Seismic Retrofitting of RCC Frame Structures Using Fiber-Reinforced Polymer Wraps and Base-Isolation Concepts: A Comparative Study on Damping, Stiffness, and Economic Feasibility

Project Abstract

This study investigates the seismic performance enhancement of reinforced concrete (RCC) frame structures through the integrated application of fiber-reinforced polymer (FRP) wraps and base-isolation concepts, with a focus on damping, stiffness, and economic feasibility. The research is motivated by the need to address retrofitting demands in aging RC frame buildings subjected to moderate to high seismicity, where conventional strengthening methods may induce brittle failures or excessive serviceability issues. A multi-layered methodology combines experimental, numerical, and life-cycle assessment approaches to provide a comprehensive evaluation of retrofitted systems under realistic seismic demands. First, a series of scaled RCC frame specimens will be tested under quasi-static and dynamic loading to characterize baseline behavior and the effectiveness of FRP wrap confinement on member strength, ductility, and crack propagation. Parallelly, a modular base-isolation system, including lead-rubber bearings and low-damping elastomeric devices, will be assessed for its impact on global lateral response, period elongation, and base shear redistribution. The study will then integrate FRP confinement with base isolation to examine synergistic effects on inter-story drift, spectral acceleration reduction, and energy dissipation capacity. Finite element models will be developed and calibrated against experimental data, enabling parametric analyses across key variables FRP material type (carbon vs glass vs aramid), wrap orientation, fiber volume fraction, retrofit sequence, isolation system type, bearing natural period, and isolation damping. Damping mechanisms will be investigated from both superstructure and base-isolated configurations, highlighting how FRP confinement enhances post-yield stiffness and crack closure, while base isolation reshapes the high-frequency content of input motions and reduces floor accelerations. Stiffness modification due to confinement, composite action, and potential interaction effects with base-isolation devices will be quantified to inform design guidelines. The economic feasibility component will perform cost-benefit analyses, incorporating material costs, installation complexity, reduced repair frequencies, lifecycle maintenance, and potential insurance incentives. Sensitivity analyses will identify which retrofit strategies offer the highest return on investment under varying seismic hazard levels, building importance factors, and occupancy restrictions. Expected outcomes include (i) a robust set of performance curves illustrating strength, stiffness, and ductility improvements for FRP-wrapped RCC frames, (ii) quantified reduction in inter-story drifts and peak floor accelerations achieved by base isolation alone and in combination with FRP wraps, (iii) validated design recommendations for hybrid retrofitting that optimizes energy dissipation without compromising serviceability, and (iv) an economically viable retrofitting framework with guidelines for life-cycle cost minimization. The research aims to contribute practical, scalable retrofit strategies for existing RCC frame buildings, bridging gap between advanced material confinement techniques and contemporary base-isolation concepts, while providing actionable data for engineers, policymakers, and stakeholders.

Project Overview

What This Project Is About

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A straightforward study on ways to strengthen concrete buildings (RCC frames) to better withstand earthquakes. It looks at two approaches: wrapping the columns and beams with a lightweight material called fiber-reinforced polymer (FRP) and adding base isolation to reduce movement during quakes. The aim is to compare how these methods affect the building’s ability to dampen vibrations, become stiffer, and cost less or more over time.

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The Problem It Addresses

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Objectives of the Project

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1. Explain how FRP wraps and base isolators work in simple terms.
2. Assess how each method changes a building’s response to earthquakes in terms of damping, stiffness, and movement.
3. Compare the costs and long-term maintenance of the two retrofits.
4. Provide guidelines for when to choose FRP wrap or base isolation.

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What You Will Do Step by Step

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1) Review basic concepts of RCC frames, FRP wraps, and base isolation. 2) Gather simple data from case studies or literature. 3) Model how retrofits affect building behavior under earthquake loads. 4) Compare damping and stiffness changes for each method. 5) Estimate costs and maintenance needs. 6) Discuss practicality, limitations, and safety implications.

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Expected Outcome

A clear comparison report showing which retrofit is better for different situations, with easy-to-understand conclusions on safety, performance, and cost, helping engineers choose the right retrofit option.