Performance-based seismic retrofit of aging reinforced concrete school buildings using fiber-recrete cementitious composites (FRC-C).

Project Abstract

This study investigates a performance-based seismic retrofit approach for aging reinforced concrete school buildings utilizing fiber-reinforced cementitious composites (FRC-C) to enhance structural resilience, life safety, and post-earthquake operability. The research addresses vulnerabilities in aging RC school facilities that exhibit brittle failure modes, limited ductility, and deteriorated materials, which compromise occupant safety and continuity of educational functions after seismic events. The methodology combines experimental, analytical, and numerical components to develop and validate retrofit strategies that optimize strength, stiffness, and energy dissipation while preserving architectural footprints and minimizing disruption to use. The experimental program comprises material characterization of FRC-C mixes, including crack-bridging capacity, residual strength, and durability under cyclic loading and environmental exposure. Mock-up beam-column joints and full-scale or quasi-full-scale RC frame specimens representing typical school building configurations are tested to quantify improvements in seismic performance, including cap-plastic rotation, joint shear strength, and collapse prevention under pushover and bidirectional earthquake scenarios. The analytical phase develops constitutive models for FRC-C-reinforced sections, calibrated against experimental results, and integrates these models into performance-based design frameworks. Numerical simulations employ nonlinear static (P–?) and dynamic time-history analyses to evaluate retrofit effectiveness across a spectrum of ground motion records, with attention to variability in material properties, aging, and construction quality. A probabilistic reliability assessment is conducted to quantify reductions in collapse probability, damage indices, and life-cycle costs under design-basis and beyond-design earthquakes. The retrofit strategy emphasizes compatibility with existing structures, ease of implementation, and constructability in school environments, including minimal masonry de-bonding risk, spray-applied or shotcrete-based FRC-C overlays, and retrofit of joint regions to restore shear transfer and ductility. The study also examines durability concerns, such as moisture ingress and freeze-thaw effects on FRC-C performance, and proposes maintenance protocols to preserve retrofit benefits over the structure’s life span. Results are benchmarked against conventional retrofit approaches, such as externally bonded steel or traditional RC jacketing, highlighting improvements in energy dissipation, residual strength, damage limitation, and rapid post-event reoccupation potential. Sensitivity analyses identify critical design parameters—FRC-C content, fiber type and length, matrix toughness, and retrofit thickness—that most significantly influence performance outcomes. The research culminates in a decision-support framework for engineers and building administrators that integrates performance objectives, cost implications, constructability, and safety requirements, enabling informed selection of retrofit schemes tailored to mid-rise RC school buildings in moderate to high seismicity regions. Policy and practice implications include guidelines for code updates, standards for FRC-C applications in retrofit, and recommendations for stakeholder engagement to minimize downtime and educational disruption following seismic events.

Project Overview

What This Project Is About

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A straightforward study of how to strengthen aging school buildings made with reinforced concrete so they perform better during earthquakes. It looks at a material called fiber-recrete cementitious composites (FRC-C) and how adding fibers can improve safety without replacing entire buildings.

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The Problem It Addresses

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Many school buildings built decades ago are at risk in earthquakes. Traditional concrete can crack and fail, threatening lives. The project explores safer retrofit options that are practical, affordable, and effective for existing structures.

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Objectives of the Project

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1. Understand the basics of earthquake loads and reinforced concrete behavior.
2. Explain what FRC-C is and why it might help retrofit older buildings.
3. Assess possible retrofit approaches and compare their safety benefits.
4. Propose a practical retrofit plan for a typical aging school building.
5. Identify key costs, installation steps, and maintenance needs.

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What You Will Do Step by Step

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1) Review current literature on seismic retrofit and FRC-C. 2) Select a representative school building model. 3) Model earthquake scenarios and predict performance with/without retrofit. 4) Compare safety outcomes and costs. 5) Develop a simple retrofit design and installation plan. 6) Outline implementation steps and monitoring needs. 7) Discuss limitations and real-world considerations. 8) Prepare a concise recommendations section for stakeholders.

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Expected Outcome

Clear, practical retrofit guidance for aging concrete school buildings using FRC-C, including a basic design approach, expected performance improvements, and cost considerations. The project aims to offer a feasible option to reduce earthquake risk and protect student safety.