Tests of High-Performance Fiber- Reinforced Concrete Coupling Beams

plantcitybusinessUrban and Civil

Nov 26, 2013 (3 years and 8 months ago)

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Tests of High
-
Performance Fiber
-
Reinforced Concrete Coupling Beams

James K.
Wight

F.E. Richart, Jr. Collegiate Professor

Dept. of Civil and
Env
. Eng.

University of
Michigan


Co
-
Researchers: Gustavo Parra
-
Montesinos and Remy
Lequesne,
Afsin

Canbolat

and Monthian Setkit


Key Thought



Change from better rebar details to
enhanced material properties

Mt. McKinley Bldg., Anchorage, Alaska
-

1964

Diagonal
Reinforcement, L/d ≈ 1

100% of flexural and shear strength

Construction
Issues, L/d ≈ 2

Low angle and reinforcement congestion

Research Objectives


Use HPFRC to
reduce

transverse and
diagonal reinforcement requirements in
coupling
beams


Develop information on shear strength
and damage tolerance of HPFRC members
subjected to large displacement reversals


Investigate
the use of
precast

HPFRC
coupling beams in earthquake
-
resistant
coupled wall
systems

Test Specimens

4 D13

SP
-
1

SP
-
2

3 D16

Test Setup

Actuator

Precast Coupling
Beam

“Rigid” Links

Wall Block

Wall Block

Test Specimens

4 D13

SP
-
1

SP
-
2

3 D16

Test Specimens

2 D16

2 D16

SP
-
3

SP
-
4

2 D16

Construction
issues: Beam embedment

CB
-
2 design (L/d = 1.75)

Precast Coupling Beam

Extra mid
-
depth reinforcement used to move

flexural hinging away from cold joint

CB
-
2 behavior

CB
-
2 During Testing

3% Drift

5.5% Drift

Four story
coupled
-
wall
specimen


25% scale


axial load in lower
stories


slabs for load
transfer at 2
nd

and
4
th

levels

Reinforcement
Detail,

RC Wall

Beam 1
Beam 2
Beam 3
Beam 4
48 in. (1200 mm)
24 in. (600 mm)
26 in. (650 mm)
54 in. (1350 mm)
42 in. (1050 mm)
42 in. (1050 mm)
42 in. (1050 mm)
12 in. (300 mm)
#2
#3
7 in. (175 mm)
2.3 in. (60 mm)
3.5 in. (88 mm)
7.5 in. (188 mm)


Confinement spacing:




Design wall concrete
shear stress

3
w
b
2'
c c
f


Reinforcement details, RC Wall

RC Wall
Behavior;
~ 42% coupling ratio

Reinforcement
Detail,

FRC Wall



Confinement spacing:




Design wall concrete
shear stress

2
w w
b b
or

4'
c c
f


Beam 1
Beam 2
Beam 3
Beam 4
48 in. (1200 mm)
24 in. (600 mm)
26 in. (650 mm)
54 in. (1350 mm)
42 in. (1050 mm)
42 in. (1050 mm)
42 in. (1050 mm)
12 in. (300 mm)
7 in. (175 mm)
3.5 in. (88 mm)
10.5 in. (263 mm)
8 in. (200 mm)
Comparison of Wall Behavior

R/C

HPFRC


At system drift of 1.5%:

o
HPFRC: 1 mm cracks

o
RC: Spalling of cover to
expose many stirrups

Damage Tolerance

HPFRC coupling beams
are significantly more
damage tolerant than
reinforced concrete
beams

HPFRC

R/C

HPFRC Wall Damage

Conclusions


stout
c
oupling
b
eams


Adequate confinement of diagonal reinforcement is
achieved by HPFRC without the need for bar
-
type
confinement reinforcement



Contribution of HPFRC to shear capacity of coupling
beams is significant and must be considered in design



Precast coupling beam placement proved to be simple
and is believed to be a viable alternative method for
assembling a coupled
-
wall system

http://nees.org/warehouse/project/47

Innovative Applications of Damage Tolerant
Fiber
-
Reinforced Cementitious Materials for
New Earthquake
-
Resistant Structural
Systems and Retrofit of Existing Structures