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	<title>structural optimization &#8211; Science</title>
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	<title>structural optimization &#8211; Science</title>
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		<title>AI and Genetic Algorithms Shrink Giant Floating Wind Platforms While Predicting Steel Costs</title>
		<link>https://scienmag.com/ai-and-genetic-algorithms-shrink-giant-floating-wind-platforms-while-predicting-steel-costs/</link>
		
		<dc:creator><![CDATA[Juliet Wilcox]]></dc:creator>
		<pubDate>Fri, 09 Oct 2026 08:57:53 +0000</pubDate>
				<category><![CDATA[Climate]]></category>
		<category><![CDATA[Technology and Engineering]]></category>
		<category><![CDATA[15 MW wind turbine]]></category>
		<category><![CDATA[advanced computational tools in wind energy]]></category>
		<category><![CDATA[CAPEX]]></category>
		<category><![CDATA[cost reduction in floating wind platforms]]></category>
		<category><![CDATA[deep water wind energy development]]></category>
		<category><![CDATA[floating offshore wind]]></category>
		<category><![CDATA[floating wind turbine technology]]></category>
		<category><![CDATA[genetic algorithm]]></category>
		<category><![CDATA[genetic algorithms for structural design]]></category>
		<category><![CDATA[impact of steel costs on wind energy projects]]></category>
		<category><![CDATA[levelized cost of energy]]></category>
		<category><![CDATA[machine learning for steel price prediction]]></category>
		<category><![CDATA[offshore wind farm engineering]]></category>
		<category><![CDATA[Offshore wind platform optimization]]></category>
		<category><![CDATA[renewable energy economic analysis]]></category>
		<category><![CDATA[renewable energy economics]]></category>
		<category><![CDATA[SARIMAX]]></category>
		<category><![CDATA[semi-submersible platform]]></category>
		<category><![CDATA[semi-submersible wind turbine design]]></category>
		<category><![CDATA[steel price volatility]]></category>
		<category><![CDATA[steel weight reduction in offshore structures]]></category>
		<category><![CDATA[structural optimization]]></category>
		<category><![CDATA[time-series forecasting]]></category>
		<category><![CDATA[XGBoost]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=252893</guid>

					<description><![CDATA[Researchers combined a genetic algorithm with machine learning price forecasting to cut 643 tonnes of steel from a 15 MW floating wind platform and quantify how volatile steel markets swing project costs by up to 200 million euros per gigawatt.]]></description>
										<content:encoded><![CDATA[<p>Floating offshore wind has long promised to unlock the vast wind resources of deep waters far from shore, but the technology has hit a stubborn economic wall. A new study published in the journal Wind Energy Science by Craig White of WavEC Offshore Renewables and colleagues demonstrates a way through that wall by combining two very different computational tools: a genetic algorithm that slims down the steel skeleton of a giant floating platform, and a machine learning forecasting system that predicts how the price of steel will swing in the years ahead. The result is a 15 megawatt semi-submersible platform that sheds hundreds of tonnes of steel while still riding out the worst seas the North Atlantic can throw at it, together with a far clearer picture of what the electricity it produces will actually cost.</p>
<p>The team started from a well-known reference design, the Volturn-US-S platform developed at the University of Maine, paired with the International Energy Agency&#8217;s 15 megawatt reference wind turbine. That turbine is a monster by any measure, with a rotor diameter of 240 metres and a hub height of 150 metres, and it rests on a steel platform built around a central column connected to three outer columns through pontoons and upper supports. The researchers defined six continuous design variables, including the main platform diameter, the diameters of the central and outer columns, and the height, width and thickness of the pontoons, and then let an optimization algorithm search that design space for the lightest structure that could still survive.</p>
<p>The search itself was conducted with a genetic algorithm, a computational technique that mimics biological evolution. A population of candidate platform designs, each described by its six geometric parameters, is evaluated for fitness, and the fittest individuals are combined through simulated binary crossover and polynomial mutation to produce offspring designs. Infeasible solutions that violate physical constraints are handled with a penalty scheme that lets the algorithm compare them purely on how badly they fail. Because the algorithm is inherently random, the team ran the entire optimization ten separate times, each starting from a population of one hundred individuals and running for up to one thousand generations, to gather statistics and confirm the results were not a fluke of a single lucky run.</p>
<p>Evaluating each candidate design required a physics model, and for that the researchers turned to RAFT, an open-source frequency-domain code that models the full floating wind turbine system as a rigid body with six degrees of freedom: surge, sway, heave, roll, pitch and yaw. Rather than simulating every turbulent gust and extreme wave in the time domain, which would be computationally prohibitive across thousands of design iterations, RAFT linearizes the dynamic equations around a mean steady state, computing how the platform responds to each excitation frequency under steady winds and stochastic sea states described by a JONSWAP wave spectrum. Aerodynamic loads on the rotor come from a steady-state blade-element momentum solver, while mooring forces are handled with a quasi-static approach. The code has been validated against higher-fidelity tools such as OpenFAST and showed good agreement, making it an ideal engine for rapid design iteration.</p>
<p>Crucially, the optimization was not allowed to produce a flimsy platform that would capsize or batter its turbine. The team imposed hard constraints on maximum platform offset, platform pitch, and nacelle acceleration at the tower top, along with limits on the fore-aft bending moment at the tower base and the static stress at the critical junction where the central column meets the pontoons. These quantities were computed for a set of representative load cases, including the turbine&#8217;s rated wind speed and harsh sea states typical of European waters, with the worst result across all cases checked against each limit. A static stress analysis using a free-body approach estimated bending stresses at the pontoon base from structure weight and buoyancy loads. The outcome was striking: primary steel mass fell from 3916 tonnes to 3273 tonnes, a reduction of roughly 16 percent, while every dynamic and structural constraint remained satisfied. The optimized design features slightly larger outer columns and pontoons but a smaller overall platform diameter.</p>
<p>With a leaner platform in hand, the researchers confronted a problem that engineering alone cannot solve: the price of steel. Commodity markets have been violently volatile in recent years, particularly after the global pandemic, and steel prices feed directly into the capital expenditure of any floating wind project, since primary steel accounts for around 83 percent of total platform cost. To bring order to this uncertainty, the team built a hybrid time series forecasting tool that blends two complementary models. The first is XGBoost, a gradient-boosted decision tree algorithm that excels at capturing short-term stochastic fluctuations in market data. The second is SARIMAX, a seasonal autoregressive statistical model that tracks longer-term trends and seasonal cycles while incorporating exogenous variables, external economic indicators such as rebar and copper prices, coal costs, and London Metal Exchange indices that act as leading indicators for steel.</p>
<p>The selection of those supporting variables was itself a rigorous filtering exercise. Candidate exogenous datasets were compared against the target hot-rolled coil steel prices using correlation metrics, monthly lag testing, and rolling stability analysis, with multiple transformations including log-differences applied to the data. Only indicators that passed thresholds for predictive strength, stability, sign consistency and non-redundancy made it into the final model. When tested against hindcast data covering the turbulent market period from 2022 to 2024, the hybrid approach clearly outperformed either model alone. Without supporting data, forecasts failed to revert to the mean after the 2020 price spike; with them, the hybrid model achieved a mean absolute error of 187.5, kept its average bias close to zero, and produced the most consistent performance across root mean square error and symmetric mean absolute percentage error metrics. Interestingly, the statistical SARIMAX model actually performed best in the earliest forecast months, while the machine learning model showed a tendency to overpredict and SARIMAX alone to underpredict, suggesting the two errors partially cancel in the blend.</p>
<p>The forecasting results were then translated into money. Monthly steel price predictions were aggregated into yearly values, converted to marine-grade steel prices, and multiplied by the platform mass to yield capital costs, with other components such as secondary steel, ballast and controls costed from published industry references. For a one gigawatt floating wind farm using a net capacity factor of 0.4925, the team calculated the levelized cost of energy over a thirty-year project lifetime with an eight percent discount rate. The numbers that emerged carry a sobering message for the industry: uncertainty in steel prices alone swings total capital expenditure by roughly 150 to 200 million euros at the gigawatt scale, a variation of 40 to 50 percent across the forecast scenarios. The XGBoost forecast, which sees prices rebounding 10 to 15 percent, represents a market recovery upper bound, while the SARIMAX forecast with its continued downward drift forms the lower bound, and the hybrid model provides a balanced baseline.</p>
<p>Against that backdrop of market turbulence, the engineering gains look meaningful but partial. The optimized platform achieved cost savings of approximately 10 to 15 percent across all scenarios, and structural optimization reduced the levelized cost of energy by around one euro per megawatt-hour or more in high-price scenarios. The overall LCoE variation across the steel price forecasts was more moderate, at roughly 3 to 5 euros per megawatt-hour, because the long project lifetime and high discount rate dampen the effect of upfront capital swings. The authors are careful to note the limits of their structural analysis, which uses a relatively simple static stress check rather than a full dynamic finite-element assessment, and they deliberately selected the least successful of their ten optimization runs to build in a safety margin. Still, the framework demonstrates that design improvements are possible for reference platforms while respecting real load constraints, and that hybrid forecasting can give developers and investors a defensible range of future costs.</p>
<p>What makes this study notable is its refusal to treat engineering and economics as separate silos. Floating offshore wind grew rapidly from its first full-scale prototype in 2009 to 88 megawatts of installed capacity by 2023, but progress has since stagnated as costs have risen in a difficult macroeconomic climate. To compete in renewable energy auctions, floating wind must cut costs across dimensions, materials and site-specific design, and the floating substructure has been identified as one of the highest-potential areas for savings. By showing that a genetic algorithm can carve 643 tonnes of steel out of a commercial-scale platform, and that machine learning can put credible bounds on the commodity price risk that dominates the remaining bill, the research offers the industry a template for making both the hardware and the financial case for floating wind more robust at the same time. The forecasting code, the genetic algorithm and the RAFT model are all openly available, inviting other teams to push the approach further.</p>
<p><strong>Subject of Research:</strong> Structural and economic optimization of a 15 MW floating offshore wind platform using genetic algorithms and time series forecasting of steel prices</p>
<p><strong>Article Title:</strong> Economic and design optimization of a 15 MW floating offshore wind platform using time series forecasting</p>
<p><strong>Article References:</strong> White, C., Benifla, V., Cândido, J., &amp; Gato, L. M. C. (2026). Economic and design optimization of a 15 MW floating offshore wind platform using time series forecasting. <em>Wind Energy Science, 11</em>(9), 3703-3717. <a href="https://doi.org/10.5194/wes-11-3703-2026" rel="noopener noreferrer">https://doi.org/10.5194/wes-11-3703-2026</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.5194/wes-11-3703-2026" rel="noopener noreferrer">10.5194/wes-11-3703-2026</a></p>
<p><strong>Keywords:</strong> floating offshore wind, semi-submersible platform, genetic algorithm, time series forecasting, steel price volatility, levelized cost of energy, 15 MW wind turbine, structural optimization, XGBoost, SARIMAX, CAPEX, renewable energy economics</p>
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		<post-id xmlns="com-wordpress:feed-additions:1">252893</post-id>	</item>
		<item>
		<title>AI Discovers Multiple Growth Recipes That Build Identical Carbon Nanotube Forests</title>
		<link>https://scienmag.com/ai-discovers-multiple-growth-recipes-that-build-identical-carbon-nanotube-forests/</link>
		
		<dc:creator><![CDATA[Denise Maddox]]></dc:creator>
		<pubDate>Wed, 07 Oct 2026 07:09:28 +0000</pubDate>
				<category><![CDATA[Technology and Engineering]]></category>
		<category><![CDATA[advanced methods for carbon nanotube alignment]]></category>
		<category><![CDATA[AI-driven nanomaterials fabrication]]></category>
		<category><![CDATA[Artificial Intelligence]]></category>
		<category><![CDATA[artificial intelligence in nanomaterial manufacturing]]></category>
		<category><![CDATA[carbon nanotube synthesis optimization]]></category>
		<category><![CDATA[carbon nanotubes]]></category>
		<category><![CDATA[chemical vapour deposition]]></category>
		<category><![CDATA[controlled growth of carbon nanotube forests]]></category>
		<category><![CDATA[innovative approaches to nanotube growth]]></category>
		<category><![CDATA[inverse design]]></category>
		<category><![CDATA[Machine learning]]></category>
		<category><![CDATA[materials synthesis]]></category>
		<category><![CDATA[multi-path synthesis strategies for nanomaterials]]></category>
		<category><![CDATA[multiple synthesis recipes for nanotube arrays]]></category>
		<category><![CDATA[nanomaterials]]></category>
		<category><![CDATA[nanoscale structural assembly using AI]]></category>
		<category><![CDATA[nanostructure design via AI]]></category>
		<category><![CDATA[nanotechnology]]></category>
		<category><![CDATA[nanotechnology process convergence]]></category>
		<category><![CDATA[nanotube arrays]]></category>
		<category><![CDATA[nanotube forest height and density control]]></category>
		<category><![CDATA[National Science Review]]></category>
		<category><![CDATA[neural networks]]></category>
		<category><![CDATA[structural optimization]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=243603</guid>

					<description><![CDATA[An AI-driven inverse-design framework has identified multiple distinct chemical vapour deposition recipes that grow carbon nanotube arrays with nearly identical height, density and alignment, revealing that structurally matched nanotube forests can arise from very different processing conditions.]]></description>
										<content:encoded><![CDATA[<p>Reaching the summit of a mountain rarely demands a single path. Climbers can approach the same peak from different valleys, following routes that look nothing alike on a map yet deliver them to precisely the same point. A new study published in National Science Review suggests that the same principle governs one of nanotechnology&#8217;s most delicate manufacturing challenges: growing a forest of carbon nanotubes with exactly the height, density and alignment that an engineer specifies. Using an artificial intelligence framework that works backward from a desired structure to the conditions that produce it, researchers have shown that several genuinely different processing recipes can converge on the same structural target, a finding that could reshape how scientists think about controlled synthesis at the nanoscale.</p>
<p>Carbon nanotubes are hollow cylinders of carbon atoms with walls only one atom thick in their most extreme form, yet they possess remarkable mechanical strength, thermal conductivity and electrical properties. When millions of them grow simultaneously on a substrate, they rise in parallel like blades of grass, forming what researchers call an array or, more evocatively, a nanotube forest. The way this forest stands, how tall it grows, how tightly packed the individual tubes are, and how well they align with one another, determines how the material performs in real devices. Thermal interface materials rely on dense, well-aligned arrays to channel heat away from hotspots in electronics. Energy storage electrodes benefit from high surface area and controlled porosity. Flexible electronics demand forests that can bend and recover without collapsing. In each case, the macroscopic usefulness of the material traces directly back to those three structural descriptors: height, density and alignment.</p>
<p>The trouble is that these descriptors cannot be tuned independently. Growing nanotube forests typically relies on chemical vapour deposition, a process in which a carbon feedstock gas decomposes on catalytic nanoparticles, allowing tubes to grow upward from the surface. Water-assisted chemical vapour deposition, the variant used in this study, introduces controlled amounts of water vapour to keep the catalyst active and extend growth. But the process is a web of interdependent variables. Raising the growth temperature might accelerate catalysis and increase height, while simultaneously altering how quickly the catalyst particles sinter or deactivate, which in turn changes tube density. Adjusting gas flows, treatment times, or the timing of water injection can shift several structural features at once. A modification that nudges height toward its target may push density or alignment further away, forcing researchers into laborious trial-and-error cycles. The scale of the search space is staggering: with eight processing variables and even ten candidate settings per variable, the number of possible combinations reaches one hundred million.</p>
<p>To tame this complexity, the research team, drawn from Huazhong University of Science and Technology and Beihang University, developed an AI-assisted inverse-design framework. Inverse design flips the usual logic of materials synthesis. Instead of running an experiment and measuring what comes out, the researcher specifies the outcome first, the desired height, density and alignment, and asks an algorithm to find the processing conditions most likely to deliver it. The team began by assembling an experimental database of two hundred distinct recipes for water-assisted chemical vapour deposition, each recording the full set of processing conditions alongside the structural features of the resulting array. A neural network then absorbed this dataset, learning the intricate mapping from processing space to structural space, including the nonlinear couplings that make manual optimization so difficult.</p>
<p>On top of this learned model, the researchers deployed an optimization algorithm that searches processing space in reverse, proposing recipes predicted to hit a prescribed structural target. Crucially, the framework was designed not to find one answer but many. For each of three distinct structural targets, repeated computational searches generated two hundred candidate solutions. Rather than accepting the single best-scoring recipe, the team deliberately selected three candidates whose processing conditions differed substantially from one another. This is where the mountain analogy becomes more than a metaphor: the optimization landscape contains many peaks that satisfy the same structural criteria, and a navigator equipped with a learned map can explore routes far from the well-worn trail surrounding a familiar recipe.</p>
<p>The experimental validation was rigorous. Each of the three selected recipes for each target was tested in three independent growth batches, producing twenty-seven validation runs in total. Of these, twenty-six achieved structural descriptor matching scores above ninety-five percent, meaning the measured height, density and alignment of the grown arrays came within a few percent of the prescribed targets. The consistency across independent batches matters as much as the scores themselves, because it demonstrates that the AI-identified recipes are not statistical flukes but reproducible synthesis protocols. For all three targets, the framework had successfully converted a specification into working laboratory instructions, and it had done so through multiple, demonstrably different routes.</p>
<p>Yet the story acquires its most intriguing twist at smaller length scales. When the researchers examined the nanotubes themselves under electron microscopy, the forests that looked identical at the array level turned out to be built from different trees. For one target, the three successful routes produced arrays with closely matched overall features, but the mean outer diameters of the individual nanotubes measured approximately 3.8, 4.8 and 7.2 nanometres respectively. The wall structures of the tubes, whether single-walled or multi-walled and how many concentric layers they contained, also differed between routes. Similar forests, in other words, need not contain identical trees. This observation carries practical weight: applications sensitive to nanotube diameter or wall number, such as electronic transport or optical absorption, may respond differently to arrays that satisfy the same coarse structural specification.</p>
<p>The broader implication is a shift in what inverse synthesis aims to accomplish. Traditional optimization seeks a single best recipe, but this work demonstrates that the goal can be reframed as identifying a family of experimentally accessible alternatives, each satisfying the same structural target while differing in the practical demands they place on a laboratory. One route might use a temperature that a particular furnace reaches easily; another might favour gas flows that are cheaper or safer. The AI framework functions as a navigation aid built from accumulated experimental knowledge, and its learned relationship between processing and structure can be reused to screen additional targets without repeating the full experimental investment. The initial database of two hundred recipes remains a significant cost, and extending the approach to other catalysts, feedstocks or growth methods would require new experimental data and model retraining, but within its trained domain the framework offers a reusable map of synthesis space.</p>
<p>For a field that has long treated nanotube growth as something of an artisanal craft, the study offers a glimpse of a more flexible future, one in which engineers specify the structure they need and choose among several validated paths to reach it, constrained only by the equipment and materials at hand. The work, led by first author Lei Zhu, a doctoral student at Huazhong University of Science and Technology, with Professor Ming Xu as corresponding author, suggests that the one hundred million possible combinations of processing variables are not an obstacle but an opportunity: hidden within that vast space lie many recipes for the same material, and artificial intelligence is now capable of finding them, testing them against reality, and revealing that even at the nanoscale, there is more than one way to grow a forest.</p>
<p><strong>Subject of Research:</strong> AI-assisted inverse design of carbon nanotube array synthesis by chemical vapour deposition</p>
<p><strong>Article Title:</strong> AI finds different recipes for carbon nanotube forests with matching structures</p>
<p><strong>Article References:</strong> AI finds different recipes for carbon nanotube forests with matching structures. (n.d.). <a href="https://www.eurekalert.org/news-releases/1146639" rel="noopener noreferrer">Original publication</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> Not provided</p>
<p><strong>Keywords:</strong> carbon nanotubes, inverse design, artificial intelligence, chemical vapour deposition, nanomaterials, machine learning, materials synthesis, nanotube arrays, neural networks, National Science Review, nanotechnology, structural optimization</p>
]]></content:encoded>
					
		
		
		<post-id xmlns="com-wordpress:feed-additions:1">243603</post-id>	</item>
		<item>
		<title>AI Learns to Predict How Friction Dampers Shield Buildings from Earthquakes</title>
		<link>https://scienmag.com/ai-learns-to-predict-how-friction-dampers-shield-buildings-from-earthquakes/</link>
		
		<dc:creator><![CDATA[Denise Maddox]]></dc:creator>
		<pubDate>Fri, 02 Oct 2026 05:13:40 +0000</pubDate>
				<category><![CDATA[Technology and Engineering]]></category>
		<category><![CDATA[Coulomb's law in damping devices]]></category>
		<category><![CDATA[coverage density]]></category>
		<category><![CDATA[Earthquake engineering]]></category>
		<category><![CDATA[earthquake engineering innovations]]></category>
		<category><![CDATA[earthquake-resistant building design]]></category>
		<category><![CDATA[energy dissipation]]></category>
		<category><![CDATA[friction damper placement optimization]]></category>
		<category><![CDATA[hysteretic energy dissipation]]></category>
		<category><![CDATA[Machine learning]]></category>
		<category><![CDATA[machine learning in structural engineering]]></category>
		<category><![CDATA[non-smooth dynamics]]></category>
		<category><![CDATA[nonlinear time-history simulations]]></category>
		<category><![CDATA[predictive modeling for seismic protection]]></category>
		<category><![CDATA[rotational friction dampers]]></category>
		<category><![CDATA[seismic energy dissipation]]></category>
		<category><![CDATA[seismic response]]></category>
		<category><![CDATA[steel frame earthquake response]]></category>
		<category><![CDATA[steel moment frames]]></category>
		<category><![CDATA[structural damage mitigation during earthquakes]]></category>
		<category><![CDATA[structural optimization]]></category>
		<category><![CDATA[surrogate model]]></category>
		<category><![CDATA[time-history analysis]]></category>
		<category><![CDATA[XGBoost]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=225842</guid>

					<description><![CDATA[A new machine learning framework trained on roughly 434,000 nonlinear earthquake simulations reveals that taller steel buildings need proportionally fewer friction dampers than low-rise ones, and identifies the exact coverage thresholds where added devices stop paying off.]]></description>
										<content:encoded><![CDATA[<p>Earthquake engineers have long sought a way to protect buildings without sacrificing the structure itself, and rotational friction dampers (RFDs) have emerged as one of the most promising answers. These devices, which dissipate seismic energy through controlled dry friction between rotating plates, redirect destructive ground-motion energy away from load-bearing steel members and into replaceable mechanical components. Now, a new study published in Machine Learning with Applications by Emiliano Ponce-López and Humberto Yáñez-Godoy has combined an exact simulation method for friction with machine learning to map, for the first time at this scale, how damper placement and capacity shape the seismic response of steel frames. The result is a design blueprint distilled from roughly 434,000 nonlinear time-history simulations.</p>
<p>The appeal of friction dampers lies in their physics. Conventional steel frames absorb earthquake energy by yielding, which means the structure itself accumulates damage with every loading cycle, a phenomenon engineers call cyclic deterioration or pinching. An RFD behaves differently. Governed by Coulomb&#8217;s law of dry friction, it produces stable, rectangular hysteretic loops whose enclosed area, and therefore the energy dissipated per cycle, remains constant no matter how many times the ground shakes. The device consists of a central rotating plate sandwiched between side plates with friction discs, all clamped by a pre-tensioned bolt. When inter-story drift forces the plates to rotate against one another, friction resists the motion with a constant moment, protecting the primary frame. Experimental work dating back to Mualla and Belev in 2002 showed reductions of up to 89 percent in lateral displacement and 41 percent in base shear under optimized configurations.</p>
<p>Simulating such devices accurately, however, is notoriously difficult. The abrupt transition between sticking and slipping is mathematically discontinuous, and the two common workarounds both introduce error. Regularization smooths the discontinuity with an artificial curve, adding fake compliance exactly where the response should be sharp, while equivalent-damping approaches replace the device with a viscous dashpot that cannot reproduce the rate-independent, rectangular hysteretic loop. Both require case-specific calibration, which would be hopeless at the scale of hundreds of thousands of simulations. The authors instead built on the Non-Smooth Dynamics method, reformulating Coulomb friction as a Linear Complementarity Problem solved at each timestep with a Projected Successive Over-Relaxation algorithm. This formulation reproduces the exact friction law with no tuning parameters, and because each step typically converges in fewer than five iterations, sweeping thousands of structural configurations becomes computationally feasible. Crucially, it also means the training labels fed to the machine learning models contain pure physics rather than artifacts of a smoothing choice.</p>
<p>The dataset behind the study is staggering in scope. The team generated 1,000 shear-type frames ranging from 3 to 20 stories, with randomized Latin Hypercube sampling covering fundamental periods from 0.3 to 3.0 seconds, floor masses from 150 to 350 tonnes, and four different mass and stiffness distributions. Each frame was fitted with roughly 50 different damper configurations, varying the number of devices, their vertical placement, and friction moments between 25 and 500 kilonewton-meters. Eight real seismic records, including El Centro 1940, Kobe 1995, and Northridge 1994, were applied at their original historical intensities. In total, 433,984 nonlinear simulations were run, each quantified with a composite index called CR2 that combines peak roof displacement, peak roof acceleration, and peak base shear, each normalized by the uncontrolled response, so that lower values mean better performance.</p>
<p>Six regression models were then trained to predict seismic performance from the design variables, and the comparison itself delivered a scientific finding. Linear models achieved a cross-validated coefficient of determination of only 0.64 for the typical scenario, while XGBoost reached 0.907 and Random Forest 0.904, cutting prediction error nearly in half. The gap proves that the relationship between damper design and seismic response is fundamentally nonlinear, with threshold effects and interactions that simple equations cannot capture. The nonlinearity deepens under severe ground motion: for the conservative 90th-percentile scenario, linear models managed only 0.31, while Random Forest reached 0.786. To prevent data leakage, the team used structure-grouped cross-validation, ensuring models were always evaluated on buildings they had never seen, and verified accuracy on 200 entirely held-out structures with calibrated 90 percent prediction intervals.</p>
<p>The most striking practical insight concerns coverage density, the fraction of floors equipped with dampers. Feature importance analysis identified this single variable as the dominant predictor of performance, and the response surface revealed clear diminishing returns. By formulating the threshold as an explicit optimization over the trained surrogate, the researchers found that the median coverage at which 80 percent of the maximum achievable gain is reached sits at about 0.83, or 0.86 when read from the empirical envelope across the whole population. Resolved by building height, the picture inverts common intuition: low-rise frames of 3 to 5 stories require full coverage, mid-rise frames of 6 to 12 stories need at least 86 percent, and high-rise frames of 13 to 20 stories need only about 73 percent, with none requiring full instrumentation. The mechanical explanation is elegant, since tall buildings concentrate drift demand in a subset of stories that can be covered selectively, whereas the flat drift profile of a low-rise frame leaves no inexpensive stories to omit.</p>
<p>The analysis also uncovered a counterintuitive failure mode. A small number of oversized dampers, high friction moments paired with low coverage, can leave a frame worse off than no dampers at all. In this lock-up regime, the devices never reach their slip threshold under the imposed demand, act as rigid links, and locally stiffen the structure, amplifying floor accelerations and base shear. These configurations account for just 1.4 percent of the dataset but nearly 10 percent of the total prediction error, and more than 80 percent of them occur in frames of five stories or fewer. The practical lesson is a lower bound on coverage for any given device capacity: coverage cannot be traded freely against friction moment. The study identifies an optimal friction moment window of roughly 300 to 460 kilonewton-meters for mid- and high-rise frames, with a lower optimum near 250 kilonewton-meters for short buildings.</p>
<p>Robustness across seismic scenarios proved to be another strength of the framework. When the researchers compared the optimal damper count recommended under typical conditions with that recommended under the conservative 90th-percentile scenario, 67.9 percent of the 1,000 structures received identical recommendations, and in the remaining cases the median discrepancy was just one damper. The conservative scenario never suggested fewer devices, only occasionally one or two more, meaning designers can optimize for typical demand and then verify against severe conditions with minimal adjustment. This multi-record approach, summarizing performance with 10th-percentile, median, and 90th-percentile statistics consistent with the FEMA P-58 framework, addresses a long-standing gap in earlier studies that optimized dampers against a single ground motion.</p>
<p>The authors are candid about the limits of their results. The structural models are elastic shear frames, and a substantial fraction of the simulated demand levels actually lie at or beyond the yield limit of real steel frames, so the coverage recommendation should be read as an upper bound for quasi-elastic serviceability design rather than a validated rule for ductile response. The design space is a factorial sweep rather than a representative building stock, and the eight-record suite carries sampling uncertainty of about 0.10 in CR2 units, which exceeds the surrogate&#8217;s own prediction error of 0.070 by roughly half. That last point may be the study&#8217;s most consequential methodological message: enlarging the ground motion database, not refining the machine learning model, is what would most sharpen future design guidance. Future extensions include soil-structure interaction, three-dimensional frames with torsional coupling, nonlinear material behavior, floor-specific friction moments, and cost-based optimization.</p>
<p>Even with those caveats, the work marks a genuine shift in how earthquake protection devices might be designed. Instead of running expensive simulations case by case, engineers can now query a trained surrogate that exposes the entire response surface across damper placement, capacity, and building geometry in milliseconds, complete with calibrated uncertainty bounds. The finding that taller buildings need proportionally fewer instrumented floors, that a coverage threshold near 86 percent captures most of the achievable benefit for mid-rise construction, and that a handful of oversized devices can actively harm a structure, together give practitioners an evidence-based starting point that previously required months of computation. As machine learning surrogates spread through earthquake engineering, this study offers both a template, exact physics in the labels, grouped validation, honest uncertainty, and a reminder that the biggest gains sometimes come from questioning design intuition.</p>
<p><strong>Subject of Research:</strong> Machine learning surrogate modeling of nonlinear seismic response of steel moment frames with rotational friction dampers</p>
<p><strong>Article Title:</strong> A machine learning-based surrogate model for analyzing the nonlinear seismic response of steel moment frames with rotational friction dampers</p>
<p><strong>Article References:</strong> Ponce-López, E., &amp; Yáñez-Godoy, H. (2026). A machine learning-based surrogate model for analyzing the nonlinear seismic response of steel moment frames with rotational friction dampers. <em>Machine Learning with Applications, 26</em>, Article 101030. <a href="https://doi.org/10.1016/j.mlwa.2026.101030" rel="noopener noreferrer">https://doi.org/10.1016/j.mlwa.2026.101030</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1016/j.mlwa.2026.101030" rel="noopener noreferrer">10.1016/j.mlwa.2026.101030</a></p>
<p><strong>Keywords:</strong> rotational friction dampers, machine learning, seismic response, steel moment frames, XGBoost, non-smooth dynamics, earthquake engineering, surrogate model, coverage density, structural optimization, energy dissipation, time-history analysis</p>
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		<title>Simple Algorithms Outsmart Heavyweights in Earthquake-Resistant Roof Design</title>
		<link>https://scienmag.com/simple-algorithms-outsmart-heavyweights-in-earthquake-resistant-roof-design/</link>
		
		<dc:creator><![CDATA[Violet Maxwell]]></dc:creator>
		<pubDate>Wed, 30 Sep 2026 22:12:50 +0000</pubDate>
				<category><![CDATA[Earth Science]]></category>
		<category><![CDATA[computational optimization in structural engineering]]></category>
		<category><![CDATA[cost-effective structural design]]></category>
		<category><![CDATA[earthqauke-resistant architecture]]></category>
		<category><![CDATA[Earthquake engineering]]></category>
		<category><![CDATA[earthquake-resistant roof design]]></category>
		<category><![CDATA[far-fault ground motions]]></category>
		<category><![CDATA[innovative engineering solutions]]></category>
		<category><![CDATA[lightweight steel roof structures]]></category>
		<category><![CDATA[MATLAB]]></category>
		<category><![CDATA[metaheuristic algorithms]]></category>
		<category><![CDATA[metaheuristic algorithms for structural design]]></category>
		<category><![CDATA[near-fault ground motions]]></category>
		<category><![CDATA[nonlinear seismic simulation]]></category>
		<category><![CDATA[nonlinear time-history analysis]]></category>
		<category><![CDATA[performance comparison of optimization algorithms]]></category>
		<category><![CDATA[Rao algorithms]]></category>
		<category><![CDATA[SAP2000]]></category>
		<category><![CDATA[seismic isolation]]></category>
		<category><![CDATA[seismic load resistance in engineering]]></category>
		<category><![CDATA[steel space truss]]></category>
		<category><![CDATA[steel space truss structures]]></category>
		<category><![CDATA[structural optimization]]></category>
		<category><![CDATA[structural optimization methods]]></category>
		<category><![CDATA[TLBO]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=219646</guid>

					<description><![CDATA[A new study shows that simple Rao optimization algorithms match established methods in designing seismically isolated steel space truss roofs while halving computation time and revealing that far-fault ground motions can still challenge isolated structures.]]></description>
										<content:encoded><![CDATA[<p>Engineers have long faced a stubborn dilemma when designing the vast steel space truss roofs that span stadiums, hangars, and industrial halls: the structures must be light enough to be economical, yet strong enough to survive some of the most violent ground motions nature can deliver. A new study published in the Bulletin of Earthquake Engineering by Muhammet Yurdakul of Karadeniz Technical University in Türkiye tackles that dilemma head-on, combining cutting-edge computational optimization with detailed nonlinear seismic simulation. The results suggest that some of the newest and simplest optimization algorithms in the metaheuristic toolbox can match the performance of established methods while cutting the computational bill nearly in half.</p>
<p>The research focuses on the Steel Space Truss Roof Structure, or SSTRS, a three-dimensional lattice of steel members whose individual tube sizes collectively determine both the weight of the roof and its capacity to resist gravity and seismic loads. Because each member can, in principle, be drawn from a catalog of available profiles, the design space is enormous, and searching it exhaustively is impossible. This is where metaheuristic algorithms come in: inspired loosely by natural processes such as learning and evolution, they explore the design space intelligently, iteratively refining candidate solutions until an optimal or near-optimal configuration emerges.</p>
<p>Yurdakul&#8217;s framework pits four algorithms against one another. Three belong to the relatively recent Rao family, developed by engineer R. Venkata Rao: the standard Rao-1 and Rao-2, and a self-adaptive variant called SapRao. These algorithms are notable for being metaphor-free, meaning they rely on straightforward mathematical comparisons between the best and worst candidate designs in a population rather than elaborate analogies drawn from animal behavior or physical phenomena. They are benchmarked against the well-established Teaching-Learning-Based Optimization algorithm, or TLBO, which simulates a classroom in which learners improve through interaction with teachers and with one another.</p>
<p>The computational engine behind the study is an integrated SAP2000-MATLAB environment. MATLAB scripts drive the finite element software SAP2000 through its Open Application Programming Interface, automating the otherwise laborious cycle of model updating, structural analysis, and constraint checking. Each candidate design is subjected to multiple load scenarios, including dead load, wind, snow, cladding, and seismic actions, with the sizing rules drawn from codes such as the AISC allowable stress design provisions, the Turkish building earthquake code, and Turkish loading standards. The automation means that thousands of design iterations, each requiring a full structural analysis, can be executed without human intervention.</p>
<p>To assess seismic performance, the study goes well beyond simplified equivalent static methods. Both fixed-base and seismically isolated versions of the truss roof were analyzed using nonlinear time-history analyses under scaled bi-directional ground motions, including the often-neglected vertical components of earthquake shaking. The ground motion suites distinguish between near-fault records, which carry the characteristic velocity pulses and directional effects of shaking close to a rupturing fault, and far-fault records, which lack those intense directivity pulses but can still be demanding in their own way. This distinction matters, because the two classes of motion excite structures differently and can expose different vulnerabilities.</p>
<p>The headline computational finding is striking. The standard Rao-1 algorithm achieved exactly the same minimum structural weights as TLBO across the evaluated fixed-base seismic design suites, yet it did so with a 50.68 percent reduction in total execution time. In a field where a single optimization run can consume hours or days of computing, halving the runtime without sacrificing solution quality is a meaningful advance. It suggests that the elegant simplicity of the Rao formulation, far from being a limitation, may actually be an asset when the underlying structural analyses are themselves computationally expensive.</p>
<p>The seismic findings carry equally important implications for practice. Near-fault ground motions induced locally elevated structural demands in the truss, concentrating forces and displacements in ways that designers of long-span roofs cannot afford to ignore. Perhaps more surprising, far-fault records with large displacement pulses could still produce relatively high response ratios even in the seismically isolated configuration. The result is a caution against the assumption that isolation alone guarantees protection: the character of the ground motion, not merely its proximity to the fault, governs how much demand reaches the superstructure.</p>
<p>That said, the isolation system proved remarkably effective at filtering out severe accelerations. Across all optimization algorithms and all ground motion records, the optimized weight of the isolated structure converged to exactly 47.4 percent of the maximum weight obtained for the fixed-base case. In other words, decoupling the roof from the ground through seismic isolation allowed the members to be sized at less than half the weight required for a conventionally fixed design, a difference that translates directly into material savings, lower fabrication costs, and a reduced carbon footprint for large-span construction.</p>
<p>The study situates itself within a rapidly growing body of work on metaheuristic structural optimization, which spans genetic algorithms, particle swarm methods, and hybrid schemes applied to trusses, domes, and bridges. It also connects to an active literature on optimizing seismic isolation systems, including friction pendulum bearings and other sliding devices, whose nonlinear behavior must be captured realistically in analysis. By bringing these two threads together, optimizing the steel superstructure while simultaneously evaluating a nonlinear isolation system under realistic, bi-directional, multi-component earthquake loading, the research offers one of the more complete pictures to date of how long-span roofs can be designed for seismic regions.</p>
<p>For engineers, the practical message is twofold. First, the choice of optimization algorithm matters less for the quality of the final design than for the cost of finding it, and simple, metaphor-free algorithms like Rao-1 deserve a place in the production toolkit. Second, seismic isolation can deliver dramatic weight savings for space truss roofs, but the design must be verified against both near-fault and far-fault suites, because large displacement pulses in distant records can still push response ratios upward. As computational tools become ever more tightly integrated with design codes, studies of this kind point toward a future in which earthquake-resistant long-span structures are not only safer but substantially lighter and cheaper to build.</p>
<p><strong>Subject of Research:</strong> Metaheuristic optimization and seismic response of steel space truss roof structures with base isolation</p>
<p><strong>Article Title:</strong> Metaheuristic-based optimization of steel space truss roof structures with seismic isolation</p>
<p><strong>Article References:</strong> Yurdakul, M. (2026). Metaheuristic-based optimization of steel space truss roof structures with seismic isolation. <em>Bulletin of Earthquake Engineering</em>. <a href="https://doi.org/10.1007/s10518-026-02702-7" rel="noopener noreferrer">https://doi.org/10.1007/s10518-026-02702-7</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1007/s10518-026-02702-7" rel="noopener noreferrer">10.1007/s10518-026-02702-7</a></p>
<p><strong>Keywords:</strong> structural optimization, metaheuristic algorithms, Rao algorithms, TLBO, steel space truss, seismic isolation, near-fault ground motions, far-fault ground motions, nonlinear time-history analysis, SAP2000, MATLAB, earthquake engineering</p>
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