BIM-based seismic damage and repair cost estimation of a reinforced concrete building

Recently, there has been increasing interest in simulating all aspects of the seismic risk problem, from the source mechanism to the propagation of seismic waves to nonlinear time-history analysis of structural response and finally to building damage and repair costs. This study presents a framework for performing truly “end-to-end” simulation. A recent region-wide study of tall steel-frame building response to a M_w 7.9 scenario earthquake on the southern portion of the San Andreas Fault is extended to consider economic losses. In that study a source mechanism model and a velocity model, in conjunction with a finite-element model of Southern California, were used to calculate ground motions at 636 sites throughout the San Fernando and Los Angeles basins. At each site, time history analyses of a nonlinear deteriorating structural model of an 18-story steel moment-resisting frame building were performed, using both a pre-Northridge earthquake design (with welds at the moment-resisting connections that are susceptible to fracture) and a modern code (UBC 1997) design. This work uses the simulation results to estimate losses by applying the MDLA (Matlab Damage and Loss Analysis) toolbox, developed to implement the PEER loss-estimation methodology. The toolbox includes damage prediction and repair cost estimation for structural and non-structural components and allows for the computation of the mean and variance of building repair costs conditional on engineering demand parameters (i.e. inter-story drift ratios and peak floor accelerations). Here, it is modified to treat steel-frame high-rises, including aspects such as mechanical, electrical and plumbing systems, traction elevators, and the possibility of irreparable structural damage. Contour plots of conditional mean losses are generated for the San Fernando and the Los Angeles basins for the pre-Northridge and modern code designed buildings, allowing for comparison of the economic effects of the updated code for the scenario event. In principle, by simulating multiple seismic events, consistent with the probabilistic seismic hazard for a building site, the same basic approach could be used to quantify the uncertain losses from future earthquakes.

One of the new lateral force-resisting systems introduced to improve seismic performance of structures is the rocking buckling restrained braced frame (RBRBF). In this system, conventional braces and adjacent columns are designed to remain elastic until near seismic collapse. In this paper, RBRBFs are designed according to a displacement-based design approach. Maximum interstory drift ratio (MIDR) and maximum residual interstory drift ratio (MRIDR) are among the most critical engineering demand parameters (EDPs) used to assess the safety of structures after an earthquake. MIDR is the largest peak interstory drift ratio (IDR) observed among all the stories of a structure. The primary aim of this study is to investigate the effects of utilizing RBRBFs on MIDR and MRIDR responses compared with buckling restrained braced frames (BRBFs). For this purpose, 4-, 8-, and 12-story structures with the RBRBF and BRBF systems are considered, and their collapse capacity values and residual drift capacity values, given different levels of MRIDR, are computed using incremental dynamic analyses (IDAs). After computing the capacity values, the mean annual frequencies (MAFs) of collapse ([Formula: see text]) and exceeding different MRIDR levels ([Formula: see text] are obtained. The results demonstrate that all the RBRBFs have considerably better collapse and residual drift performance than the BRBFs. Based on these results, the use of RBRBF significantly reduces the weaknesses of BRBF including damage concentration in a single story and low post-yield stiffness. Cloud analyses are performed on the structures to investigate the height-wise distributions of peak floor accelerations (PFAs), peak IDRs, and residual interstory drift ratios (RIDRs). The results indicate that the RBRBFs have a uniform height-wise distribution of peak IDR, but the BRBFs have considerable peak IDR concentrations. Furthermore, the RBRBFs have much lower RIDRs than the BRBFs, whereas they experience higher PFAs than the BRBFs. Nevertheless, their PFAs, on average, are not significantly higher than those of the BRBFs.

The present study investigates the effects of directivity‐induced near‐fault pulse characteristics on the inter‐story drift ratio (IDR) and peak floor acceleration (PFA) responses of inter‐story isolated (ISI) building frames. In the absence of a thorough understanding and general design methodology for ISI frames subjected to near‐fault pulse (NFP) type ground motions, this investigation addresses two key aspects: (i) evaluating the seismic behavior of ISI building frames under pulse characteristics using an equivalent mathematical pulse (EMP) model and (ii) proposing empirical seismic demand prediction equations based on responses from both recorded NFP‐type ground motions and the EMP model with pertinent modeling characteristics. These modeling characteristics are calibrated with the recorded NFP‐type ground motion to retain the same spectral characteristics. Non‐linear dynamic analysis is performed to assess IDR and PFA demands under both datasets, recorded NFP‐type ground motions and artificial time histories generated by the EMP model. The IDR response statistics obtained from the EMP model and recorded NFP‐type ground motions are compared, and the 84th percentile response shows a good agreement between the two observed datasets. However, the PFA response below the isolation layer is amplified under‐recorded NFP‐type ground motions compared to the EMP model. A detailed parametric investigation is carried out to understand the effects of amplitude, pulse period, oscillatory characteristics and phase angle of the EMP model. Moreover, significant deviations are observed in IDR and PFA responses for different isolation bearings when the pulse period approaches the fundamental period of the ISI building frame, while deviations diminish for higher modal periods. The ISI building system exhibits two distinct local peaks in the drift spectra corresponding to fundamental and second modal periods. Near the fundamental mode, the drift response is highly sensitive to the oscillatory characteristics of the EMP model. The maximum IDR ratios between the fundamental and second modal periods are observed as 3.24 and 1.75 for oscillatory characteristic values of 1 and 2.5, respectively. Finally, a set of new empirical seismic demand prediction equations is developed to obtain the expected IDR and PFA demands. The developed models demonstrate a coefficient of determination value greater than 0.80, which demonstrates the efficacy of the proposed model. In addition, a two‐step design procedure is recommended, considering the fault characteristics such as the moment magnitude and the closest distance to the rupture . Given the absence of general design guidelines for the ISI building frames, this investigation would be valuable to professional structural engineers, especially in the near‐fault region.

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

Engineering demand parameters for the definition of the collapse limit state for code-conforming reinforced concrete buildings

Nonmodel rapid seismic assessment of eccentrically braced frames incorporating masonry infills using machine learning techniques

Correlation between seismic intensity measures and engineering demand parameters of reinforced concrete frame buildings through nonlinear time history analysis

Early earthquake design codes used peak ground accelerations (PGAs) as intensity measures (IMs) to characterize the demands of ground motions on structures, but have since shifted towards using spectral accelerations because they provide a better indication of demand. The design of acceleration‐sensitive nonstructural components has followed a similar approach, with modern codes being based on an estimate of the spectral acceleration at the period of the nonstructural component. However, most fragility curves for loss assessment of acceleration‐sensitive nonstructural components, including the existing FEMA P58 library, continue to be based on peak floor accelerations (PFAs). Similar to PGAs as an IM for buildings, a limitation of PFA as an engineering demand parameter (EDP) for nonstructural components is its lack of dependence on the period of those components. In this study, fifteen alternative EDPs suggested in the literature are evaluated as potential candidates for developing seismic damage fragility curves. Acceleration‐sensitive nonstructural components are simulated by single‐degree‐of‐freedom (SDOF) components with elastic perfectly plastic behavior, with a period range of 0.01 to 1 s, and varying strength levels. Nonlinear response history analyses are conducted for the SDOFs, using floor motions obtained from both the first floor and the roof of buildings designed with four distinct seismic force‐resisting systems. Ductility demands for each SDOF are taken as an indicator of damage and are predicted using a linear regression model developed for each specific EDP. The suitability of candidate EDPs is evaluated based on their efficiency and relative sufficiency. Furthermore, a comparison is made between the expected annual loss calculated using fragility curves derived from the selected EDPs to quantify how the EDP used for a fragility curve can affect the seismic loss assessment. The results reveal that the PFA is a suitable EDP only for nonstructural components with very short periods (i.e., less than 0.1 s). Moreover, although the spectral acceleration at the period of the SDOF nonstructural component is a suitable EDP for components that are nearly elastic and are located on the roof of buildings, the peaks that develop in the floor spectra can grossly overstate the demands on nonstructural components that experience significant nonlinearity in their response. In such situations, an average of the spectral accelerations in a range of periods near the period of the SDOF nonstructural component is more appropriate.

During past earthquakes, seismic pounding has caused severe devastation and buildings in the hilly region have experienced great damage. It is important to study the effect of seismic pounding on typical building configurations practiced in hilly regions. Herein, an attempt has been made to investigate the effect of seismic pounding on the response of two adjacent reinforced concrete hill-side buildings having typical configurations, i.e., stepback and split-foundation, with five different gap distances. Based on bi-directional non-linear time history analyses, a comparative study is made considering different engineering demand parameters. The effect of seismic pounding is also studied on one acceleration-sensitive building component mounted in hill-side buildings, i.e., suspended ceiling system. Further, the performance of considered hill-side buildings and suspended ceiling system mounted in them is investigated under the effect of seismic pounding through the development of fragility curves for different gap distances. This study highlights that among the two considered hill-side building configurations, stepback is more critical to seismic pounding scenario in comparison to split-foundation building configuration. It is also seen that the peak interstory drift ratio and peak floor acceleration are critical at different relative story heights under the effect of seismic pounding in adjacent hill-side buildings. Thus, different stories and floor levels are identified which are critical to seismic pounding in terms of drift-sensitive and acceleration-sensitive building components, respectively. In addition to this, the gap distances that are causing the maximum probability of exceeding a damage state in considered hill-side buildings as well as in suspended ceiling systems are identified.

Seismic Performance of 3-D Infilled and Bare Frame RC Building Models using Average Spectral Acceleration

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

Evaluation of engineering demand parameters for seismic analyses of CLT-glulam hybrid structures

Viscous dampers mitigate the interstory drift ratios (IDRs) and peak floor accelerations (PFAs) of buildings subjected to earthquakes. This leads to a multi-objective optimization problem (MOOP) for a viscous damper placement along the building height to minimize IDRs and PFAs simultaneously. This paper proposes innovative methods to address the MOOP and compares those proposed methods to non-dominated sorting algorithm II (NSGA-II) through case studies. Subsequently, the meaning of solutions on the Pareto optimal front in future earthquake events is investigated. The case studies apply each method to a two-dimensional ten-story shear building and adopt four measures to evaluate the performance of searched solutions in multiple aspects. The results show that the proposed methods, by executing fewer number of time history analyses and with convergence comparable to that of NSGA-II, successfully offer improvement against NSGA-II in the aspect of productivity and diversity. As for understanding solutions on the Pareto front in future earthquake events, the knee point solution’s design, which proposed methods can arrive at or approach, successfully reduces both peaks IDR and PFA under 20 ground motions.

This paper presents a study on the selection of engineering demand parameters (EDPs) for the definition of collapse for code-conforming reinforced concrete buildings. The definition of collapse for buildings is not unique, as different codes and authors define it with respect to different EDPs and different values of the EDPs. Since collapse is associated with large plastic deformations, collapse is typically defined by deformation, displacement, and eventually energy EDPs. The EDPs can be either local when they refer to a single structural element response parameter (such as element rotation with respect to the chord) or global when they refer to an overall building response parameter (such as inter-story drift or top floor displacement). The Italian buildings code NTC2008 and Eurocode 8 use the chord rotation as EDP, while FEMA 356 and other North American literature use inter-story drift ratio. This study compares different definitions of EDPs and different values of the selected EDPs by analyzing two code-conforming benchmark buildings, one six-story and the other nine-story high, designed according to Italian code. Multiple-stripe, non-linear dynamic analyses are carried out on the two buildings modeled with concentrated hinges. The results show that different collapse definitions lead to very different safety evaluations and point to the need for the definition of a single EDP and a single value to make collapse analyses (and risk assessment) studies comparable.

The use of Stick-IT model in loss assessment at the large scale