Damage To Non-structural Components Research Articles

Video comprehension-based approach for seismic damage recognition of freestanding non-structural components

With the emergence of seismic resilience concepts, the objective of buildings’ seismic design shifts from life safety to earthquake-induced functional consequences. The seismic damage of nonstructural components (NSCs) is paramount in economical loss assessment and post-earthquake functional recovery. To rapidly assess the seismic damage of NSCs, this paper leverages the video-comprehension techniques to customize a novel deep learning model (which is called two-pathway vision transformer for the damage state recognition, TPViT-DMSR) that can recognize the freestanding NSCs’ damage states through the video footage. This model includes a slow and fast pathways to analyze the object’s movement at different speeds. The two pathways are fused through a unidirectional connection, which allows damage information to be better shared across two pathways. To improve the robustness of the model, the trajectory attention mechanism is integrated. To demonstrate the model’s applicability and efficacy, a comprehensive video dataset that describes various freestanding NSCs’ movement behavior is compiled via a series of shaking table tests. The application result reveals that the TPViT-DMSR model performs at a desired level with the mean average precision achieving at 74.87%. The model is also applied to the video footage collected from past earthquake events. The application results highlight that the model can deliver a reliable estimate of the damage state for NSCs.

Mixed reality drills of indoor earthquake safety considering seismic damage of nonstructural components

The damaged indoor nonstructural components in the earthquake often cause casualties. To improve the indoor earthquake safety capacity of occupants, a mixed reality (MR) drill method for indoor earthquake safety considering seismic damage of nonstructural components is proposed. First, an MR device, HoloLens, is used to capture indoor point clouds, and the indoor three-dimensional scene is reconstructed using point clouds. Subsequently, the seismic motion models of indoor components are established, so that the indoor nonstructural seismic damage scene is constructed using the physics engine and displayed using HoloLens. Finally, a guidance algorithm for a safe zone was designed for the drills. Taking a typical office as an example, an indoor earthquake safety drill was performed. The drill results show that the proposed MR method can increase the average efficiency of moving to a safe zone by 43.1%. Therefore, the outcome of this study can effectively improve the earthquake safety ability of occupants, thereby reducing casualties.

Seismic damage evaluation of unanchored nonstructural components under combined effects of horizontal and vertical near‐fault ground motions

AbstractWith consideration of seismic resilience, damage of nonstructural components (NSCs) attracts significant attentions. Most previous studies focused on dynamic behaviors of NSCs under horizontal excitations. Near‐fault earthquakes, however, have strong vertical ground motion components, but few studies assessed their influence on seismic damage of NSCs. In this study, the seismic responses of unanchored NSCs under near‐fault earthquakes with strong vertical components are investigated. Response history analyses of steel moment frames with different heights under near‐fault earthquakes are performed and the derived floor acceleration responses are taken as the inputs of unanchored NSCs. The sliding and rocking responses of NSCs under horizontal and vertical excitations are used to quantify the influence of near‐fault earthquake characteristics. The results highlighted that bidirectional excitations (horizontal & vertical) would elevate the uncertainty in the sliding demands of NSCs and more likely to induce the occurrence of overturning failures for slender NSCs. The relation between rocking demands of NSCs and common intensity measures like PFA would be weakened due to the presence of vertical excitations.

Evaluating post-earthquake functionality and surge capacity of hospital emergency departments using discrete event simulation

Past earthquakes have illustrated the impacts of reduced hospital functionality due to physical damage resulting in a health service deficit immediately after a major seismic event. In this article, a methodology was developed to quantify the deficit in health care anticipated due to a loss of functionality of a hospital emergency department (ED) and a surge in demand due to regional damage in an earthquake scenario. Earthquake-induced patient arrivals were calculated using multi-severity casualty estimation for the catchment area of the hospital. The surge in patients (demand) was then compared to the ability of the hospital to treat patients (capacity) based on anticipated functionality. Nonlinear response history analysis of the hospital building was performed using simplified structural models, and the structural and non-structural component damage was estimated based on FEMA P-58. Expected damage was linked to the post-earthquake functionality of the ED service areas on each floor by incorporating the fault-tree analysis method. Finally, discrete event simulation was used to evaluate the ED surge capacity, providing hospital performance metrics, such as wait times (WTs) and length of stay (LOS) for patients of ranging acuity. A case study of a hospital in the City of Vancouver subjected to an Mw9.0 Cascadia Subduction Zone scenario earthquake was presented. Emergency rooms (ERs) were identified as the ED bottleneck during the emergency response. The mean ER WT exceeded its limit of 2 h and reached up to 17 h in the most unfavorable simulation. Likewise, the mean LOS nearly doubled from 6.5 to 12 h, also exceeding the established target of 10 h. The deployment of field hospitals for less severe patients as an emergency plan to mitigate the ED overcrowding was also analyzed to demonstrate that the methodology can be used as a decision support tool to improve healthcare disaster planning.

Seismic performance of suspended‐floor structures with viscous dampers considering acceptable interstory drift

SummaryNumerical studies of suspended‐floor structures were conducted, and viscous dampers were applied to improve their seismic performances. The following issues were analyzed under 20 earthquake records: seismic responses of the primary structure and suspended floors, the distributions of the damping coefficient c0, and the interstory stiffness of the suspended floors. There was a significant reduction in the roof drift and the base shear force of the cores after replacing the steel bars with viscous dampers. The suspended‐floor structures with viscous dampers exhibited an optimal c0. The suspended‐floor structure with a triangular distribution of c0 showed a smaller seismic response than the one with a uniform distribution of c0. Under the design‐based earthquake, there was complete damage of nonstructural components in the y‐direction. Hence, applications of diagonal steel braces within the 1st to 10th floors were suggested to increase the lateral stiffness of the suspended floors in the y‐direction. The application of diagonal steel braces reduced the story drift Sd of the suspended floors, resulting in slight damage to nonstructural components under the design basis earthquake (DBE) hazard level. However, the roof floor, which contains electrical and mechanical components, exhibited an increase in Sd after the application of the diagonal steel braces. With increasing stiffness of the diagonal brace, the story drift profile of the suspended floors tended to be uniform, and the suspended‐floor structures with the uniform distribution of c0 exhibited seismic performances closer to those of the suspended‐floor structures with the triangular distribution of c0.

Comparative Study of Seismic Acceleration Amplification Models for RC Frame Structures

As the current aspect, the nonstructural components (NSCs) linked with the structures are more affected during the seismic motion. It causes not only loss of the economy but also affected life. The various codal provision has been available for minimizing the damages of primary components, but for NSCs, a minimal requirement is functional. So that more investigation is required for understating the behavior of NSCs during the seismic motion. The research aims to understand the behavior of acceleration demand on NSCs in a building. Structures subjected to inertia forces due to earthquakes experience damage of nonstructural components (NSC). The inertia force acting the NSCs are related to acceleration amplification factor. For obtaining the peak horizontal floor acceleration with respect to tectonic ground motion, these factors are used. In this paper, mathematical models of the acceleration amplification factor defined as the peak floor acceleration with respect to peak ground acceleration, given by previous researchers, has been compared. For this 2,4,6,8 and 10 storey moment-resisting frame models considering 29 ground motion data ranging between 0.1g to 0.2g, is analyzed using linear time history method. The supports of the models are considered fixed. The ETABS software is used for the analysis of the models. To analyses the models, the modal mass participation ratio plays a significant role. ASCE 7-05 defines that the structure should be investigated and designed when the model mass participation ratio is equal to or more than 90 per cent. Based on the results, a comparison of the reported models is made. There is a strong need for further research to refine the models for the realistic prediction of acceleration amplification factor.

Performance of flexible frame building with horizontal and 3D seismic isolation when subjected to 3D ground shaking

Seismic isolation is known to effectively mitigate the effects of horizontal ground shaking in building structures. Recent research has suggested that vertical excitation causes high-intensity slab vibrations that lead to nonstructural component damage. A detailed case study of the application of three-dimensional (3D) isolation in a realistic multi-story frame building is presented. Specifically, the seismic responses of hypothetical special concentric braced frame buildings with horizontal and 3D isolation are compared to evaluate the effectiveness of 3D isolation to mitigate the vertical ground shaking. Overall, 3D isolation with a relatively short isolation period (0.5 s) is adequate to significantly mitigate the vertical acceleration in a flexible frame building, including the amplification at mid-slab relative to adjacent columns, without compromising the usual reductions in horizontal responses.

Scenario simulation of indoor post-earthquake fire rescue based on building information model and virtual reality

Post-earthquake fires occur frequently, and the seismic damage to non-structural components results in dangerous fire and evacuation environments. Both firefighters and trapped people will face serious threats to life during the rescue. Consequently, a simulation framework of an indoor post-earthquake fire rescue scenario based on building information model (BIM) and virtual reality (VR) is proposed herein. Information of structural and non-structural components is extracted from the BIM. Subsequently, the seismic damage of non-structural components is predicted according to the time-history results and fragility curves. Moreover, a smoke visualization method combining volume rendering and the particle system is also proposed. A case study of a 19-story hospital is conducted using the proposed method for establishing the fire rescue scenario. The results show that the established VR scenario has high realism and smooth interactivity, and the influence of smoke on the fire rescue is more significant than that of fallen debris.

Seismic fragility assessment of nonstructural components in unreinforced clay brick masonry buildings

SummaryThe results of an investigation of the probability of earthquake damage to nonstructural unreinforced masonry (URM) components are presented. The components include parapets, chimneys, and out‐of‐plane loaded facades typical of low‐rise pre‐1940 construction in Australia and New Zealand. The study is based on a street survey of component geometry, in situ data on material strength, and simplified mechanical models. Uncertainties in capacity and demand were quantified based on, respectively, stochastic and deterministic approaches. The damage probabilities were compared with relevant guidelines and empirical damage data from three earthquakes. The study established a link between the qualitative damage states reported in existing guidelines and the quantitative URM component damage states. While some median damage state thresholds correlated well with the data from the guidelines, a larger dispersion value was found in the current study due to the large variations in component properties. Comparisons with empirical data suggest that the developed fragility data provide a realistic estimate of nonstructural component damage that occurred in similar buildings, with a reasonable level of conservatism. The outcome is useful in rapid assessment of the seismic risks due to nonstructural component collapse in URM precincts.

Tsunami Hazard and Built Environment Damage Observations from Palu City after the September 28 2018 Sulawesi Earthquake and Tsunami

The 2018 Sulawesi earthquake (Mw 7.5) and tsunami destroyed many buildings and caused more than 3300 fatalities in Sulawesi, Indonesia. Damage reports and satellite images from Palu City indicated severe tsunami impacts to buildings and lifelines infrastructure within 300 m from the coastline. Seven-weeks after the earthquake a field survey was carried out in Palu City to measure tsunami flow depths and record damage levels for buildings, roads and electricity infrastructure. Above ground level tsunami flow depths measured at 371 building sites ranged from 0.1 to 3.65 m, with a 1.05 m mean and 0.55 m standard deviation. The survey team also recorded attributes and damage levels for 463 buildings, 7.9 km of road and 455 utility poles. We observed that non-engineered ‘light timber’ and ‘lightly reinforced concrete’ construction frame buildings were highly susceptible to ‘non-structural’ component damage when tsunami flow depths respectively exceed 0.4 m and 1 m above the first finished floor level, while unrepairable or complete building damage was regularly observed when flow depths exceeded 1.2 m. Only non-structural component damage was observed for engineered ‘reinforced concrete’ buildings. While tsunami flow depth traces could not be measured for affected road and utility pole components, hazard intensity parameters can be obtained from tsunami inundation maps to estimate the conditions contributing to observed damage levels. The information presented herein forms an important evidence base to support future tsunami hazard and risk research in Indonesia.

A Framework to Assess the Seismic Resilience of Urban Hospitals

The phenomenon of hospital functional interruption has been widely observed in the historical moderate‐strong earthquakes, indicating that hospital functionality cannot be well considered in the current seismic design methods. The concept of seismic resilience pays enough attention to postearthquake functionality of buildings, and it is particularly significant for the urban hospitals which play critical role in the urban postearthquake rescue and recovery. This study proposes a framework to assess the seismic resilience of urban hospitals, by incorporating the fault tree analysis (FTA) to consider the interdependency between the damage of nonstructural components and the functionality of medical equipment, as well as the effect of external supplies on the functionality of hospital. The proposed framework is then applied to a case‐study hospital, and the results indicate that this hospital needs 1.1 days to resume emergency functionality under REDi repair strategy after design basis earthquake (DBE), while it needs 28.8 days to resume emergency functionality under REDi repair strategy after maximum considered earthquake (MCE). It is found that the seismic resilience of this hospital after MCE cannot meet the community requirements on the recovery time, and necessary measures are needed to improve the seismic resilience. The proposed framework provides the quantitative results of seismic resilience assessment in the preearthquake environment and can further support emergency response planning and seismic retrofits strategies.

Integrated shape memory alloy devices toward a high-performance glazed curtain wall seismic retrofit

Recent dynamic events, such as Alaska and San Fernando earthquakes, have shown shortcomings in contemporary façade design processes, exacerbated by the occurrence of non-structural component damage and failure when subjected to extreme wind loads or seismic events. Accordingly, in the present work the feasibility of an original and advanced dissipation technology is pursued investigating on the façade performance by testing and modeling strategies.Initially, based on the experimental activities performed at the Construction Technologies Institute (ITC) laboratories of the Italian National Research Council (CNR), numerical simulations are run to interpret and reproduce the experimentally tested response of two full-scale façade units. Thereafter, sophisticated 3D finite element models are calibrated acquiring information on the fundamental mechanisms accountable for the dynamics in façades.Subsequently, by virtue of the peculiar properties of Shape Memory Alloys (SMA), such as superelasticity and shape memory effect, innovative curtain wall joints are designed, focusing on the improvement of the façade energy dissipation performance and on the enhancement of the overall structural behavior.Finally, the improvements are demonstrated both globally and locally: on one hand, traditional and novel curtain wall force-drift capacity curves are compared; on the other hand, the effectiveness of the suggested device is shown, when built on a reference structure.

Adaptive base isolation system to achieve structural resiliency under both short- and long-period earthquake ground motions

Base isolation system is widely used to protect important and essential buildings from seismic hazards. The use of high damping is effective in reducing the resonance effect under long-period earthquake ground motions. However, high damping increases the acceleration demand under short-period ground motions, leading to a higher risk of damage of nonstructural components. Actually, low damping is beneficial to reduce the acceleration demand under short-period ground motions, suggesting the use of adaptive damping control, that is, high damping under long-period motions and low damping under short-period motions. In order to implement this concept, a semi-actively controlled base isolation system is provided in this article along with a new control law based on the transmissibility theory. Unlike existing studies, the proposed method enables a systematic design procedure for base isolated structures with semi-active dampers, which is called the simplified design procedure in this article. The performance of the proposed system is evaluated with numerical simulations for a base isolated three-story building with magneto-rheological dampers. It was shown that the proposed system achieves a high level of performance under long-period ground motions, while maintaining the exceptional performance of a conventional base isolation system with low damping under short-period ground motions.

Empirical drift-fragility functions and loss estimation for infills in reinforced concrete frames under seismic loading

Earthquakes that have occurred in the last twenty years in the Mediterranean area have had significant economic and social impacts. Most of the economic losses of reinforced concrete (RC) frames was due to nonstructural component damage, particularly masonry infills and partitions. Therefore, the seismic behaviour of masonry infills should be reliably characterized. The main goals of this study for a more reliable loss estimation for infilled RC frames are: (i) the analysis of the inter-story drift ratio (IDR) capacity at given damage states (DSs) with the aim to define drift-based fragility functions and (ii) analyse direct losses due to infill damage following seismic events. First, a database of experimental tests performed on 1-bay, 1-story scaled RC frames infilled with clay bricks or concrete blocks is collected. Drift-based fragility curves are obtained, which depend on the infill brick materials and properties. Then, the drift capacity threshold at each DS is correlated to the in-plane response of the infill panel to directly quantify the relationship that exists among them. The influence of openings on drift capacities is also evaluated. Then, seismic losses related to infills are computed, providing expected monetary losses depending on the infill typology. The required reparation activities and their costs are also listed. The bearing of each activity and cost at each DS is explicitly evaluated. Additionally, loss functions that directly depend on IDR demand are provided, thus fusing together the damage analysis and loss analysis. Finally, a simplified formulation for loss functions is proposed for a simple, practice-oriented loss calculation.

Out-of-plane seismic design by testing of non-structural lightweight steel drywall partition walls

Seismic damage of non-structural components could involve functionality interruption of the most affected buildings and substantial economic losses. Among non-structural components, the ceiling-partition wall systems represent a significant investment in the construction sector. Nevertheless, the seismic design of these systems plays a secondary role within the structural design, by leading to a lack of specific design provisions. Because the behaviour of these systems cannot be easily simulated with traditional analysis methods, the experimental characterization is an effective procedure. For these reasons, an important collaboration between an international company and the University of Naples Federico II was established over the last few years. The main objective of the research is to investigate the seismic performance of non-structural lightweight steel drywall building components, i.e. partition walls and suspended continuous ceilings made of lightweight steel profiles and sheathed with gypsum-based panels. The presented paper describes and discusses particularly the out-of-plane quasi-static monotonic tests and dynamic identification tests carried out on lightweight steel drywall partition walls, mainly devoted to develop the seismic design criteria by testing of these systems.

Factors influencing the repair costs of soft-story RC frame buildings and implications for their seismic retrofit

This paper examines the factors affecting the repair costs following major earthquakes, of reinforced concrete (RC) frame buildings with non-ductile detailing typical of construction practices in Italy and other parts of the world during the 1950s and 1960s. Two configurations of a RC frame structure, one with full infills and the other with partial infills, are numerically studied. Results of incremental dynamic analyses confirm that the partial infill RC structures, in which soft-story mechanisms form in the open story, are more likely to collapse. However, by undertaking a loss estimation study for different scenarios it is shown that the lower losses that are expected due to the reduced damage of non-structural components in upper levels could be an advantage of soft-story buildings provided that the collapse propensity is reduced at the first level. It is further shown that losses in soft-story buildings will be strongly affected by the repair value of the structural and non-structural components at the soft-story level relative to other levels and the magnitude of P-Delta effects. These observations indicate that an effective retrofit strategy, that would reduce both monetary losses and the probability of collapse, could be achieved by increasing the deformation capacity at the soft-story level without altering the isolating effect that the soft-story mechanism provides to the levels above and without any further intervention in the stories above. The changes in losses resulting from such a conceptual retrofit solution are presented in order to illustrate the merits of such an approach, that should therefore become the focus of future research.

Seismic performance evaluation of plasterboard partitions via shake table tests

The damage of nonstructural components represents the largest contribution to the economic loss caused by an earthquake. Since nonstructural components are not amenable to traditional structural analysis, full-scale experimental testing is crucial to understand their behaviour under earthquake. For this reason, shaking table tests are performed to investigate the seismic behaviour of plasterboard partitions. A steel test frame is properly designed in order to simulate the seismic effects at a generic building storey. The tests are performed shaking the table simultaneously in both horizontal directions. To investigate a wide range of interstorey drift demand and seismic damage, the shakes are performed scaling the accelerograms at eleven different intensity levels. The tested plasterboard partitions from Siniat exhibit a good seismic behaviour, both in their own plane and out of plane, showing limited damage up to 1.1 % interstorey drift ratio. The correlation between the dynamic characteristics of the test setup and the recorded damage is evidenced. Finally, an interesting comparison between the experimental results and the analytical model is also performed.

비구조요소의 내진 설계를 위한 기존 층응답스펙트럼의 평가

The seismic damage of non-structural components, such as communication facilities, causes direct economic losses as well as indirect losses which result from social chaos occurring with downtime of communication and financial management network systems. The current Korean seismic code, KBC2009, prescribes the design criteria and requirements of non-structural components based on their elastic response. However, it is difficult for KBC to reflect the dynamic characteristics of structures where non-structural components exist. In this study, both linear and nonlinear time history analyses of structures with various analysis parameters were carried out and floor acceleration spectra obtained from analyses were compared with both ground acceleration spectra used for input records of the analyses and the design floor acceleration spectrum proposed by National Radio Research Agency. Also, this study investigates to find out the influence of structural dynamic characteristics on the floor acceleration spectra. The analysis results show that the acceleration amplification is observed due to the resonance phenomenon and such amplification increases with the increase of building heights and with the decrease of structure`s energy dissipation capacities.

Effect of Supplemental Viscous Damping on the Seismic Response of Structural Systems with Metallic Dampers

Metallic dampers can enhance structural performance by reducing seismically induced lateral displacements, and by reducing inelastic behavior of beams and columns. Limiting story drift also indirectly allows us to mitigate damage of nonstructural components that are sensitive to lateral deformations. However, many nonstructural elements and components are vulnerable to excessive accelerations. Therefore, in order to protect these components, floor accelerations in buildings should be kept below certain limits. In this perspective, this paper investigates the seismic performance of single-degree-of-freedom (SDOF) systems with metallic and viscous dampers installed in parallel, to determine the effectiveness or appropriateness of using metallic dampers to mitigate lateral displacements, simultaneously with viscous dampers to reduce acceleration demands, knowing that their behavior is fundamentally different (i.e., metallic dampers are displacement dependent, whereas velocity dampers are velocity dependent). The effect of a combination of these damping systems is, therefore, studied for SDOF structures as a contribution to the state-of-the-art of seismic protection of nonstructural components. Parametric analyses investigate the effectiveness of adding various levels of viscous damping on the equivalent hysteretic damping and on the spectral floor acceleration for short, intermediate, and long period structures. Argand diagrams are used to explain why in some instances it is observed that adding viscous dampers to strongly inelastic systems can result in increases in floor acceleration (rather than the intended decreases). Results from this study are also applicable to buildings that have been retrofitted with viscous dampers and whose original frame still behaves inelastically after the retrofit.

地震時における建物防災機能リスク評価手法について―評価手法の概要と電力供給建物に対する適用結果―

Recent earthquake damages show that damage of non-structural components, such as walls and ceilings, mechanical and electrical components, often cause malfunctions of functional requirements of buildings. Authors propose a practical seismic risk assessment for functional requirements of buildings using Fault Tree and Monte Carlo simulation, considering secondary damages and restoration scenarios. By using this risk assessment, priority of prior countermeasures can be evaluated.