Upload
others
View
12
Download
0
Embed Size (px)
Citation preview
Seismic Evaluation of Grouted Splice Sleeve Connections for Reinforced Precast Concrete Bridge Piers
Chris P. Pantelides, PhD, PE, SE
M.J. Ameli, PhD Candidate
Saratoga Springs, NY
April 2015
1
1-1) Accelerated Bridge Construction (ABC)
• ABC connections acceptable performance:
1- Lateral load capacity
2- Ductility levels
3- Repairability
2
• Reduced construction time and traffic disruption
• Higher level of work-zone safety
• Environmental-friendly
1-2) Grouted Splice Sleeve (GSS) Connections
• Alternatively called: - Mechanical rebar splices
- Grout-filled steel sleeves
• Components: - Rebar
- Sleeve
- Grout
• GSS in Design Codes
- ACI 550 (Type 1, Type 2)
- AASHTO (Full mechanical connection)
- Caltrans (Service and ultimate couplers)
Column-to-footing connection (NCHRP 698)
3
1-3) Research Objectives
• GSS used in research:
GGSS for column-to-footing
[NMB Splice Sleeve]
FGSS for column-to-cap beam
[Lenton Interlok]
4
1-3) Research Objectives
• GSS in precast components:
5
GGSS for column-to-footing
[NMB Splice Sleeve]
FGSS for column-to-cap beam
[Lenton Interlok]
1-3) Research Objectives
• Half-Scale Test Matrix [Alternatives]:
6
Test Connection Type Designation Sleeve Type Sleeve Other
ID Location
Category I
1 Column-Footing GGSS-1 NMB-8UX In Column
2 Column-Footing GGSS-2 NMB-8UX In Footing
3 Column-Footing GGSS-3 NMB-8UX In Column Unbonded Rebar
4 Column-Footing GGSS-CIP NA NA Cast-In-Place
Category II
5 Column-Cap Beam FGSS-1 LK-8 In Column
6 Column-Cap Beam FGSS-2 LK-8 In Cap beam
7 Column-Cap Beam FGSS-CIP NA NA Cast-In-Place
1-3) Research Objectives
7
1-4) Individual GSS Tests
• 6 specimens for each category
• Monotonic tests only
• Instrumentation on GSS and bars
8
1-4) Individual GSS Tests
GGSS air test specimen 9 FGSS air test specimen
Rebar fracture
169%fy on average
Type 2 (Building)
FMC (Bridge)
1-4) Individual GSS Tests
10
Pull-out failure
145%fy on average
Type 1 (Building)
FMC (Bridge)
[GGSS] [FGSS]
2) Design and Construction of Test Specimens • Prototype bridges in Utah considered
• Capacity-based design procedure
• AASHTO LRFD and AASHTO Seismic for detailing
• Sectional and Pushover analyses conducted
11
2-1) Design of Test Specimens (Col-Footing) • Effective Height of Column is 8 ft
• Octagonal Column (1.3% longitudinal, 1.9% transverse rebar)
12
• Footing dimensions 6X3X2 ft
2-1) Design of Test Specimens (Col-cap beam)
• Cap beam dimensions 9X2X2 ft
13
2-2-1) Column-to-Footing Connections [GGSS-1]
14
2-2-1) Column-to-Footing Connections [GGSS-2]
15
2-2-1) Column-to-Footing Connections [GGSS-3]
16
2-2-1) Column-to-Footing Connections [GGSS-CIP]
17
2-2-2) Column-to-Cap Beam Connections [FGSS-1]
18
2-2-2) Column-to-Cap Beam Connections [FGSS-2]
19
2-2-2) Column-to-Cap Beam Connections [FGSS-CIP]
20
3) Experimental Setup [Col-Footing Configuration]
• 120-kip or 250-kip actuator
• 500-kip axial actuator
• Spreader Beam
• High-Strength Rods
• Bottom Plate
• 4-ft support distance
21
-12-10-8-6-4-202468
1012
0 2 4 6 8 10 12 14 16 18 20 22
Drift
(%)
Cycles
(4) Test Results
22
4-1) Column-to-Footing Connections [GGSS-1]
23
µ∆ = 5.4
4-1) Column-to-Footing Connections [GGSS-1]
24
@ 3% drift
@ 6% drift
@ 8% drift
@ 8% drift- rebar fracture
4-1) Column-to-Footing Connections [GGSS-2]
25
µ∆ = 6.1
4-1) Column-to-Footing Connections [GGSS-2]
26
@ 3% drift
@ 7% drift
@ 7% drift- rebar fracture
4-1) Column-to-Footing Connections [GGSS-3]
27
µ∆ = 6.8
4-1) Column-to-Footing Connections [GGSS-3]
28
@ 3% drift
@ 8% drift
@ 8% drift- rebar fracture
4-1) Column-to-Footing Connections [GGSS-CIP]
29
µ∆ = 8.9
4-1) Column-to-Footing Connections [GGSS-CIP]
30
@ 3% drift
@ 6% drift
@ 9% drift
4-2) Column-to-Cap Beam Connections [FGSS-1]
31
µ∆ = 4.9
4-2) Column-to-Cap Beam Connections [FGSS-1]
32
@ 3% drift- Peak
@ 3% drift
@ 6% drift- Peak
@ 6% drift
4-2) Column-to-Cap Beam Connections [FGSS-2]
33
µ∆ = 5.8
4-2) Column-to-Cap Beam Connections [FGSS-2]
34
@ 3% drift
@ 7% drift
@ 7% drift
4-2) Column-to-Cap Beam Connections [FGSS-CIP]
35
µ∆ = 9.9
4-2) Column-to-Cap Beam Connections [FGSS-CIP]
36
@ 3% drift
@ 6% drift
@ 10% drift
Summary of Most Significant Experimental Findings: Desirable performance (ductile), rebar fracture, µ∆ equal to 8.9 for
GGSS-CIP; very good hysteretic performance, energy dissipation
capacity, and well-distributed flexural cracks.
Localized damage for GGSS-1 and GGSS-3. Smaller region of
spalling with respect to GGSS-CIP.
Similar damage states for GGSS-2 and GGSS-CIP, with no sleeves
in the column base.
Rebar fracture for GGSS-CIP and premature rebar fracture for all
precast specimens due to higher values of concentrated strains at
interface.
5-1) Column-to-Footing Connections
37
Summary of Most Significant Experimental Findings,
cont’d: A more ductile response achieved by incorporating sleeves inside
footing. Displacement ductility capacity increased from 5.4 to 6.1.
A postponed rebar fracture along with better strain distribution
achieved when 8db debonded rebar zone was implemented for
GGSS-3, i.e. sleeves in column base + debonding in footing.
Compare displacement ductility of 6.8 vs. 6.1.
Different distribution of inelasticity for GGSS-1 and GGSS-3, as
sleeve connectors were in the column base. Similar inelasticity
distribution for GGSS-2 and GGSS-CIP.
Strain gauge data showed both field and factory dowel yielded for
GGSS-1 and GGSS-3. The factory dowel of GGSS-2 did not yield.
Displacement ductility for all specimens exceeded minimum
component ductility of 3 per Caltrans SDC and maximum ductility
demand of 5 per AASHTO-Seismic for single-column bents.
5-1) Column-to-Footing Connections
38
Summary of Most Significant Experimental Findings: Desirable performance (ductile), rebar fracture, µ∆ equal to 9.9 for
FGSS-CIP; very good hysteretic performance, energy dissipation
capacity, and well-distributed flexural cracks.
Localized damage for FGSS-1. Smaller region of spalling with
respect to FGSS-CIP.
Similar damage states for FGSS-2 (sleeves in cap beam) and FGSS-
CIP.
Rebar fracture for FGSS-CIP and premature rebar fracture for one
FGSS-2 bar due to higher values of concentrated strains at interface.
Excessive bond-slip led to pull-out failure of east rebar in
FGSS-1 and FGSS-2.
5-2) Column-to-Cap Beam Connections
39
Summary of Most Significant Experimental Findings,
cont’d: A more ductile response was achieved by incorporating sleeves
inside cap beam. One bar fractured and µ∆ increased from 4.9 to 5.8.
Different distribution of inelasticity for FGSS-1, when sleeves were in
the column base. Similar inelasticity distribution for FGSS-2 and
FGSS-CIP.
Strain gauge data showed both field and factory dowel yielded for
FGSS-1. The factory dowel of FGSS-2 did not yield.
Displacement ductility for all specimens exceeded minimum
component ductility of 3 per Caltrans SDC. µ∆ of 5.8 (FGSS-2) was
greater than maximum ductility demand of 5 per AASHTO-Seismic
for single-column bents.
5-2) Column-to-Cap Beam Connections
40
For flexural-dominant precast components connected
by sleeves: Well-confined connector zone is advantageous. Transverse
reinforcement shall be used to secure the sleeves.
Spiral splice length equal to two extra turns was found satisfactory.
FG sleeve was found promising for moderate-seismic zones, if the
limitation on displacement ductility is accounted for.
Enhanced ductility capacity may be achieved when FG sleeve is
inside the cap beam.
GG sleeve was found promising for high-seismic zones, if the
limitation on displacement ductility is accounted for.
Enhanced ductility capacity may be achieved when GG sleeve is
inside the footing.
More ductile performance is achievable when GG sleeve is in the
column base and a debonded rebar zone in the top of the footing is
implemented.
5-3) Design Recommendations
41
CFRP composite doughnut with headed steel bars
Repairability
42
University of Utah Joel Parks
Dylan Brown
Prof. Lawrence D. Reaveley
Mark Bryant
Utah Department of Transportation Carmen Swanwick
Joshua Sletten
New York State Department of Transportation Harry White
Texas Department of Transportation
NMB Splice Sleeve
Erico
Acknowledgements
43