- CONCEPT NOTE -

Introduction

Natural resource depletion, global warming, economic insecurity, and health concerns leads to sustainable development movements across the world. There is a need for mechanisms or approaches that can mitigate the negative effects of development, construction and urbanisation to the environment. Retrofitting an existing building is one of the most environmentally friendly, sustainable and efficient solutions to optimize the energy performance of building. As a matter of fact, when compared to new buildings construction, this kind of intervention reduces the consumption of land energy and could be applied to a large building stock.

Many structures have been constructed in the country without any structural or proper structural design. In addition to this, there are many structures constructed with poor quality, in terms of materials, workmanship and design. Such structures show distress after a few years of construction. Rehabilitation and retrofitting becomes a necessity in such structures, though a costly affair. In case structures are not rehabilitated in time, deterioration of such structures accelerates at a faster rate. Since a large number of such structures exist in the country particularly in semi urban and urban areas, this is high time that rehabilitation is carried out on large scale, both in government and private sectors.

Decision on Repair and Rehabilitation

Cost of distressed structures depends upon the quality of the design, construction, maintenance, and aging of structures. A structure having design deficiencies requires retrofitting as per latest codes. As per the guidelines for repair, restoration, condition assessment and seismic strengthening of masonry building. “As a thumb rule, if the cost of repair and seismic strengthening is less than about 30% of the reconstruction cost, retrofitting is adopted”. This cost may be only 5 – 6% of cost of reproduction of a building if only seismic members are to be provided but repair and rehabilitation is also to be carried out, it may lead to a very high cost. In case of poor quality construction, rate of distress is very high and cost of repair, rehabilitation and retrofitting is also very high. Also, such structures cannot be brought to the required quality level. For example, if the joints of brickwork have not been filled up properly, any rehabilitation work such as grouting may not fill up all the hollow joints.

Sometimes, it becomes economical to go for reconstruction but due to some other considerations such as non availability of buildings for the users, short life of structures, and litigation etc., repair, rehabilitation and retrofitting are carried out. Even after repair and rehabilitation, such structures need continuous maintenance and may not last for originally designed life.

Rehabilitation and Retrofitting Methods

Repair and rehabilitation methods are to be planned carefully and to be followed in the required sequence. Structural repairs are to be carried out first and thereafter retrofitting works for seismic requirements and then repair of non structural members. Finally, repair and rehabilitation of architectural components should be taken up. Such a sequence is followed as repair of non structural members initially may cover up structural cracks or members requiring structural strengthening.

Weak protective surfaces and materials like concrete, plaster, water proofing materials, and corroded steel are to be removed first. Repair is thereafter to be carried out by ensuring design requirements, compatibility of materials and also other factors mentioned earlier. Repair should also be compatible to design requirements. For example, if a lintel is to be repaired, it should be compatible to seismic retrofitting, if being carried out. For repair of all distressed structures, no standard method and materials may be listed but depend upon structure to structure.

During rehabilitation of distressed structures or retrofitting, following methods may be carried out:

  • Sand blasting to remove rust

  • Binding/adding additional reinforcement

  • Binding of wire mesh

  • Anchoring to the existing members through shear keys or anchors

  • Welding

  • Shotcreting

  • Plate bonding

  • Jacketing

  • Fibre wrapping

  • Underpinning

Retrofitting Matrix

The matrix was first developed by the East Midlands Development Agency. It is a self assessment tool that was created to help any individual or organisation to develop their own retrofit strategy or integrated and holistic approach on energy efficient projects that meet the local demands or requirement and achieving the goals of the projects. It also aimed to help the users to assess their current situation or activities and what is needed to solve problems or enhance their retrofit strategy. It highlights eight critical themes and each one of it sets out a series of suggestion for the users. The eight critical themes in the retrofit strategic matrix tools are - partnership, governance and leadership, evidence and monitoring base, finance and investment, planning, development and regulatory control, skills and knowledge, industry and business development, procurement, cultural and social factors.

Structural Evaluation

Structural evaluation is carried out through condition survey and non destructive testing. Condition survey is carried out at four stages through preliminary inspection, planning, detailed visual inspection and field and laboratory testing. Non destructive testing tests include tests for insitu compressive strength like rebound hammer test, ultrasonic pulse velocity test, Windsor probe test, pull out test, core tests and load tests. Tests for chemical attack include carbonation tests, chloride test and sulphate test. Corrosion potential assessment can be made from cover meter/Profo meter, half cell method, and resistivity meter. Normally a series of tests or a combination of tests or all tests are carried out based on condition assessment and importance of the structure. Though interpretation of tests is important and to be carried out by the experts, testing procedure is equally or more important as incorrect testing procedure may provide incorrect results. Problem sometimes is that field testing is not normally carried out by the experts themselves. Sometimes results are so erratic that one may require retesting. Results also vary with the equipments used, calibration conditions of the equipments and site conditions and accessibility of the members. Hence, there are numerous factors on which correctness of indirect tests depends and thus one has to be very cautious while doing such tests and interpreting results based on them.

Materials for Repair and Rehabilitation

Selection of materials for repair and rehabilitation depends upon many factors such as:

  • Technical requirements

  • Cost

  • Availability

  • Expert’s advice

  • Importance of the structure

  • Balance life of the structure

  • Toxicity

  • Aesthetic requirements

Technical requirements of materials used for repair may include their shrinkage properties, compatibility to base materials, setting and hardening properties, workability, bond strength, thermal expansion properties, mechanical strength, curing requirements, permeability, and durability. Most of the materials used for repair are cements, admixtures, polymer modified mortars/concrete, aggregates, polymers, epoxies, resins, grouts, plasticizers, steel in the form of reinforcement, sections, nuts/bolts, wire mesh, metallic sheets, glass fibre sheets, carbon fibre sheets, geo-synthetics in the same form or in modified form.

The Benefits & Challenges of Retrofitting

The contribution of existing buildings in regards to sustainability should not be underestimate. Through retrofitting, existing buildings can be benefited for sustainability purposes hence lessening the wastage. The time has come to begin concentrating on retrofitting the existing buildings. Tangible and intangible benefits from greening the existing buildings could be achieved through retrofitting. The tangible benefits are any benefits or advantages that can be measured in financial terms such as cost of construction and intangible benefits are any benefits or advantages that cannot be measured by financial term but it still has significant impact to business or project such as comfort level and satisfactory level.

Suggestion

Retrofitting the existing buildings is one of the most environmentally friendly, economical competent and proven as an efficient solutions to optimize the energy performance and could also helps to prolong the life of the existing building especially to the historical buildings. Thus, the application of retrofit should be promoted across the construction and conservation industries. More research need to be done in order to have complete sets of detail data on the direct and indirect impacts of retrofit to the environment, cost differences between retrofit with the normal construction of a building, cost of maintenances as well as, the impacts to the end users and to the surround area of retrofitted buildings.

There are large number of un-engineered and engineered structures constructed with poor quality of design, materials and workmanship. Some structures are not even maintained with proper quality. All such structures are highly prone to distress and require frequent repair and rehabilitation. Such structures cannot be demolished due to high cost involved in reconstruction and non availability of assets. Thus, there is a need to develop simple and user friendly guidelines for municipalities, individuals, engineers, architects and contractors.

- SCHEDULE -

DAY 1 - Wednesday, February 23rd, 2022 (3:00 PM - 5:30 PM)

Sub Theme - Health Checkup of Built-Up Facilities

  • Keynote Address by - Prof. Chandan Ghosh, Professor & Head – Resilient Infrastructure Division, National Institute Of Disaster Management (NIDM)

  • Lead Lecture on “Health Checkup of Built-Up Concrete Structures” by - Dr. Bishwajit Bhattacharjee, Emeritus Professor, Dept of Civil Engineering,
    IIT, Delhi

  • Presentation on  “ONLINE Certification and Assessment of Building Health”  by - Mr. Manish Bharti, CEO, Cortex Construction Solutions Pvt. Ltd.

  • Panel Discussion & Question and Answer

DAY 2 - Thursday, February 24th, 2022 (3:00 PM - 5:30 PM)

Sub Theme - Tools and Techniques for Retrofitting

  • Presentation on “Rehabilitation of Infrastructure as Nation Building”  by - Dr. Gopal Rai, Director, R&M International

  • Presentation on “Tools and Techniques for Retrofitting Structures” by - Mr. Nitin S. Verma, Managing – Partner, Adhar Consultancy & Infrastructure (AC&I)

  • Presentation on “Resistoflex Building In NOIDA- Construction & Experience Sharing” by - Mr. Ratish Jain, Managing Director, Resistoflex Group

  • Panel Discussion & Question and Answer

DAY 3 - Friday, February 25th, 2022 (3:00 PM - 5:30 PM)

Sub Theme - Performance of Retrofitted Facilities

  • Presentation on “Seismic Upgrade of New Udaan Bhawan Using Fluid Viscous Dampers” by - Mr. Sandeep Shah, Country Head and MD – India
    Miyamoto International

  • Presentation on “Performance Evaluation of Retrofitted Structures – Case Study” by - Er. Chetan R. Raikar, Managing Director, Structwel Designers & Consultants Pvt. Ltd.

  • Presentation on “Service Life Enhancement Technologies for Repair of Reinforced Concrete And Steel Structures” by - Er. Sourabh Manjrekar, Director SUNANDA Speciality Coatings Pvt. Ltd.

  • Panel Discussion & Question and Answer

For sponsorship opportunities, please contact -

Prabir Bhattacharya | Mobile - +91 98105 70345 | E-mail - prabir@cecr.in