Floor Acceleration Research Articles

Unbiased rank selection for automatic hysteretic response extraction of RC frame buildings using acceleration recordings for post‐earthquake safety evaluations

AbstractA framework to extract a building's hysteretic response based on decomposing floor acceleration recordings into different ranks (i.e., decomposition levels) using the discrete wavelet transform (DWT) and then reconstructing signals considering only ranks which corresponded to the building's predominant response mode was recently proposed. However, current rank selection approaches require subjective judgment. This study looks to develop an unbiased rank selection method to enable automation of the hysteresis extraction framework for easier adoption in practice. The selection methodology was developed using response history analysis of several multistory reinforced concrete (RC) frame buildings and validated using data from large‐scale shake‐table tests performed at the E‐Defense testing facility. It was observed that the proposed approach was able to accurately capture the response of RC frame buildings well in majority of cases. The exception to this was for significantly damaged buildings as the use of double integration of accelerations to estimate displacements and the DWT method meant that residual deformations were not well captured. However, significant strength degradation was still observed in the extracted hysteresis behavior for these cases, and thus these buildings would have been correctly classified as being heavily damaged. The step‐by‐step process to automatically select ranks is presented in the paper, and possible revenues for further improvement of the hysteretic response extraction framework are discussed.

Fragility and risk assessment for sliding artifacts in artifact-showcase-museum systems subjected to three-component ground motions

Vertical ground motions may increase irregularity of sliding response, while the subsequent impact on the sliding fragility of building contents is not clear. Moreover, seismic risk of structural collapse contributes to the total sliding risk of building contents, while it is usually ignored. This paper first introduces a seismic fragility and risk assessment method for the sliding artifact in the artifact-showcase-museum (ASM) system subjected to three-component ground motions. In this method, the square roots of the sums of the squares of peak ground accelerations and peak sliding displacements in two orthogonal horizontal directions are implemented as the intensity measurement and the engineering demand parameter, respectively. Incremental dynamic analysis using the nonlinear three-dimensional finite element model of the ASM system is performed to generate seismic fragility curves of sliding artifacts. The total sliding risk of the artifact is estimated as the sum of the sliding risk of the artifact on the premise of no structural collapse and the structural collapse risk. Then, the seismic fragility and risk of the sliding artifacts within a four-story frame structure and an existing museum is assessed when the systems are subjected to three-component ground motions, respectively. Effects of vertical ground motions, freestanding and restrained showcases, floor levels, sliding thresholds, structural collapse and different structures on the sliding fragility and risk of the artifact are investigated. Results show that the influence of vertical ground motions on the sliding fragility of artifacts in different structures may be significant or marginal depending on the ratios of peak vertical to horizontal floor acceleration. Moreover, the artifact in the freestanding showcase is less fragile than that in the restrained showcase regarding sliding failure. Furthermore, neglecting the structural collapse risk and estimating the sliding risk of the artifact by not removing the structural collapse data would underestimate the total sliding risk of the artifact.

Analytical approach for vertical floor acceleration of regular RC frames under earthquake excitation

Vertical floor acceleration (VFA) analysis arises as an important issue for seismic design of floor-attached nonstructural components (e.g., ceilings). However, to date, estimating the VFA is hardly accessible in the literature. In this paper, an analytical method is proposed for the VFA of regular RC frames. Here “regular” means the frame has uniform spans along each principal direction, so the structure can be represented by a single-span analogy. Firstly, the fundamental frequency, modal mass, and modal participation factor of a clamped floor slab are analyzed based on the classic thin-plate theory. Then, the dynamic properties of the clamped floor slab are adjusted to account for the effect of the flexible beam restraints (non-clamped). According to the adjusted dynamic parameters, the beam-restrained slab is substituted by a single-degree-of-freedom system, and is assembled with the column-beam system to form the global dynamic model for the structure. Based on the assembled model, the analytical process for the VFA is presented. The feasibility of the model is validated using the finite element modelling (FEM) method. The vertical dynamic properties and the peak VFA of a single-, 3-, 6-, and 9-story frame are computed using the FEM and the proposed analytical approach. Results show that the VFA obtained from the analytical approach is close to the FEM outcomes. Furthermore, important features of VFA are revealed by the computation. It is shown that the VFA could be 10 times as large as the peak vertical ground acceleration. A larger VFA appears at the higher stories, yet the relationship between the VFA and the height is nonlinear because of the effects of the higher-order modes.

Towards Seismic Design of Nonstructural Elements: Italian Code-Compliant Acceleration Floor Response Spectra

Seismic risk reduction of a building system, meant as primary building structure and nonstructural elements (NSEs) as a whole, must rely upon an adequate design of each of these two items. As far as NSEs are concerned, adequate seismic design means understanding of some basic principles and concepts that involve different actors, such as designers, manufacturers, installers, and directors of works. The current Italian Building Code, referred to as NTC18 hereinafter, defines each set of tasks and responsibilities in a sufficiently detailed manner, rendering now evident that achieving the desired performance level stems from a jointed contribution of all actors involved. Bearing in mind that seismic design is nothing else than proportioning properly seismic demand, in terms of acceleration and/or displacement, and the corresponding capacity, this paper gives a synthetic and informative overview on how to evaluate these two parameters. To shed some light on this, the concept of acceleration floor response spectrum (AFRS) is firstly brought in, along with basics of building structure-NSEs interaction, and is then deepened by means of calculation methods. Both the most rigorous method based on nonlinear dynamic simulations and the simplified analytical formulations provided by the NTC18 are briefly discussed and reviewed, trying to make them clearer even to readers with no structural/earthquake engineering background because, as a matter of fact, NSEs are often selected by architects and/or mechanical or electrical engineers. Lastly, a simple case study, representative of a European code-compliant five-storey masonry-infilled reinforced concrete frame building, is presented to examine differences between numerical and analytical AFRS and to quantify accuracy of different NTC18 procedures.

Three-dimensional analysis of eccentric pounding between two-storey structures using explicit non-smooth dynamics

Pounding research has been gaining momentum in the last decades with large earthquakes hitting cities with insufficiently separated buildings. Even if no major structural damage may be observed in the case of slab–slab pounding, large acceleration pulses may influence the response of equipment and cause disruption in their functionality. In this work, two different models are set up for reproducing shake table tests concerning two-storey adjacent structures, with slab–slab pounding. For the slab representation, the first model uses hexahedral finite elements, while the second one uses shell elements. One of the main objectives of the study is to predict the floor response spectra over a broad frequency range, up to 400Hz. Transient computations of the pounding problem under earthquake excitation are carried out using the explicit CD-Lagrange approach. Rayleigh damping is employed to filter out the spurious high frequency oscillations. The comparison between numerical and experimental results in terms of displacements and floor acceleration spectra shows that the numerical models are able to reproduce the eccentric pounding during the shake table tests. No parameter adjustment related to the contact is required underlining the robustness of the approach.

Seismic demands of structural and non-structural components in self-centering precast concrete wall buildings

Self-centering (SC) precast concrete wall structures have been developed as an earthquake resilient structural system characterized by low structural damage and controllable residual drift. Despite the superior structural performance, harmonizing to seismic performance between structural and non-structural components is expected to be considered for further comprehensive performance assessment. This paper extensively evaluates the seismic demands of structural and non-structural components, especially for those sensitive to accelerations in SC precast concrete wall structures. Factors considered include building heights, earthquake ground motion types and intensities, energy dissipation, as well as base rocking, and impact against the foundation. The seismic demands of SC precast concrete walls are firstly compared with conventional reinforced concrete (RC) walls by nonlinear time history analysis (NTHA) in terms of displacement and acceleration responses. Then, attention is focused on investigating the dominant factors for the seismic demands of acceleration-sensitive non-structural components in SC precast wall structures through floor response spectrum analysis and parametric analyses. The results confirm that the SC precast walls exhibit excellent lateral response, especially with limited residual drifts. However, for the floor acceleration response, which is highly related to the demands of non-structural components, the results show that higher modes have a critical influence on SC precast wall structures. It also indicates that the floor acceleration response of SC precast wall structures is strongly influenced by the location of the story levels but not strongly influenced by the base rocking impact and energy dissipation capability.

Floor acceleration response spectra of elastic reinforced concrete frames

Nonstructural components are the members attached to building structures to realize and maintain the building functionality. Although they are not intended to bear loads, nonstructural components could be subjected to earthquake loading that may lead to failures. The floor acceleration response spectrum is used as the input for the seismic design of acceleration-sensitive nonstructural components. However, it is time-consuming to conduct time-history analyses to generate accurate floor response spectrum for a typical building, and it is therefore not convenient for seismic design. To avoid the computational cost of time history analyses, this study proposes a simplified method based on the modification of an existing methodology for the generation of floor acceleration response spectrum. The first step is to conduct a modal analysis to determine the modal properties of the supporting structure. Then, the floor response spectrum of each mode of the supporting structure is generated and combined based on modal combination rules to obtain the floor response spectrum of the supporting structure. The component dynamic amplification factors that reflect the amplification effects of the nonstructural components on the floor acceleration responses are important for the generation of floor response spectra. Three reinforced concrete moment-resisting frames are designed to evaluate the component dynamic amplification factors for which an empirical fitted formula is proposed to generate more accurate floor response spectrum for structures designed in accordance with Chinese seismic design codes. The results calculated by time history analyses are used to validate the proposed amplification factors and demonstrate the feasibility and effectiveness of the newly modified method.

Influence of Pulse-Like Near-Fault Ground Motions on the Base-Isolated Buildings with LRB Devices

Seismic base isolation is a passive structural control system that has been effectively utilized as an innovative seismic-resistant design method in the past decades. The properties of earthquake ground motions have significant effects on the response of the base isolation system. Many recent studies were dedicated to the influence of near-fault ground motions on the response of seismically isolated buildings. These previous studies concluded that near-fault ground motions mostly impose larger displacement on the seismic isolators and, in some cases, larger floor acceleration; furthermore, the velocity pulse period influences the seismic isolator displacement and the floor acceleration. Most of the previous studies were conducted using ground motions simulated with certain parametric conditions of near-fault ground motions and/or a limited number of real earthquake ground motions. This study intended to examine the conclusions of previous studies through response history analysis of a seismically isolated prototype building with lead–rubber bearing (LRB) isolators using a large number of real near-fault earthquake ground accelerations. It was found that no consistent resonance phenomenon can be observed when the velocity pulse period is close to the natural period of the isolated building in terms of floor acceleration and isolator displacement, in contrast to the findings of other studies.

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.

Comparative response assessment of base-isolated braced-frame buildings considering effects of ductility design

This paper evaluates seismic responses of steel concentrically bracing frames isolated by double friction pendulum bearings with two levels of ductility. The seismic responses of base-isolated buildings are compared to their comparable fixed-base buildings. For this purpose, two isolated and two conventional concentrically braced-frame low-rise buildings are seismically designed, and their three-dimensional finite element models are developed in OpenSees. To investigate the impact of ductility, seismic responses of both ordinary and special levels of ductility are computed and analyzed. The results indicate that the ductility levels significantly affect seismic responses of base-isolated buildings. The superstructure with special level of ductility decreases the peak floor acceleration compared to the ordinary ones. The maximum reduction is calculated by about 20%. Moreover, special ductility level increases peak drift demand compared to the ordinary ones up to 75% in base-isolated buildings. Furthermore, the results show that the ordinary superstructure reduces the maximum and residual displacement of double friction pendulum bearings compared to the special ones. • Effects of level of ductility on seismic responses of isolated concentrically braced-frame buildings. • Seismic assessment of buildings with double friction pendulum bearings. • Comparative response evaluation of base-isolated and conventional steel frames. • Considering different hazard levels in assessment of base-isolated buildings.

Examining wind-induced floor accelerations in an unconventionally shaped, high-rise building for the design of “smart” screen walls

This paper describes the results of a numerical and experimental study on the wind-induced effects relevant to the design of specialized nonstructural elements in an unconventionally shaped high-rise building. The purpose was to estimate the wind-induced floor acceleration and to examine the lateral drift ratio for the design of nonstructural elements and the occupants' comfort. Nonstructural elements consist of “smart” screen walls, anchored through stiff, steel connection details to the floor. Wind tunnel measurements of floor accelerations were derived from an aeroelastic model of the high-rise building, replicating the fundamental mode response characteristics of the prototype structure. The model's dynamical properties were inferred from a pilot experiment conducted on a shaking table; estimated natural frequencies and modal damping ratios were used to re-scale accelerations measured in wind tunnel. The model's dynamic properties, influenced by wind loads, were later reconstructed through the Random Decrement Technique (RDT). Ranges of acceptability for accelerations and lateral inter-story drift are provided and examined in the context of nonstructural element design.

Optimal placement of viscous wall dampers in RC moment resisting frames using metaheuristic search methods

Viscous wall dampers (VWDs) are one of the most effective energy dissipation devices for the seismic performance enhancement of buildings. The number of VWDs as well as their positions in the building directly affects the seismic performance. In this study, two of the metaheuristic algorithms were employed for the optimal placement of VWDs in a reinforced concrete (RC) special moment resisting frame (SMRF) in order to achieve a safe yet cost effective solution. Bat algorithm (BA) and dragonfly algorithm (DA) were adopted to achieve the minimum number of VWDs by placing them in the most suitable positions of a 15 story RC SMRF. The floor accelerations and inter-story drift ratios (ISDRs) are considered as the constraints for the position optimization of VWDs with the objective of minimum number of VWDs. The application-programming interface (API) was employed for the interaction and data transfer between the structural analysis program ETABS and the Matlab program for optimization operations. Nonlinear response history analyses (NRHA) were conducted using recorded earthquake ground motions. Optimal placement for the minimum number of VWDs was achieved by using metaheuristic search algorithms. The additional damping provided by VWDs is effective in reducing the max ISDRs. However, higher damping ratios do not always result in the minimum floor accelerations. Therefore, an optimum damping ratio provided by VWDs needs to be sought for achieving minimum floor accelerations.

Seismic acceleration demand and fragility assessment of storage tanks installed in industrial steel moment-resisting frame structures

Recent seismic events highlighted the importance of non-structural elements in seismic assessment and performance-based earthquake engineering. When referring to industrial facilities, storage tanks represent one of the most critical components for the continuous functionality of industrial and building plants after seismic events. At the same time, the dispersion of dangerous or inflammable materials, due to their collapse, could become a safety issue in terms of both human life and environmental impact. This study focuses on the seismic performance assessment of a liquid-storage tank installed in an industrial steel moment-resisting frame building. The performance is assessed in terms of fragility curves, that are provided for the meaningful limit states that affect the liquid-storage tank and considering several intensity measures. The results related to the structural performance are also discussed in detail in terms of fragility functions and floor response. The assessment is performed through nonlinear dynamic analyses using two different modelling approaches to evaluate the structural and non-structural performance. The first modelling approach explicitly accounts for the tank-structure interaction, while in the second one the tank is only modelled considering its seismic mass. The results show the importance of the modelling assumptions to accurately estimate the seismic demand on liquid-storage tanks and corresponding fragility, which is calculated in terms of different intensity measures (IM): average ground spectral acceleration, peak floor acceleration, and floor spectral accelerations. Peak floor acceleration, drift profiles, and absolute acceleration and relative displacement floor response spectra are instead scrutinised for what concerns demand. The comparison with the code formulations available in the literature for estimating the seismic demand to non-structural elements pointed out their inaccuracy for the analysed liquid-storage tank and the need for further efforts to develop more accurate procedures. Furthermore, the outcomes indicate that the IM adopted for secondary components, i.e. peak floor acceleration, may not always be the optimal one hence additional attention should also be paid to the definition of updated fragility curves for non-structural elements, identifying and adopting more suitable IMs.

Time-Dependent Damage Estimation of a High-Rise Steel Building Equipped with Buckling-Restrained Brace under a Series of Earthquakes and Winds

This study investigates the cumulative damage of a 20-story high-rise steel building equipped with buckling-restrained braces (BRB) under the likely occurrence of earthquake and wind events in the design life of the building. The objective of this research is to introduce a method for evaluating the cumulative damage of BRBs under multi-hazard events that are expected to occur during the service life of a high-rise building in order to achieve a safer building. A methodology is proposed using a Poisson point process to estimate the timeline of earthquake and wind events, wherein the events are assumed to be independent in nature. The 20-story high-rise steel building with BRBs is designed according to the Japanese standard and analyzed using the finite element approach, considering nonlinearities in the structural elements and BRBs. The building is analyzed consecutively using the timeline of earthquakes and winds, and the results are compared with those under individual earthquakes and winds. In addition to the responses of the frame such as the floor displacement and acceleration, the damage of BRBs in terms of the damage index, the energy absorption, the plastic strain energy, and the maximum and cumulative ductility factor are evaluated. It is observed that the BRB’s fatigue life under multi-hazard scenarios is a multi-criteria issue that requires more precise investigation. Moreover, the overall building’s performance and BRB’s cumulative damage induced by the sequence of events in the design life of the building is significantly larger than that under an individual event.

Determination of seismic isolation effects on irregular RC buildings using friction pendulums

This study aims to evaluate influences of isolation made using friction pendulum type isolators on seismic behavior of irregular mid-rise RC frame buildings without shear walls. For this at first, a 4-storey 3D reference building model which have no irregularity is designed as residential building. Afterwards, models including heavy overhang, short column and soft storey irregularities are created through the reference building. A total of 88 nonlinear time history analyses of regular and irregular building models subjected to 11 pairs of ground motion records are performed for non-isolated and isolated cases. There has been a significant reduction in base shear ratios for isolated reference and irregular buildings. Roof drift ratios of isolated-base models are generally higher compared to fixed-base models for both regular and irregular buildings. Unlike the results of roof displacement demands, lower average interstorey drift ratios have been obtained for especially isolated reference and heavy overhang buildings. Evaluations on the effects of the isolation for floor accelerations, interstorey drift ratio (IDR) profiles and damages of structural elements are also given in the paper. This study emphasizes that advances are made in terms of behavior against earthquakes for irregular buildings thanks to isolation.

Synthesis of a vector-valued intensity measure for improved prediction of seismic demands in Inter-Story-Isolated (ISI) buildings subjected to near fault ground motions

An optimal Intensity Measure (IM) is key to accurate prediction of the Engineering Demand Parameters (EDPs) in structures subjected to seismic excitations. This study synthesizes a structure-specific, vector-valued IM for assessing the EDPs in Inter-Story-Isolated (ISI) buildings under near-fault (pulse and non-pulse type) ground motions. The synthesis is inspired by the comparable modal masses in the fundamental and another higher (generally second) mode in ISI buildings. The synthesis accommodates the dual mode participation by employing the respective pseudo-spectral accelerations Spa and the spectral shape (‘epsilon’ε) parameters in the proposed IM as components. A suite of pulse and non-pulse type motions are employed for the synthesis and subsequently fitting an IM vs. EDP regression model. Thereafter, the “Efficiency” and “Sufficiency” analysis are conducted for validation. The EDPs are obtained by non-linear dynamic analyses on alternative building frames with High Damping Rubber Bearing (HDRB) based ISI systems. A Principal Component Regression (PCR) is employed for accommodating the multi-collinearity in the IM. The choice of the Principal Components (PCs) adopts a leave-one-out cross-validation approach. The proposed IM is shown to offer higher Efficiency and Sufficiency compared with the existing non-structure-specific (Peak Ground Acceleration, Velocity, Displacement, Arias Intensity, Cumulative Absolute Velocity, Characteristic Intensity, Specific Energy Density etc.) and structure-specific (Acceleration/Velocity Spectrum Intensity, Housner Intensity, Pseudo-spectral acceleration at fundamental time period etc.) IMs. Higher Efficiency is also noted under the pulse type motions comparing the non-pulse ones. The IM is more efficient in predicting the Inter-Story Drift Ratios (IDRs), Total Drift Ratios (TDRs) than the Peak Floor Accelerations (PFA) and Bearing Displacements (PBD). The proposed IM is shown to be unbiased and robust.

Effect of the infill panels in the floor response spectra of an 8-storey RC building

One of the significant challenges concerning earthquake risk mitigation is the seismic vulnerability assessment of existing buildings that were not designed according to modern codes. Several authors recognized that the infill walls might significantly affect the seismic response of reinforced concrete structures (RC). Still, they are treated as “non-structural” elements by the national and international codes and they are not considered in the seismic assessment of existing RC buildings, and their impact on the seismic response of the structure is neglected. This manuscript aims to study the seismic response of an 8-storey RC structure simulated in the software OpenSees with and without masonry infill walls. The masonry infill walls were simulated considering their in-plane and out-of-plane (OOP) behaviour interaction. Two different studies were performed. First, the study of the impact of the infill walls in the global building seismic response and after that the study of the infill walls seismic performance. Several incremental dynamic analyses were carried out for these studies to study floor accelerations and velocities and determine peak floor acceleration and peak floor velocity. At the same time, floor response spectra were drawn for the design peak ground acceleration, according to Eurocode 8. Acceleration-Displacement Response Spectrum is also obtained and presented according to Eurocode 8. The OOP accelerations and OOP velocities of the masonry infill walls were recorded for all the input ground-motions. The maximum OOP accelerations and velocities reached by the infill panels at each floor were obtained and discussed. The respective infill acceleration and infill acceleration-displacement response spectrum and infill velocity response spectra were then derived and presented. Finally, the amplification of the infills OOP accelerations along the building height will be evaluated and compared with the Eurocode 8 demands. The results show that the infills increase the peak floor accelerations and modify the floor response spectra. The infills OOP accelerations are always 1.2–2 times higher than PFA. The infills acceleration response spectra do not change with the increase of the building height.

Study of isolation effectiveness of nuclear reactor building with three-dimensional seismic base isolation

PurposeIn recent years, three-dimensional (3D) seismic base isolation system has been studied extensively. This paper aims to propose a new 3D combined isolation bearing (3D-CIB) to mitigate the seismic response in both the horizontal and vertical directions.Design/methodology/approachThe new 3D-CIB composed of laminated rubber bearing coupled with combined disk spring bearing (CDSB) was proposed. Comprehensive analysis of constitution and theoretical derivation for 3D-CIB were presented. The advantage of CDSB is that the constitution can be flexibly adjusted according to the requirements of the bearing capacity and vertical stiffness. Hence, four different combinations of CDSB were designed for the 3D-CIB and employed to isolate nuclear reactor building. A comparative study of the seismic response in terms of seismic action, acceleration floor response spectra (FRS), peak acceleration and relative displacement response was carried out.Findings3D-CIB can effectively reduce seismic action, FRS and peak acceleration response of the superstructure in both the horizontal and vertical directions. Overall, the horizontal isolation effectiveness of 3D-CIB was slightly influenced by vertical stiffness. The decrease in the vertical stiffness of the 3D-CIB can reduce the vertical FRS and shift the peak values to a lower frequency. The vertical peak acceleration decreased with a decrease in the vertical stiffness. The superstructure exhibited a rocking effect during the earthquake, and the decrease in the vertical stiffness may increase the rocking of the superstructure.Originality/valueAlthough the advantage of 3D-CIB is that the vertical stiffness can be flexibly adjusted by different constitutions, the vertical stiffness should be designed by properly accounting for the balance between the isolation effectiveness and displacement response. This study of isolation effectiveness can provide the technical basis for the application of 3D-CIB into real engineering of nuclear power plants.

A Physical-organizational Method for the Functionality Assessment of A Hospital Subjected to Earthquakes

ABSTRACT Hospitals play vital roles in mitigation and recovery in earthquake-hit communities. This paper aims to clarify the effect of physical damage on hospital organizations and represent a holistic method for the functionality assessment of a hospital. The efficiency of the method is demonstrated based on the case study of a general hospital. The results indicate that the functionality of hospitals would be significantly affected after the maximum considered earthquake. A considerable gap exists between the hospital treatment capacity and the patient demand for medical services. The method will assist hospital stakeholders and managers in design and upgrade criteria selection. Abbreviation: CT: Imaging Procedure; DBE: Design Basis Earthquake; DES: Discrete Event Simulation; DR: Digital Radiography; EDPs: Engineering Demand Parameters; HVAC: Heating Ventilation and Air Conditions; MCE: Maximum Considered Earthquake; OR: Operation Room; PFA: Peak Floor Acceleration; PFV: Peak Floor Velocity; PIDR: Peak Inter-story Drift ratio; RC: Reinforced Concrete; RIDR: Residual Inter-story Drift Ratio; RR: Resuscitation Room; SLE: Service Level Earthquake; UPS: Uninterruptible Power Supply; US: Ultrasound Room; WT: Waiting Time

Application of Mean-covariance Regression Methods for Estimation of EDP|IM Distributions for Small Record Sets

ABSTRACT The performance of several regression methods is investigated to estimate the distribution of engineering demand parameters conditioned on intensity measures (EDP|IM) for small record sets. In particular, the performance of the multivariate ordinary least squares (OLS), a simultaneous mean-variance regression (MVR) done by a penalized weighted least-square loss function, and a mean-covariance/variance regression based on expectation maximization method (EM) are assessed. The efficiency of the introduced methods is compared with FEMA-P58 methodology. Performance assessment of EM and MVR methods shows that the overall increase in efficiency is about 25–45% for maximum inter-story drift ratios, and 30–50% for maximum absolute floor acceleration.