Chapter-1.pptx

Structural Repair & Rehabilitation
VEB4523
Course Introduction
Chapter-1
By
Professor Dr. Nasir Shafiq

Rationale of this course
Todays Civil Engineers are not only designing and constructing new
buildings & infrastructures but maintaining them through out the service
life is becoming popular to facilitate ageing structures to perform the
desired functions.
Concrete is the most prevalent structural material and many concrete
structures have suffered many distresses withing the services life due to
variety of causes.
Therefor the aim of this Three credit elective is to prepare future graduates to
handle the challenges of maintaining ageing buildings & infrastructures by
designing appropriate Repair, Rehabilitation, or Retrofitting technique.

Objective of the course
To plan appropriate structural assessment scheme for
monitoring the current health of structures using destructive
and non-destructive examinations.
To understand the causes of distresses in concrete structures and
their likely modes and consequences
To design most effective repair, rehabilitation, and retrofitting
(RRR) techniques for reinstating the desired function of the
structure.

Course Learning Outcome, CLO vs PO
COURSE LEARNING OUTCOME
PROGRAM
OUTCOME
(PO)
PO1 PO3
CLO1 Determine the underlying cause or causes of
concrete distress and deterioration
√
CLO2
Evaluate materials and methods used for
the concrete repair
√

Course Outline and Planning
Chapter Description Planning CLO
Assessment
1 Introduction W-1 1 Formative
2
Evaluation Of Concrete
In Concrete Structures
W2 & W3 1
Formative
Summative
Term Project
Test-1
Final Exam
3
Causes Of Distress And
Deterioration Of
Concrete
W4 & W5 1
4
Planning And Design
Of Concrete Repair
W6 & W7 2

Course Outline and Planning
Chapter Description Planning CLO
Assessment
5
Concrete Removal And
Preparation For Repair
W8 2
Summative
Term Project
Test-2
Final Exam
6
Strengthening Of
Concrete Structures
W9, W10 2
7
Maintenance Of
Concrete
W11 2
8
Concrete Investigation
Reports
W12 2

References
Reference-1 Reference-2

Assessments
Summative Assessments (100%)
1. Final Exam: 50%
2. Coursework: 50%
a. Group Term Project: 20%
b. Tests: 2 -Test-1: Week-6, 15%, Test-2: Week-11, 15%

Great Liability of the Engineer
“The great liability of the engineer…compared to men of other professions…is
that his works are out in the open, where all can see them.
 His acts …step by step…are hard substance.
 He cannot bury his mistakes in the grave like doctors.
 He cannot argue them into thin air …or blame the judge …like the lawyers.
 He cannot, like the architect, cover his failures with trees and vines.
 He cannot, like the politicians, screen his shortcomings by blaming his
opponents…and hope that people will forget.
 The engineer simply cannot deny he did it.
 If his works do not work…he is damned.”
Herbert Hoover

Concrete as a Principal Construction Material
 Many times, concrete is viewed as a maintenance-free material.
 Modern concrete is a very durable construction material.
 If properly proportioned and placed, concrete will have a very long
service life, usually without the need for any maintenance, at least for
some time.
 Unfortunately, there are times when concrete does need maintenance to
extend or prolong its service life.
 Many concrete structures were constructed using early concrete
technology, and they have already provided well over 50 years of service
under harsh conditions.
 Concrete in these circumstances should be inspected regularly to ensure
that it is receiving the maintenance necessary to retain serviceability.

Background of Concrete Maintenance and Repair
 Since the inception of concrete as structural material in 1903,
many structures went through repairs and maintenance during
expected service life to keep them operational for the desired
functions.
 Unfortunately, even though the best available knowledge and
materials were used, many repair failures have occurred during
the 119 years since that first concrete was placed.
 As a first step to increase the likelihood of a successful repair, it
is paramount to use a consistent, systematic approach to
concrete repair.

Background of Concrete Maintenance and Repair
 Performing an effective maintenance program to prolong the
life of a concrete structure is usually much more economical
than taking no action.
 Failure to promptly provide the proper maintenance will
usually result in expensive repairs or replacement.
 Figures on next slides demonstrate the consequences of
inadequate or inappropriate maintenance.
 These structures now require replacement at a cost many times
greater than the preventive maintenance that could have
extended their serviceability.

Real Life Examples
Istanbul Turkey

Maintenance of Structure – Performance VS Time
 The following model (graph) is indicating performance level of
a structure with the time of operation

How to Maintain Buildings and Infrastructures
 Assessment of existing structures is an important topic for
experts working in construction in most industrial countries,
where rehabilitation including repairs and upgrading of
construction works represent about half of all construction
activities. It is due to several circumstances including following
items.
 Existing structures represent substantial, continually increasing economic
contribution
 Users are interested in a new way of exploitation of existing structures
 Many existing structures do not fulfil requirements of currently valid
standards.

 An European standard for the assessment and retrofitting of existing
structures has not been developed yet.
 Assessment of existing structures often requires knowledge overlapping
the framework of standards for the design of new structures.
 Assessment should be focused on minimal construction interventions to
existing
 structures.
 Civil engineers, owners and representatives of governmental authorities
need new guidance for the assessment of existing structures.

Schematic presentation of a repair cycle conducted as a result of a building structure’s premature
degradation, e.g., due to impact. 1—repair restoring the use potential before damage; 2—repair
restoring the original use potential; tkr—service life until damage; tp—designed service life; Δtn—
service life regained owing to repair (restoring the designed service life); Δtn
+—additional service
life gained owing to restoring the original use potential.

Deterioration of Structures – Bridges & Tunnels

Deterioration of Structures – Buildings

Structural Maintenance and Codes & Standards
 ISO 13822 provides general requirements and procedures for
the assessment of existing structures (buildings, bridges,
industrial structures etc.), based on the principles of structural
reliability and taking into account specific problems of existing
structures.
 This is a materially independent prescriptive document applicable
to the assessment of any type of existing structure designed and
executed according to theoretical basis and original design rules
or based on long-term experience and professional procedures.

 Concrete Repair Standards & Approvals: he European
Standards EN 1504 Parts 1 to 10
 EN 1504 – 1 Describes the terminology and definitions used within the
Standards.
 EN 1504 – 2 Provides specifications for concrete surface protection
products and systems.
 EN 1504 – 3 Provides specifications for the structural and non-structural
repair with replacement concrete or mortars etc.
 EN 1504 – 4 Provides specifications for structural bonding and
strengthening applications.
 EN 1504 – 5 Provides specifications for concrete injection with resins or
other sealing or bonding materials.

 EN 1504 – 6 Provides specifications for the anchoring of reinforcing steel
bars with resin adhesives etc.
 EN 1504 – 7 Provides specifications for exposed and embedded steel
reinforcement corrosion protection.
 EN 1504 – 8 Describes the Quality Control and evaluation of conformity
required for the product manufacturers.
 EN 1504 – 9 Defines the general Principles and Methods to be used with
products and systems for the repair and protection of concrete.
 EN 1504 – 10 Provides information on site application of the repair and
protection products, together with the necessary Quality Control of the works.
 These Standards have been designed to help owners, engineers and
contractors successfully complete concrete repair and protection
works to all types of concrete structures.

Introduction to Repair, Rehabilitation and Retrofitting
What is Repair – Definition and Philosophy?
 Action taken to reinstate to an acceptable level the current
functionality of a structure or its components which are
defective or deteriorated, degraded or damaged in some way is
called repair.

The actions to structural repair include the following:
 Patching up of defects such as cracks and fall of plaster.
 Repairing doors, windows, replacement of glass panes.
 Checking and repairing electric wiring.
 Checking and repairing gas pipes, water pipes and
plumbing services.
 Re-building non-structural walls, smoke chimneys, boundary walls, etc.
 Re-plastering of walls as required.
 Rearranging disturbed roofing tiles.
 Relaying cracked flooring at ground level.
 Redecoration, whitewashing, painting, etc.

Concept of Rehabilitation
 It is the process of bringing the structure to its original level of
function including durability and strength.

Structural Rehabilitation includes:
 Removal of portions of cracked masonry walls and piers and
rebuilding them in richer mortar.
 Use of non-shrinking mortar will be preferable.
 Addition of reinforcing mesh on both -faces of the cracked
wall, holding it to the wall through spikes or bolts and then
covering it suitably. Several alternatives have been used.
 Injecting epoxy like material, which is strong in tension, into
the cracks in walls, columns, beams, etc.

Concept of Retrofitting
 Action to modify the functionality of a structure and to
improve future performance in terms of load carrying
capacity is called retrofitting.

Lifecycle of a Building
 The expected economic life of the building under normal
occupancy and maintenance conditions is considered to be as
below:
 Monumental buildings 100 years.
 RCC Framed construction 75 years
 Load bearing construction 55 years.
 Semi permanent structures 30 years
 Purely temporary structures 5 years

Lifecycle of a Building - Objectives

Lifecycle of a Building – Process Overview

Strength Requirements for Repair, Rehab & Retrofit

Modes of Distress of Concrete Structures

Structural Health Management VS Human Health
Management

Framework For Repair, Rehabilitation and Retrofitting

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