Seismic Failure Modes Research Articles

Seismic performance of round-end hollow RC tall bridge piers considering to higher-order vibration mode effect

Round-end hollow reinforced concrete (RC) tall piers have been widespreadly utilized for railway bridges in river valleys and mountainous regions. The post-earthquake damage state of such bridge piers differs significantly from that of traditional short-to-medium piers. To investigate the seismic performance and failure mode of RC round-end hollow tall piers, a finite element model was developed using the OpenSees platform and calibrated against previous test results. Subsequently, incremental dynamic analysis (IDA) and modal pushover analysis (MPA) were conducted to obtain bending moment and curvature distributions as well as damage ranges for piers subjected to different intensities of ground motion. The results indicate that: The RC round-end hollow tall piers subjected to strong ground motions can crack up to 75% and 80% of its height according to IDA and MPA, respectively. The MPA incorporating mode coupling up to the third order is capable of predicting crack distribution of the pier as demonstrated in this study. Furthermore, it is recommended that the damage range of the pier be considered as a primary control indicator in seismic design.

Seismic fragility analysis of an anchored vertical gas steel storage tank using tri-axial shaking table testing

Hydrogen and gas storage tanks installed in facilities are typically vertical cylindrical structures made of steel. To allow for the discharge of stored materials, these tanks are anchored onto concrete blocks with sufficient height. However, this design results in a higher center of gravity, making the tanks more vulnerable to external forces such as earthquakes. This study fabricated a storage tank model and foundation concrete based on the results of the field investigation of the hydrogen storage tank. Then, an artificial earthquake was generated by referring to ICC-ES AC 156, a shaking table test method for non-structural elements. Experimenting on a full-scale structure is ideal; however, a storage tank model was fabricated and settled on the foundation concrete for tri-axial shaking table testing due to limited testing facilities and equipment performance. In the shaking table test, the presence or absence of water inside the storage tank was set as the condition for storing gases and liquids. The seismic behavior characteristics and failure mode of the storage tank model fixed in the foundation concrete were analyzed using the testing results. A seismic fragility curve was drawn up, and the high confidence and low probability of failure (HCLPF) was calculated.

Physics-based natural gradient boosting probabilistic prediction model for seismic failure modes of reinforced concrete columns

A novel physics-based natural gradient boosting (PNGB) probabilistic prediction model for flexure failure (FF), flexure-shear failure (FSF) and shear failure (SF) of reinforced concrete (RC) columns under strong earthquakes has been developed to address the limitations of empirical and machine learning (ML) models, which often fail to learn physical laws, insufficiently consider uncertainties, and exhibit poor generalization performance. Firstly, an improved natural gradient boosting (NGB) probabilistic model of seismic failure modes was created by using natural gradient boosting and gradient boosting regressor algorithms. Then a new hyperparameter optimization method for the improved NGB probabilistic model was proposed based on the ML algorithms and the physical laws. Finally, the predictive performance and engineering practicability of the PNGB probabilistic model were verified compared to empirical and ML models. According to the analysis results, the PNGB model can effectively improve the predictive recall of FF, FSF and SF by about 19–65 %, 20–67 % and 20–56 % respectively compared with empirical models, and by about 1–7 %, 7–43 % and 6–32 % respectively compared with ML models. Moreover, the PNGB model exhibits satisfactory generalization performance and minimal dispersion, which can be used to calibrate the ML models based on the confidence intervals. Furthermore, the result predicted by the PNGB model satisfies the physical laws relating to the seismic failure modes and design parameters, which can further represent the competitive relationships of various seismic failure modes.

Finite Element Analysis of Seismic Performance of RCS Hybrid Joints of Steel Hoop Structure

Reinforced concrete column-steel beam (RCS) composite structures are widely used in super highrise buildings due to their excellent performance. In this paper, the numerical simulation analysis of the RCS hybrid joints of “beam through” and “column through” RCS constructed with steel hoop structure are carried out, and the influence of five different parameters, i. e. , flange width-thickness ratio, steel yield strength, axial compression ratio, concrete strength and end plate thickness, on the seismic performance and failure mode of RCS hybrid joints is investigated. The results show that the ABAQUS finite element model can simulate the performance of RCS mixing under static load through reasonable parameter settings, which is in good agreement with the experimental results. Under the mechanism of “strong column and weak beam”, the combined node firstly undergoes beam-hinge damage, and the change of the axial compression ratio and the concrete strength parameter of the joint have little effect on the ultimate bearing capacity and deformation performance of the joint. Increasing the flange width-thickness ratio reduces the bearing capacity of the joint by up to 11%, and increases the yield strength of the steel, and increases the bearing capacity of the joint by 36. 4%. The thickness of the end plate of the column through specimen is increased, and the bearing capacity and deformation performance of the joint are improved to a certain extent. The changes of each parameter have no significant effect on the final plastic hinge failure mode of the joint. The research in this paper provides theoretical support for the design and research of this type of node in the future.

Experimental investigation on the seismic performance of square concrete/ECC filled stiffened high-strength steel tubular columns

Seismic action can lead to severe damage in the plastic hinge zone of concrete-filled steel tubular (CFST) columns, such as the localized buckling of the steel tubes and the crushing of the core concrete. Despite the numerous proposed cross-sectional configurations for CFST columns, the core concrete exhibits substantial damage under intense seismic action, making post-earthquake maintenance challenging. To mitigate the spalling of the core concrete under seismic action, this paper proposes the utilization of engineered cementitious composites (ECC), which is a cement-based composite material, for a certain height within the plastic hinge zone as a substitute for common concrete. Six square concrete/ECC-filled stiffened high-strength steel tubular (CFSHST) columns were fabricated and subjected to quasi-static tests. The effects of the yield strength of the steel tubes, cross-sectional configurations, and axial compression ratio on the seismic performance and failure modes of the CFSHST columns were investigated. Subsequently, a numerical analysis of these columns was conducted to discuss the effects of the compressive strength of the core concrete, the yield strength of the steel tubes, and the axial compression ratio on the seismic performance of the columns. Finally, a design formula for the load-bearing capacity of this type of column was established, and its accuracy was verified using experimental results and numerical model results. The results showed that the CFSHST columns with the ECC in the plastic hinge zone exhibited only minor cracks and no evident ECC spalling occurred. Moreover, the longitudinal steel bars were beneficial in alleviating the spalling issue of the core concrete in these columns. The proposed design formula for the load-bearing capacity can accurately predict the peak load of CFSHST columns.

Probabilistic identification method for seismic failure modes of reinforced concrete beam-column joints using Gaussian process with deep kernel

Identifying the seismic failure modes of beam-column joints (BCJs) is crucial for the safety and integrity of reinforced concrete (RC) buildings or structures withstanding seismic forces. However, traditional identification methods fail to provide any indication about the uncertainties within their predictions, which is beneficial for evaluating, interpreting and improving these predictions. This study develops a probabilistic identification method for seismic failure modes of BCJs using Gaussian process (GP) with a deep kernel, which integrates the representational power of deep neural networks with the flexible structure of kernel functions to accurately represent the evolution characteristics of seismic failure modes of BCJs. Analysis results demonstrated the potential of the proposed method for improving the classification accuracy of traditional GPs, as well as its superiority over the prediction accuracy of traditional shear-resistance design methods and machine learning techniques. Furthermore, the proposed method also provides an efficient approach to estimate the uncertainties within their predictions for seismic failure modes of BCJs.

Data-driven crack image-based seismic failure mode identification for damaged RC columns

The seismic failure mode identification of reinforced concrete columns is crucial for post-earthquake stability and safety assessment of the damaged concrete buildings. In this paper, a multi-feature crack image-based methodology is proposed for non-destructive non-contact failure mode prediction in reinforced concrete columns damaged in an earthquake. A databank of 455 surface crack patterns from quasi-static experiments on 111 reinforced concrete columns with a variety of structural and geometric properties is collected by the authors aimed at the development and validation of the methodology. For the intricacy retrieval of the surface crack maps, multi-feature fractal-based procedures are taken into consideration. Various machine learning algorithms are employed to train the seismic failure mode predictive models using the characteristics of the damaged RC columns. Ten scenarios are defined based on the image-extracted indices, and structural and geometric characteristics of rectangular reinforced concrete columns. Hyperparameter tuning of the machine learning algorithms using GridsearchCV function has optimized the performance of the models. A k-fold cross-validation procedure is also executed to examine the robustness of the results. Results reveal that the predictive model in which the image-extracted indices and structural parameters are jointly used as input features of supervised learning provides 98% accuracy for the testing dataset with Extreme gradient boost algorithm. In addition, among the scenarios that only image-derived parameters are considered as input features, an accuracy of 83% is obtained with Extreme gradient boost algorithm for the testing dataset.

Experimental Investigate on Seismic Performance of RC Hill-Side Stilted Buildings Affected by Vertical Stiffness Irregularity

ABSTRACT In this study, the ratio of lateral stiffness of the stilted story to that of the second story was proposed as the story stiffness ratio (SSR) to quantify vertical stiffness irregularities of hillside stilted buildings. A quasi-static experiment was conducted on a plane stilted frame with an SSR of 40 in the slope direction. Experimental results were compared with those of a stilted frame with an SSR of 1.01. The results show that SSR is an important factor influencing seismic failure modes of stilted buildings. As SSR decreases, structural ductility and deformation capacity improve, and stiffness degradation decelerates.

Seismic behavior of precast prestressed concrete frame joints with different energy dissipation designs

The unbonded post-tensioned precast concrete joint based on PRESSS (Precast Seismic Structural System) technology has a simple form, convenient construction, and strong deformation-recovery properties. In this paper, both experimental and theoretical analysis methods were used to study the influence of different energy dissipation components on the seismic performance of the unbonded post-tensioned precast concrete joint. First, based on the existing ‘plug-and-play’ energy dissipation device, this paper improved its construction and designed two types of joints with new external energy dissipaters and internal energy-dissipating bars, respectively. Subsequently, low-reversed cyclic loading experiments were conducted. The two joints’ seismic performance indexes, failure mode, hysteresis curve, skeleton curve, ductility coefficient, and residual deformation were compared and analyzed. The experimental results showed that internal energy-dissipating bars exhibited greater energy dissipation. In contrast, the joint with the new external energy dissipater had higher initial stiffness than the joint with internal energy-dissipating bars. In addition, the force transmission mechanism and the calculation formula of the initial rotational stiffness of the joints were deduced through theoretical analysis, and the theoretical derivation was further verified by combining the experimental values. Overall, both joints conformed to the definition of semi-rigid connections in EC3, and the joint design conformed to the “strong column and weak beam, strong joint and weak member” principle. Finally, a new anchoring system for the energy dissipaters is proposed to ensure the effective connection between the energy dissipater and the bearing.

Seismic responses and failure mechanism of the superstructure-integrated underground structure considering the seismic aboveground-underground interaction

The superstructure-integrated underground structure (SIUS) is an innovative infrastructure in an urban city, in which the aboveground part and underground part are coupled together to be a large synthesis structure. During earthquakes, the SIUS is primarily influenced by the soil deformation and structural vibration, and the seismic aboveground-underground interaction (SAUI) would be considerable due to structural characteristics. This paper aims to investigate the seismic response and failure mechanism of the SIUS and reveal the influence mechanism of the SAUI with a quantitative method for the seismic aboveground-underground interaction coefficient (SAUIC). In this paper, a credible numerical model of the whole soil-SIUS system compiled with the viscous-spring artificial boundary is established. The modal analysis of the SIUS is carried out, and the distinctive structural characteristics are discussed. The seismic responses of the SIUS are thoroughly investigated, and the failure mechanism of vulnerable positions is further revealed. Based on the modal frequency response analysis and a novel correlation analysis, the SAUIC is quantitatively proposed to evaluate influence effects of the SAUI on seismic responses of the SIUS. The results show that the SAUI has great influence effects on seismic responses of the SIUS, even changes the seismic failure mode of the underground part to be flexural failure; the quantitative SAUIC demonstrates the SAUI increases with the increasing seismic intensity and increases from outside to inside of the SIUS, and the SAUI would be highly considerable on positions with irregularities in structural stiffness, especially on the aboveground-underground interface.

Experimental recognition of seismic performance of simple bolt-connected precast frame by comparing with equal stiffness cast-in-situ frame

Multi-story industry buildings composed of precast concrete members and simple bolt-type connections are widely constructed in the world, and there is enormous need for future construction market. Based on the equal stiffness and stiffness distribution along the height, a 1/5-scale precast RC frame utilizing simple bolt-type connections and a reference cast-in-situ monolithic RC frame were designed and constructed to conduct shaking table tests. According to the test results, the seismic responses, failure modes and energy dissipation behaviors of the two models were analyzed and compared. The vibration modes of the precast frame performed bending deformation pattern, while the cast-in-situ one presented shear deformation pattern. The damage and inter-story drift of the precast frame was comparatively uniformly distributed along the stories, whereas that of the cast-in-situ frame was concentrated in the first story. The energy dissipation capacity of the precast frame was inferior to that of the reference frame, as the bolt-type connections couldn't have plastic damages and plastic hinges that occurred in the cast-in-situ joint zones. In general, the global seismic performance of the precast frame was close to the reference frame and its collapse resisting capacity under severe earthquakes was reliable. Some serious local failure modes and less of energy dissipation capacity of the precast frame should be concerned in high seismic regions.

Seismic response and failure modes analysis of pile foundations in liquefiable soils using various design criteria

Pile foundations may fail by bending, shear forces and buckling etc., if soil surrounding the pile liquefies during earthquake. In this paper, a detailed 3D numerical model was developed based on the Showa Bridge that collapsed during the Niigata earthquake, estimations have been made of the times that the Showa Bridge collapsed based on a soil and pile seismic response. Then, seismic design criteria of pile foundations corresponding to different failure modes are selected, it is found that the pile of Showa Bridge may have fail by buckling. Furthermore, the effects of the pile flexural rigidity, earthquake type, peak ground acceleration, and degree of soil layer liquefaction on the ground and pile response in liquefiable soil are examined. The peak bending moment of pile and pile top displacement increases with increasing degree of soil layer liquefaction. Finally, evaluates those criteria by comparing and contrasting the results in various conditions. Nonlinear discriminant methods considering the effect of pore pressure distribution can identify different failure modes with higher reliability compared to those obtained by linear theories., and suggested flowchart of evaluating bearing capacity of pile in liquefiable soils was purposed It is recommended that develop a more comprehensive theory of pile foundation failure discrimination.

Seismic failure modes of masonry structures exposed to Kahramanmaraş earthquakes (Mw 7.7 and 7.6) on February 6, 2023

In this study, the failure modes of masonry structures after the earthquakes (Mw 7.7 and 7.6) occurred in Kahramanmaraş on February 6, 2023 were investigated by fieldwork. Within the scope of the study, information of the building stock in Türkiye and the Middle East countries was given, and a literature regarding the major failure modes in masonry structures was mentioned. The characteristics of the ground acceleration and earthquake parameters measured during the earthquake were presented. Damage distributions in historic masonry structures and masonry dwellings were examined. In addition to the out-of-plane behavior which is the most common failure mechanism in masonry structures, the corner failure mechanism has been also observed in many masonry buildings. It has been determined that the corner failure mechanism is triggered by the combination of the in-plane and out-of-plane failure behaviors. In this manner, the observed damages were classified as in-plane, out-of-plane, and corner failures. It has been determined that damaged masonry structures are mostly out of use with out-of-plane and corner failure mechanisms. These two failure mechanisms were directly related to inadequate wall-roof and wall-floor connections, insufficient axial load, low material strength, poor workmanship, and the lack of engineering service. In-plane failure mechanisms are triggered by irregular door and window openings exceeding the limits given in the regulations. In addition, it has been revealed that many masonry buildings do not have adequate vertical and horizontal lintel band to increase the lateral seismic performance of the walls. In the last part of the study, the advantages and disadvantages of the strengthening methods that can be used in masonry structures with light and moderate damage were examined, and some suggestions were made.

Near-surface-mounted retrofitting of adobe walls using different materials: Evaluation of seismic performance

This study focuses on the seismic strengthening of adobe walls using different reinforcement materials and different reinforcement schemes through the near-surface-mounted (NSM) technique. Six adobe wall panels (1900 × 1200 × 200 mm) were quasi-statically tested and comprised one unreinforced wall and five specimens reinforced with reinforced mortar strip, bamboo plywood and wood, respectively. The strengthening procedure involved insertion of the reinforcing materials into the grooves cut symmetrically on both sides of the walls. The results were described in terms of energy dissipation, lateral resistance, ultimate displacement, stiffness degradation, ductility, and tolerate maximum peak ground accelerations. The tolerate maximum peak ground accelerations (PGA) of the specimens were analyzed using the N2 method. The test results indicated that the tensile strength, elastic modulus and scheme of reinforcement materials had a significant impact on the seismic performance and failure mode of specimens. The reinforced mortar strips significantly improved the seismic performance of adobe walls, particularly when using horizontal and vertical reinforcement schemes. The reinforcement of adobe walls with bamboo plywood and wood had achieved satisfactory results in terms of ductility, energy dissipation, and PGA. Finally, the masonry calculation formula was modified to establish the formula for estimating lateral resistance of adobe wall.

Seismic performance of fabricated reinforced concrete bridge piers based on durable grouting material

To meet the high durable requirements of assembled bridge piers in the marine environment, a new grout is used in the grout sleeve to improve the corrosion resistance of the pier bottom. The seismic performance of piers adopting this new grout is studied. Firstly, a dynamic analysis model of the assembled reinforced concrete bridge pier with this grout is established using the finite element software ABAQUS. Moreover, the damage modes, hysteresis curves, and energy consumption for low reversal cyclic loading are investigated. The results indicate that the seismic failure mode of the precast piers is the concrete damage at the joints of the precast members, and the local damage of the grout in the grout sleeve does not affect the integral seismic performance of the bridge pier.

Seismic response and instability analysis of the liquefiable soil-piles-superstructure interaction system

Based on the shaking table test of the liquefiable soil-piles-superstructure system, the liquefaction process and seismic failure mode of the liquefiable site with an overlying non-liquefiable soil layer, as well as the instability or damage mechanism of a low pile cap-pile group-superstructure system are analyzed by a two-dimensional finite element model. The model considers the post-liquefaction shear deformation of sand, the interface models for the pile and cap with the liquefiable and non-liquefiable soil, and the interface model between the liquefiable and non-liquefiable soil to account for the discontinuity of interface deformation. The typical calculation results, including the excess pore pressures, accelerations, displacements of soil, and bending moments of the piles, are compared with the experimental results to verify the developed models and reveal the effects of site liquefaction and the soil-structure dynamic interaction on the seismic responses and instability mechanisms of the piles-superstructure system.

Quantifying site-response effect of spatial variability earthquake on seismic failure mode of long-span sea-crossing cable-stayed bridges

Long-span cable-stayed bridge is a prevalent bridge type for sea-crossing passages and occupies an essential role in the transportation system. Non-uniform excitations significantly impact the response of long-span cable-stayed bridges, especially the site-response effect (ESR), which is one of the three primary characteristics. This paper employs a long-span sea-crossing cable-stayed bridge with consideration of hydrodynamic and pile-soil effects to systematically study the influence regularity and parameter sensitivity of the site parameter ωc on the response of critical components, and develop probabilistic seismic demand models between each component and ωc. The results reveal that the fragility of each component exhibits dissimilar sensitivities related to ωc, specifically, the changing amplitude of bearing fragility is greater than that of the bridge pylon. Consequently, when the soil type at the pylons changes from soft to solid, the damage sequence of the main pylon, pier and bearing has been changed, which exhibits different damage mechanism and failure mode. Furthermore, the mathematical model between the seismic parameters and damage mechanism is established to quantify the impact of ESR on the failure mode of sea-crossing cable-stayed bridges. Thus, it could provide a theoretical basis for the earthquake damage assessment and seismic optimization of long-span cable-stayed bridges.

Seismic behavior of steel frames with different joints: Shaking table test and finite element analysis

This paper discusses the effect of different joint types (common joint (CJ), reduced beam section joint (RJ), and cover plate joint (CPJ)) on the seismic behavior of steel frames. Three steel frames (1:2 scale) with different joints were tested under the shaking table. El Centro wave was selected as the input seismic wave. The failure modes, dynamic response, displacement response, strain response, and acceleration response of steel frame specimens under five peak ground accelerations (PGA) were measured and analyzed. The experimental results indicated that the seismic damage of the steel frame specimens was mainly concentrated at the beam-column joints on the first story. The plastic hinge could be achieved shift-away by reinforcing and reducing the flange at the beam end and significantly improving the structure's seismic capacity. In addition, the ductile joints used also affected the overall structural stiffness. The steel frame specimens' dynamic response (seismic shear coefficient, structural capacity curve, and fundamental frequency attenuation curve) was discussed. As the dynamic loading was applied, the seismic shear coefficients of CPJ and RJ steel frame increased continuously, and the structural capacity curves rose steadily, which indicated that the RJ and CPJ had excellent seismic performance and ductility. The finite element analysis was performed to elaborate further on the seismic performance and failure modes of steel frames. The experimental results were verified by the finite element analysis, and the finite element model could be used for the subsequent research on the steel frame.

Seismic Response and Damage Characteristics of RCC Gravity Dams Considering Weak Layers Based on the Cohesive Model

Due to the construction technology of roller compacted concrete (RCC) gravity dams, there are many weak layers that have the potential to affect the seismic performance of dams. However, research on the seismic response and failure characteristics of RCC dams considering their layered characteristic is still lacking. In this paper, the zero-thickness cohesive element is presented to model the mechanical behavior of the RCC layers. An impacted concrete beam is selected to verify its effects on simulating crack propagation. Subsequently, the concrete damaged plasticity model is utilized to model concrete under seismic loading. The dynamic interaction in the gravity dam-reservoir-foundation system is considered by coupled acoustic-structural method, whose rationality is validated by seismic failure mode analysis of the Koyna dam under the 1967 Koyna earthquake. The validated algorithms are applied to investigate the influence of the weak layer at different elevations on the seismic response and the failure process of the Guandi RCC gravity dam. On this basis, the effects of well-bonded RCC layers set at intervals along the dam on the nonlinear response and failure modes under strong earthquakes are further investigated. The results reveal that the weak layer will influence the anti-seismic capacity of RCC gravity dams, and the damage characteristics of the dam are significantly changed. In addition, well-bonded RCC layers still affect the seismic response of RCC gravity dams. Increasing displacement response and energy dissipation can be observed. Meanwhile, RCC layers lead to more severe damage to the dam under the same seismic input.

The multi-dimensional fragility analysis of the underground large-scale frame structure based on the internal relationships of different seismic performance evaluating indexes

In this paper, the seismic performance of the underground large-scale frame structure (ULSFS) is thoroughly investigated aiming at the drift deformation and rotation deformation of vulnerable positions, and the multi-dimensional fragility analysis of the ULSFS is further developed based on the internal relationship of different seismic performance evaluating indexes. Employing the increment dynamic analysis (IDA) method, the seismic performance of the ULSFS is investigated during diverse earthquakes. The interlayer deformation ratio (IDR) and interlayer rotation angle (IRA) are adopted as Damage measures (DM) to assess the drift deformation and rotation deformation, respectively. The internal relationships of two DMs are revealed, and the correlation coefficients are proposed by the correlation analysis. Assuming the DMs subordinated to the joint lognormal distribution, the generalized equations are established to describe performance states of the ULSFS aiming at different seismic failure modes. Considering the seismic thresholds and correlation coefficients of two DMs in different performance limit states, the 2-D fragility curves of the ULSFS are achieved. The results shows that the correlation of seismic evaluating indexes would decrease with the increase seismic intensities due to the structural inelastic damage; and the 2-D fragility curves with considering the reasonable internal relationships of two DMs would be more accurate and conservative. This paper provides the theoretical basis and technical support for the seismic performance assessment of large underground frame structures with complicate seismic failure modes.