Search Results (416)

Existing studies have demonstrated that insufficient horizontal deformation capacity of columns under high axial compression ratios constitutes a key factor leading to seismic damage in ordinary concrete frame structures. This paper proposes a novel framed structure incorporating composite columns by combining ultra-high performance concrete (UHPC), which exhibits excellent mechanical properties, with normal concrete (NC). The design concept maintains the overall mechanical performance of the composite column frame structure while significantly reducing the lateral stiffness when the composite columns are configured in a “split-column form.” For instance, the lateral stiffness of ZH-5 in the “split-column form” is only one-tenth of that of ZT-1 in its initial state, leading to a substantial enhancement in horizontal deformation capacity. This design approach maintains the overall mechanical performance of the composite column frame structure while significantly enhancing its horizontal deformation capacity by reducing lateral stiffness through the “split-column” configuration. Using the ABAQUS finite element software 2021, a finite element model of a multi-story frame column structure was developed. Research findings indicate that the frame structure utilizing UHPC-NC composite columns exhibits reduced tensile damage, lower peak and plastic displacements, and a relatively smaller inter-story drift angle. Specifically, the plastic drift angle of the UHPC-NC composite column frame structure from the first to the fourth story is 5% to 31% smaller than that of the conventional reinforced concrete column frame structure. The novel UHPC-NC composite column frame structure demonstrates superior seismic performance. Full article

To address poor seismic performance, large residual displacement, and insufficient self-centering capacity of prefabricated frame joints in building industrialization, this study proposes a novel self-centering prefabricated frame joint reinforced with shape memory alloy fiber (SMAF)–engineered cementitious composite (ECC) composites (SMAF-ECC). A validated finite element model of the proposed joint was established using ABAQUS, with comparative analyses conducted against conventional reinforced concrete (RC) and ECC-strengthened (RC-E) joint models to explore the effect of SMAF volume content on seismic performance. Results show that replacing the joint core zone concrete with SMAF-ECC significantly enhances the joint’s seismic and self-centering capabilities, reducing residual displacement and optimizing hysteretic behavior. SMAF volume content is a key factor affecting performance, with an optimal value identified and excessive content leading to fiber agglomeration and degraded self-centering ability. This study provides a feasible solution to improve the seismic resilience of prefabricated frame joints, laying a foundation for the application of SMAF-ECC in prefabricated structures. Full article

The use of drywall as a non-structural infill has grown significantly due to its rapid and economical installation. Despite this widespread use, a common assumption in structural design is that these elements do not significantly affect seismic performance and are often ignored in analysis. This assumption, however, is increasingly questioned. This study presents a full-scale experimental evaluation of the influence of drywall infill on the seismic response of reinforced concrete frames under cyclic loading. The results quantify how the inclusion of these non-structural elements alters the dynamic properties and structural response of the frame. The infill increased the initial lateral stiffness by approximately three times with respect to the bare frame, thus modifying the structure’s fundamental period. The infill also altered the failure mechanism, initiating with a transient compression strut action at very low drifts, which rapidly and concurrently transitioned into a dominant membrane behavior. This membrane contribution ceased abruptly at a drift of 0.89%, prior to the life-safety limits specified by Eurocode 8. The study’s findings demonstrate the necessity of incorporating the non-linear stiffness and energy dissipation of drywall into structural models to ensure reliable and accurate predictions in seismic design methodologies. 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

Corrosion in reinforced concrete (RC) structures increases seismic fragility by reducing strength, ductility, and bond integrity, which becomes critical in aging infrastructure. This study provides a systematic fragility comparison of intact, corroded, and FRP-strengthened structures across multiple corrosion levels under sequential earthquakes. The seismic fragility of corroded RC frames, with and without fiber-reinforced polymer (FRP) retrofitting, is investigated under both mainshock and aftershock loading conditions. A total of 508 real recorded mainshock–aftershock ground motion sequences are selected as seismic inputs to ensure the representation of earthquake demands. Nonlinear time history analyses are carried out to establish fragility curves for four limit states based on probabilistic demand–capacity relationships. The results show that corrosion significantly decreases the collapse prevention capacity (LS₄), with the maximum reduction reaching about 62%. FRP retrofitting restores seismic performance to varying degrees depending on corrosion severity. For the structure with a 10% corrosion rate, FRP retrofitting enhances the collapse capacity beyond that of the intact case. For the structure with a 20% corrosion rate, FRP retrofitting recovers approximately two-thirds of the lost capacity caused by reduced ductility. The consideration of aftershock effects further increases the fragility of corroded structures, yet FRP retrofitting continues to provide improvement by reducing cumulative damage and improving deformation capacity. The study confirms that the FRP confinement effectively enhances the seismic resilience of aging RC structures and provides a practical basis for performance-based retrofit strategies under sequential earthquake events. 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

Seismic design of reinforced concrete buildings in highly active seismic regions is challenging, as structural members are often oversized due to conservative design practices, leading to inefficient use of materials. This study proposes an optimization methodology based on the Peruvian seismic code E.030, implemented with the OpenSeesPy library for modeling and numerical analysis. The methodology automates the linear analysis of frame structures through the parametrization of member dimensions, span lengths, and material properties. Optimization is carried out using the Hill Climbing algorithm, which iteratively explores design alternatives and verifies compliance with code requirements for interstory drift and base shear. Results show material savings of up to 20% in beams and columns. Although interstory drifts increased by 60–85% compared to the initial configuration, they remained within code limits. The methodology establishes a framework for integrating optimization techniques into the seismic design of reinforced concrete frame buildings. Full article

Urban infrastructure in seismic zones demands efficient and scalable tools for damage prediction. This study introduces an attention-integrated progressive transfer learning (PTL) framework for the seismic vulnerability assessment (SVA) of reinforced concrete (RC) frame buildings. Traditional simulation-based vulnerability models are computationally expensive and dataset-specific, limiting their adaptability. To address this, we leverage a pretrained artificial neural network (ANN) model based on nonlinear static pushover analysis (NSPA) and Monte Carlo simulations for a 4-story RC frame, and extended its applicability to 2-, 8-, and 12-story configurations via PTL. An attention mechanism is incorporated to prioritize critical features, enhancing interpretability and classification accuracy. The model achieves 95.64% accuracy across five damage categories and an R² of 0.98 for regression-based damage index predictions. Comparative evaluation against classical and deep learning models demonstrates superior generalization and computational efficiency. The proposed framework reduced retraining requirements across varying building heights, shows potential adaptability to other structural typologies, and maintains high predictive fidelity, making it a practical AI solution for structural risk evaluation in seismically active regions. Full article

The increasing integration of Chinese-engineered infrastructure in Pakistan under the China–Pakistan Economic Corridor (CPEC) necessitates a comparative evaluation of seismic resilience between the Chinese and Pakistani building codes. This study focused on the seismic performance of reinforced concrete (RC) frames designed according to these two codes. Fragility curves were generated for 4-story, 8-story, and 12-story buildings subjected to varying seismic intensities using Incremental Dynamic Analysis (IDA). The results indicate that structures designed under the Chinese code exhibit up to 12% lower fragility values, suggesting enhanced seismic resilience, particularly at higher seismic intensities. Additionally, the study investigates the effectiveness of Lead Rubber Bearings (LRBs) for seismic isolation, demonstrating that their integration improves the seismic performance of RC frames by enhancing energy dissipation and reducing the likelihood of exceeding various damage states by up to 25%. These findings underscore the importance of adopting stringent seismic design provisions, such as those found in the Chinese code, to enhance the resilience and safety of infrastructure, especially in seismic-prone regions. Full article

Colombia is located in a region of significant seismic hazard, where reinforced concrete portal frame systems represent a dominant structural typology. Despite this relevance, the existing literature lacks an integrated evaluation that simultaneously examines the evolution of Colombian seismic design regulations (NSR) and the scientific production associated with their development and application. This study addresses this gap by conducting a two-part analysis. First, a comparative engineering review of the three main versions of the Colombian Earthquake Resistant Standard (CCCSR-84, NSR-98, NSR-10) demonstrates substantial changes in material requirements, detailing rules, structural system classification, and capacity design principles. Results indicate that adopting NSR-10 led to a 15–25% increase in concrete and steel demand, thereby improving structural resilience and ductility in reinforced concrete buildings. Second, a bibliometric analysis using Scopus and processed through Bibliometrix examined 87 documents, involving 286 authors, 93 institutions, and 17 countries, revealing an annual publication growth rate of 4.85% between 1989 and 2023. Approximately 75% of the publications focus on reinforced concrete and seismic design, whereas 19.5% involve international collaboration. The thematic mapping highlights clusters related to capacity design, ductility, seismic vulnerability, and retrofitting. These findings underscore the progressive refinement of Colombian seismic regulations and their growing impact on academic research, advancing safer, more resilient seismic design practices in the country. Full article

This study examines Phase B of the GREENERGY project focusing on the seismic performance and structural health monitoring of a renovated single-story RC frame with brick masonry infills that received significant strategic structural interventions. The columns were confined with basalt fiber ropes (FR, 4 mm thickness, two layers) in critical regions, the vertical interfaces between infill and concrete were filled with polyurethane PM forming PUFJ (PolyUrethane Flexible Joints), and glass fiber mesh embedded in polyurethane PS was applied as FRPU (Fiber Reinforced PolyUrethane) jacket on the infills. Further, greenery renovations included the attachment of five double-stack concrete planters (each weighing 153 kg) with different support-anchoring configurations and of eight steel frame constructions (40 kg/m²) simulating vertical living walls (VLW) with eight different connection methods. The specimen was subjected to progressively increasing earthquake excitation based on the Thessaloniki 1978 earthquake record with peak ground acceleration ranging from EQ0.07 g to EQ1.40 g. Comprehensive instrumentation included twelve accelerometers, eight draw wire sensors, twenty-two strain gauges, and a network of sixty-one PZTs utilizing the EMI (Electromechanical Impedance) technique. Results demonstrated that the structure sustained extremely high displacement drift levels of 2.62% at EQ1.40 g while maintaining structural integrity and avoiding collapse. The PUFJ and FRPU systems maintained their integrity throughout all excitations, with limited FRPU fracture only locally at extreme crushing zones of two opposite bottom bricks. Columns’ longitudinal reinforcement entered yielding and strain hardening at top and bottom critical regions provided the FR confinement. VLW frames exhibited equally remarkably resilient performance, avoiding collapse despite local anchor degradation in some investigated cases. The planter performance varied significantly, yet avoiding overturning in all cases. Steel rod anchored planter demonstrated superior performance while simply supported configurations on polyurethane pads exhibited significant rocking and base sliding displacement of ±4 cm at maximum intensity. PZT structural health monitoring (SHM) sensors successfully tracked damage progression. RMSD indices of PZT recordings provided quantifiable damage assessment. Elevated RMSD values corresponded well to visually observed local damages while lower RMSD values in columns 1 and 2 compared with columns 3 and 4 suggested that basalt rope wrapping together with PUFJ and FRPU jacketed infills in two directions could restrict concrete core disintegration more effectively. The experiments validate the advanced structural interventions and vertical forest renovations, ensuring human life protection during successive extreme EQ excitations of deficient existing building stock. Full article

Prescriptive building culture, as a form of determinism, shapes architects’ tectonic approaches by imposing prescriptive technical limits (PTLs) during the building process. Exploring PTLs provides a foundation for describing overarching tectonic approaches in practice that have not been systematically studied. This research provides a comprehensive overview of emerging PTLs among Turkish Cypriot architects in Northern Cyprus, examining their types, sources, emergence stages, root causes, and impact on tectonic design strategies. The study employed mixed-methods Sequential Explanatory Design (SED), combining survey and interview data. Findings reveal that architects mainly adopt conservative tectonic approaches in response to PTLs, reflecting limited innovative attitudes in technical and structural design, with rare tendencies towards more innovative strategies. Qualitative analysis maps structural engineers and legal frameworks as primary initiators, while PTLs mainly occur during preliminary design, construction documentation, and application visa stages. The key contributions are: (i) a transferable coding framework linking PTLs’ initiators, stages, and effects; (ii) empirical evidence of predominant affirmative tectonic approaches in a prescriptive, seismic context; (iii) identified innovative design attitudes; and (iv) a regionally grounded dataset informing comparative studies. The uncovered indicative patterns also provide an applicable model for examining PTLs and tectonic approaches worldwide across other prescriptive cultures and seismic regions. Full article

Aiming at the signal interference and feature recognition difficulties existing in the detection of concealed defects such as cracks and voids behind the tunnel lining, this study carried out a 1:1 reinforced concrete–steel arch frame composite lining model test; simulated the surrounding rock defects scenarios of three types of filling media, namely crushed stone, air, and water; and analyzed the time-domain, frequency-domain, and time–frequency-domain characteristics of the geological radar signal data. The research finds that the water-filled area generates a strong reflection due to the high dielectric constant, with the spectral peak reaching 712 MHz and the high-frequency component significantly enhanced. The peak frequency of the air-filled zone spectrum is 531 MHz, and the high-frequency bandwidth is broadened. The spectral peak of the crushed stone filling area is 507 MHz, with fast high-frequency attenuation and energy dispersion. The time-domain waveforms show that the amplitude in the water-filled area is the highest and the tailing is obvious, the waveform in the air-filled area is sharp, and the amplitude in the crushed stone-filled area is gentle. The peak frequency of the spectrum, the amplitude attenuation law, and the waveform shape can be used as the key indicators for discriminating the category of filling materials. The analysis method of feature fusion in the time–frequency domain has important engineering application value for improving the detection accuracy of geological radar in complex lining structures. Full article

Existing Mediterranean reinforced concrete buildings with masonry infills exhibit critical seismic vulnerabilities, yet real-time damage detection capabilities remain limited. This study validates a novel dense piezoelectric transducer (PZT) network concept for early damage detection in deficient RC structures under progressive seismic loading. A three-dimensional single-story RC frame with brick infills, representative of pre-Eurocode Mediterranean construction (non-ductile detailing, inadequate transverse reinforcement), was tested at serviceability limit states (SLSs) (Phase A) using a dynamic pushover approach with the 1978 Thessaloniki earthquake record, progressively scaled from EQ0.1g to EQ1.1g within the GREENERGY vertical forest renovation project. The specimen featured 48 PZTs using electromechanical impedance (EMI) methodology, 12 accelerometers, 8 displacement sensors, and 20 strain gauges. Progressive infill deterioration initiated at EQ0.5g while steel reinforcement remained elastic (max 2350 μstrain < 2890 μstrain yield). Maximum inter-story drift reached 11.37‰ with negligible residual drift (0.204‰). The PZT network, analyzed through Root Mean Square Deviation (RMSD), successfully detected internal cracking and infill-frame debonding before visible manifestation, validating its early warning capability. Floor acceleration amplification increased from 1.26 to 1.57, quantifying structural stiffness degradation. These SLS results provide critical baseline data enabling the Phase B implementation of sustainable vertical forest retrofitting strategies for aging Mediterranean building stock. Full article

This paper presents a global performance-based seismic assessment of an existing reinforced concrete hospital building retrofitted with dissipative bracing systems. The study aims to evaluate the overall effectiveness of different dissipative configurations, two traditional systems and one innovative low-activation solution in enhancing the seismic performance of the structure in compliance with the Italian Building Code (NTC 2018). The analyses were carried out using nonlinear static (pushover) procedures to determine the global capacity, equivalent damping, and displacement demand at the Life Safety (SLV) and Near Collapse (SLC) limit states. The retrofitting interventions were modeled assuming elastic connections between the existing RC frames and the added steel members, consistent with standard design practice in which connections are dimensioned with overstrength to avoid premature failure. The results demonstrate that the integration of dissipative systems significantly increases stiffness and damping, effectively reducing lateral displacements and improving the seismic safety index above the 60% threshold required for strategic facilities. The study highlights the importance of global assessment methodologies in guiding the seismic upgrading of hospitals and other critical infrastructures, while local detailing and device-level optimization are identified as topics for future research. Full article