Search Results (614)

Top-and-seat angle connections (TSACs) exhibit inherently asymmetric and nonlinear moment–rotation behavior, which can significantly influence the global response of steel frames subjected to combined gravity and lateral loading. In this study, a three-dimensional finite element model of an unstiffened TSAC is developed and validated against experimental moment–rotation data from the literature under monotonic loading conditions. The validated model is then used to investigate the influence of key geometric parameters, including top angle thickness, bolt diameter, and beam depth, on the connection’s moment–rotation response in both positive and negative bending directions. Subsequently, the monotonic connection behavior is incorporated into nonlinear static analyses of steel portal frames to examine the effects of asymmetric connection response and moment reversal on frame-level stiffness degradation and capacity. A practical SAP2000 modeling workflow is proposed in which the finite element-derived monotonic moment–rotation curves are implemented using zero-length rotational link elements, allowing combined consideration of material, geometric, and connection nonlinearities at the structural level. The comparisons between Abaqus and SAP2000 results demonstrate consistent frame-level responses when identical monotonic connection characteristics are employed, highlighting the ability of the proposed workflow to reproduce detailed finite element predictions at the structural analysis level. The results indicate that increasing top angle thickness, bolt diameter, and beam depth enhances the lateral stiffness and base shear resistance of steel frames. Positive and negative bending directions are defined consistently with the applied gravity-plus-lateral loading sequence. Full article

To improve the seismic performance of buildings and reduce earthquake-related disaster risks, this study employs the MIDAS finite element analysis platform to establish a numerical model of a 15-story concrete-filled steel tube frame-shear wall structure. Recorded natural ground motion data are used as the primary input, and a main shock-aftershock sequence is constructed using an attenuation-based method. On this basis, a seismic fragility analysis framework is adopted to derive structural fragility curves, which are subsequently assembled into a comprehensive seismic fragility matrix. The results indicate that, under identical main shock-aftershock sequences, aftershock effects increase the collapse probability of the unretrofitted structure by approximately 17–37%. Furthermore, when buckling-restrained braces are introduced, the structural strength at the same damage state increases by about 8% under the action of the main shock alone and by nearly 24% when both the main shock and aftershocks are considered. Full article

To enhance construction efficiency and structural stability, this study investigates the mechanical behavior and deformation characteristics of a jacking steel platform system used in the core-tube construction of a supertall building. Field monitoring was conducted on site to record stress, settlement, and inclination during the jacking, construction, and self-climbing stages. A finite element model was developed to simulate the platform’s mechanical response and validated against the field measurements. Results indicate that stress and deformation remained within safe limits throughout all stages, and the vertical deformation difference between the core tube and the outer frame was primarily governed by concrete shrinkage and creep. An improved modular design was proposed to address connection limitations in the steel truss, and cross-section optimization was applied using the stress ratio method. Comparative analysis against the original diamond-type truss baseline showed that the improved system increased overall strength by 5.88% and stiffness by 4.82% while enhancing truss versatility and structural stability. These findings provide a technical basis for the modular design and optimization of jacking steel platform systems, contributing to safer and more efficient construction practices. Full article

This study presents a framework for assessing the resilience of steel special moment-resisting frame (SMRF) buildings under sequential earthquake–flood hazards. Surrogate models, including a stacked attention-based LSTM network (Stack-AttenLSTM) and CatBoost, are developed to predict key engineering demand parameters (EDPs), particularly maximum inter-storey drift ratios (MIDRs), avoiding the need for computationally expensive nonlinear time history analysis (NLTHA). The predicted EDPs are integrated with the FEMA P-58 methodology to estimate repair costs and durations, while the REDi framework is used to capture recovery delays and functionality loss. A two-storey code-compliant SMRF building is evaluated under a design-basis earthquake (DBE) with and without a subsequent 4.0 m flood. Results show that the combined hazard nearly doubles repair costs (from 0.33 to 0.77 of replacement value), increases downtime from 194 to over 411 days, and reduces the resilience index (R_i) from 0.873 to 0.265. These findings highlight the severe impacts of cascading multi-hazard events and the need to extend performance-based design toward resilience-focused strategies. The proposed surrogate-based framework provides a practical tool for evaluating multi-hazard risks and guiding the design of more resilient structures. Full article

Historic department stores are an underexamined lever for circular, low-carbon urban transition. This study tests whether Langston’s Adaptive Reuse Potential (ARP) can be applied retrospectively and how contextual readiness shapes the timing of interventions. Using the Renoma Department Store in Wroclaw, Poland (1930–2025), we reconstruct five adaptive phases and combine expert scoring of seven obsolescence dimensions (O1–O7) with a Readiness index covering finance, governance/approvals, use commitment, delivery/supply chain, and policy priority. Decision windows are interpreted via a WAIT–PREPARE–GO lens. Results show that peaks in ARP and Readiness aligned with major reinvestments—post-war reconstruction, socialist modernisation, and post-EU-accession renewal—while the original steel frame retained high structural reserves, indicating that timing was driven more by institutional and economic conditions than by technical decay. We propose ARP as an interpretive lens for circular regeneration and show that the Readiness index clarifies feasibility and risk. The combined ARP × Readiness approach yields a replicable, phase-sensitive diagnosis of adaptive capacity and intervention timing, contributing evidence to circular city practice and aligning with New European Bauhaus principles of sustainability, inclusion, and quality of place. Full article

Steel frame structures have been increasingly widely used in high-rise and multi-story building design. However, traditional rigid welded beam–column joints exhibit poor ductility and high residual stress, which are key reasons for their susceptibility to brittle failure under strong earthquake actions. This study proposes a new type of beam–column joint for steel frames: the corrugated web beam–column joint. In this new joint, the web of the I-beam near the beam flange is partially replaced with a corrugated web that exhibits a folding effect—this modification weakens the plastic bending capacity of the I-beam and promotes the outward movement of plastic hinges. Low-cycle reciprocating loading tests were conducted to verify the performance of two specimens, namely one with the traditional beam–column joint and the other with the corrugated web beam–column joint. Through experimental comparison, it was found that plastic hinges in the new corrugated web joint are generated at the corrugated web, while no damage occurs at the beam-end welds. This indicates that the corrugated web beam–column joint can stably achieve the outward movement of plastic hinges and avoid the location of the beam-end welds, thereby providing theoretical and experimental foundations for the structural design of new ductile steel frames. Full article

Tensegrity structures have developed greatly in recent years due to their unique mechanical, structural, and mathematical properties. This study presents the design and fabrication of a tensegrity structure prototype. A pretensioning device is designed, and it is directly integrated into the tension element. This component enables precise application and regulation of cable pretension. Another instrumentation device was designed to enable internal force monitoring during structural testing. A physical prototype of the second member of the Octahedron family, known as the expanded octahedron, was constructed using 1 m long steel struts with a rigid auxiliary support frame specifically designed for this purpose. This frame allows the geometry of the tensegrity structure to be controlled at any stage of the fabrication process, and it proved highly effective—maximum nodal displacements were restricted to ±0.4 mm, and the final prestress state in all 24 cables was achieved within a tight tolerance of ±5% (i.e., 600 ± 30 N). This paper provides an essential methodological reference for the structure’s fabrication and assembly, supporting future experimental analysis of its mechanical response. Full article

The construction sector faces increasing pressure to decarbonize, as embodied emissions from structural materials often dominate the environmental footprint of reinforced concrete (RC) buildings. Although reinforcement ratios are key drivers of structural capacity, their environmental implications under seismic design remain insufficiently quantified. This study investigates the relationship between longitudinal reinforcement ratios and both seismic performance and life-cycle environmental impacts in RC frame buildings. Three code-compliant reinforcement configurations (1%, 3%, and 5%) were analyzed for three- and nine-story structures designed under Eurocode 8. Mechanical performance was evaluated using nonlinear pushover analysis, while embodied impacts were quantified through Life Cycle Impact Assessment (LCIA) using the ReCiPe 2016 midpoint and endpoint methods. Results show that increasing steel content reduces concrete volume and increases lateral capacity, but may significantly decrease ductility and increase environmental burdens. Optimal performance is achieved with moderate reinforcement ratios, which reduce embodied impacts while preserving seismic safety. Furthermore, reducing the amount of concrete while increasing the amount of steel reduces the weight of structures by between 19% (3 stories) and 22% (9 stories), improving their seismic resistance due to the reduction in seismic forces in areas of moderate seismicity. These findings demonstrate that reinforcement selection introduces a measurable trade-off between structural integrity and sustainability, providing designers with quantitative guidance for low- and medium-rise RC buildings in seismic regions. Full article

Damage to structural members or joints can change the load transfer path of the structure. Additionally, structures may experience severe damage or even collapse due to the impact of aftershocks. To investigate the effects of beam-column joint damage, link damage, and aftershocks on the seismic performance of K-shaped eccentrically braced steel frame (K-EBF) structures, incremental dynamic analysis, fragility analysis, and collapse resistance evaluation were conducted using examples of 12-story and 18-story K-EBF structures. The results showed that considering beam-column joint damage, link damage, and aftershocks compared to not considering them, and the maximum inter-story drift ratio (θ_max) of the 12-story and 18-story K-EBF structures increased by 11.1% and 20.1%, respectively, under fortification earthquakes, and by 30.0% and 56.7%, respectively, under rare earthquakes. The failure probability of the severe damage limit state of the 12-story and 18-story K-EBF structures increased by 1.0% and 3.0%, respectively, under fortification earthquakes, and by 15.3% and 24.0%, respectively, under rare earthquakes. Additionally, the minimum collapse margin ratios (CMR_{P = 10%}) of the two structures decrease by 27.8% and 32.3%, respectively. The influence of aftershocks on the structural seismic response tends to intensify as the intensity of ground motion increases, and the beam-column joint damage and link damage further increases the failure probability of different damage limit states, leading to a decrease in the minimum collapse resistance coefficient of the structure. Therefore, in the seismic performance analysis of K-EBF structures, the effects of beam-column joint damage, link damage, and aftershocks should be fully considered to accurately reflect the response of structures under seismic actions. Overall, the impact of link damage, as well as aftershocks, on the structural collapse resistance is greater than that of beam-column joint damage. Full article

Installing shear walls in a load-bearing system is one of the most rational, economical, and effective strengthening methods for improving a building system that is vulnerable to seismic effects. One of the most significant points to consider in a reinforced concrete building strengthened with a shear wall is the sufficiency and reliability of anchorage elements in the shear wall–foundation joints, where significant bending moments will occur due to the impact of lateral loads. This study investigated the behaviour of different foundation anchorage methods, including internal anchorage (anchor bars) and external anchorage (steel angle and carbon-fibre-reinforced polymer (CFRP)) applied at the wall–foundation interface in retrofitted weak reinforced concrete frames, which were multi-span, multi-storey, lacking sufficient seismic detailing, and strengthened using wing-type shear walls, under quasi-static lateral loading. It was also aimed to determine the most effective anchorage method for improving the structural performance. A total of six undamaged, but seismically deficient, two-storey, two-span reinforced concrete frames were strengthened with added shear walls that incorporated different anchorage details at the shear wall–foundation joint. According to the test results, the addition of wing-shaped reinforced concrete rehabilitative walls significantly increased the lateral load-carrying capacity, lateral stiffness, and energy dissipation capacity of reinforced concrete frames with poor seismic behaviour. It was observed that additional strengthening was not required in the edge columns of frames with rehabilitative walls of a sufficient length, but that additional measures were required in the foundation anchors at the base of the strengthening wall due to the further increase in the rehabilitative wall capacity. Consequently, the most suitable shear wall foundation anchorage arrangement was achieved with test specimens where one internal anchor bar was used for each vertical shear reinforcement, independently of the shear wall length, and the development length was the highest. Full article

Modern weeding technologies include chemical weeding, non-contact methods such as laser weeding, and conventional mechanical inter-row cultivation characterized by soil loosening and weed uprooting. For maize, mechanical inter-row cultivation is key to cutting herbicide use and enhancing the soil–crop environment. This study developed a vision-guided intelligent inter-row cultivator with electric lateral shifting—its frame fabricated from Q235 low-carbon structural steel and assembled mainly via bolted and pinned joints—that computes real-time lateral deviation between the implement and crop rows through maize plant recognition and crop row fitting and uses delay compensation to command a servo-electric cylinder for precise ±15 cm inter-row adjustments corresponding to 30% of the 50 cm row spacing. To test the system’s dynamic response, 1–15 cm-commanded lateral displacements were evaluated at 0.31, 0.42, and 0.51 m/s to characterize the time-displacement response of the servo-electric shift mechanism; field tests were conducted at 0.51 m/s with three 30 m passes per maize growth stage to collect row-guidance error and root-injury data. Field results show that at an initial offset of 5 cm, the mean absolute error is 0.76–1.03 cm, and at 15 cm, the 95th percentile error is 7.5 cm. A root damage quantification method based on geometric overlap arc length was established, with rates rising with crop growth: 0.12% at the V2 to V3 stage, 1.46% at the V4 to V5 stage, and 9.61% at the V6 to V8 stage, making the V4 to V5 stage the optimal operating window. Compared with chemical weeding, the system requires no herbicide application, avoiding issues related to residues, drift, and resistance management. Compared with laser weeding, which requires high tool power density and has limited effective width, the tractor–implement system enables full-width weeding and shallow inter-row tillage in one pass, facilitating integration with existing mechanized operations. These results, obtained at a single forward speed of 0.51 m/s in one field and implement configuration, still require validation under higher speeds and broader field conditions; within this scope they support improving the precision of maize mechanical inter-row cultivation. Full article

This article presents the design process and structural analysis for Halls 3, 4, and 6 commissioned by Fira de la Gran Vía in Barcelona. Its objective is to document the complete development of a real structure—from the initial briefing to final execution—highlighting key decisions related to cost, quality, construction speed, and standardization. Rather than simply describing the finished building, the article compares alternative solutions considered at each stage and explains the rationale behind the choices made. Close collaboration between the architectural and structural teams has resulted in a cost-effective solution that has remained relevant twenty-five years after completion. Each structural component is examined in detail, considering its behavior, preliminary sizing, fabrication, transportation, and rapid on-site assembly, all essential under the client’s demanding schedule. It also describes how specific structural details were resolved under project constraints, including instances that required unconventional approaches. Finally, it discusses the role of prestressed longitudinal frames as a strategy for reducing steel consumption. This article underscores the value of integrated architectural and structural thinking in shaping the building from the ground up. Full article

Steel portal frames are widely used in industrial buildings due to their high strength-to-weight ratio and rapid erection capability. However, many existing structures exhibit insufficient load-carrying capacity under current design requirements. This study investigates the use of external post-tensioning (PT) cables and rigid wedge anchorages to enhance the overall performance of steel portal frames. Two stages of numerical analysis were performed: (i) two-dimensional parametric studies to identify the most efficient configuration and (ii) three-dimensional verification under combined gravity, wind, and seismic loading conditions. Results show that the proposed PT system significantly increases the load-carrying capacity of both beams and columns, reduces bending demands, and improves global stability without major geometric modification. The strengthening method is safe, reversible, and offers a practical alternative to conventional welded or plated retrofit techniques. Full article

Surrogate models are widely used in science and engineering to approximate other methods that are usually computationally expensive. Here, artificial neural networks (ANNs) are employed as surrogate regression models to approximate the finite element method in the problem of structural analysis of steel frames. The focus is on a multi-objective neural architecture search (NAS) that minimizes the training time and maximizes the surrogate accuracy. To this end, several configurations of the non-dominated sorting genetic algorithm (NSGA-II) are tested versus random search. The robustness of the methodology is demonstrated by the statistical significance of the hypervolume indicator. Non-dominated solutions (consisting of the set of best designs in terms of accuracy for each training time or in terms of training time for each accuracy) reveal the importance of multi-objective hyperparameter tuning in the performance of ANNs as regression surrogates. Non-evident optimal values were attained for the number of hidden layers, the number of nodes per layer, the batch size, and alpha parameter of the Leaky ReLU transfer function. These results are useful for comparing with state-of-the-art ANN regression surrogates recently attained in the recent structural engineering literature. This approach facilitates the selection of models that achieve the optimal balance between training speed and predictive accuracy, according to the specific requirements of the application. Full article

Steel moment-resisting frames rely on strength and ductility to perform under seismic loads. Conventional techniques such as reduced beam section (RBS) and reduced web section (RWS) improve ductility by relocating plastic hinges but can suffer from local buckling, fabrication challenges, and costly post-earthquake repairs. This study proposes a sacrificial steel sleeve fuse system for bolted endplate connections, designed to concentrate inelastic deformation within a replaceable sleeve while preserving the primary structural components. Experimental tests included standalone sleeve compression, bolted sleeve assemblies, and T-stub connections with and without sleeves, all validated with finite element models. A parametric study evaluated two sleeve geometries—circular wave (CW) and U-shaped (US)—and compared the sleeve fuse system’s monotonic performance with RWS and standard connections. Results indicate that properly designed sleeve fuses significantly enhance ductility and energy dissipation without compromising initial stiffness or strength, achieving up to 1.8 times the ductility and 25.9% higher energy absorption relative to RWS connections. The findings highlight the sleeve fuse as an innovative, easily replaceable, and resilient solution for seismic applications, offering a practical path for both retrofitting existing frames and designing new structures. Full article