The core idea behind the framework is staged, or incremental, seismic retrofit. Rather than committing to a single, massive construction campaign, an owner can spread the work over multiple phases, strengthening the most critical parts of the building first and deferring less urgent interventions until funds become available. The concept is not new; the Federal Emergency Management Agency has published incremental rehabilitation guidelines for schools, hospitals, offices, and apartment buildings since the early 2000s. What has been missing, the authors argue, is a systematic method for deciding the sequence of those interventions at the level of individual stories, optimized against explicit economic and safety metrics. Their framework fills that gap by combining probabilistic loss estimation with optimization and multi-criteria decision analysis.

The researchers propose two complementary approaches. The first, which they call the rigorous approach, employs a Greedy search algorithm as a zero-order optimization tool. Greedy algorithms work by making the locally best choice at each step, and here the method groups and prioritizes economically viable stories for retrofit one stage at a time. At every stage, the algorithm evaluates candidate retrofit packages using three financial metrics: expected annual loss, which captures the average yearly economic damage a building is likely to suffer; net present value of benefit, which discounts future risk reduction into today’s money; and marginal benefit, which measures how much additional value each successive retrofit stage delivers. Crucially, all three metrics can be computed both with and without accounting for fatality losses, allowing decision-makers to see how the ranking of interventions changes when human lives are assigned an economic value.

Underpinning these metrics is a probabilistic seismic loss engine built on iterated cloud analyses. Cloud analysis is a technique in performance-based earthquake engineering in which a structural model is subjected to a suite of ground motion records of varying intensities, and the resulting engineering demand parameters, such as interstory drift ratios and floor accelerations, are regressed against ground motion intensity measures. By fitting these demand-intensity relationships probabilistically, the method captures both the aleatory variability of ground motions and the uncertainty in structural response. The resulting fragility and vulnerability functions feed directly into loss calculations consistent with the FEMA P-58 performance assessment methodology, giving the economic metrics a defensible, hazard-consistent foundation rather than relying on simplified empirical rules.

The second, simplified approach is designed for practitioners who lack the computational resources or time for repeated loss analyses. It prioritizes stories based on cost efficiency using the Technique for Order of Preference by Similarity to Ideal Solution, or TOPSIS, a well-established multi-criteria decision-making method. TOPSIS ranks alternatives by measuring their geometric distance from an ideal positive solution, which maximizes all beneficial criteria, and from a negative ideal solution, which minimizes them. In this application, the alternatives are stories of the building, and the criteria are engineering demand parameters obtained from a single cloud analysis, a pushover analysis, and a response spectrum analysis. Pushover analysis pushes a nonlinear structural model laterally to reveal its strength, stiffness, and yielding sequence, while response spectrum analysis captures modal demands efficiently. Together these three analyses supply a rich but tractable set of indicators for each story.

Because the criteria in the TOPSIS framework carry different degrees of importance, the researchers needed a principled way to weight them. They applied two independent weighting schemes: the Analytical Hierarchy Process, a subjective method introduced by Thomas Saaty in which experts make pairwise comparisons to express relative priorities, and the Entropy-Based Method, an objective technique rooted in Claude Shannon’s information theory that assigns weights according to the dispersion of criterion values across alternatives. Using both methods side by side allows the analysts to test whether the resulting story rankings are sensitive to how the weights are chosen, an important robustness check in any multi-criteria study.

To demonstrate the framework, the authors applied both approaches to two case study buildings: a nine-story and a three-story steel moment-resisting frame. In these structures, the staged rehabilitation targeted the beam-column connections, the welded joints that are notorious failure points in older steel frames, as dramatically illustrated by the 1994 Northridge earthquake. The results were striking: the rigorous Greedy search approach and the simplified TOPSIS approach yielded similar story groups and similar priorities for both buildings. This convergence matters because it suggests that engineers who cannot afford the full probabilistic machinery can still arrive at nearly the same retrofit sequence using a handful of standard analyses and a spreadsheet-implementable decision method.

The practical implications extend well beyond steel moment frames. Although the demonstration focused on connection rehabilitation, the underlying decision-making architecture is agnostic to structural system and material. It could, in principle, guide the staged strengthening of reinforced concrete frames, masonry buildings, or any structure subjected to comparable rehabilitation strategies. For public agencies managing portfolios of schools and hospitals, for insurance companies pricing retrofit incentives, and for owners of aging commercial buildings, the framework provides a defensible way to allocate scarce funds across years or decades. It also aligns with a broader shift in earthquake engineering from prescriptive code compliance toward risk-informed decision-making, in which the value of an intervention is measured in avoided losses rather than in abstract performance targets.

The study also contributes a subtle but important insight: the ranking of retrofit stages can shift depending on whether fatality losses are included in the economic calculus. When the value of a statistical life is folded into expected annual loss and net present value calculations, stories whose failure would endanger many occupants may rise in priority even if their direct repair costs would be modest. By reporting metrics both ways, the framework makes this trade-off explicit rather than hiding it inside a single number, giving stakeholders the information they need to weigh economic efficiency against life safety in a transparent manner. The authors report no external funding for the work, and both the rigorous and simplified procedures are presented as flexible yet robust tools that support risk-informed, economically optimized, and practically implementable retrofit strategies.

As cities from Tehran to Los Angeles grapple with vast stocks of seismically deficient buildings, tools like this one may prove decisive in converting awareness into action. The promise of the framework lies in its pragmatism: it does not demand unlimited budgets or heroic assumptions, but instead meets owners where they are, offering a mathematically sound path to safer buildings one stage at a time. If widely adopted, staged retrofit guided by such risk-based prioritization could steadily chip away at urban seismic vulnerability, ensuring that every dollar spent on strengthening delivers the maximum possible reduction in losses and, ultimately, in lives saved when the next major earthquake strikes.

Subject of Research: Risk-based multi-criteria decision-making for sequencing multi-stage seismic retrofit of buildings

Article Title: Multi-stage seismic retrofit of buildings: a risk-based multi criteria decision-making procedure

Article References: Orumiyehei, A., & Dolatshahi, K. M. (2026). Multi-stage seismic retrofit of buildings: a risk-based multi criteria decision-making procedure. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02673-9

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02673-9

Keywords: seismic retrofit, earthquake engineering, decision-making, TOPSIS, Greedy search, expected annual loss, cost-benefit analysis, steel moment frames, cloud analysis, incremental rehabilitation, structural safety, risk assessment

The scale of the problem motivating this work is striking. According to the most recent Italian census of residential buildings, more than seventy percent of the country’s housing stock was built before 1981, when seismic design provisions were absent or only partially enforced, and horizontal earthquake forces were rarely considered in routine design. Concrete buildings erected between the 1960s and the 1990s typically lack the ductility that modern capacity design principles provide, and their unreinforced masonry infill walls interact with the frame in ways that can drastically alter seismic behaviour. The consequences have been visible in the devastating earthquakes that struck Molise in 2003, L’Aquila in 2009, Emilia in 2012, and Central Italy in 2016. At the same time, the building sector accounts for roughly forty percent of energy consumption and thirty-six percent of greenhouse gas emissions in Europe, making integrated renovation an environmental as well as a life-safety imperative.

Existing retrofit strategies each carry significant drawbacks. External steel exoskeletons allow buildings to remain occupied during construction, but they are expensive to fabricate, demand complex connections to the existing structure, and require free space around the entire perimeter for independent foundations, a luxury rarely available in dense cities. Internal solutions such as added shear walls or steel bracing avoid that problem but consume usable floor area and force occupants to endure invasive interior works. Earlier timber-based proposals have shown promise, since cross-laminated timber is lightweight, insulating, and prefabricated, yet most previous systems required removing existing infill walls or transferring substantial new loads into columns that may themselves be degraded. The e-CLT system was conceived to sidestep these limitations by mounting panels externally and letting friction dampers control how forces flow between the new panels and the old frame.

The operating logic of the system is elegantly two-tiered. Under low to moderate ground shaking, the friction dampers hold the CLT panels rigidly against the concrete frame, increasing the building’s lateral stiffness and strength, which reduces inter-storey drift and the internal forces that would otherwise damage columns and beams. When a severe earthquake strikes, the dampers activate and begin to slide, converting seismic energy into heat through friction while capping the forces transmitted to the timber. This deliberate cap keeps the CLT panels within their elastic range even under extreme excitation, meaning the panels themselves should survive a major event without replacement. A companion prefabricated envelope, called e-PANEL, wraps the assembly to deliver the thermal upgrade, so a single intervention on the façade addresses both earthquake safety and energy performance.

Getting there required fixing a subtle but critical engineering flaw. An earlier version of the friction damper had been validated under idealised laboratory conditions in which only displacements parallel to the friction plane were applied. In a real two-dimensional frame, however, the rocking of the panel during an earthquake generates parasitic forces perpendicular to the friction plane. Preliminary tests showed these out-of-plane actions severely compromised the damper, destabilising its dissipative behaviour, overloading the screws and preloaded bolts, and concentrating stresses at the edges of the concrete elements. The research team therefore redesigned the device from the ground up, decoupling the connection system along the two directions parallel and perpendicular to the friction plane so that rocking motions could no longer corrupt the friction mechanism.

The improved damper consists of two principal steel components: an anchor profile mechanically fixed to the concrete inter-storey beam, and a free profile screwed to the back of the CLT panel that is free to slide horizontally. Between them sits a stiffened alignment component housed in a box formed by three plates welded to the free profile. Energy dissipation occurs as the alignment component slides against the anchor profile across shim layers lubricated with graphite, all clamped together by three bolts tightened to a torque of 100 newton-metres, corresponding to a preload of roughly 31 kilonewtons. The geometry is carefully proportioned using capacity design principles: the friction force is deliberately kept below the resistance of both the timber and concrete fastening systems so that sliding, rather than brittle connection failure, governs, and all steel components remain elastic under the maximum expected friction force. Installation requires just three straightforward operations and no specialist equipment.

To validate the system under realistic conditions, the team built two identical full-scale, single-storey, single-bay concrete frames replicating 1970s Italian construction practice, complete with the strong-beam-weak-column behaviour and low concrete strength typical of that era. Columns measured 300 by 300 millimetres, beams 300 by 500 millimetres, with a 4-metre span and 3.2-metre storey height. Four cyclic quasi-static tests were performed at the University of Bologna’s structural laboratory: a bare frame loaded only within its elastic range, a masonry-infilled frame pushed to failure, an identical infilled frame retrofitted with the e-CLT system, and finally the retrofit system itself mounted on a deliberately damaged frame whose columns had their reinforcement cut to create a pendulum-like substructure with almost no lateral resistance. This clever arrangement allowed the dampers to be characterised within the real geometric interaction of panel, damper, and frame, rather than in isolation. A constant vertical force of 250 kilonewtons per column simulated the gravity load of a three-storey residential building.

The results were dramatic. The unstrengthened infilled frame developed an initial stiffness of 47.0 kilonewtons per millimetre and reached a peak base shear of 157 kilonewtons at a drift ratio of three percent, by which point plastic hinges had formed at the column ends and the longitudinal reinforcement had buckled. The retrofitted frame, by contrast, exhibited an initial stiffness of 70.1 kilonewtons per millimetre, a 49 percent increase, and a peak base shear of 263 kilonewtons, a 67 percent gain. The friction dampers activated at a drift ratio of about 0.5 percent and then delivered stable, repeatable hysteretic loops of the nearly rectangular shape characteristic of friction devices. Crucially, the CLT panel stayed elastic throughout, with maximum reversible diagonal elongation of only 0.6 millimetres, roughly 200 microstrain, confirming that it behaved as a rigid diaphragm protected by the capped damper forces.

The energy numbers are perhaps the most compelling headline figure. Up to 0.5 percent drift, dissipation was minimal because the dampers had not yet engaged. Beyond that threshold, the retrofitted system’s cumulative dissipated energy climbed steeply while the unstrengthened specimen’s performance deteriorated with progressive infill and column damage. At a drift level of three percent, close to the collapse-prevention limits defined in FEMA and Eurocode 8 documents, the strengthened frame dissipated approximately three times as much energy as its unstrengthened counterpart. The equivalent viscous damping ratio of the retrofitted system rose to about 58 percent at three percent drift, compared with a range of roughly 16 to 28 percent for the unstrengthened frame, and showed negligible degradation across repeated cycles. Damage to the concrete members themselves was markedly reduced: cracking remained limited to transverse cracks at column ends, with no bar buckling or concrete cover spalling, in stark contrast to the extensive degradation observed in the control specimen.

The authors conclude that e-CLT is a robust, sustainable route to upgrading seismically vulnerable concrete buildings, one whose stiffness and strength gains can be tailored by adjusting the number and size of dampers and panels, and whose prefabricated, external, lightweight installation minimises disruption to occupants. They also note honest limitations: façades with large openings may not accommodate the panels, brittle failure modes may require supplementary local interventions, and long-term effects such as bolt preload relaxation and temperature fluctuations on the friction interfaces still warrant study. Future work will include shaking-table tests on large-scale three-dimensional specimens and comprehensive cost-benefit analyses. For now, the message is clear: a renewable material, a cleverly decoupled steel damper, and a full-scale laboratory frame have together shown that Europe’s ageing concrete stock can be made dramatically safer without demolishing a single wall.

Subject of Research: Seismic retrofit of pre-code reinforced concrete frames using cross-laminated timber panels with friction dampers

Article Title: Structural performance of RC frames retrofitted with CLT panels: experimental evidence from the e-CLT system

Article References: Pozza, L., Barbagallo, F., Morganti, A., Licciardello, E., Marino, E. M., & Mazzotti, C. (2026). Structural performance of RC frames retrofitted with CLT panels: experimental evidence from the e-CLT system. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02690-8

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02690-8

Keywords: cross-laminated timber, seismic retrofit, friction damper, reinforced concrete frames, energy dissipation, quasi-static cyclic testing, e-SAFE project, masonry infill, building renovation, earthquake engineering, energy efficiency, Horizon 2020

The team focused on a type of structure that is deceptively common: a bridge pier founded on a group of piles, embedded in a slope affected by a slow-moving landslide. Unlike catastrophic, fast-moving slope failures that destroy bridges in seconds, slow-moving landslides creep at rates of millimeters to centimeters per year, often going unnoticed until cumulative deformation begins to distort the superstructure or crack the foundations. Yet these quiescent masses of soil are not necessarily benign. When an earthquake arrives, the weakened, sheared, and sometimes saturated landslide material can be reactivated, subjecting the piles to a combination of inertial forces from the shaking structure and kinematic forces from the moving ground. The study’s central question was deceptively simple: does the state of the slope before the earthquake matter for the pier’s seismic performance?

To answer it, the researchers built a nonlinear finite element model of the coupled soil-foundation-structure system, using a reference case study chosen precisely because it is paradigmatic of the numerous Italian bridges located in areas exposed to both seismic and hydrogeological hazards. Bridge piers, after all, may sit on the crest of a slope, along its face, or downstream of it, and the relative position of the bridge and the slope strongly influences the type and severity of the actions the structure must resist. The numerical model captured the essential mechanics of the problem: the nonlinear, strain-dependent behavior of the soil under cyclic loading, the interaction between the piles and the surrounding ground, and the dynamic response of the pier itself.

The analysis compared three distinct scenarios. In the first, the pier stands in a stable slope, representing the conventional design assumption in which the ground is competent and the only seismic demand comes from the shaking itself. In the second, the slope hosts a quiescent landslide that the earthquake reactivates, so the ground begins to move as the shaking progresses. In the third, the landslide is already active before the earthquake, meaning the piles have already accumulated deformation and stress from the creeping soil. This progression allowed the researchers to isolate the influence of pre-seismic slope conditions on the dynamic response of the pier, something that standard seismic assessment procedures, which typically assume stable ground, simply do not address.

The results, expressed in terms of maximum and residual displacements and rotations of the pier, show that the starting condition of the slope is far from a secondary detail. When the landslide is active before the earthquake, the piles enter the seismic event already stressed and deformed, and the ground movement during shaking adds kinematic demands on top of the inertial ones. The interaction between the two loading mechanisms can amplify displacements and, critically, leave the pier with larger residual deformations after the shaking stops. Residual displacement matters enormously for bridges, because permanent tilting or lateral shifting of a pier changes the geometry of the deck, alters load paths, and can compromise serviceability or trigger collapse even when the structure survives the earthquake itself.

Underpinning these findings is the physics of soil-structure interaction, a phenomenon that simplified design methods often reduce to a set of springs or, worse, ignore altogether. In reality, the piles, the surrounding soil and the pier form a single dynamic system whose response depends on the stiffness and damping of every component. Decades of research, from classical work on dynamic pile stiffness to modern studies of kinematic pile bending in layered soils, have shown that the ground is not a passive support but an active participant in the seismic response. The new study extends this understanding to the multi-hazard setting, demonstrating that the dynamic properties of a slope containing a landslide mass differ from those of a stable slope, and that these differences propagate directly into the demands on the foundation.

The Italian context gives the work particular urgency. The national landslide inventory compiled by the Institute for Environmental Protection and Research documents hundreds of thousands of landslide phenomena across the country, and recent research has catalogued extensive interactions between landslides and bridge foundations in Italian case studies. At the same time, Italy has endured repeated bridge failures, some linked to the degradation of structures subjected to unanticipated environmental actions. The national guidelines for classifying and managing the risk of existing bridges, introduced in 2020 and operationalized in subsequent years, pushed owners to assess their assets systematically, and recent technical guidance has begun to address landslide interaction explicitly. The new study provides a quantitative basis for that effort, showing what is at stake when a bridge pier’s foundation crosses a slowly moving mass of soil.

What makes the study especially valuable for practitioners is its methodological clarity. By using a nonlinear finite element approach within a single consistent model, the researchers could track the full path from static slope condition to dynamic seismic response, capturing the state of stress and strain in the soil at the moment the earthquake begins. This matters because the initial stress state governs how the soil stiffens or softens under cyclic loading, how pore pressures evolve, and how much permanent deformation accumulates. The approach also reflects the reality of earthquake-triggered landslide reactivation, a phenomenon documented in devastating detail after events such as the 2008 Wenchuan earthquake in China and the 2016 Kumamoto earthquakes in Japan, where seismically induced slope failures destroyed bridges that had performed adequately under shaking alone.

The broader message is a call for multi-hazard thinking in the assessment and retrofit of existing infrastructure. A bridge evaluated only for seismic loads, assuming stable ground, may be far more vulnerable than its safety factor suggests if it stands in the path of a slow-moving landslide. Conversely, retrofit strategies designed for landslide stabilization alone may leave the structure exposed to seismic demands that the modified soil-foundation system now transmits differently. The authors argue that accounting for soil-foundation-structure interaction is essential when assessing the seismic response of bridge piers in the presence of slow-moving landslides, and that a multi-hazard approach is needed to enhance both the assessment of existing bridges and the sustainability of retrofit strategies. As climate change alters rainfall patterns and slope hydrology, and as seismic hazard remains a permanent feature of the Mediterranean landscape, the quiet creep of a hillside may prove to be the hidden variable that determines whether the next earthquake is survivable for the bridges that carry our lifelines.

Subject of Research: Seismic response of pile-supported bridge piers founded in slopes affected by slow-moving landslides

Article Title: Seismic response of a pile-supported bridge pier under multi-hazard conditions in slow-moving landslides: a numerical investigation

Article References: Ambrosino, A., Servodio, M., Sica, S., Losanno, D., Parisi, F., & Santolo, A. S. D. (2026). Seismic response of a pile-supported bridge pier under multi-hazard conditions in slow-moving landslides: a numerical investigation. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02678-4

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02678-4

Keywords: soil-structure interaction, landslides, earthquake engineering, multi-hazard assessment, bridge piers, pile foundations, finite element analysis, slope stability, seismic retrofit, geotechnical engineering, infrastructure resilience, residual displacement

The study, published in the Bulletin of Earthquake Engineering by Ju-Seong Jung of Chungwoon University and colleagues at Hanyang University’s Innovative Durable Building and Infrastructure Research Center, proposes a hybrid system the authors call BFC-FRP: a combination of prefabricated basalt fiber sheets and fiber-reinforced polymer panels applied to the surface of reinforced concrete columns. Basalt fiber, drawn by melting volcanic rock at high temperature, has attracted growing attention in structural engineering because it offers a favorable balance of mechanical performance, chemical stability, and cost compared with the glass and carbon fibers that have traditionally dominated the retrofit market.

To test the concept, the team fabricated seven large-scale columns, each with a square cross section of 350 by 350 millimeters and a clear height of 1.5 meters, dimensions representative of real building columns rather than miniature laboratory proxies. Three of the specimens were detailed to fail in shear, the most dangerous failure mode because it is sudden and brittle, while four were designed to be flexure-controlled, meaning their response is governed by bending and tends to be more ductile. Every column was then pushed sideways under reversed cyclic lateral loading, the laboratory equivalent of the back-and-forth motion an earthquake imposes, while a constant axial load corresponding to a ratio of 0.10 pressed down from above.

The strengthening scheme varied along two experimental axes. The first was coverage: some columns received strengthening only in the end regions, where damage typically concentrates, while others were wrapped over their full surface. The second was the arrangement of the prefabricated basalt fiber sheets and the FRP panels, allowing the researchers to compare how different configurations of the composite layers influenced confinement of the concrete and restraint of the longitudinal reinforcement. This systematic variation is what gives the study its practical value, because retrofit budgets rarely allow blanket coverage, and engineers need to know whether partial wrapping is enough.

The results for the shear-critical columns were striking. Full-surface BFC-FRP strengthening increased the ultimate strength by approximately 1.5 times compared with the unstrengthened control specimen, but the more important gain was in deformation: the displacement reached at ultimate strength grew by a factor of 2.0 to 2.6. In seismic terms, that transformation matters more than raw strength. A column that can keep carrying load while being pushed far sideways gives occupants time to evacuate and prevents the soft-story collapse mechanism that has killed thousands of people in recent earthquakes worldwide, from Turkey and Syria to Morocco and Japan.

For the flexure-controlled columns, which started from a more forgiving baseline, the retrofit delivered different but equally consequential improvements. The ultimate displacement increased by roughly 1.4 times, and the ductility ratio, a normalized measure of how much inelastic deformation a member can sustain before losing capacity, nearly doubled. Most notably, the energy dissipation capacity, which quantifies how much seismic energy the column can absorb and dissipate through hysteretic behavior in each loading cycle, rose by approximately 2.4 to 2.5 times. Since earthquake-resistant design fundamentally relies on structures dissipating energy rather than simply resisting force, this multiplication of dissipative capacity is arguably the study’s headline finding.

Alongside the physical tests, the researchers built nonlinear quasi-static cyclic finite element models of the columns using the disturbed stress field model, a mechanics-based formulation for reinforced concrete developed at the University of Toronto and implemented in analysis software widely used for shear-dominated members. The modeling work serves a purpose beyond reproducing the experiments: if a numerical framework can reliably predict how a wrapped column will deform and dissipate energy, engineers can extend the findings to configurations that were never tested, and design codes can eventually incorporate the strengthening system with confidence.

The models performed well. They reproduced both the load-displacement envelopes and the energy-dissipation responses of the tested columns with average deviations of approximately 10 percent, a level of accuracy that is respectable for nonlinear analysis of reinforced concrete, a material whose cracking, crushing, and bond-slip behavior is notoriously difficult to capture. The authors note that these results demonstrate the proposed BFC-FRP system can improve the deformation and energy-dissipation capacities of both shear- and flexure-controlled columns within the tested conditions, a carefully scoped conclusion that reflects the bounded nature of laboratory evidence.

The work sits within a broader and urgent engineering challenge: seismic strengthening of existing buildings. International guidelines, including documents from the American Concrete Institute and the Japan Building Disaster Prevention Association, already recognize externally bonded FRP systems as a legitimate retrofit strategy, but the field continues to search for materials that lower cost and improve sustainability. Basalt fiber fits that agenda well because its raw material is abundant volcanic rock, requiring no energy-intensive precursor chemistry of the kind needed for carbon fiber. Recent studies have explored basalt composites for repairing earthquake-damaged and corroded beam-column joints, for strengthening precast bridge piers, and even for confining columns built with recycled brick aggregates, suggesting a rapidly maturing research ecosystem.

For practitioners, the Korean team’s findings offer a concrete, quantified case for considering basalt-based wrapping when assessing older building stock, particularly in regions where shear-critical columns from pre-modern-code construction remain common. The demonstration that full-surface wrapping can more than double the deformability of brittle shear-critical columns, while partial schemes remain available where budgets constrain coverage, gives retrofit designers a tested menu of options. As with any laboratory campaign, the caveats are real: the tests covered a single axial load ratio, one column size, and specific composite arrangements, and fire performance of FRP-strengthened members remains a recognized consideration in practice. But the combination of large-scale testing, systematic parameter variation, and validated numerical modeling makes a persuasive case that volcanic rock, spun into fiber and bonded onto concrete, can help the world’s aging buildings stand up to the next big shake.

Subject of Research: Seismic retrofit of reinforced concrete columns using basalt fiber-reinforced polymer composites

Article Title: Experimental and numerical investigation on the seismic performance of reinforced concrete columns retrofitted with basalt FRP composites

Article References: Jung, J.-S., Lee, B.-G., Kim, K., & Lee, K.-S. (2026). Experimental and numerical investigation on the seismic performance of reinforced concrete columns retrofitted with basalt FRP composites. Bulletin of Earthquake Engineering. https://doi.org/10.1007/s10518-026-02653-z

Image Credits: AI Generated

DOI: 10.1007/s10518-026-02653-z

Keywords: basalt fiber, FRP, seismic retrofit, reinforced concrete columns, cyclic loading, ductility, energy dissipation, finite element analysis, disturbed stress field model, shear-controlled columns, flexure-controlled columns, earthquake engineering