1) The document discusses the retrofitting of the Prakasam Barrage irrigation structure across the Krishna River in Andhra Pradesh. 2) Retrofitting is done to strengthen structures and prolong their lifespan by enhancing safety against damage from loads, disasters, or aging. 3) The Prakasam Barrage was originally conceived in the 19th century and upgraded in the 20th century. It underwent retrofitting from 2002-2004 to reinforce it and sustain its life in response to changing design standards.

1. retrofitting of irrigation structures- Prakasam Barrage, Andhra Pradesh,
-A case Study
Dr. I Satyanarayana Raju,FIE,Ph.D.
Former Chief Engineer, Irrigation Dept.(AP)
Chairman, Institution of Engineers (India)
APState Centre, Hyderabad,Telangana State

2. Preamble
• In early twentieth Century engineers devoted more time to develop
methods of analysis and construction of different kind of structures
but spared very little time in repair/retrofitting/rehabilitation of
Structures.
• New construction of Dams, Highways, Sea Ports, Airways, Industries,
and other Infra-structural facilities was focused for long term
development and economic growth as a global scenario.
• In the second half of twentieth century the structures earlier built
had passed half of their life span and situation demanded repairs,
rehabilitation and retrofitting.
• Structures during their service life have a specified level of safety and
serviceability under the design working load and anticipated condition
of use.
• The deterioration structures may be due to inadequate design,
deficient construction, overloading, inadequate maintenance,
weathering, unforeseen events (Natural disasters)etc.,
• Repair, Rehabilitation, retrofitting and strengthening of structures
needed due to any one or combination those reasons.

3. What is Retrofitting ?
• Retrofitting is method or process for the strengthening of a structure.
• It is a Technique used to enhance the safety against any likely damage
to save the structure.
• The retrofitting avoids the expenses for a new structure and prolongs
life of structure.
• Reasons for retrofitting :
-Change in the intended use of structure (Ex: Increase in loading
pattern).
-Change in prevailing Codes- Ex: Grades of concrete.
-Damage to structure due to aging.
-Protect from disasters.
-Add additional strength to structure.
Rehabilitation: It is act of restoring some thing to its original position
after damage by an external or internal force. It denotes repairing
damaged structure during service or by natural disaters.

4. Vulnerability of Irrigation Structures:
• These are more vulnerable to natural disasters such as Floods, Cyclones,
Tsunamis, Earthquakes, Volcanoes etc.
• The Design Standards BIS or International Standards are dynamic and
change due to passage of time by updating.
• The Irrigation Structure built with certain standards are needing stability
analysis against modified standards in life span.
• Earlier Max. Design Flood of 100yrs/500yrs/1000yrs are now needed to
check for passage of PMF( Probable Max Flood) as per latest BIS.
• For safety point of all such Irrigation Structures needs rechecking for
their stability with Present standards.
• Some of the Structures due to their proneness for floods and cyclones
could have effected and damaged requiring rehabilitation.
• Hence the retrofitting or rehabilitation of Irrigation structures is a
common phenomenon, a case study of barrage is Presented.
• The Case study taken is Prakasam barrage across Krishna River in
Vijayawada town ( Famous for Goddess Kanakadurga and South central
Railway hub of many trains passing in all directions south,north,east and
west of India).
• It was basically an Anicut conceived by sir Arthur Cotton during in mid 19th
century and upgarded as barrage in mid 20th century.
• The Rehabilitation carried out ( By Author) is presented and very
interesting.

61. CONCLUSIONS
• Post Barrage Rehabilitation Impacts:
• The Barrage with stood Historic Krishna flood -2009 of 10.60 lakhs
Cusecs.
• The downstream boils of Post rehabilitation of -7M is changed to
+0.00M indicating positive sign due to execution of sheet pile cut-off on
upstream and down stream of Barrage.
• The Expert Committee suggested to go in for second line of sheet pile
cut off on downstream.
• The barrage life sustained by rehabilitation works carried out during
2002-2004.
• Vulnerability to Vijayawada City of Prakasam Barrage minimised,
otherwise the 2009 floods to Krishna could have created scare among
Public.
• The Hydro-mechanical components(Gates) are periodically getting
painted to avoid corrosion and Gates upkeeping.
• The New upstream KLRao Pulichintala Project relieved pressure on
Prakasam barrage during floods becoming an intermittent flood
moderation Dam.