Geometry of Bentsand Instrumentation
for Dynamic Tests
Joshua Black and Sharon Wood
Department of Civil, Architectural and Environmental Engineering
University of Texas at Austin
Overview
• Bent Geometry• Instrumentation for Dynamic Tests
Bent Geometry
• Elevations of Bent 1• Elevations of Bent 2• Coordinate systems• Terminology
Bent 1
Bent 2
Shaft 1W Shaft 1E
Shaft 2N
Shaft 2S
(a) Transverse Elevation
12"
12'-0"
6'-0"
6'-3"
~18"
18"
10'-0"
12"
~18"
24"
(b) Longitudinal Elevation
Bent 1
(a) Transverse Elevation
12"
12'-0"
3'-0"
6'-3"
~18"
18"
10'-0"
12"
~18"
24"
(b) Longitudinal Elevation
Bent 2
Coordinate System – Bent 1
1E1W
x
y
z
z = 0 is at ground level
ProjectNorth
Coordinate System – Bent 2
z = 0 is at ground level
ProjectNorth
2S
2N
x
y
z
Terminology
Longitudinal Responseof Bridge
Transverse Responseof Bridge
Instrumentation
• Accelerometers and geophones• Strain gages
Bent 1
Shaft 1W Shaft 1E
3D Accelerometer
Acc1EAcc1W
Geo1W Geo1E
3D GeophoneGeoG1
Geophone 23
Geophone 24
Geophone 15
Geophone 14
Bent 2
Shaft 2N Shaft 2S
3D Accelerometer
Acc2SAcc2N
Geo2N Geo2S
3D Geophone
Geophone 17
Geophone 18
Geophone 27
Geophone 26
GeoG2
3D Accelerometers (±2g)
Orientation of Accelerometers
• Local axes of accelerometers are shown.
• Data are presented in terms of the global coordinates in data files.
ProjectNorth
2S
2N
z
y Acc2S
x
zyAcc2N
zy
x
x
1E1W
y
z
xz
x
y
Acc1E
z
x
y
Acc1W
3D Geophones (Bent 1)
Geo1WGeo1E
3D Geophones (Bent 2)
Geo2N Geo2S
Embedded 3D Geophones
Orientation of Geophones
ProjectNorth
2S
2N
Geo2S
Geo2N
T
L
T
L
zy
x• Local axes of geophones are shown.
• Data are expressed in terms of the global coordinates in data files.
1E1W
y
z
x
Geo1EGeo1W
T
L
T
L
Strain Gages
• Strain gages were attached to the surface of the longitudinal reinforcing bars.
• Each strain gage is located using three parameters:―Column―Orientation of longitudinal reinforcement―Vertical distance from grade
• Example:―Strain gage 2S:225:024―Column 2S, Bar orientation 225°, 24 in. below
grade
Orientation of Reinforcement
• Coordinate system used to define orientation of reinforcement is same as coordinate system used to define configuration of bent.
• Each pair of longitudinal bars is defined byangle θ. x
y
180
z270
045
90
135225
315
x
y
0
90
180
225270
315
z
45135
Bent 1 Bent 2
Instrumented Reinforcement
ColumnBar
OrientationNumber of Gages
ColumnBar
OrientationNumber of Gages
1E
0° 13
1W
0° 13
90° 10 90° 5
180° 13 180° 13
225° 5 225° 0
270° 10 270° 5
315° 5 315° 0
TOTAL 56 TOTAL 36
Strain Gage Locations – Bent 1
Distance from grade
(in.)*
Shaft 1E Shaft 1W
Number of gages Number of gages
-72 4 2
-66 4 2
0 2 2
12 4 2
24 6 4
36 6 4
48 6 4
60 6 4
72 6 4
84 4 2
96 4 2
108 2 2
120 2 2
* Distances are measured along the z axis. Positivevalues correspond to locations below grade. Negative values correspondto locations above grade.
Instrumented Reinforcement
ColumnBar
OrientationNumber of Gages
ColumnBar
OrientationNumber of Gages
2S
0° 12
2N
0° 13
90° 10 90° 5
180° 13 180° 13
225° 5 225° 0
270° 10 270° 5
315° 5 315° 0
TOTAL 55 TOTAL 36
Strain Gage Locations – Bent 2
Distance from grade
(in.)*
Shaft 2S Shaft 2N
Number of gages Number of gages
-36 4 2
-30 4 2
0 2 2
12 4 2
24 6 4
36 6 4
48 6 4
60 6 4
72 6 4
84 3 2
96 4 2
108 2 2
120 2 2
* Distances are measured along the z axis. Positivevalues correspond to locations below grade. Negative values correspondto locations above grade.