Structural Seismic Damage Research Articles

Construction and Verification of Composite Intensity Measures for Multi-Storey Underground Structures Based on Partial Least Squares Regression Method

In the processes of seismic design of underground structures, selecting a reasonable input ground motion is very important, which can cause severe damage to underground structures. To quantitatively evaluate the seismic damage potential of ground motions on multi-storey underground structures and solve the problem that single intensity measures are inadequate in accurately indicating the seismic damage potential of ground motions, this paper taking the input ground motions in the seismic design of underground structures as the research object, and constructing some composite intensity measures that can effectively characterize the damage potential of input ground motion. Firstly, considering that the underground structures in different characteristic period-type sites will exhibit different seismic responses under the same excitation, the soil–structure system is divided into four-period bands. Then, four representative periods are selected from four-period bands respectively, and the corresponding four soil–structure system numerical models are established. Subsequently, 40 ground motions are selected for elastoplastic numerical analysis, and the results of the numerical analysis were used as sample data to construct composite intensity measures corresponding to soil–structure systems in each period band using the partial least squares regression method. Finally, 100 additional ground motions were used to verify the correlation between the composite intensity measures and the seismic damage of underground structures. The results show that the correlation coefficient between the composite intensity measures and the seismic damage of multi-storey underground structures is better than those of commonly used single intensity measures.

Research and Modification on the Park-Ang Damage Index for Railway Rectangular Piers

ABSTRACT This study addressed the issue of distortion in evaluating the seismic damage state of railway bridge piers using the original Park-Ang damage index. By constructing a parameterized co-simulation program with two finite element models, OpenSees and Abaqus, five sets of flexural failure and five sets of flexural-shear failure rectangular pier quasi-static test results were selected to validate the rationality of the calculation program. Four hundred and eighty parameterized calculations were conducted using this program. The combination coefficient β and critical damage index DI within the Park-Ang damage index were modified using nonlinear regression algorithm and convolutional neural network algorithm. The adaptability of the damage index calculation was ultimately verified through an engineering case study of a simply supported beam bridge. The research findings are as follows: 1) The main factor influencing β is the longitudinal reinforcement ratio, while the axial compression ratio, shear span ratio, volumetric stirrup ratio, aspect ratio, concrete strength, and steel strength are secondary parameters influencing β. 2) Compared to the nonlinear regression algorithm, the convolutional neural network algorithm can better establish a calculation model between pier structural parameters and β, clarifying their relationship. 3) It is recommended to use critical values of 0.11, 0.29, 0.49, and 1.00 for assessing pier damage as no, slight, moderate, severe, and collapse damage when using the damage index calculation model. 4) The Park-Ang index corrected by convolutional neural networks demonstrates improved accuracy and computational stability, making it suitable for practical assessment of seismic damage in bridge structures.

Optimized seismic hazard and structural vulnerability model considering macroseismic intensity measures

Macroseismic intensity measures are fundamental quantitative indicators for evaluating the vulnerability and resilience of regional building clusters. The vulnerability model of building portfolios established can provide a noteworthy reference for the development of large-scale regional earthquake risk distributions. However, there are differences in the quantitative scales of the macroseismic intensity standards used in multiple regions. The positive effects of instrument intensity and probabilistic seismic hazard theory on the vulnerability assessment of regional buildings are rarely considered, resulting in significant differences in their assessment results. This paper comprehensively considers the impact of instrument intensity and seismic hazard models on traditional macroseismic intensity. An updated macroseismic intensity measure (UCMS-20) is proposed for evaluating regional buildings, which is combined with the latest version of China's seismic intensity standards. The actual seismic damage sample dataset (31,649 buildings) of four types of building clusters in three typical earthquakes in China (Wenchuan 2008, Yushu 2010, and Jiuzhaigou 2017) has been expanded and updated. Using the UCMS-20, the European Macroseismic Scale (EMS-98), the Modified Mercalli intensity (MMI), and the Medvedev, Sponheuer, and Karnik Scale (MSK-64), vulnerability assessments are conducted on the extended empirical structural seismic damage dataset, and an empirical disaster matrix model considering updating damage states is established. A nonlinear vulnerability prediction model considering updated macrointensity measures is proposed, and the optimized model is validated and compared against the developed multiscale empirical structure dataset. The multiscale vulnerability index calculation model is improved, and novel optimization curves, point clouds, and matrix probability risk models are established, considering the expansion of empirical structural vulnerability databases.

Correlation of Soil Conditions with Seismic Damage of Structures in Craiova, Romania

Correlation of Soil Conditions with Seismic Damage of Structures in Craiova, Romania

Control of Structural Seismic Damage in Prefabricated Reinforced Concrete Frames through Hybrid-Selfcentering Connections

Current seismic design philosophy of industrial structures in Chile aims at the protection of life and continuity of operation in the industry. The compliance with these requirements allows controlling structural damage based on resistance criteria, without detecting the failure mode or specifying its location in the event of a major seismic event. In this paper, we discuss the application of an innovative technique for controlling the structural damage in prefabricated reinforced concrete frames, which are founded on granular soils. This technique is applied in the construction of the Forest and Paper Pulp Plant Concepción. This is done by incorporating hybrid post-tensioned joints in precast columns of the project, and this approach aims to control energy dissipation in the union and maintain the initial stiffness of the system. Using a nonlinear dynamic analysis with 2D Ruaumoko software, potential performance in traditional design versus innovative design is compared. The analysis is performed for various Chilean representative seismic records and different types of soils. The results indicate that the structure with the traditional design could suffer displacement in the roof of the order of 40 cm, moving heavily into the inelastic range, with residual deformations and concentrating the damage generation of plastic hinges at the ends of the columns and some beams not designed for ductility. In contrast, the use of self-centering hybrid joints causes the structure to recover its original position, without the presence of remnant deformations.

Theoretical nonlinear force-displacement constitutive model of triangular-plate steel damper

Utilizing the inelastic deformation of a steel damper to dissipate seismic energy and control structural damage is a prevalent design strategy in a passive control field. Such a design strategy requires an explicit force-displacement constitutive model of the steel damper in both the elastic and plastic deformation phases. Currently, the nonlinear force-displacement relationship of the steel damper is mainly determined by quasi-static tests or numerical simulations which are generally time-consuming, and there is a lack of a theoretical and straightforward approach to determine the nonlinear force-displacement constitutive model of the steel damper. This study thus theoretically derives the nonlinear force-displacement constitutive model for a commonly used triangular-plate steel damper. The theoretical formula is derived based on the equal curvature assumption commonly applied to the triangular plate and is further modified based on the curvature shape function proposed in this study for the first time. After that, the force-displacement curves obtained from the theoretical formula are compared with those obtained from a large number of numerical simulations and several sets of quasi-static tests. The result shows that the theoretical formula derived based on the curvature shape function can better predict the nonlinear force-displacement curve of the triangular-plate steel damper, which significantly outperforms the theoretical formula derived based on the equal curvature assumption especially as the triangular-plate steel damper has a large plastic deformation. Furthermore, the influence factors of the strain-hardening phenomenon existing in the force-displacement curve of the triangular-plate steel damper are analyzed based on the modified theoretical formula. The result implies that the thickness-to-height ratio of the plate is the most significant factor for the strain-hardening behavior of the triangular-plate steel damper.

Seismic Damage and Disaster Reduction Analysis of Building Structures along the Surface Rupture Trace Line of Strong Earthquakes

Seismic Damage and Disaster Reduction Analysis of Building Structures along the Surface Rupture Trace Line of Strong Earthquakes

Analysis of Vibration Characteristics of Bridge Structures under Seismic Excitation.

Bridges may undergo structural vibration responses when exposed to seismic waves. An analysis of structural vibration characteristics is essential for evaluating the safety and stability of a bridge. In this paper, a signal time-frequency feature extraction method (NTFT-ESVD) integrating standard time-frequency transformation, singular value decomposition, and information entropy is proposed to analyze the vibration characteristics of structures under seismic excitation. First, the experiment simulates the response signal of the structure when exposed to seismic waves. The results of the time-frequency analysis indicate a maximum relative error of only 1% in frequency detection, and the maximum relative errors in amplitude and time parameters are 5.9% and 6%, respectively. These simulation results demonstrate the reliability of the NTFT-ESVD method in extracting the time-frequency characteristics of the signal and its suitability for analyzing the seismic response of the structure. Then, a real seismic wave event of the Su-Tong Yangtze River Bridge during the Hengchun earthquake in Taiwan (2006) is analyzed. The results show that the seismic waves only have a short-term impact on the bridge, with the maximum amplitude of the vibration response no greater than 1 cm, and the maximum vibration frequency no greater than 0.2 Hz in the three-dimensional direction, indicating that the earthquake in Hengchun will not have any serious impact on the stability and security of the Su-Tong Yangtze River Bridge. Additionally, the reliability of determining the arrival time of seismic waves by extracting the time-frequency information from structural vibration response signals is validated by comparing it with results from seismic stations (SSE/WHN/QZN) at similar epicenter distances published by the USGS. The results of the case study show that the combination of dynamic GNSS monitoring technology and time-frequency analysis can be used to analyze the impact of seismic waves on the bridge, which is of great help to the manager in assessing structural seismic damage.

Study of Structural Seismic Damage Considering Seasonal Frozen Soil–Structure Interaction

Frozen soil may cause structures to have different damage statuses, as revealed by earthquakes in northeastern China. ABAQUS (2019), a numerical simulation software application, was adopted to systematically and deeply study the structural seismic response, considering seasonal frozen soil–structure interaction under different ground motion intensities and soil ambient temperatures. The results showed firstly that the variation in soil ambient temperature had a great influence on the seismic response of the structure, as indicated by the damage status of the structure obtained through numerical simulation. Secondly, through further analysis of the numerical simulation results, the influence amplitude of different soil temperatures on the structural seismic response was quantitatively analyzed and systematically summarized. Finally, the structural seismic damage with negative ambient temperature could be significantly lower than that with positive temperature normally. Additionally, such an internal change mechanism was also objectively analyzed to verify the reliability of the conclusion.

Innovative approach to estimate structural damage using linear regression and K-nearest neighbors machine learning algorithms

Conventional structural design methodologies often utilize elastic analysis techniques, such as the equivalent static force method and the response spectrum method. While these methods are known for their simplicity and computational efficiency, they prove inadequate in capturing the extent of structural damage caused by seismic forces. Additionally, employing nonlinear dynamic analysis to estimate structural damage represents a challenging and intricate task, posing difficulties for many structural designers. Consequently, the objective of this paper is to present an innovative methodology for evaluating seismic structural damage of moment-resisting frame structures. This involves the utilization of machine learning algorithms, which have been trained and tested on a large data set generated using a newly developed and numerically efficient simulation procedure. The machine learning algorithms employ both linear regression and K-nearest neighbors approaches to accurately replicate the Park-Ang structural damage index.

Feasibility Study of Earthquake-Induced Damage Assessment for Structures by Utilizing Images from Surveillance Cameras

Rapid and accurate structural damage assessment after an earthquake is important for efficient emergency management. The widespread application of surveillance cameras provides a new possibility for improving the efficiency of assessment. However, it is still challenging to directly assess the structural seismic damage based on videos captured by indoor surveillance cameras during earthquakes. In this study, we elaborate on the concept of estimating the structural natural frequency based on the relative pixel displacement of inter-stories. Furthermore, we propose a strategy for post-earthquake structural damage assessment that integrates the computer vision and time-frequency analysis. This approach aims to navigate the difficulties inherent in earthquake damage assessment and improve emergency responses. The relative pixel displacement between the camera and the fixed features on the floor is extracted from videos by using the Harris corner detection and Kanade–Lucas–Tomasi algorithms. The structural natural frequency is estimated using the synchroextracting transform-enhanced empirical wavelet transform. The natural frequency shift-related seismic damage index is defined and calculated for damage assessment. A shake table experiment of a small-scale steel model is conducted to verify the accuracy and feasibility of the approach, and the practicality of the proposed approach is further verified by utilizing the data from a full-scale reinforced concrete benchmark model experiment. The results demonstrate that the approach can accurately and efficiently evaluate the structural damage after an earthquake based on the video captured by surveillance cameras during the earthquake. The error of the acquired damage index is less than 0.1. We will apply more advanced algorithms in the future to alleviate this problem.

Seismic Performance Evaluation of Traditional Chinese Mortise-Tenon Frame Infilled with Friction Dissipative Window Frame

ABSTRACT This paper presents a new form of window frame that employs a friction dissipative connection. The design is informed by a structural analysis of the sill window in traditional wooden structures and inspired by friction dissipative mechanisms. By considering the frictional wear of the friction block, a more accurate formula for calculating the frictional torque is derived and its accuracy is verified. Additionally, a finite element model of the sill window-wooden frame system is established and verified using experimental data. Then a further finite element model of the sill window-wooden frame system with the friction dissipative window frame is established and analyzed, and the effectiveness of the reinforcement scheme of the friction dissipative connection is verified. The analysis shows that compared to the sill window-wooden frame system, the load-carrying capacity and energy dissipation of the sill window-wooden frame reinforced with the friction dissipative window frame are significantly improved. When the bolt pre-tightening force is 100 kN, the peak load and stiffness of the sill window-wooden frame system reinforced with the friction energy dissipation window frame are increased by 2.7 and 2.57 times, respectively, compared to the sill window-wooden frame, which can effectively prevent the seismic damage of ancient wooden structures.

Seismic response of expanded polystyrene (EPS) sandwiched concrete panels system in buildings: Damage distribution and correlation analysis of parameters

Lightweight wall panels and connectors between them and load-bearing structures are often significantly damaged during moderate-intensity seismic events. However, generally applicable methods and models for predicting and assessing the damage are lacking. A seismic analysis and assessment framework for the interaction among lightweight partition wall panels, energy-dissipating connectors, and main structural elements was established via the Maximum Information Coefficient method. Experiments and numerical simulations were conducted to investigate the nonlinear behavior and hysteresis-based energy-dissipation features of connectors in Expanded Polystyrene sandwiched concrete panels. A system model incorporating lightweight wall panels, connections designed to absorb energy, and load-bearing structures is proposed to elucidate their collaborative interactions. The distribution pattern of seismic damage in the Expanded Polystyrene sandwiched concrete panels system was also investigated. Based on the characteristics of the incremental dynamic analysis results, a correlation evaluation of the seismic parameters and structural damage was conducted using the refined Maximum Information Coefficient method. The proposed analysis framework can be used for the damage evaluation and prediction of assembled nonstructural elements.

Behavior and design of demountable and replaceable RC columns with bolted flange connections under eccentric compression

This study developed an innovative bolted flange connection for reinforced concrete (RC) columns, through which the RC columns could be removed and replaced in the event of a change in structural function or seismic damage. The detailed construction of the demountable and replaceable reinforced concrete columns with flange connection (DRCC-FC) is introduced firstly. Then the installation method and replacement requirement of DRCC-FC is presented, and the design formula for flange connection is also given. This study conducted experiments on nine DRCC specimens and one cast-in-place specimen under eccentric compression. The failure modes, loading capacity, deformability as well as strain on rebars and flange plates were investigated. Furthermore, finite element models of DRCCs were established and a parametric analysis was conducted. The effect of flange thickness, flange steel strength and length of connectors on mechanical properties was discussed. Results demonstrated that the failure modes of DRCC specimens were consistent with that of cast-in-place specimen, both of which exhibited yielding of rebars on the tensile side and crushing of concrete on the compressive side. The flange of the specimen with a low thickness appeared plasticity, and the other specimens did not show a significant deformation on the flange plates and bolts, which was favorable for the removal and replacement of the column components. The loading capacity of the DRCC specimens was slightly lower than that of the cast-in-place one, but the deformability was superior. Flange thickness is the main factor affecting the loading capacity and rotational stiffness of the flange connection. Finally, the formula for loading capacity of DRCCs related to flange thickness was presented. Comparison with the finite element and test results indicated that the calculation error of the formula is within 12%.

A comparative study on the seismic performance of long span Engineered Cementitious Composite (ECC) structures

The strain hardening fiber reinforced concrete—generally known as the Engineered Cementitious Composite (ECC)—has rapidly gained the attention of researchers in recent years. However, most of the research on ECC is limited to material and member level, leaving a gap in the understanding of its behavior at the structural scale. Therefore, this study investigates the global seismic response of ECC structures and compares their performance with conventional reinforced concrete (RC) structures. For this purpose, a case study long span building structure (an aircraft hangar having a span length of 40 m) is selected. Under the design-level gravity and lateral loads, its members are separately designed using the conventional RC and ECC. It is observed that for ECC members, the requirement of longitudinal steel is reduced by 30% when compared with the conventional RC members. Similarly, owing to an improved tensile behavior, the ECC members also exhibited a higher shear capacity than RC members, resulting in a significant reduction in the requirement of transverse reinforcement. The detailed inelastic finite element models for both design cases (RC and ECC) were subjected to the pushover analysis and nonlinear response history analysis (NLRHA) to assess their seismic performance. It is observed that (in terms of local and global seismic demands, structural damage, and ductile behavior) the performance of the ECC structure is significantly improved when compared to the conventional RC structure. The comparative cost analysis showed a reduction of 11.9% in the overall material cost of the ECC structure as compared to RC. These results show that ECC can be effectively used at the full structural level as an economic solution to ensure the ductile response and superior seismic performance.

Seismic response of a ground-bridge structure system in horizontal and inclined liquefiable site to near-fault pulse-like ground motions

Previous earthquake events have indicated that bridge structures are more vulnerable to severe damage when subjected to near-fault pulse-like (NF-P) ground motions. Structural seismic damage will be exacerbated when bridges are located in liquefiable site. Meanwhile, the seismic response of bridges located in inclined liquefiable site is different from that of bridges in horizontal liquefiable site. This study focuses on exploring the seismic response of a ground-bridge structure system located in horizontal and inclined liquefiable site to the NF-P ground motions. The seismic response of the whole system to the near-fault non-pulse-like (NF-NP) and far-field (FF) ground motions is studied for comparison. Two three-dimensional (3D) finite element (FE) models of the ground-structure system considering soil-pile interaction are developed. They are associated with the horizontal and inclined liquefiable site, respectively. The seismic responses of the ground-bridge structure system to the three different types of ground motions (i.e., NF-P, NF-NP and FF) are comprehensively evaluated from two perspectives. On the one hand, the seismic time history responses of the ground-bridge structure system under single representative ground motion are comprehensively assessed. On the other hand, the average responses of the ground-bridge structure system under multiple types of ground motions are explored. The results reveal that in contrast to the NF-NP and FF ground motions, the NF-P ground motions have more significant effect on various responses of the ground-bridge structure system. In addition, compared to the bridge in horizontal liquefiable site, the bridge in inclined liquefiable site exhibits larger seismic responses. Therefore, the velocity pulse effect of the NF-P ground motions and the liquefaction effect of the inclined site need to be emphasized in structural seismic design.

A Three-Dimensional Seismic Damage Assessment Method for RC Structures Based on Multi-Mode Damage Model

To rationally evaluate the seismic damage of RC structures comprehensively and multi-dimensionally, a damage index calculation method is proposed. This is a macroscopic global seismic damage model that considers torsional damage, damage in two perpendicular horizontal directions, as well as the overall damage, based on the modal characteristics of the three-dimensional structure and the multi-mode damage model. Formulas are derived, and the steps for damage evaluation are summarized. To better illustrate the results of the proposed method, an example of an asymmetric 6-story frame-shear wall structure is built using the OpenSees program. Thirteen ground motions are selected for incremental dynamic analysis. The structure’s damage indexes are evaluated according to the proposed method and compared with the corresponding structural responses, He et al.’s index, and the Final Softening index. The results demonstrate that the proposed method can fully reflect the macroscopic damage state of the structure from different perspectives. Additionally, the results show that, despite the ground motion only acting in the y-direction, the structure exhibits responses and damage in both the x-direction and the torsional direction. The overall damage to the structure is primarily controlled by the torsional damage, attributed to the asymmetric arrangement of shear walls. The torsional effect is the key factor leading to the failure of asymmetric structures during earthquakes. Therefore, ensuring the torsional strength of the structure is crucial during the structural design process.

Bidirectional graphics-based digital twin framework for quantifying seismic damage of structures using deep learning networks

Tremendous effort has been devoted toward developing automated post-earthquake inspection techniques, including automated image collection and damage identification. However, few studies have attempted to establish the complex relationship between visible damage and structural conditions. Moreover, the lack of training data further hinders the potential use of deep learning algorithms. This paper proposes a framework, termed Bidirectional Graphics-based Digital Twin (Bi-GBDT), that allows for assessment of the structural condition based on post-earthquake photographic surveys. The procedure contains two parts: (i) A GBDT of a target structure, containing a computer graphics model and a finite element (FE) model, is developed (ii) Synthetic data subsequently is generated from the GBDT to train neural networks to predict the damage measures and structural conditions. To demonstrate the proposed approach, a seismically-designed reinforced concrete shear wall is considered. First, the GBDT of the shear wall is constructed and calibrated so that the associated damage patterns simulated by the corresponding FE model match well with the experimental results. Next, synthetic images of the damage patterns are created from the validated GBDT, along with the corresponding structural damage measures, and used to train Residual Neural Network and Conditional Generative Adversarial Networks to determine the maximum drift, the stress/strain fields and the structural condition. The neural networks trained on synthetic data are shown to perform well for the experimental data, confirming the proposed approach. Subsequently, the neural networks are tested on the synthetic data for a wide variety of loading conditions to demonstrate the robustness of the approach. In addition, the realistic images rendered from the GBDT are utilized as input to predict the structural condition, showcasing the comprehensive Bi-GBDT framework. These results demonstrate the efficacy of the proposed approach to generate accurate digital twins and point toward its future application for development of automated post-earthquake assessment strategies.

Seismic performance loss evaluation of reinforced concrete frame structure based on updatable damage model

AbstractAs structural seismic damage develops, the internal force transfer and damage weight relationship of component are constantly changing, and the fixed weighted coefficient is adopted by the traditional weighted method, which cannot reflect the changes in the structural damage state. The structure is a network formed by connecting a large number of components, and the network state undergoes complex changes with the development of component damage. In this paper, a novel method for component damage transfer to structural seismic performance loss is proposed using network shortest paths. First, a directed weighted complex network based on force transfer direction and component stiffness is constructed for reinforced concrete (RC) frame structures. Then, the component damage is calculated by the degradation of its stiffness and is used to update the weight distribution of the damage network. Finally, the structural performance loss is evaluated by the degradation of damage network efficiency. Results show that the proposed method with an updated component weight relationship is able to reflect the true loss of structural performance according to the finite element dynamic elastic‐plastic analysis of RC frame structures. For the structural performance loss degree (none, slight, moderate, severe, complete), the proposed method and the weighted method both exhibit high accuracy (number correctly classified/total number of samples) when structural performance loss is none, severe, or complete loss. The accuracy of the proposed method is significantly higher than that of the weighted method when structural performance loss is slight and moderate loss, with 58.1% and 84.2% improvement, respectively. For structural typical damage modes (global, local, and weak layer damage mode), the proposed method and the weighted method both exhibit high accuracy when structures exhibit global damage mode. The accuracy of the proposed method is significantly higher than that of the weighted method when structures exhibit local and weak layer damage mode. The accuracy of the proposed method is stable at 95.2%, while the accuracy of the weighted method is 76.2% and 70.2%, respectively. Overall, the weighted method exhibits high accuracy when structural performance loss is less than slight loss or greater than moderate loss, while the proposed method exhibits high accuracy throughout the entire process of structural performance loss, especially in moderate loss.

Earthquake-induced loss assessment of hybrid self-centering piston-based braced frame with friction springs and SMA bars

A novel Self‐Centering Piston-Based Bracing (SC-PBB), integrating Friction Springs (FSs) and Shape Memory Alloy (SMA) bars, offers a promising solution for curtailing seismic damage in braced frame structures. Nevertheless, this hybrid SC-PBB may incur higher construction costs compared to conventional bracing archetypes. Accordingly, it is imperative to investigate whether the initial cost increase can be offset over the structure's lifespan. This study quantifies earthquake-induced financial losses in braced frames equipped with SC-PBBs (SC-PBBFs) compared to those equipped with Buckling-Restrained Bracings (BRBs). A building-specific Performance-Based Earthquake Engineering (PBEE) framework is employed to evaluate potential economic losses under far-field ground motions. The analysis quantifies total, collapse, irreparable, and repair losses by incorporating seismic hazards, structural demands, and damage consequences. Results reveal higher total and collapse losses for BRBFs, although their lower repair costs for non-structural components mitigate repair loss. Additionally, the low-rise SC-PBBF archetype could recoup initial construction expenses over its expected lifespan, unlike its BRBF counterpart.