Seismic vulnerability assessment in rural areas is crucial for mitigating earthquake-induced losses and promoting sustainable development. In China’s rural regions, most buildings are self-constructed with limited seismic resilience. While traditional field surveys accurately assess individual building vulnerability, they are time-consuming and expensive, making them unsuitable for extensive rural vulnerability evaluations. To address this issue, this study presents a rapid and accurate method for estimating the seismic vulnerability of rural buildings, using the rural areas of Weinan City, China, as a case study. First, several villages were randomly selected for field investigation. The seismic vulnerability of rural buildings was assessed according to EMS-98 standards. A proxy model linking building attributes to vulnerability was established by using machine learning (ML) and applied to the whole study area. Finally, the vulnerability index method of RISK-UE was employed to evaluate the seismic risk and the possible damage under different seismic intensities. The results show that the vulnerability class of rural buildings in the rural Weinan area is dominated by C, with an average VIM index of 0.67, indicating that the overall seismic performance needs to be strengthened. With increasing seismic intensity (from VII to X), the number of potentially displaced households increases from 7446 (3.39
The present study aims to evaluate the effect of the lintel beam above the window opening in perforated infilled frames by the finite element modeling of a number of specimens with and without lintel beams, calibrated against four large-scale single-story single-bay steel moment-resisting frames that were constructed in Tasnimi and Mohebkhah (2011)’s study. Box sections were used as lintel beams, while roller supports were used in the specimens without a lintel beam. It was demonstrated that the absence of this component in the numerical modeling of infilled frames with window openings led to significant errors in estimating ultimate load and its corresponding displacement, which were higher in specimens with larger openings. It also resulted in considerable errors in predicting failure modes in the infills, which can cause changes in the principal stress field of the infills. Our results suggest that there is no need to have four compressive struts for the macro-modeling of the infilled frames with central openings. The location of the lintel beam influenced the position of the struts, particularly in the samples with larger openings. The specifications of the compressive struts depend on the drift applied to the structure.
Wind loads and earthquakes are assumed to be uncorrelated in earthquake-prone areas; therefore, their interaction is ignored by existing design guidelines. However, the fact that strong earthquake events are commonly followed by strong to moderate aftershocks, and that wind is constantly flowing at high speeds, increases the probability of their joint occurrence, thus making current structural design assumptions questionable. This paper investigates the effect of the combined action of strong winds and vertical and horizontal earthquakes on the seismic response of reinforced concrete (RC) structures. Three reinforced concrete buildings that are representative of low-, medium- and high-rise buildings were analyzed in the nonlinear range using a lumped mass and distributed mass model. It is concluded that the effects of wind load and the vertical component were significant. These effects can significantly affect the axial forces in the columns but do not significantly affect base shears. It is essential to include the combined effect of earthquakes and wind to accurately predict the ductility of the structures and their respective expected failure mechanisms under multi-hazard load conditions.
Structural health monitoring (SHM) is important for rapid post-earthquake condition assessment and resilience-oriented management of civil structures. Among system identification methods, wave-based approaches are attractive because they are sensitive to localized stiffness changes and may reduce some limitations of global modal indicators, including potential influences associated with soil-structure interaction. However, many artificial-intelligence (Al)-based identification methods remain difficult to interpret physically, which limits their reliability in engineering applications. This study proposes an interpretable physics-consistent neural framework (PCNF) for wave-based system identification of buildings. The PCNF is derived directly from the layered Timoshenko beam formulation, in which the state transition of each structural layer is mapped onto a neural computational graph with physically meaningful trainable parameters. Structural parameter identification is therefore reformulated as a physics-guided gradient-based learning problem. The PCNF is applied to a 54-story office building in Los Angeles using records from nine earthquakes. The identified layer-wise shear-wave velocities exhibit coefficients of variation not exceeding 5
To investigate the canyon topography-stratigraphy effect on the dynamic response of a bridge, an analytical solution for a simply-supported bridge crossing a semi-cylindrical weathered canyon under SH waves is proposed. The simply-supported bridge is modelled as an elastic shear beam, which is supported by two rigid abutments with each having a rigid foundation embedded in half-space. The dynamic canyon-bridge interaction problem is physically decomposed into one scattering problem and two radiation problems. The proposed solution is verified by degenerating to a past exact solution for a single simply-supported bridge model in flat half-space. It is found that the surficial inhomogeneous soil layer may significantly amplify the seismic response of the bridge and foundations. The intensity of the topographic-stratigraphic amplification is influenced by the inhomogeneity and thickness of the surficial layer of the weathered canyon, as well as the frequency component and obliquity of the incident SH waves.
Furniture and equipment modeled as rocking rigid bodies within buildings are vulnerable to overturning during earthquakes, and their responses are strongly influenced by floor-level seismic amplification. However, predicting their seismic behavior typically involves analyses of building structural responses and rocking-body dynamics, making conventional approaches computationally expensive. Existing methods also struggle to adequately capture the nonlinear interactions among seismic motion characteristics, structural amplification effects, and the geometric properties of rocking bodies. To address this issue, this study proposes a data-driven method for predicting the seismic response of in-building rocking rigid bodies using a deep neural network (DNN). Floor seismic responses were obtained from city-scale nonlinear time-history analyses and used to calculate corresponding rocking-body responses. A multidimensional database was then established, covering various ground-motion intensity measures, building heights, and rigid-body geometries. Based on this database, a DNN model was developed for rapid overturning prediction. Results show that the proposed model achieves high computational efficiency and an accuracy of 94.37
This study investigates the seismic performance of skewed highway bridges retrofitted with buckling-restrained braces (BRBs) under the combined effects of translational and rotational ground motion components. Skewed bridges, with their asymmetrical geometry and irregular distribution of seismic forces, are highly susceptible to seismic excitations, particularly under complex loading scenarios involving rotational motions. While retrofitting strategies like BRBs have shown promise in enhancing seismic performance, the influence of rotational components remains insufficiently studied due to challenges in recording these motions and their limited integration into seismic design codes. To tackle these challenges, rotational ground motions were estimated using the geodetic method with data from the Chiba dense array. A nonlinear finite element model of a prestressed reinforced concrete box girder bridge was developed in OpenSees, and time-history analyses were conducted to evaluate seismic demands across varying skew angles. Key response parameters, including transverse drift, column shear force, deck rotation, and shear key deformation, were assessed. The results demonstrated that rotational components could significantly amplify deformation demands, with in-plane deck rotation and shear key deformation increasing by approximately 150
This paper presents new formulas for estimating the translational and rotational time periods of the prevailing reinforced concrete shear-wall multistory buildings (SWMBs) in Egypt. Forty distinct structural plans, featuring varying lateral and torsional stiffness, were rigorously prepared to create a sample of 142 SWMBs, with diverse heights, concrete strengths, and stiffness properties. A three-dimensional finite element modal analysis was conducted on the sample, and the first three vibration modes were identified. Regression analyses were performed using multiple combinations of eighteen geometric and mechanical parameters to derive the most accurate and simplest formulas for the translational and rotational periods. Additionally, lower-bound translational formulas were proposed for code implementation. Compared with reference modal analyses and period estimates calculated using the Egyptian code (ECL 201) alongside three international seismic codes—EC8, IBC, and UBC—the proposed formulas demonstrated superior reliability (95
Skewed beam-column connections are a common yet underexplored aspect in the design of steel structures. Existing literature and design specifications often overlook the complexities of these configurations, creating a significant gap in practical applications. This study aims to fill this gap by conducting comprehensive experiments through six full-scale tests and an extensive parametric study including 48 FE models to examine the impact of deviation angle on the behavior of beam-column connections. Specifically, the focus is on reduced beam section (RBS) connections and those without beam section reduction. The parametric study assesses various factors, including beam cross-section, beam section reduction, and deviation angle, by utilizing both experimental data and validated numerical models. Key hysteresis parameters such as hysteresis curve characteristics, backbone behavior, ductility indexes, cumulative dissipated energies, and effective stiffnesses are meticulously evaluated through these methodologies. This integrated approach provides a thorough understanding of the behavior of beam-column connections under skewed conditions, enhancing design considerations and ensuring robust structural performance in practical applications. The results reveal that connection deviation can lead to a strength reduction of 16
The present study puts forth a proposal that combines a linear motion guide with tension springs to establish a base isolation system for carrying out laboratory experiments. The methodology involves experimental analysis using a small-scale model of a single-story structure with both fixed base and base isolated configurations. The isolation systems compared include a linear motion guide with tension springs (BI-LMG) and a conventional laminated rubber bearing (BI-LRB). Free vibration tests showed the time-period shift and enhanced damping in the new isolation method proposed. In addition, the performance of the base isolation system was evaluated through sinusoidal and seismic time-history analyses employing a variety of earthquake data to determine its ability to withstand seismic excitations.
This study presents an approach for output-only, ambient vibration data time series, analysis-based damage detection in a benchmark structural model. A three-dimensional finite element model based on the benchmark laboratory model is simulated to show the efficacy of the suggested approach. Also, a new damage-sensitivity feature that is based on autoregressive time series models with exogenous inputs (ARX) is introduced by using output acceleration responses from sensors under the influence of ambient loads provided in the modeling. Minor localized damage close to supports, and more extensive damage that might occur throughout a bridge’s service lifetime are simulated with the finite element model to show the robustness and stability of the suggested damage feature. Next, numerous damage features proposed by other researchers are compared with the feature introduced in this study, utilizing the generated data and the damage scenarios that were created. The findings demonstrate that the proposed damage feature can reliably and accurately identify and locate minor damage close to supports (regarded as a challenge in identification studies) and offer a measure of the level of damage. In addition, the damage feature can accurately locate large-scale damage without producing false positive or negative results.
Crack extension and energy dissipation under conditions of coupled in-situ stress and explosion load tend to exhibit different patterns than under single stress field conditions. This study derives the coupled stress calculation expression of in-situ stress and explosion load, discusses the distribution characteristics of coupled radial stress and coupled tangential stress, and analyzes the change rule of coupled stress with explosion center distance and angle. Methods for calculating the extent of the crushed zone, fractured zone and blast energy under in-situ stress are presented. The influence laws of axial loading coefficient, lateral pressure coefficient, dynamic compressive strength and dynamic tensile strength on the extent of crushed zone, fractured zone and explosive energy distribution are analyzed. The results show that there is a suppression and orientation of the coupled stress field by the in-situ stress. Under the coupling action of in-situ stress and explosion load, the cracks around the blasthole are approximately distributed in an “X-shape”. Axial loading coefficient, lateral pressure coefficient, dynamic compressive strength and dynamic tensile strength have an important influence on the extent of the crushed zone and fractured zone under the action of the coupled stress field, as well as on the law of explosive energy dissipation. The results of the study can provide a reference for safe and efficient blasting and vibration active prevention and control in tunnels and underground spaces.
Frequency effect, in addition to time delay effect, on the response of the frame structure to sinusoidal and earthquake wave passage excitations is studied, respectively. The dynamic equilibrium equation in terms of the displacements of horizontal DOFs for a single-span, one-story plane frame structure subjected to wave passage excitation is formulated, and the relative motion method and mode superposition method are used to solve the dynamic equilibrium equation. The analytical and semi-analytical solutions of structural responses of the frame structure to sinusoidal and earthquake wave passage excitations are given, respectively. A new cognition is obtained that the wave passage effect includes not only time delay effect but also frequency effect. The frequency effect is also the mechanism of wave passage effect for the frame structure. When the excitation frequency is within a range from a frequency slightly bigger than zero to a certain frequency less than the structural fundamental frequency, the lower the excitation frequency, the more significant wave passage effect. Earthquake wave passage effect for the frame structure depends on the low-frequency content of earthquake wave besides time delay, and the more the low-frequency content, the more significant wave passage effect.
The velocity pulse duration of pulse-like ground motions (PLGMs) significantly influences the nonlinear seismic response of structures. Developing accurate pulse duration models is essential for seismic design and risk assessment. To our best knowledge, there is a lack of effective predictive models for this duration characteristic. Consequently, this study analyzes records of PLGMs from the NGA-West2 database. A predictive equation for pulse duration was developed using the random effects regression analysis method. This model incorporates moment magnitude (Mw), rupture distance (Rrup), average shear-wave velocity over the uppermost 30 m at the site (Vs30), depth to the top of rupture (Ztor), and the focal mechanism (Fm). Results indicate that pulse duration strongly depends on moment magnitude, while the effects of rupture distance and site conditions are comparatively minor. The focal mechanism also plays a significant role: strike-slip faults produce the longest durations, followed by oblique-reverse faults, and reverse faults yield the shortest. The proposed model provides reliable estimates of pulse duration for earthquakes with moment magnitudes ranging from Mw 5.7 to Mw 7.9.
To explore the dynamic deformation characteristics of expanded polystyrene (EPS) particle lightweight soil under dynamic loads, based on the Ramberg–Osgood (R-O) model with variable parameters, we extracted the parameters through dynamic triaxial test results for lightweight soil. Thus, the variation laws and applicable ranges of the model parameters R and α1 with the dynamic shear strain (γd) of the lightweight soil were obtained. The influences of the EPS particle content, cement mixing ratio, and confining pressure on the model parameters were analyzed. The applicability of the R-O model to lightweight soil was verified by changing the stress state and stress path in the dynamic triaxial tests. The results reveal that the range of R applicable to lightweight soil under dynamic loads is (1, +∞) and that α1 should be considered within the range of effective γd. When γd is less than 1×10−3, R of the R-O model with variable parameters for lightweight soil decreases rapidly and subsequently tends to remain stable with an increase in γd; the stable value range of R is (1, 2). Further, when γd is less than 1×10−3, α1 decreases rapidly and then increases with γd. The damping effect of lightweight soil exhibits two types of curve forms: bell-shaped and S-shaped curves. Notably, the variable parameters of the R-O model can be adjusted with the changes in γd. Thus, this model can adequately describe the variation laws of the dynamic shear modulus ratio and the damping ratio for lightweight soils subjected to complex dynamic loads.
Existing research indicates that seismic responses in deep soft seabeds are affected by fluid-solid coupling, seabed micro-topography, soil spatial heterogeneity, and nonlinearity. To address these complexities, this study develops an integrated nonlinear seismic response analysis for a cross-strait transect. The method comprehensively incorporates the strait basin geometry, detailed seabed microtopographic features, spatially varying soil properties (including S and P wave velocity structures), a nonuniform mesh layout of the transect, and appropriate artificial boundary conditions. Particular emphasis is placed on the seawater-seabed interaction, simulated via a weak coupling algorithm for fluid-solid interaction, and on the soil's nonlinear hysteretic behavior. Numerical simulations, conducted without considering seawater effects, reveal three key findings. First, bedrock motion components near the seabed fundamental frequency show enhanced upward propagation through the soil deposits. Second, seabed microtopography exerts a more pronounced influence on vertical seafloor motions than on horizontal components. Third, a resonance-like phenomenon occurs near 2 Hz for both horizontal and vertical motion components. The complex interplay of seismic wave reflection, refraction, and interference within heterogeneous deposits generates intricate, strongly coupled amplification patterns. However, when seawater-seabed coupling is considered, significant suppression of seafloor peak accelerations is observed, especially in deepwater regions. Vertical motions exhibit more pronounced suppression within specific narrow frequency bands compared to horizontal motions. The seabed seismic responses exhibit significant higher-frequency suppression (near 4-5 Hz) and low frequency amplification (< 0.5 Hz), while the resonance-like responses near 2.0 Hz for both horizontal and vertical components are diminished. Crucially, the degree of suppression or amplification of these resonance-like responses correlates positively with the seabed bedrock motion intensity.
This study investigated the seismic behavior of columns under different design parameters. A finite element model was established based on a low-cyclic loading experiment of five steel pipe-aeolian sand recycled concrete columns. Their seismic performance was analyzed by adjusting the axial compression ratio, the slenderness ratio, the diameter thickness ratio, and steel pipe strength. The study focused on the hysteretic curve, the skeleton curve, and the displacement ductility coefficient to understand the impact of these parameters. Sensitivity analysis was performed to evaluate the influence of each parameter on peak load and ductility. Test results revealed that stiffness initially increased and then decreased with a displacement rate of aeolian sand. Notably, when the sand replacement rate reached 30
The post-tensioned energy dissipating (PTED) connection for steel frames has drawn many researchers’ attention for its good seismic performance. This particular cable is one of the key components of post-tensioned connections. However, the value of cable force can decrease due to creep in the cable and anchor systems. To evaluate seismic response by means of transient dynamic analysis, a simplified numerical model with a friction-damped, post-tensioned connection is used. The evolution patterns of the seismic response of friction-damped, post-tensioned steel frames (FDPT), along with a decrease in cable force, is systematically investigated. The interaction mechanisms between structural displacement and post-tensioning force variations were rigorously analyzed by utilizing advanced nonlinear simulations. The influence of initial PT force and friction force are revealed through parametrical analysis. Spectral decomposition techniques were employed to evaluate vibration characteristics across different excitation frequency bands. The results indicate that the intensity of seismic response generally increases with a decrease in cable force, especially for the condition in which the cable force approaches zero. The degradation of cable force caused by the creep of a cable and anchor system should be seriously considered.
A three-tower connected reinforced concrete(RC)frame building was selected as a prototype building and used to investigate resilience-based seismic design,aiming to provide a reference for multitower-connected buildings by using seismic isolation.First,a seismic resilience assessment strategy was recommended based on the characteristics of the case study.Specifically,the restoration cost index was recommended as the ratio of the total repair cost of multiple towers and connection parts with respect to the current replacement cost.In contrast,repair time and casualties were recommended as the longest repair time and the highest casualties of multiple towers due to their uncoupled functions.The influences of the critical design parameter of the isolation system(i.e.,yield ratio)on the resilient performance of the entire building was investigated.Both the repair cost and time of the building decreased at decreasing yield ratios,which were attributed to the notable control of the maximum absolute floor acceleration.Only the case study,which showed a yield ratio of 2%,achieved the highest resilience level,as regulated by the relevant Chinese code.Hence,a 2%yield ratio is recommended for the conceptual design of seismically isolated multitower-connected buildings to achieve good seismic resilience.
The existing knowledge regarding failure mechanisms and theoretical models for mortise-tenon (M-T) joints with wooden pegs under seismic loading is insufficient. Most investigations on M-T joints focus on squeezing and friction between tenon and mortise, with limited consideration the damage at the peg hole. This paper introduces low-cyclic reversed loading tests alongside theoretical analyses of M-T joints with wooden pegs. The effects of the peg and tenon height on seismic performance parameters, including load-bearing capacity, stiffness, ductility and energy dissipation abilities were examined. The findings indicate significant differences in the behavior of M-T joints with and without wooden pegs under cyclic loading. Specifically, a decrease in tenon height and peg diameter may result in a shift from ductile failure due to tenon crushing to brittle failure associated with the peg hole. A theoretical hysteric model for the slipping, elastic, plastic, and post-failure stages of M-T joints with wooden pegs is subsequently derived, taking into account local compression effects and linear elastic fracture mechanics. A numerical simulation analysis was used to supplement and improve the test data. Compared with test and finite element analysis results, the proposed model accurately represents the failure behavior, including tenon crushing and peg hole cracking.
