Lecturer:Prof. Dr. Mohammad Ismail
Faculty of Civil Engineering, UTM-Skudai, Johor Darul Ta’zim,
MALAYSIA
March 25, 2015
Strengthening And Stabilization
3
EVALUATE
Shear CapacityFlexural Capacity
Tensile
Capacity
Compressive
Capacity
Member
Stability
REPAIR
ANALYSIS
Repair Strategy
Strengthen
Passive Load
Carrying
Active Load Carrying
Stabilize
Composite
Construction
Post-TensioningEnlargement &
OverlaysStress
Reduction
External
Grouting
Internal
Grouting
Methods for stabilization and strengtheningof concrete structures and members can becategorized by the repair and techniquesemployed:
◦ Enlargement◦ Composite Construction◦ Post-Tensioning◦ Stress Reduction◦ Internal Grouting◦ External Grouting
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Enlargement is the placement of additional concrete and reinforcing steel on an existing structural member
Beams, slabs, columns, walls can be enlarged to add stiffness or load carrying capacity
The enlargement is bonded to the existing concrete to create a monolithic member
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Composite construction is a method wherein materials other than concrete are placed in concert with an existing concrete member to add stiffness or load carrying capacity
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Steel is the most common material used in this technique
Steel plates and structural shapes can be fabricated to meet almost any configuration requirement
Load transfer in the composite member is accomplished by the use of adhesives, grouts and mechanical systems
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Post-tensioning is a technique used to prestress reinforced concrete.
The tensioning provides the member with an immediate and active load-carrying capacity
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Placement of the tension components can be achieved either internally within the member or externally to the member.
Tension components are generally steel plates, rods, tendons or strands
Tension is imparted to the components by jacking or preheating.
Post-tensioning enhances a member ability to relieve overstressed conditions in tension, shear, bending and torsion.
This technique can also be used to eliminate unwanted displacements and to turn discontinuous members to continuous members
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External Tendons consist of:
o A strand bundle
o duct of plastic or steel
o End and intermediate
anchorages as well as tendon
couplers
o A grouting compound
Stress reduction is a technique that reducesstress in a member or structure.
Common methods are cutting new expansionjoints, jacking displaced structures andinstalling isolation bearings.
Other radical technique involve the removalof portions of structures
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Internal grouting is the placement of a flow able material into an unwanted discontinuity such as cracks within the concrete member.
The flow able material, upon reaching the discontinuity, will solidify and assume necessary structural properties.
Internal grouting is used to repair fractured, honeycombed, or voided concrete placements.
The most common materials used for internal grouting are polymers and hydraulics cement-based materials
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External grouting is the placement of a pump able material outside the structure, generally within the surrounding foundation soils or at the interface between the structure and the soil.
The grouting materials can be used either to provide necessary load transfer between the structure and soil, or to displace unwanted settlement.
Most materials used include cement-based mixtures.
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REPAIR
ANALYSIS
EVALUATE
Altering
Service and
Exposure
Conditions
Methods of Protection
Enhancing the
Physical
Properties of
Repair Materials
Surface-
Applied
Barriers
Protection
Strategies
Methods of Insuring
the Long Term
Performance of
Repairs
PROTECTION STRATEGIES
Methods of achieving
User Performance
Requirements
Methods of Insuring
the Long term Life of
the Original Structure
Controlling
the Cause of
Deterioratio
n & User
Dysfunction
Altering the
Electro-
Chemical
Behaviour
USER Needs
Cause
Effect
Wear
Embedded
metal corrosion
spalling
Disintegration
Leakage