Search Results (1,441)

Triple Friction Pendulum (TFP) bearings are widely employed as seismic isolation systems to reduce seismic force and deformation demands in structures. However, the combined influence of vertical mass-distribution irregularity, soil–structure interaction (SSI), structural eccentricity, and nonstationary earthquake excitation on the nonlinear torsional response of TFP-isolated buildings remains insufficiently understood. This study investigates the seismic response of a five-storey reinforced concrete (RCC) building equipped with TFP bearings subjected to nonstationary spectrum-compatible horizontal earthquake ground motions. The investigated structure represents a low-to-medium-rise isolated building with a superstructure period Ts ≤ 0.5 s, and the conclusions are applicable within the examined structural configuration, adopted TFP properties, and equivalent SSI modelling assumptions. A nonlinear time-history analysis framework combined with Monte Carlo-based spectrum-compatible ground-motion simulations is employed to evaluate the effects of SSI, structural eccentricity, and vertical mass-distribution irregularity. Validation against OpenSees benchmark simulations demonstrates strong agreement in the predicted structural responses. Parametric analyses show that increasing the soil stiffness ratio from 0.5 to 2.0 reduces the normalized isolation displacement by approximately 46.5% and the corner rotational response by approximately 36.7%. Conversely, increasing the vertical mass-irregularity ratio from 1.0 to 1.5 increases the inter-storey drift ratio by approximately 60% and corner-displacement magnification by approximately 48.6% within the investigated cases. The results demonstrate that seismic response is governed not only by the magnitude of vertical mass irregularity but also by its location due to changes in inertia-force distribution, modal participation, and lateral–torsional coupling. These findings highlight the importance of considering SSI and vertical mass distribution simultaneously when assessing the seismic performance of torsionally asymmetric TFP-isolated RCC buildings. Further studies incorporating taller structures, multidirectional excitation, detailed soil–foundation interaction models, and experimentally calibrated TFP properties are required to extend the applicability of the findings. Full article

On 6 February 2023, a sequence of earthquakes in Kahramanmaraş affected eleven cities in southeastern Türkiye. Following the main earthquakes, which caused severe destruction, numerous aftershocks occurred, further amplifying the damage in the region. In this paper, the seismic damage to 51 mosques and their minarets located in Kahramanmaraş city and its districts are structurally evaluated. Based on the field observations, the qualitative damage and performance levels of the structures were determined. Seismic parameters of Kahramanmaraş and its districts, the epicenters of the two earthquakes, were compared. The results show that mosques and minarets with masonry and reinforced concrete structural systems suffered severe damage and collapse. The observed failure modes in the mosques and minarets were analyzed within a cause-and-effect framework. Damage criteria for mosques and minarets have been adapted and assigned to standardized performance levels specified in the Earthquake Risk Management Guide for Historical Buildings by the General Directorate of Foundations in Türkiye: of the mosque complexes examined, 13 reached a level of Collapse; 27 were at the Collapse Prevention level; 3 were classified as having Controlled Damage; 5 as having Limited Damage; and 3 remained undamaged. In addition to the specific structural weaknesses and low mechanical properties of masonry and reinforced concrete building systems, the lack of engineering consultancy during construction and non-compliance with seismic design regulations are also among the causes of failures. Finally, repair and retrofitting solutions for masonry and RC mosques and minarets are proposed. While numerous post-earthquake surveys have primarily examined individual case studies, the novelty of this study lies in the systematic assessment of failure mechanisms in religious buildings located in Kahramanmaraş, the epicenter of the 6th of February 2023 earthquakes, considering both masonry and reinforced concrete systems. Full article

The Hatay province, which was most affected by the 6 February 2023 Kahramanmaraş earthquakes, causing significant losses in both Türkiye and Syria, is the main study area of this research. Furthermore, following this pair of earthquakes, Hatay became the province with the most structural and geotechnical damage. The low seismic performance of reinforced concrete (RC) structures, which constitute the dominant urban building stock of the province with its rich historical architecture, has clearly revealed critical structural weaknesses and defects. This study first provides information about the seismicity of the province and its surroundings, and then obtains intensity values for four major earthquakes using two different approaches. Considering the last two earthquake hazard maps, a comparison of seismic design parameters was made for all districts within the province. Considering the high incidence of damage in RC structures built before 2000, numerical analyses were performed on structural models created using the seismic design codes of that period. The results of the numerical analysis were consistent with the damage observed in the field. In columns where shear force capacities were exceeded, reinforcement with fiber-reinforced polymer (FRP) was applied, and the results were compared. Nonlinear static pushover analyses of a 5-story RC reference building showed that the 1968-code model had shear-capacity exceedances in a significant number of columns, whereas only two ground-story columns exceeded their shear capacity in the 1975-code model. The corresponding performance ratios (PRs) reached approximately 1.46–1.48 and 1.10 for the 1968 and 1975 models, respectively. Targeted FRP strengthening reduced the PR values of deficient members to 0.14–0.17 and eliminated the identified shear-capacity exceedances. This study aims to assess geotechnical and structural damage after earthquakes, compare seismic parameters, perform structural analysis, and determine the applicability of strengthening methods. The results of this study will be an important resource, especially for the evaluation and strengthening of RC structures built before the year 2000. Full article

Tower cranes are highly vulnerable to seismic excitation owing to their slender geometry and pronounced dynamic behaviour. Although carbon fibre reinforced polymer (CFRP) materials offer significant lightweight potential, and damping devices are widely adopted for seismic protection, their combined application to tower cranes has received limited attention. This study numerically investigates the seismic response of a rearing jib tower crane equipped with a CFRP jib and base joint dampers. A finite element model was developed and analysed under four critical operating configurations through static structural, modal and response spectrum analyses in accordance with the Italian Building Code (NTC 2018). The performance of the CFRP solution was compared with that of a conventional steel crane, while two damper configurations with different stiffness values were also assessed. The proposed lightweight design reduced the total crane mass by 34% and the jib weight by 77%. Compared with the steel configuration, the CFRP solution decreased static displacements by 38–56% and equivalent stresses by 22–44%. Under seismic loading, the adoption of joint dampers reduced the maximum equivalent stress by up to 35%, while increasing structural displacements by 5–19% because of the lower support stiffness. The results demonstrate that combining CFRP lightweight design with seismic damping devices effectively improves the earthquake performance of tower cranes while maintaining structural safety. Full article

Seismic assessment of reinforced concrete structures requires characterization of member and connection behavior under large cyclic deformations. Moment-resisting frames are widely adopted in seismic regions, but meeting code requirements is problematic when beams are reinforced with prestressing steel strands because their ultimate elongation differs substantially from that of conventional high-ductility reinforcement (e.g., ε_u,k ≈ 3.5% for Y1770S7 strands versus ε_u,k ≈ 7.5% for B500C rebars). This study reports the findings of an experimental program conducted on reinforced concrete beam–column joints (NGS), representative of moment-resisting frame systems typically employed in seismic regions. To explore innovative structural solutions, a biomimetic design strategy was adopted, drawing inspiration from the micromechanics of Picea abies (Norway spruce). Five half-scale (1:2) specimens were subjected to quasi-static, displacement-controlled cyclic loading following the ACI 374.2R-13 (ACI T.1.1R-01) protocol, and their performance was evaluated against prescribed acceptance criteria. Adding one longitudinal steel strand and partially anchoring it in normal concrete (NGS2) and in biomaterial-adapted grout (NGS4) did not increase the amount of dissipated energy when compared to the reinforced concrete conventional solution (NGS1). Moreover, the effects of replacing the rebars with partially anchored steel strands (NGS3 and NGS5) proved to be negative. Full article

Deep saturated layered foundations are common in coastal and reclaimed areas, where weak interlayers can significantly influence seismic response and settlement. To investigate the seismic behavior of ultra-deep strata and the effectiveness of targeted reinforcement, a large-scale shaking table test was conducted at a geometric similitude ratio of 1:200, representing a 640 m thick prototype. The shallow soil was densified, while a deep silty clay weak interlayer was selectively reinforced using vertical rotary jetting piles (VRJPs). Horizontal and vertical accelerations, Fourier spectra, excess pore water pressure ratio, and residual settlement were evaluated under 0.1 g, 0.2 g, and 0.4 g excitations. Under 0.4 g excitation, horizontal acceleration generally attenuated in the middle and lower strata, whereas vertical acceleration showed pronounced shallow amplification, reaching 0.87 g in the untreated zone. VRJP reinforcement reduced pore pressure buildup near the weak interlayer and decreased residual settlement from 1.12–1.20 mm to 0.94–1.02 mm. However, acceleration and pore pressure responses were redistributed in some overlying strata. The results support a hierarchical strategy combining shallow liquefaction mitigation with targeted deep deformation control for coastal and marine foundations. Full article

Traditional brick masonry buildings in China are commonly constructed using fired clay grey bricks bonded with glutinous rice mortar, forming a unique historical masonry system with significant cultural value. During long-term service, these structures are vulnerable to environmental deterioration, material aging, and seismic actions, resulting in cracking, deformation, and degradation of structural integrity and load-carrying capacity. Carbon fiber-reinforced polymer (CFRP) sheets have been increasingly applied for strengthening masonry structures due to their high strength-to-weight ratio, corrosion resistance, and convenient installation. However, most existing studies on Fiber-reinforced polymer (FRP)–masonry interfaces have focused on conventional masonry systems, while the interfacial bond behavior and load-transfer characteristics between CFRP sheets and traditional grey brick masonry bonded with glutinous rice mortar remain insufficiently investigated. This study investigates the interfacial bond behavior of CFRP-strengthened traditional grey brick masonry through combined experimental testing and numerical analysis. First, uniaxial compression tests were conducted to determine the mechanical properties of glutinous rice mortar and fired clay grey bricks. Subsequently, double-shear tests considering different CFRP bond widths, bond lengths, and interface integrity conditions were performed to characterize the failure modes, force–displacement responses, and interfacial load-carrying behavior. The effects of interface geometric and integrity conditions were considered to evaluate the load-transfer characteristics of the strengthened interface. Based on the experimental results, a finite element model considering interface behavior was established and verified through comparison with the experimental results, which was subsequently employed to investigate the influence of bond width on interfacial stress transfer behavior beyond the experimental conditions. The results show that interfacial debonding accompanied by near-surface masonry damage dominates the failure process of CFRP–glutinous rice mortar masonry interfaces. Increasing the CFRP bond width enhances the interfacial load-carrying capacity and initial stiffness, while the ultimate capacity exhibits an approximately linear relationship with bond width within the investigated range. Numerical analyses further demonstrate that increasing bond width expands the effective load-transfer region, redistributes interfacial stresses, and delays stiffness degradation. These findings improve the understanding of interfacial bond behavior and load-transfer characteristics in CFRP-strengthened traditional masonry systems and provide references for the design and performance evaluation of strengthening applications in historic masonry structures. Full article

Additional loads from new buildings spanning existing underground utility tunnels, together with seismic action, may induce uneven settlement and structural damage in tunnel systems. To mitigate this risk, a precast cavity structure is proposed to replace the soil above the tunnel, isolating load transfer and controlling settlement. In the proposed structure, precast reinforced concrete shear walls with openings serve as key vertical load-carrying and lateral-force-resisting members. To clarify the cyclic behavior, two shear walls with openings were designed to possess the same geometry and reinforcement details but were tested under reversed cyclic loading in two orthogonal in-plane orientations. The failure modes, hysteretic behavior, backbone curves, stiffness degradation, and energy-dissipation capacity were analyzed. The results show that flexural-shear failure occurred in both wall limbs under horizontal cyclic loading, whereas flexural-shear failure developed only in the right wall limb under vertical cyclic loading. The initial stiffness, peak load, peak drift ratio, and ultimate drift ratio under horizontal cyclic loading were 1.87, 2.06, 1.76, and 1.64 times those under vertical cyclic loading, respectively, indicating that the performance of the shear wall with opening is more unfavorable under vertical cyclic loading. Further, existing models were used to predict the loading-carrying capacity. The results indicate that the strut-and-tie model (STM) and GB 50010-2010 gave the best and acceptable overall predictions, respectively. The findings provide experimental evidence for component design and seismic performance evaluation of cavity replacement structures used in projects spanning underground utility tunnels. Full article

Existing comparative studies on metallic mild steel dampers (SDs) and fluid viscous dampers (FVDs) are primarily limited by the coupling of device type with layout variations, the lack of a unified performance metric, and the absence of multi-level evidence under fixed structural configurations. This study overcomes these limitations by comparing SDs and FVDs under strictly identical conditions—same RC frame, same 26 damper locations, same ground motions, and a unified code-specified drift target—across frequent, design-basis, and rare earthquake levels, supplemented by energy dissipation and added damping ratio analyses. Under frequent earthquakes (FEs), the FVD achieves a maximum story-shear reduction of 33% and effectively controls inter-story drift through its velocity-dependent energy-dissipation mechanism. Under rare earthquakes (REs), the SD demonstrates superior performance, providing a 35% maximum story-shear reduction, while maintaining inter-story drift ratios within code-specified limits, owing to its combined stiffness and damping contributions. In terms of energy dissipation, the total cumulative energy dissipated by FVDs is 39.4–67.6% higher than that of SDs under the same ground motions, with added damping ratios averaging 2.42% for FVDs and 2.86% for SDs. These findings suggest that FVDs are more favorable for serviceability and frequent seismic performance, while SDs exhibit better response reduction effects under rare earthquake excitations. Full article

Carbon-fiber-reinforced polymer (CFRP) reinforcement is a potential alternative to steel in corrosive environments. However, CFRP is elastic without ductility, and the seismic performance of CFRP-reinforced concrete (RC) columns is inadequately understood. This study characterizes the intrinsic seismic response of concrete columns reinforced with CFRP cable-type bars and spirals under recorded near-fault ground motions. Three reference steel-RC columns are designed as seismic-resistant, non-seismic-resistant, and with post-cracking stiffness equivalent to the CFRP-RC column. The CFRP-RC and seismic-resistant steel-RC columns were tested under cyclic loading, and the results validated finite element (FE) models. Validated models simulated four columns under cyclic loading, and under 11 near-fault records matched to a capacity-derived elastic target spectrum. The results, bounded by selected ground motions and material constitutive models, show that: (1) The tested CFRP-RC column dissipated about 50% less energy than the steel-RC reference; (2) No material-level failure criterion was met under the suite, although peak base shears exceeded the nominal quasi-static capacities; (3) The CFRP-RC column developed the largest transient drift but minimal residual drift, whereas the steel-RC columns limited transient amplitude via hysteretic dissipation yet accumulated permanent offsets; (4) Response of the CFRP-RC column depends on ground motion energy delivery characteristics: concentration, symmetry, and duration. Full article

The numerical modelling of existing reinforced concrete (RC) bridges represents one of the most time-consuming and operator-dependent phases of seismic vulnerability assessment. Although advanced nonlinear analysis procedures are widely available, the generation of finite element (FE) models is still commonly performed through manual operations, limiting modelling efficiency, repeatability, and interoperability between design and analysis environments. This paper presents a layer-based CAD-to-FEM workflow for the structured generation of simplified FE models of existing RC bridges. The proposed methodology uses a standardized layer-based CAD organization and direct DXF interoperability with MIDAS Civil to transfer a centroidal representation of the bridge into a simplified beam-based finite element model. The centroidal axes of the bridge components are extracted from the original engineering drawings and classified into dedicated structural layers, providing a structured basis for subsequent FE model generation. The proposed workflow is designed to reduce manual preprocessing operations and improve modelling consistency by organizing the structural geometry through standardized CAD layers, thereby facilitating the generation of analysis-ready models for seismic assessment. The workflow is integrated with a Multi-Modal Pushover Analysis (MPA) procedure to evaluate the seismic vulnerability of bridges characterized by multiple significant vibration modes. A case study involving an existing Italian RC bridge demonstrates the feasibility of using the proposed simplified modelling strategy within a multi-modal nonlinear seismic assessment, including the evaluation of both ductile and brittle collapse mechanisms through seismic risk indices. The proposed workflow provides a structured framework for integrating conventional engineering drawings with nonlinear seismic assessment procedures. Full article

To achieve the optimal balance between structural safety and stripping economy for the rock slopes of a specific open-pit iron mine, a rigorous mathematical modeling and computational framework was established. In contrast to traditional simplified pseudo-static evaluations, authentic monitored seismic and blasting waveforms were integrated within an explicit dynamic strength reduction model to ensure that transient stress wave propagation and progressive failure paths of rock slopes were accurately captured. Furthermore, a constrained multi-objective optimization model was established so that the nonlinear trade-off between dynamic safety margins and stripping volumes could be quantitatively resolved. Based on the application to the studied open-pit slopes, it was revealed that severe deep plastic yielding and topological shear band coalescence were caused by transient dynamic stress waves when the slope angle was steepened to 45°. Consequently, the factor of safety (FS) was abruptly reduced to an unsafe range of 1.01 to 1.20. Through the effective exclusion of this high-risk 45° configuration, a global optimal mining slope angle of 42° was rigorously established. At this optimal angle, a robust factor of safety ranging from 1.45 to 1.98 was consistently maintained across all extreme multi-field coupled conditions. Ultimately, from an engineering perspective, dynamic shear failure paths were successfully interrupted, and the need for expensive structural reinforcement was eliminated. Economically, waste rock stripping volumes were significantly minimized, whereby the overall stripping ratio was optimized, and life-cycle excavation efficiency was maximized. Full article

This study investigates the seismic performance of a low-rise, nonductile reinforced concrete building retrofitted with high-strength masonry infill walls having a compressive strength of approximately 25 MPa. Three infill layouts were evaluated using nonlinear pushover analysis. A multi-criteria evaluation framework was then applied by considering stiffness, lateral strength, added weight, and a preliminary wall-volume-based cost indicator. The most favorable configuration was further assessed using Multiple Stripe Analysis, and system-level fragility curves were developed using PGA and Sa(T₁) as intensity measures. The results show that high-strength masonry infills substantially enhance the lateral capacity of the RC frame, with peak base-shear capacities increasing by approximately 3.6, 3.3, and 2.3 times for HBW1, HBW2, and HBW3, respectively. The multi-criteria evaluation identified HBW1 as the most favorable configuration. A preliminary stiffness–weight–strength relationship was also proposed as a screening tool; its evaluation against 11 independent building-scale cases showed reasonable consistency, with eight predictions within ±10% and all predictions within approximately ±15% of the literature-derived strength gains, and a mean absolute error of about 5.2%. Full article

The structural application of 3D printed concrete (3DPC) is still constrained by the difficulty of qualifying a layered, process-dependent material using standards developed mainly for cast concrete and conventional masonry. This review examines 3DPC through masonry construction to clarify how interface-controlled behaviour should be interpreted, tested and standardised. The comparison is not based on material similarity, but on the shared structural role of joints, interfaces and assemblage-level load transfer. Most previous reviews mainly discuss printability, mixture design, material development or general mechanical performance. This review instead places the printed interface at the centre of structural qualification, using masonry only as a reference for interpreting joint-controlled load transfer. The review shows that compressive strength alone is insufficient for structural qualification, since printed elements may fail through interlayer debonding, direction-dependent cracking, filament instability, reinforcement discontinuity or connection weakness. Flexural, shear, cyclic and seismic responses are particularly sensitive to interlayer quality, loading orientation and print-path geometry. Existing concrete, mortar and masonry standards remain useful references, but require 3DPC-specific reporting and testing. Accordingly, a tiered qualification route is proposed, progressing from fresh-state characterisation to interface-dominated testing and structural-scale validation. Full article

Steel-framed modular structures, assembled by stacking modules, show distinct lateral behavior. However, the role of steel plate shear walls (SPSWs) in such structures is rarely studied. This study investigates their influence on the lateral behavior of steel-framed modular structures. Two six-story modular structures are designed: one without SPSWs while the other one with SPSWs. The base shear, failure process, and resisting mechanism of modular structures are studied by pushover analyses. Parametric studies address effects of plate thickness, bolt number, and cross-section of horizontal inter-module links. Contributions of SPSWs and concrete shear walls are compared. For the first time, three distinct resisting mechanisms—individual resisting unit, double-column system, and double-beam system—are identified and systematically explained in the context of SPSWs-enhanced modular structures. A novel tension-tie strip model is developed to quantify the contribution of SPSWs to lateral resistance. Results demonstrate that SPSWs work as tension-tie strips, significantly increasing the stiffness and resisting capacity of modular structures by three to five times depending on the loading direction. The resisting capacity grows with plate thickness. Insufficient bolts or link cross-section can lead to premature failure. Compared to concrete shear walls, SPSWs offer better integrity and drift control under extreme seismic loads. A design scheme is proposed to estimate the increased resistance due to SPSWs with good accuracy and efficiency, offering a practical tool for structural engineers to enhance lateral behavior. The findings provide new insights into the seismic design of modular buildings and establish a foundation for performance-based design of SPSW-reinforced modular structures. Full article