Geometry of Bents and Instrumentation for Dynamic Tests

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.