedges are advanced relative to phases of the annular portions of the first and the second optical wedges, respectively; and
means for counter-rotating the first and the second optical wedges whereby rotation of one of the optical wedges is in one direction while rotation of the other optical wedge is in the opposite direction and with a fixed phase offset \u0394\u03c6; and
an array of two-dimensional pixellated detectors for detecting the second beam of light received from the scanning means and generating signals responsive to the light; and
a processor system for processing signals from the detectors.
17. A method of imaging a contiguous map of ground from an aircraft or a spacecraft comprising:
providing a laser beam;
scanning the laser beam transmitted to a surface of the around;
scanning the laser beam received from the surface of the ground such that transmission scanning of the field of view of the surface is ahead of reception scanning of field of view of the surface wherein the step of scanning the transmission beam and the step of the scanning the reception beam are effected by a dual wedge scanner comprising:
a first optical wedge, with a first cone half-angle, comprising a central portion and an annular portion;
a second optical wedge, with a second cone half-angle, comprising a central portion and an annular portion;
wherein phases of the central portions of the first and the second optical wedges are advanced relative to phases of the annular portions of the first and the second optical wedges, respectively;
counter-rotating the first and the second optical wedges whereby rotation of one of the optical wedges is in one direction while rotation of the other optical wedge is in the opposite direction; and,
detecting the laser beam returned from the surface of the ground and processing a signals responsive to the returned beam.
18. The method of imaging in claim 17, wherein the laser beam is pumped by diode laser arrays operating in CW mode and passively Q-switched by a saturable absorber.
19. The method of imaging in claim 17, wherein the instantaneous position of the receiver field of view on the surface at time t is determined by the following equations:
x(t)=\u03b8Rr+R tan \u03b1 cos \u03c9t+cos(\u2212\u03c9t+\u0394\u03c6)
y(t)=R tan \u03b1 sin \u03c9t+sin(\u2212\u03c9t+\u0394\u03c6)
wherein \u03bdg is the ground velocity an aircraft or a spacecraft in the positive x-direction; \u03c9 is the angular velocity of the counter-rotating optical wedges; \u03b1 is the cone half-angle of optical wedges; R is the perpendicular distance from the scanner to the surface; and \u0394\u03c6 is the relative starting phase of the optical wedges.
20. The method of imaging in claim 17, wherein the means for counter-rotating the first and second optical wedges comprises in combination:
a first annular bevel gear connected relative to the first optical wedge;
a second annular bevel gear connected relative to the second optical wedge;
a bevel miter gear rotatably journaled between the first annular bevel gear and the second annular bevel gear for engagement therewith;
motor means; and
means for operatively connecting said motor means to the first optical wedge, the second optical wedge or the bevel miter gear whereby rotation of one of the wedges in one direction will rotate the other of the wedges in the opposite direction.
21. The method of imaging in claim 17, further comprising:
angularly displacing the laser beam in the forward direction of the motion of an aircraft or a spacecraft prior to the step of scanning the laser beam transmitted to surface.
22. The method of imaging in claim 21, wherein the step of angularly displacing the laser beam is effected by passing the beam through a prism or a mirror.
23. The method of imaging in claim 17, wherein the step of detecting the returned laser beam comprises:
counting photons returned from the surface; and
generating signals responsive to the number of the returned photons.
24. The method of imaging in claim 17, wherein the step of detecting the returned laser beam is effected by a two-dimensional array of pixellated detectors and a multi-channel timing receiver wherein the number of channels is equal to the number of pixels of the array detectors.
25. The method of imaging in claim 17, wherein the step of processing signals responsive to the returned beam comprises:
producing a ranging signal responsive to the returned beam.