Structures, be they buildings or bridges, undergo stresses beyond their original design, leading to potential failures. Retrofitting, a method to extend the usable life of a structure, addresses these issues. Let’s delve into the reasons behind structural failures before exploring the various retrofitting methods.
Structures may face unforeseen loads, like seismic forces, or simply reach the end of their designed life, questioning their strength and durability.
Retrofitting methods can be broadly categorized into four types:
Preservation Retrofitting : A preventive approach to maintain the original structure, materials, and value.
Rehabilitation Retrofitting : Required when the purpose of the structure changes over time.
Restoration Retrofitting : Involves bringing a structure back to its original form as it deteriorates over time.
Reconstruction : Creating a replica of a structure.
Methods vary based on the purpose, divided into local and global methods.
Local Methods (Concrete Member Retrofitting)
Jacketing : Reinforces an existing RCC member with a casing, enhancing strength.
Prestressing : Increases load-carrying capacity by binding prestressing wires to structural members.
Repaving Method : Involves replacing existing structural members with new ones.
Global Methods (Structure Retrofitting)
Beam Addition : Introduces secondary beams to distribute loads evenly between main beams.
Shear Wall Addition : Enhances structural integrity by adding RCC shear walls between columns.
Support Point Addition : Addresses deflection in longer span beams.
Seismic Isolation Method : Improves seismic performance by isolating the structure’s base.
Crack Fill Method : Seals cracks with low viscosity resin and ultra-fine cement.
Dampers : Limits seismic vibrations by introducing various types of dampers.
Foundation Retrofitting : Various methods, including underground wall addition and pile/footing addition.
FRP Strengthening : Uses Fibre Reinforced Polymer (FRP) to enhance structural capacity.
Use of Steel Bracing : Utilizes concentric or eccentric bracings to increase lateral resistance.
Retrofitting presents both advantages and disadvantages, making its feasibility project-specific. Assessing suitability through structural testing, with the guidance of a subject-matter expert, optimizes the retrofitting process. The method chosen depends on the unique needs and challenges of each project.
