Post-earthquake Performance Research Articles

Post-earthquake functional state assessment of communication base station using Bayesian network

The reliability and resilience of communication base stations are critical to the post-earthquake performance of the communication system, and consequently influence the communication, rescue, and emergence management after an earthquake. There is a lack of models that can fully evaluate the post-earthquake functional states of base stations with the consideration of the dependencies between different components. This paper proposes a Bayesian network method to evaluate the post-earthquake functionality of communication base stations. The method considers the dependence between the equipment and its hosting building structure, and the impact of power outages. This model produces seismic functional fragility curves for typical base stations that enable both qualitative and quantitative evaluations of base station functionality. The model is validated using seismic damage data from the Ludian Earthquake. It was found that the proposed model can reasonably predict the post-earthquake functional failure of base stations, in good agreement with the observed seismic damage data. The application of this model provides support for the operation and maintenance of communication base stations, and insights for managing seismic risk and resilience of the communication system.

Seismic Upgradation of Building Using Shear Wall and Bracing

Abstract: The seismic assessment prepare comprises of exploring in case the structure meets the defined target structural performance levels. The main goal during earthquakes is to assure to people is minimized and beyond that to satisfy postearthquake performance level for defined range of seismic hazards. Rehabilitation prepares points to progress seismic execution and adjust the lacks by increasing quality, firmness or distortion capacity and making strides associations. Hence, a proposed retrofit execution can be said to be fruitful in the event that it comes about an increment in strength and ductility capacity of the structure which is more noteworthy than the requests forced by earthquakes. Seismic force, predominantly being an inertia force depends on the mass of the structure. As the mass of the structure increases the seismic forces also increase causing the requirement of even heavier sections to counter that heavy forces. And these heavy sections further increase the mass of the structure leading to even heavier seismic forces. Structural designers are met with huge challenge to balance these contradictory physical phenomena to make the structure safe. The structure no more can afford to be rigid. This introduces the concept of ductility. The structures are made ductile, allowing it yield in order to dissipate the seismic forces. A framed structure can be easily made ductile by properly detailing of the reinforcement. But again, as the building height goes beyond a certain limit, these framed structure sections (columns) get larger and larger to the extent that they are no more practically feasible in a structure. There comes the role of shear walls. Shear walls provide ample amount of stiffness to the building frame resisting loads through in plane bending. But they inherently make the structure stiffer. So, there must be a balance between the amount of shear walls and frame elements present in a structure for safe and economic design of high-rise structures

A hybrid model for post-earthquake performance assessments in challenging contexts

AbstractDisasters provide an invaluable opportunity to evaluate contemporary design standards and construction practices; these evaluations have historically relied upon experts, which inherently limited the speed, scope and coverage of post-disaster reconnaissance. However, hybrid assessments that localize data collection and engage remote expertise offer a promising alternative, particularly in challenging contexts. This paper describes a multi-phase hybrid assessment conducting rapid assessments with wide coverage followed by detailed assessments of specific building subclasses following the 2021 M7.2 earthquake in Haiti, where security issues limited international participation. The rapid assessment classified and assigned global damage ratings to over 12,500 buildings using over 40 non-expert local data collectors to feed imagery to dozens of remote engineers. A detailed assessment protocol then conducted component-level evaluations of over 200 homes employing enhanced vernacular construction, identified via machine learning from nearly 40,000 acquired images. A second mobile application guided local data collectors through a systematic forensic documentation of 30 of these homes, providing remote engineers with essential implementation details. In total, this hybrid assessment underscored that performance in the 2021 earthquake fundamentally depended upon the type and consistency of the bracing scheme. The developed assessment tools and mobile apps have been shared as a demonstration of how a hybrid approach can be used for rapid and detailed assessments following major earthquakes in challenging contexts. More importantly, the open datasets generated continue to inform efforts to promote greater use of enhanced vernacular architecture as a multi-hazard resilient typology that can deliver life-safety in low-income countries.

An explicit approach for modeling the performance of transportation networks immediately after an earthquake

Surface transportation systems play a vital role in supporting a region’s functionalities. They are expected to remain operational before and even after a hazardous event (e.g. an earthquake). The importance is evident to estimate the post-disaster performance of traffic systems under a probability-based framework, considering the uncertainties arising from both the hazards and the transportation infrastructure fragilities. This paper proposes an explicit approach for evaluating the performance of transportation systems immediately after an earthquake event. The method estimates the spatial distribution of vehicles in the traffic network in a closed form and thus is relatively efficient compared with traditional methods (e.g. an agent-based method). The applicability of the proposed approach is demonstrated through an application to the post-earthquake performance assessment of the traffic network in Tangshan City, China, a city that suffered catastrophically from the 1976 Tangshan Earthquake. Analytical results show that the proposed method can well reflect both the temporal and the spatial variations of the traffic flow, and thus offers rational support for predicting the post-earthquake traffic scenarios and for optimizing strategies to improve the transportation capability under emergent conditions.

The Parameter Identification of Structure with TMD considering Seismic Soil-Structure Interaction

Parameter identification is of great significance for the postearthquake performance evaluation of structure equipped with tuned mass damper (TMD). However, the soil-structure interaction (SSI) effects have not been considered in the parameter identification of structure with TMD yet, which influence the dynamic characteristics and seismic responses of structures. This paper aims at proposing a framework for identifying the physical parameters of soil-structure-TMD system. Firstly, the accelerated particle swarm optimization (APSO) algorithm is combined with the search space reduction (SSR) method. Then, the frequency response function and transmissibility function are adopted for output-input and input-only cases, respectively, and a simplified mechanical model for soil-structure-TMD system is employed. Next, the measured responses are used to identify the physical parameters of structure with TMD considering SSI effects. Finally, the effectiveness of the proposed identification method is investigated, and the influences of frequency band and noise pollution on the identification performance are discussed. The results show that the proposed strategy can identify the system physical parameters accurately and quickly. It is worth noting that high frequency bands and noise pollution may lead to estimation error, especially for output-only case.

Damage inference and residual capacity assessment for an E-Defense 2018 ten-story RC test structure

This paper presents an enhanced vision-based, post-earthquake performance assessment framework for RC building structures. This framework incorporates a damage inference method that can estimate the stiffness and strength reduction factors of components in stories without damage inspection based on the inter-story drift. The framework was validated by the application to the full-scale shaking table test of an E-Defense 2018 ten-story RC structure. The vision-based damage detection method effectively detected multicategory seismic damage on the component surfaces, and the damage states estimated by the vision-based method were consistent with the results estimated by the measured plastic hinge rotation. The proposed inter-story drift-based damage inference method reasonably estimated the reduction factors of components in the stories without damage photos. The numerical model updated by the reduction factors of damaged components provided accurate estimates of the fundamental vibrational frequencies after different levels of seismic shaking, and the drift-based inference method significantly improved the results compared with the trivial linear interpolation method. The residual capacity curves provided by pushover analysis of the updated model using the reduction factors as per FEMA 306 & Chiu et al. reasonably captured the hysteretic responses of the structure.

Performance-based damage quantification and evaluation for self-centering concrete frames

Self-centering concrete frames (SCCFs) are designed to provide superior seismic capacities with resilient features. Although a well-designed SCCF can limit damage development, it still impairs post-earthquake performance and shall be considered properly. Quantifying and evaluating structural damage can provide valuable guidance for seismic designs and post-earthquake assessments, yet related studies towards SCCFs are still limited. This paper aims to conduct damage quantification and evaluation for SCCFs. The damage development and distribution within SCCFs are investigated. A modified damage model is adopted to quantify the damage developed in beam-column joints. Weighting coefficients based on the hysteretic energy demands are introduced to assess story and integral structural damage. 12 SCCFs with different structural features are designed and analyzed under 44 ground motions. The damage development within structures is quantified and evaluated using the performance-based damage intervals. The results show that damage developed in SCCFs exhibit stable growth with seismic intensities, implying superiorities in the damage controllability and stability. Meanwhile, increasing the self-centering parameter λ proves effective in reducing damage developed in SCCFs. A method to estimate integral structural damage is proposed, while proper design parameters are suggested to further assist seismic designs for SCCFs based on analytical results.

Effectiveness of structural walls in improving the serviceability of a seismically-retrofitted RC building

AbstractA moderate earthquake with a magnitude Mw of 6.8 hit the Elazig Province of Turkey on January 24th, 2020, causing fatalities and structural damage/failure. Following the earthquake, a field reconnaissance was conducted at the Administration and Operation Campus of Karakaya Dam, which is 19 km from the earthquake epicenter. The exhibited performances in two side-by-side nominally identical reinforced concrete (RC) buildings with the same material properties and soil conditions differed significantly. The main reason lies in the preventive action taken before the earthquake in one of the buildings. The building retrofitted with additional structural walls had a slight/no damage level. However, the non-retrofitted building suffered severe damage due to large cracks in numerous infill walls, some of which were exposed to partial collapse. That makes the non-retrofitted building unserviceable, requiring evacuation after the earthquake. The field-observed building damage was compared with the seismic performances acquired from their refined numerical models for the recorded ground motions. The photographic documentation exposing the entire performance and damage level in non-retrofitted and retrofitted buildings was quantified by static pushover and nonlinear response history analyses. The post-earthquake performance of nonstructural members in retrofitted and non-retrofitted buildings was simulated with reasonable accuracy.

Post-earthquake performance and damage evaluation of self-centering shear wall with replaceable devices

Self-centering structures have been demonstrated to be an effective method by which to improve seismic resilience. Most related research is focused on the seismic performance of self-centering structures without initial damage, whereas the post-earthquake performance of structures, which is significant for their repair and operation, is less investigated. Based on this, this study aims to evaluate the post-earthquake behavior and explore the damage evolution of a novel self-centering shear wall with replaceable devices, including disc springs to apply restoring force and friction pads to dissipate energy. Cyclic loading tests were conducted on two intact self-centering shear walls to investigate their seismic performance in our previous studies, and limited damage was observed after the tests. Thus, in this study, cyclic loading was directly applied to the two damaged self-centering shear walls to obtain their post-earthquake performance. The results indicate that the damaged self-centering shear walls exhibited satisfactory seismic behavior; their bearing capacity was reduced at small drift ratios as compared to that of the intact specimens, whereas no decrease of their bearing capacity occurred even at a 3% drift ratio. Moreover, the damaged self-centering shear wall exhibited appreciable energy dissipation and self-centering capabilities, and the residual drift ratio was less than 0.5% at a 2.1% drift ratio. However, the damage at the bottom of the RC wall after the post-earthquake test was obvious, revealing that the novel self-centering RC shear wall would need to be repaired after several earthquakes. Therefore, two effective methods were further developed to improve the post-earthquake performance of the novel self-centering shear wall.

Comparative study on seismic performance of prefabricated and cast-in-place underground structures under different site conditions

Since the seismic performance of prefabricated underground structures is not yet clear, they not have been constructed in high seismic intensity areas or poor sites. This paper aims to study the applicability of rectangular prefabricated (semi-rigid prefabricated, ASF, and rigid prefabricated, AMT) underground structures in soft soil sites located in high seismic intensity areas. The structures were compared with cast-in-place (CIP) underground structures. Three-dimensional soil-structure interaction advanced finite element models were established to simulate the seismic behavior of the three types of underground structures (ASF, AMT and CIP) constructed in two different sites (soft rock site and soft soil site). The pre-earthquake stress states, dynamic responses, and post-earthquake performance states of the three underground structures were systematically analyzed, considering various static and dynamic conditions. Additionally, the results of dynamic time history were compared with those of the standard procedures available in the literature. The results demonstrated that: i) site conditions have a significant effect on the structures’ static and dynamic responses, ii) the seismic response in soft soil site is much larger than that in soft rock site, but the ratio of response of prefabricated underground structures to that of CIP is almost the same for both soft soil and soft rock sites. Furthermore, as the peak ground acceleration increases, the percentage difference of inter-story displacement ratio (IDR) between ASF, AMT and CIP underground structures in soft soil site decreases, and iii) prefabricated underground structures can be used in both soft rock and soft soil sites. In addition, the seismic performance of ASF is better than that of the AMT structure, which is better than that of the CIP structure. However, when the ASF structure is built in a site with high seismic intensity and poor soil conditions, special consideration must be given to waterproofing measures for wall-slab joints or setting up tongue and groove to improve the connection stiffness and reduce the deformation.

Two-Parameter–Based Damage Measure for Probabilistic Seismic Analysis of Concrete Structures

Traditional seismic fragility analysis defines the structural damage measure (DM) as a single parameter based on either strength, displacement, damage, or energy to evaluate the postearthquake performance of the structure, thus it is difficult to fully catch the behavior characteristics of the structures, e.g., both the maximum deformation capacity and the repairability of the structure. In this paper, we developed a multiparameter-based DM (mDM) index (here actually two parameters) for the probabilistic seismic analysis of reinforced concrete (RC) structures to capture a more comprehensive view of structural performance. Two parameters (i.e., the maximum interstory drift ratio θmax and the maximum residual interstory drift ratio θr,max) are combined to represent the overall structural performance, and different combination rules are investigated. To verify the superiority of the proposed mDM, the fragility analysis of three different structures is conducted, i.e., ordinary RC structure, aging RC structure, and new self-centering structure. The fragility curves derived from single DM and mDM are compared, and it is found that fragility curves with mDM can reflect both the maximum displacement and residual displacement features of the structure, thus mDM gives a more comprehensive and synthesis assessment of the postearthquake performance of the structure, which is beneficial for informed decision-making.

Preliminary proposal of a probabilistic framework for the post-earthquake performance assessment of road networks

The safety of infrastructural systems is of paramount importance since high socio-economic impacts would be expected in case of disruptions or, even worse, people life could be seriously endangered in case of severe damages or collapses.The relevance of the issue at hand pushed the scientific community to develop increasingly accurate probabilistic tools for the risk assessment, with particular attention to the vulnerability of existing bridges, which may show different damage mechanisms and which can lead multiple post-disaster scenarios. Then, the quantification of consequences plays a fundamental role in the forecast of the optimal intervention strategy to minimize the losses not only at local but also at network level. In this paper, a probabilistic framework for the post-earthquake performance assessment of road networks is preliminary proposed and an overview of the multiple steps that differently contribute to the final quantification of losses is provided. A preliminary application of the proposed framework is illustrated referring to one of the major road networks in the Marche region, in Central Italy. Results show the potentiality of the framework in the description of the post-disaster consequences for which monetary indicators are proposed relatively to indirect costs of practical interest. Moreover, the framework reveals sufficiently flexible to be used also in case of natural hazards other than the seismic one and to be furtherly expanded taking into account additional aspects affecting the bridges performances.

Vision‐based seismic damage detection and residual capacity assessment for an RC shaking table test structure

AbstractIn this paper, the existing postearthquake performance assessment framework for reinforced concrete (RC) building structures is improved by adding a new feature of the computer vision‐based damage detection. In this framework, visible seismic damage is classified and quantified from photographs of damaged RC components using the developed deep convolutional network (CNN) Damage‐Net of semantic segmentation, and then the mechanical property degradation factors of components determined from the detected damage states are used to update the numerical model. Pushover analysis of the updated model assesses the residual capacity of the damaged structure. Large‐scale shaking table tests of a three‐story RC building structure, which was heavily instrumented with sensors and recorded with a large volume of photographs, were used as a case study to demonstrate the improved postearthquake performance assessment framework. The vision‐based approach accurately detected multicategory seismic damage of the test structure and effectively estimated the residual crack widths and angles under various lighting, image acquisition, and surface conditions. The updated model, which incorporated the mechanical property degradation of the damaged components, provided accurate estimate on the fundamental vibrational frequencies of the damaged structure after various levels of seismic motion shaking, which matched well with the system identification results. Using the mechanical property reduction factor values recommended by FEMA 306 & Chiu et al., pushover analysis of the updated models provided residual capacity curves that reasonably captured the measured hysteretic responses of the structure. In addition, the damage states of components as estimated by the vision‐based methods were also compared with the measured plastic hinge rotation data. The successful implementation of the vision‐based assessment in this test case indicates its potential for application in the postearthquake evaluation of buildings.

System dynamics modeling of the earthquake-induced interruption of a business

ABSTRACT This study proposes a system dynamics simulation model that characterizes the dynamics post-earthquake performance of a business considering its dependency on lifelines (i.e., utilities and road networks) and the state of the market. The model characterizes the relationships between the business’s profitability and the resources it needs to operate (e.g., staff, raw materials, and equipment). It also considers the supply and demand dynamics that govern the prices of goods or services the business produces. It can be used to holistically investigate a business’s post-earthquake performance and recovery. It helps administrators acquire an insight into how to reduce the vulnerability of their businesses against probable future earthquakes. The model application is showcased by applying it to simulate the post-earthquake performance and recovery of a manufacturing business. The results indicate that, unlike retrofits, post-earthquake measures like increasing prices or changing shipping policies do not adequately mitigate earthquake-induced business losses.

Review of the energy-based design theory: Towards the application to self-centering systems

Self-centering systems exhibit superior performance during earthquake shaking with lower damage and less residual deformations. Although the equivalent static force design procedure is the commonly used one for most structural systems for seismic applications, the cumulative damage and the effective duration of earthquakes cannot be explicitly considered, which has significantly affected the behaviors and post-earthquake performance of self-centering systems. Energy-based design theory (EBDT), which introduces the energy demand as the critical parameter to establish relations with structural damage, has gained attention around the world in recent decades. The EBDT can provide comprehensive considerations for structural responses and damage in design procedures, especially for self-centering systems. However, few researches and actual energy design projects focus on the use of EBDT for self-centering systems. This paper intends to present thorough review of several critical issues in EBDT. Meanwhile, pivotal gaps that need to be further investigated towards the application of EBDT to self-centering systems are identified and discussed in the paper.

Seismic response of geogrid-reinforced fiber-cement soil walls using shaking table tests

Improving the characteristics of local low-strength soils at the construction site is one of the appropriate approaches to employ the soils as a backfill of geogrid-reinforced soil (GRS) walls. In this study, the fiber-cement-treated sand–silt mixture was used as the backfill of walls. The post-earthquake performance of the walls was evaluated by applying the sinusoidal waves on 1 m high reduced-scale physical models and conducting a series of 1g shaking table tests. A comparison of the wall models constructed with treated and untreated backfill indicated the advantages of geogrid-reinforced fiber-cement-treated soil walls subjected to strong ground motion. The results revealed the better behavior of the wall models backfilled with treated soil mixtures under dynamic loading. Such improved performance was more evident in (i) deformation responses, including the lateral displacement of wall facing, deformation mode, failure surfaces, and settlement of backfill surface and (ii) acceleration response in different locations, including facing, reinforced, and retained zones of walls.

Performance of repaired steel plate shear wall with earthquake-induced damage

To investigate the repair method of damaged steel plate shear wall in a steel frame, a scaled specimen was designed and tested under a two-phase pseudo-static loading. The damaged infilled steel plates were replaced with new steel plates between the two loading phases. The test results showed that after replacing the damaged infilled plates, the stiffness of the specimen increased. The bearing capacity was 577.3 kN, with a ductility of 3.5. The seismic performance of the repaired specimen was favorable. Replacing the infilled plate was an effective repair method for the steel plate shear wall structure while the columns were still in good integrity. To ensure a reliable post-earthquake performance of the boundary frame and an easy repair for the steel plate shear wall, the plastic development of the boundary column was investigate. By introducing the damage criterion into the finite element (FE) model, the stress redistribution caused by the damage of the infilled steel plate was considered. The shear force of the column at different lateral displacement, especially in the inelastic phase, was obtained. The yielding and damage state of the boundary column can be determined from the proportion of sustained shear force of the column at different displacements.

Post-earthquake Performance Level Investigation of ACI-Based Designed Simplified Reinforced Concrete Structures

Post-earthquake Performance Level Investigation of ACI-Based Designed Simplified Reinforced Concrete Structures

Performance evaluation of RC-MRFs with UHPSFRC and SMA rebars subjected to mainshock-aftershock sequences

Although structures are generally subjected to mainshock-aftershock sequences, the current structural design process merely considers the main seismic event. This study aims to compare the performance of Reinforced Concrete Moment Resisting Frames (RC-MRFs) with Shape Memory Alloy (SMA) and Ultra-High-Performance Steel Fiber Reinforced Concrete (UHPSFRC) under the influences of mainshock and aftershock sequence. To achieve this aim, 3, 6, and 8-story five-span frames were simulated considering three different approaches: (i) RC frames; (ii) RC frames with SMA rebars in the plastic hinge length of the beams; (iii) RC frames with UHPSFRC and SMA in the plastic hinge length of the beams.Each frame was analyzed under two different scenarios, with and without considering seismic sequences to assess the post-earthquake performance of damaged RC frames. Time history analyses were conducted using seven real accelerograms. Maximum transient inter-story and roof drifts, as well as residual inter-story drifts, were determined and compared in undamaged and damaged structures to assess the effect of seismic sequence. As the performance evaluation of the damaged structures appears to be essential to make repair policy decisions and rescue operations, damage states were defined according to FEMA-356 based on maximum transient and residual drifts. Numerical results illustrate the salient effect of using SMA and UHPSFRC synergistically in reducing transient and residual drifts and enhancing the functionality of structures in both mainshock and aftershock.

Seismic fragility analysis for tall pier bridges with rocking foundations

Costal bridge systems usually contain tall piers with heights over 40 m, due to the engineering site exposed to deep water circumstances. Note that the conventional seismic isolation devices (e.g., isolation bearings) are not that effective for tall piers, since their dynamic performance is significantly affected by the distributed mass and vibration modes of columns; therefore, base isolation design philosophy could be a promising alternative for mitigating seismic demands of this type of bridges. This paper mainly investigates the efficiency of rocking foundations in improving seismic performance of tall pier bridges, with the results presented in the format of fragility curves. Finite element model of the prototype tall pier bridge is developed, and the responses subjected to near-fault motions are obtained using nonlinear time history analysis. Probability seismic demand models and fragility curves are then developed accordingly, based on which the performance of tall pier bridges are assessed. The results show that employment of rocking foundations could significantly reduce the demands of tall piers and the probability of being damaged. Before the initiation of uplifting at pier base, the behavior of rocking piers resembles that of conventional ones with integrated foundation. While rocking initiates under strong excitations, the demands of rocking piers reduce drastically compared with integrated ones and tend to be similar under different motions, which benefits the post-earthquake performance assessment of these bridges.