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.