Innovative ABC solutions using UHPC By Mohamadreza Shafieifar Mahsa Farzad Alireza Valikhani Atorod Azizinamini
[email protected] ABC-UTC Florida International University 2016 TRB Washington DC
This presentation will provide overview of work being carried out at ABC-UTC at FIU to utilize UHPC in ABC applications
Following UHPC research areas will be overviewed in this presentation a) Development of new cap beam to column connection using UHPC b) Development of rapid repair technique using UHPC c) Development of connections for prefabricated substructure elements using UHPC d) Sandwiched steel-concrete bridge system
Following UHPC research areas will be overviewed in this presentation a) Development of new cap beam to column connection using UHPC b) Development of rapid repair technique using UHPC c) Development of connections for prefabricated substructure elements using UHPC d) Sandwiched steel-concrete bridge system
Problem Statement
Currently all ABC Connections to connect cap beam to columns uses types of connections that penetrates into the cap beam, creating a very challenging detailing Requirements within the cap beam
Problem Statement Next several slides provides typical ABC cap beam to column connections used in practice
Bar Couplers
Bar Couplers
Grouted Ducts
Pocket Connections
Integral Connections
Introducing the new ABC Cap beam to column Connection detail using UHPC
Details of the new connection Seismic Version Cap Beam
Plastic Hinge Splice region using UHPC Column
Advantages Defined plastic hinge location and size
Plastic Hinge
Advantages Large tolerances
Splice region using UHPC
Advantages Developing the reinforcement over short length Minimal volume of concrete to be casted in the
field
Advantages Eliminating the potential interferences with reinforcement in the cap beam
Advantages Potentially eliminating or reducing the need for having shear or confining reinforcement
Splice region using UHPC
Numerical and Experimental Studies Next few slides shows overview of numerical and experimental studies being carried out.
Test Specimen Dimension
Numerical Studies
Details of Numerical studies – Non-Linear FEA • Software: Abaqus • Material Properties: • Steel: fy=60 ksi • Concrete: f’c=5 ksi • UHPC: f’c=23 ksi , ft=1.2 ksi • Elements type: Eight-node brick element with reduced integration (C3D8R)
Details of Numerical studies – Non-Linear FEA
Stress development in the reinforcement showing the yielding patterns in the plastic hinge region
Load Displacement response of the test specimen Load Displacement
(P=200 Kips, P/Pu=10%)
45
Applied Load (kip)
40 35 30 25
20
Axial Load
15 10
Maximum Load
5
200 kips P/Pu=10% & Pu=f’c X (A) 41 Kips
0 0
0.5
1 1.5 2 2.5 Displacement at load location (in)
3
3.5
Experimental Studies
Experimental Program
Regular Concrete Regular Concrete
Experimental Studies
Experimental Studies Regular Concrete (Support)
Regular Concrete (Column)
UHPC (Connect ion)
Regular Concrete (Plastic Hinge)
Construction procedure a)
b)
c)
d)
Construction procedure f)
g)
h)
i)
Construction procedure j)
k)
Material Properties f’c (28) =6.1 ksi f’c(28) =19.8 ksi
f’c (28)=8.6 ksi f’c (28) =18.85 ksi f’c (28) =5.5 ksi fy=60 ksi
Detail of Loading Axial load: P/Pcr=10% , Pcr=f’c × (Area)=100 Kips Maximum Expected Lateral Load= 40 Kips
Detail of Loading
Detail of Loading Δ /Δ y
P
3
2
3 Cycles
1
Time Δy
Δ
Applied Load Δy
Instrumentation 7 Strain gauges
Potentiometers (2x8) Load Cell Load Cell
String Pot
String Pot
Non-Seismic Connection
UHPC
UHPC UHPC
None- Seismic Connection
Seismic Connection
Tension Development Length
There is a need for additional work Investigating tension development Length, especially for large bar sizes And at early ages
UHPC Properties
Stress-Strain responses for Untreated UHPC (Graybeal,2006).
Tension Development Length
Tension force is transferred from Reinforcement to Concrete through - Adhesion - Friction - Mechanical action
Tension Development Length f’c 5000 10000 20000
ft 530 750 1060
ft/f’c 0.106 0.075 0.053
7.5/(f’c)^0.5
Early Tension Development Length Splitting crack Along the bar
Transverse Reinforcement Or to a limit, larger cover
Acting like a water Pressure inside a pipe Responsible for Splitting the concrete
Early Tension Development Length
ACI 318 Tension Splice Design Provisions are Based on mainly spliced beam test specimens Test Specimen that should be used for Development of design provisions Especially for large bars
Following UHPC research areas will be overviewed in this presentation a) Development of new cap beam to column connection using UHPC b) Development of rapid repair technique using UHPC c) Development of connections for prefabricated substructure elements using UHPC d) Sandwiched steel-concrete bridge system
High Performing Protective Shell
Reduced service life for bridge elements exposed to sever environment
Example damages due to corrosion
Introduction Idea is to construct a thin UHPC shell, in a configuration that will cover the damaged area and attached to the element.
List of issues to be researched •Fabrication of thin shell •Curing methods •Handling method •Transportation issue •Methods for attaching to damaged area
Following UHPC research areas will be overviewed in this presentation a) Development of new cap beam to column connection using UHPC b) Development of rapid repair technique using UHPC c) Development of connections for prefabricated substructure elements using UHPC d) Sandwiched steel-concrete bridge system
Following UHPC research areas will be overviewed in this presentation a) Development of new cap beam to column connection using UHPC b) Development of rapid repair technique using UHPC c) Development of connections for prefabricated substructure elements using UHPC d) Sandwiched steel-concrete bridge system
Approach and Philosophy Use combination of durable materials to develop durable bridge systems
Use of A1010 steel for steel
Use of UHPC for concrete
Overview of the system
Casting UHPC
Features of system Need for shear studs is eliminated
Features of system UHPC is used to enhance durability
Applied Load=160 kips, Residual Displacement= 8.5in
Thank You. Any Question?
