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This paper presents a methodology to evaluate life safety risk of coastal communities vulnerable to seismic and tsunami hazards. The work explicitly incorporates two important aspects in tsunami evacuation modeling: (1) the effect of earthquake-induced damage to buildings on building egress time, (2) the effect of earthquake-induced debris on horizontal evacuation time. The city of Seaside, Oregon, is selected as a testbed community. The hazard is based on a megathrust earthquake and tsunami from the Cascadia Subduction Zone that was defined in a previous study. The built environment consists of buildings and the transportation network for the city. Fragility analysis is used to estimate the seismic damage to buildings and resulting debris that covers portions of the road network. The horizontal evacuation time is determined based on the shortest path to shelters, including the increased travel time due to the earthquake-generated debris. The effects of different mitigation strategies are quantified. Results indicate the fatality and life safety risk of a near-field tsunami increases by 4.2–8.3 times when the effects of building egress and earthquake-induced debris are considered. The choice of population layer affects the life safety risk and thus the maximum risk is obtained when daytime populations are considered. Use of mitigation strategies result in a significant decrease in the number of fatalities. For hazards with recurrence intervals larger than 500- to 1000-years, the seismic retrofit is comparable to vertical evacuation and an effective strategy in reducing fatalities and associated risks. Implementing all mitigation strategies reduces the life safety risk by 90%. [ABSTRACT FROM AUTHOR]

Experimental tests of cross-laminated timber (CLT)-concrete composite floor panels were conducted. The tests consisted of linear-elastic tests of square CLT-concrete composite panels with a novel shear connector to determine elastic orthotropic plate properties. After the linear-elastic tests, the panels were subjected to a patch load at the center of the panel and tested to failure. To investigate load transfer across longitudinal joints between adjacent panels, nonuniform bending tests were conducted. Results from the experimentally measured orthotropic plate properties showed that the shear connector increased the bending stiffness in the weak direction of the panel compared to prior test results using conventional shear connectors. The tests to failure exhibited larger differences in behavior between the strong and weak orientations of the specimens, with both showing substantial inelastic behavior prior to failure. Numerical finite element models of the patch-load test showed good agreement with experimental results. Analytical formulas using the obtained orthotropic plate properties did not agree with experimental results for the patch-load at linear scales, suggesting the simplified method is currently not suited for CLT-concrete two-way bending. Load-transfer tests found that the reinforced concrete topping is capable of transferring load across the longitudinal joint of two parallel panels to enable two-way bending of composite timber–concrete floors and that the addition of a plywood spline with closely spaced screws enables a higher degree of force transfer. [ABSTRACT FROM AUTHOR]

The main objective of this work is to characterize the stress–strain relationship of cross-laminated timber (CLT) wall panels when loaded in compression and how different confinement mechanisms provide compression reinforcement for the CLT panels. CLT crushing tests were performed to define the behavior of CLT under compression up to the failure point, defined here as the strain at which the gross stress falls by 20% from the peak value. Testing included monotonic uniform compression experiments of five-ply CLT with specimens that were 0.457 m wide by 1.52 m long. The motion of the specimens perpendicular to loading direction was restrained at midlength to prevent buckling. Twelve specimens were tested, including six bare CLT specimens and six reinforced specimens of CLT—three with self-tapping screws while the other three with self-tapping screws and an additional U-shape steel plate at the bottom of the specimens. Various damage points were observed during the tests, including (1) point at the onset of damage (through visual observation and instrumental observation) (2) point of initiation of strength degradation, (3) point at which buckling occurs, (4) point at which 25.4 mm delamination was observed, and (5) failure point. Three axial compression stress–strain models were adopted, calibrated, and compared. Results indicate that a stress–strain model combining linear and cubic functions for the elastic and softening responses, respectively, captures well the CLT inelastic behavior under compression. [ABSTRACT FROM AUTHOR]

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

Mass timber construction has seen a growing interest in North America and worldwide. In the US, code provisions allow mass timber buildings to be up to 82 m tall, but with floor slabs requiring a noncombustible, usually cementitious, topping over mass timber panels (MTPs). Designing the MTP and concrete topping to act compositely can increase the strength and stiffness compared to noncomposite MTP floors. Several connections are available to create composite action between an MTP and a concrete topping, with self-tapping screws being the most widely considered practice. A new test fixture and testing method were developed to characterize connection properties and facilitate the selection of fasteners most suitable for developing composite action. Three conventional self-tapping screws were experimentally investigated at the single-fastener scale. The screws were subjected to withdrawal at 90° and 45° orientations to the interface plane between the MTP and concrete. Withdrawal from both the MTP substrate and concrete topping was investigated. Three MTP materials were tested: cross-laminated timber (CLT) consisting of two different wood species and a mass ply panel (MPP). Results demonstrated that the pullout failure of the screwhead from the concrete was the limiting failure mode. Comparisons were made between the experimental results and analytical models for screw withdrawal to assess the applicability of available models to the different MTPs. These models underestimated the capacity of the tested fasteners for all samples except for the fully threaded screws. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to evaluate the direct and general equilibrium losses for a testbed community subjected to a megathrust earthquake and tsunami hazard originating in the Cascadia Subduction Zone. The testbed community studied consists of buildings for all residential and commercial sectors in the economy. A fragility analysis and functionality model are applied to estimate the direct damage and losses of these buildings at the parcel level. The process relies on Monte Carlo simulations (MCS) that propagate uncertainties from the hazards through to the damage and loss models. A computable general equilibrium (CGE) model is used to assess aggregated general equilibrium losses to the community. As an important mitigation strategy, seismic retrofit reduces the direct loss to building functionality and general equilibrium losses. Results show that the vulnerability of economic sectors depends on the hazard type, hazard intensity, economic zone, and building type, and the risks vary with the recurrence interval. The highest risks are associated with 500-year and 1,000-year mean recurrence intervals for joint seismic–tsunami hazards, respectively. Results from assessing different design alternatives show that whereas retrofitting all buildings to the highest code level considered results in the lowest losses, retrofitting only commercial buildings can be an efficient retrofit option for enhancing community resilience when controlling for costs. Last, a sensitivity analysis shows that losses and associated risks are sensitive to the definition of building functionality, which highlights the necessity for a common definition of building functionality when performing vulnerability analyses. [ABSTRACT FROM AUTHOR]

Fragility functions and recovery models are often used to assess lifeline systems subjected to extreme hazards. However, even though many databases for fragility and recovery models exist for essential buildings and transportation systems, fragility and recovery models for other lifelines are fragmented across the literature. This article provides a comprehensive review of the state-of-the-art seismic fragility functions and recovery models for energy (power, liquid fuel, and gas), water, and wastewater systems that can be applied in hazard risk and resiliency assessments of communities. The review focuses on fragility and recovery model parameters and summarizes the methods and validation used in developing the models. In addition, the reviewed fragility functions are compiled in an open-source database with a graphical user interface. Critical gaps in the literature are discussed to guide future research endeavors. [ABSTRACT FROM AUTHOR]

Timber–concrete composite (TCC) floors exposed to fire experience charring and thermal degradation of timber, leading to a reduction in load-carrying capacity. Finite element (FE) modeling supplements data from experimental fire testing and allows for fast and economical investigation of additional design parameters. This research presents fire test results of three large-scale TCC floor specimens and development of an FE modeling methodology for TCC floors in a fire. TCC floors constructed with nail-laminated timber, cross-laminated timber, or mass ply panel, with truss plates or angled screws as shear connectors, are loaded with a uniformly distributed service-level live load and exposed to the ASTM E119-20 standard fire curve. A 2D FE modeling methodology is presented and benchmarked against the test data. The methodology integrates sequentially coupled thermal-structural analyses, which make use of temperature-dependent thermal and mechanical properties of timber and concrete. The deflection and failure times of the FE models are benchmarked against test data. Connector forces from FE models show that shear connectors remain elastic throughout the fire exposure. FE results indicate that the load-carrying capacity is dependent on tensile stress redistribution to the uncharred timber section. The FE modeling methodology effectively calculates the mechanical and fire behavior of TCC floors and highlights limits of the applicability of analytical design methods. [ABSTRACT FROM AUTHOR]

Maintaining the functionality of wastewater networks is critical to individual well-being, business continuity, public health, and safety. However, seismic damage and loss assessments of wastewater networks traditionally use fragility functions based on median repair rates without considering relevant sources of uncertainty and correlations of damage when estimating potential damage states and pipe repairs. This study presents a probabilistic methodology to incorporate modeling uncertainty (e.g. model parameter and model class uncertainty) and spatial correlations (e.g. spatial auto- and cross-correlation) of pipe repairs. The methodology was applied to a case study backbone system of a wastewater network in Portland, OR, using the expected hazard intensity maps for multiple deterministic earthquake scenarios, including a moment magnitude M6.8 Portland Hills Fault and M8.1, M8.4, M8.7, and M9.0 Cascadia Subduction Zone (CSZ) events. As spatial-correlation models of pipeline damage were non-existent in the literature and local information on costs to repair the pipes was limited at the time of this study, correlation methods and repair costs were proposed to estimate lower and upper bounds of pipe damage and loss. The results show how the consideration of different levels of uncertainty and spatial correlation for pipe repair rate could lead to different probabilistic estimates of damage and loss at the system level of the wastewater network, even though the point estimates, such as the mean and median, remain essentially unaltered. [ABSTRACT FROM AUTHOR]

New building code changes enable mass timber panels (MTP), including cross-laminated timber (CLT), to be used in moderate and tall buildings as a floor system, usually with a concrete topping. A floor system of CLT composite with a reinforced concrete topping slab can provide increased stiffness and strength, making the system more advantageous. Present connection methods used to produce composite action within timber-concrete composites (TCC) have limitations when considering constructability or performance. This study presents experimental results from four (4) shear connectors for CLT-concrete composite floor systems, including three developed for this study. The connectors included self-tapping screws (STS) at 45-degrees, a modified lag screw with an integral plate washer that bears on the CLT surface at installation, a steel angle anchored only at the end of the span, and an inverted-T steel section with stem perforations. Different tests were performed on the different connectors including individual fastener tests, push-off group tests, and full-scale one-way bending tests. The push-off group tests showed that the proposed washer-screw exhibited higher stiffness and strength than a conventional STS. The full-scale one-way bending testing showed that the STS specimen exhibited the lowest strength of the alternatives. The inverted-T section exhibited the highest stiffness, while the other three connections had similar stiffness to the STS. [ABSTRACT FROM AUTHOR]

Connections play a vital role in the transfer of lateral forces and energy dissipation in cross-laminated timber (CLT) structural systems. However, moisture exposure (e.g., rain during or after construction) can affect the durability of CLT structural members and their connections due to the hygroscopic nature of wood. Limited knowledge exists on the moisture performance of CLT connections. Therefore, in this study, a CLT shear wall-to-diaphragm angle bracket connection was exposed to simulated rain and relative humidity cycling (wetting) and subsequent redrying followed by mechanical loading cyclic testing. Four wood species (Douglas-fir, southern pine, Norway spruce, and spruce-pine-fir) and three wetting durations were applied to understand the effect of moisture intrusion on the connection performance, which was evaluated in terms of strength, stiffness, and energy dissipation. Two force–displacement backbone models were fitted to the experimental data. The results suggest a statistically significant increase (9%–15% for different species) in the peak strength and no change in the stiffness and energy dissipation capacity after the wetting and redrying cycles. However, additional studies should be conducted to gain further insight into the observed increase in load-carrying capacity. Additionally, the authors caution against considering any strength increase until further studies are conducted. [ABSTRACT FROM AUTHOR]

This paper presents a new coupled urban change and hazard consequence model that considers population growth, a changing built environment, natural hazard mitigation planning, and future acute hazards. Urban change is simulated as an agent‐based land market with six agent types and six land use types. Agents compete for parcels with successful bids leading to changes in both urban land use—affecting where agents are located—and structural properties of buildings—affecting the building's ability to resist damage to natural hazards. IN‐CORE, an open‐source community resilience model, is used to compute damages to the built environment. The coupled model operates under constraints imposed by planning policies defined at the start of a simulation. The model is applied to Seaside, Oregon, a coastal community in the North American Pacific Northwest subject to seismic‐tsunami hazards emanating from the Cascadia Subduction Zone. Ten planning scenarios are considered including caps on the number of vacation homes, relocating community assets, limiting new development, and mandatory seismic retrofits. By applying this coupled model to the testbed community, we show that: (a) placing a cap on the number of vacation homes results in more visitors in damaged buildings, (b) that mandatory seismic retrofits do not reduce the number of people in damaged buildings when considering population growth, (c) polices diverge beyond year 10 in the model, indicating that many policies take time to realize their implications, and (d) the most effective policies were those that incorporated elements of both urban planning and enforced building codes. Plain Language Summary: Natural hazards negatively impact communities resulting in significant infrastructure damages. Natural hazard mitigation planning attempts to reduce these damages and modeling can be used to measure how effective different mitigation plans can be. A new modeling framework is presented that accounts for population growth, a changing built environment, natural hazard mitigation planning, and future hazards. The model is applied to a testbed community with a large tourist population that is exposed to earthquake and tsunami hazards. Using this model, we consider different combinations of policies such as limiting the number of vacation homes in the community, relocating community assets, limiting new development, and enforcing building codes. Interestingly, we show that while placing a cap on the number of vacation homes does free up housing for full time residents, this also results in more visitors in damaged buildings. It is also shown how even with building codes in place, population growth contributes to an increased number of people in damaged buildings. Lastly, we show how the most effective policies incorporate elements of both urban planning and building codes. Key Points: An urban change model is coupled with a hazard consequence model to consider future hazards, population growth, and planning policiesThe model is applied to a coastal community in the Pacific Northwest considering Cascadia Subduction Zone seismic‐tsunami hazardsPlacing a cap on the number of vacation homes in a community could result in more visitors in damaged buildings [ABSTRACT FROM AUTHOR]

This correction notice addresses an error in the article "Application of Multidisciplinary Community Resilience Modeling to Reduce Disaster Risk: Building Back Better" by Wanting "Lisa" Wang and others. The correction reinstates a reference to a study by Rosenheim et al. (2021) that was inadvertently removed. The correction also provides missing information for another reference by Rosenheim (2021). The American Society of Civil Engineers (ASCE) regrets the error and has made the necessary corrections in this erratum. [Extracted from the article]

The high cost of manufacturing high-performance fiber-reinforced cementitious composites (HPFRCCs) and low confidence in predicting their mechanical properties have limited their widespread use as construction materials. Also, the lack of reliable numerical stress-strain cyclic behavior models prevents the analysis and study of potential industrial applications. In this research, a new uniaxial fiber-reinforced cementitious composite constitutive model (FRCC model in OpenSees) is developed and validated for use in monotonic and cyclic analyses consisting of fiber section finite elements. The model is validated at the material and structural level through correlations of the numerical results with the limited laboratory test data available in the literature, as well as some new experimental results. The quantification of the uncertainties in structural response parameters due to model input parameter uncertainties is conducted via sensitivity analysis. The validation results make the model useful for performance-based assessment and design of civil engineering structures that use HPFRCCs. [ABSTRACT FROM AUTHOR]

Many communities around the world are facing increasing flood-induced damage to bridges due to climate change and rising urbanisation. It is thus crucial to understand how different bridge types suffer from flooding and how this may affect surrounding networks. Despite the large body of literature for seismic and hurricane taxonomies, few classifications exist for bridges at flood risk. In this work, existing global bridge classifications were reviewed in order to derive a bridge–flood taxonomy. The review revealed that existing studies mainly classify bridges according to the superstructure material, whereas subclasses consider superstructure and substructure components. A taxonomy of 20 attributes for riverine roadway bridges susceptible to flood hazards is proposed in this paper. Its applicability for three bridge datasets in the UK was verified. The results showed that the considered datasets have data for 13 attributes, which can be used to derive regional bridge classes. In general, the taxonomy is functional for standardising different bridge datasets and applying/developing damage models for given bridge portfolios of flood-prone countries. Future works could apply the taxonomy to additional bridge datasets within a network for risk assessments; the proposed taxonomy could also be extended to allow integration with functionality and restoration models. [ABSTRACT FROM AUTHOR]

This paper presents a framework to evaluate the regional and local resilience of infrastructure networks following disruptions from natural hazards. Herein, the regional resilience of a network relates to the accessibility of a community within a larger network, whereas the local resilience concerns the ability of a network to provide its intended service within the boundaries of a community. Using this framework, a methodology is developed to demonstrate its application to a road and highway transportation network disrupted by ground shaking and inundation under a Cascadia Subduction Zone earthquake and tsunami scenario. The regional network extents encompass the entire coast of the US state of Oregon. Embedded within this regional network are 18 local networks associated with coastal communities. Regional and local connectivity indexes are defined to identify the initial damage and then track the postdisaster recovery of the transportation network, i.e., evaluate the network resilience. The study results identify the attributes that lead to a regionally or locally resilient network and highlight the importance of considering local infrastructure networks embedded within larger regional networks. It is shown that without regional considerations, the time to recover may be severely underpredicted. The methodology is further used as a decision support tool to demonstrate how mitigation options impact the transportation network's resilience. The importance of strategically considering mitigation options is emphasized as some communities see significant reductions in time to recover, whereas others see little to no improvement. [ABSTRACT FROM AUTHOR]

The role of spatially variable soil stiffness and strength on structural performance has been increasingly recognized with the rapid development of geotechnical reliability-based design tools. Performance criteria linked to the angular distortion between foundations and the probability of exceeding certain limit states as a function of linear-elastic soil property autocorrelation have shed light on the link between foundation soils and potential structural damage. However, the role of soil-structure interaction (SSI), especially considering nonlinearity in soil and structural elements, to redistribute shear and flexure within structures that result from differential foundation movements, has been largely neglected. This study presents a critical examination of the effect of nonlinear SSI to redistribute flexural demands within a steel structure founded in soils exhibiting spatial variability and the corresponding differential settlements through a comparison of uncoupled and coupled Monte Carlo simulations (MCS). This study shows that the differential settlement, Δs , computed using coupled (i.e., SSI) analyses are significantly smaller than those derived from the uncoupled analyses for the random field models (RFMs) used to simulate soil spatial variability. The effect of SSI is to substantially reduce the probability of exceeding selected limit state criteria due to differential movements that vary in magnitude with the level of stringency of the limit state criteria; the most significant reduction corresponds to the structural ultimate limit state (ULS). Furthermore, the effect of SSI on structural performance and the critical scale of fluctuation, δcrit , becomes more apparent and beneficial as the severity of differential movement increases. Smaller and/or "allowable" angular distortions are governed by the local footing-to-footing distance, whereas the probability of exceeding the ULS (i.e., yielding of beams) is controlled by the entire structure working to redistribute the flexural demands. Limit state severity appears to control the critical soil autocorrelation length for angular distortion, indicating that the role of SSI in the performance of structures in spatially varying soils cannot be ignored. [ABSTRACT FROM AUTHOR]

Over the past decade, cross-laminated timber (CLT) panels have gained popularity worldwide. To achieve larger spans and to increase the resistance to diaphragm seismic and wind forces to be transferred through CLT floor or roof systems, CLT-concrete composite (CCC) floors have been developed as an alternative. While significant testing has been performed under gravity loading, limited experimental data exist on the in-plane performance of CCC systems. This study presents results from an experimental program designed to characterize the in-plane shear behavior of CCC diaphragm connections using different CLT to concrete screw connector orientations in a test setup that simulates the expected seismic load path in diaphragms for platform-type construction. Tested variables include concrete slab thickness, composite screw angle, and single spline connection systems consisting of nails or screws. Experimental results and observed damage progression from cyclic testing are presented and discussed. Results indicate that CCC systems achieved increased stiffness and strength values when compared to bare-CLT systems, but slab thickness did not influence the strength and stiffness of the system for the load paths simulated. Additionally, CCC floor systems with 45° composite screw connectors displayed increased strength but overall similar stiffness values when compared to the CCC systems with 90° composite screws. The results provide useful engineering parameters, such as elastic stiffness, peak load, displacement capacity, and ductility ratios that can be used in the development of codified design parameters or in performance-based designs. [ABSTRACT FROM AUTHOR]

Tsunamis are low-probability high-consequence events, usually caused by an earthquake in the ocean and can result in high casualty rates and billions of dollars in damage. Tsunamis can be divided into two main categories: near-field and far-field tsunamis, based on the location of their origin with respect to the site of interest. To perform risk assessment of communities subjected to tsunamis, the current approach would be to use empirical data from historical events, making the data site specific. Recently, researchers have developed approaches to estimate the risk of structures subjected to far-field earthquake generated tsunamis using a simulated tsunami force on a structure numerically. However, for near-field tsunamis, ground motions caused by the earthquake will reach the structure earlier than the tsunami, damaging the structure, which can substantially impair its structural performance in the following tsunami. The multi-hazard case of tsunami following earthquake is discussed herein and a physics-based approach to estimate the risk of structures subjected to them is presented. An illustrative example is presented to elaborate the methodology for a steel building. Successive nonlinear analyses are used to develop fragility functions based on joint earthquake-tsunami intensity measures (spectral acceleration-flow depth-flow velocity). These functions are used in combination with hazard analysis of a specific location to obtain loss estimates. Three different approaches were used for this process and the results showed that the use of the joint three intensity-measure fragilities is essential for the accuracy when estimating damage or structural loss and neglecting their interaction results in substantial errors. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) is an engineered wood product offering several advantages for wood utilization in midrise and tall buildings. However, moisture intrusion poses significant risks since it can affect the durability of CLT structural members and their connections. There has been much research on connection performance to understand their seismic response. However, the impact of moisture on the performance of CLT connectors is less understood. Cyclic tests were conducted on a series of CLT shear wall-to-diaphragm L-bracket (angle bracket) connections after subjecting them to a wetting and redrying cycle. The study includes three exposure durations and four wood species (Douglas fir, Southern yellow pine, Norway spruce, and spruce-pine-fir) to investigate the effect of moisture exposure on the connection performance. The performance was characterized in terms of strength, stiffness, and energy dissipation. In addition, two existing engineering force-displacement models were fitted to the experimental data. Results indicate that the changes due to wetting and redrying cycling were not statistically significant for the load-carrying capacity and stiffness. In contrast, a statistically significant decrease in the total energy dissipation capacity was observed. [ABSTRACT FROM AUTHOR]

A full-scale 2-story mass timber building was tested on the University of California San Diego Natural Hazards Engineering Research Infrastructure (UCSD-NHERI) uniaxial shake table during the period from June 2017 to September 2017. The main objective of the experimental program was to test the performance of mass timber building designs with different seismic lateral force–resisting systems. The focus of this study is on a building configuration designed using self-centering post-tensioned cross-laminated timber (CLT) rocking walls with U-shaped steel flexural plate energy dissipators. The shake-table tests were designed to subject the building to a series of earthquake ground motions of increasing intensity, ranging from a service-level earthquake to 1.20 times the maximum considered earthquake intensity. Between each ground motion, low-amplitude white-noise excitations were applied to the building, which responded as a quasilinear system. In this paper, two output-only operational modal analysis methods are used to estimate the modal parameters (frequency, damping, and mode shapes) based on acceleration data collected during the white-noise shake-table tests. The correlations of observed damage and repairs performed during the experimental program with changes in estimated modal features are reported. The modal parameters estimated from the testing program are also compared with a linear finite-element model that is used to validate the modal identification results and study the performance of the two system identification methods for CLT rocking structures. [ABSTRACT FROM AUTHOR]

This paper presents the behavior of floor diaphragms of a shake-table experiment of a full-scale 2-story mass-timber building structure. The structure consists of glued-laminated timber beams and columns, and floors and walls were designed and built making use of cross-laminated timber panels. Two different floor systems were designed, where the roof consists of a topped cross-laminated timber (CLT)-concrete composite system, and the floor level consists of untopped CLT panels connected with plywood single-surface splines. The CLT floor systems were designed to remain essentially elastic over the whole series of shake-table tests, which included testing of three lateral force–resisting systems tested at three different seismic intensity levels (service level, design basis, and maximum considered earthquake) for a total of 34 shake-table earthquake tests. Results from the testing indicate that CLT diaphragms designed to remain essentially elastic based on basic principles of structural mechanics and existing test data can achieve desired seismic performance objectives. In addition, sources of overstrength in certain elements of the diaphragm need to be explicitly considered for a holistic diaphragm design. [ABSTRACT FROM AUTHOR]

This paper presents the use of modern survey techniques, particularly light detection and ranging (LiDAR) scanning, to collect time-sensitive information before and after shake table experiments. Two full-scale, three-story residential buildings were tested simultaneously on the largest shake table in the world. The focus of this study is on the use of LiDAR to document observations during these tests. The challenges experienced during this study prompted the development of a formalized survey procedure using LiDAR scanning techniques, which can be used by other researchers when planning to collect such time-sensitive data from similar experimental programs. In this paper, damage assessment through visual inspection, which is commonly performed during full-scale tests, is compared to postexperiment assessments using postprocessed LiDAR-derived point clouds. Various examples of damage to structural and nonstructural components, including columns, bracing, partition walls, and façades, are illustrated through postshaking visual inspections as well as LiDAR-derived point clouds. The feasibility of making accurate measurements using LiDAR point clouds, and automatically detecting damage using the point-to-point cloud comparison, is presented. Finally, the relationship between observations through traditional instruments (e.g., accelerometers and laser meters) and LiDAR is discussed. In one example, the measurements from eight laser meters around the buildings are used to validate the measurements obtained using LiDAR point clouds. It is concluded that observations through LiDAR are complementary to those from traditional instruments, while permanent/residual displacements after the tests can be measured from both traditional and modern instruments. [ABSTRACT FROM AUTHOR]

Timber-concrete composite (TCC) floors are becoming more commonly used in mass timber construction due to their increased stiffness and strength relative to nonconcrete composite timber floors. Current building codes do not recognize the contribution of the composite action of TCC floors to their combined strength and fire performance. Extensive structural testing is required for structural engineers to design fire protection in timber buildings that use TCC floors using either alternate means and methods or structural fire engineering. This paper presents two experimental studies conducted to examine (1) properties of shear connection systems used in TCC floors through ambient temperature direct shear tests, and (2) the behavior of TCC floors through large-scale fire tests performed at the National Research Council (NRC) in Canada. The main objective of this research is to collect data on the fundamental behavior of TCC floors in a fire. The results indicate that TCC floors have improved fire performance when compared with mass timber floors. In addition, the research quantifies the force-slip behavior of the shear connectors used and benchmarks the flexural behavior of TCC floors at ambient and elevated temperatures to existing analytical models. [ABSTRACT FROM AUTHOR]

Probabilistic seismic risk is affected by several sources of uncertainty. Investigating their influence on loss analysis results is essential to obtain reliable quantitative estimations of seismic performance. Within the framework developed by the Pacific Earthquake Engineering Research (PEER) Center for probabilistic seismic loss analysis, this study incorporates the effect of seismic demand model class uncertainty on seismic risk performance metric estimation. The extended formulation is illustrated with an application example code-designed reinforced concrete moment resisting frame building with unreinforced masonry (URM) infill walls, where model class uncertainty related to URM infill walls modeling is propagated to the estimation of seismic financial losses. Model class uncertainty accounts for the variability arising from the use of different modeling solutions, such as the ones associated with the adoption of three equivalent strut macro-models and their modeling parameters. Probabilistic distributions are assigned to selected infill strut model parameters, and a large set of finite element models (FEMs) are generated for each infill strut model class by sampling the model parameter distributions through Latin Hypercube Sampling (LHS). Expected values of repair cost and life-cycle annualized loss are evaluated and compared for two sets of three building performance models. The first set considers the original (median) values of infill strut backbone parameters, while the second set includes model parameter uncertainty. The uncertainty propagation from structural response results to repair costs is also reported for the six performance models. Finally, the contribution of different structural and non-structural element categories to the financial losses is presented. [ABSTRACT FROM AUTHOR]

The damage caused by tsunamis to coastal communities is often not only the result of the flowing water itself, but also of transported debris. Although there have been efforts to characterize forces from single-debris impacts, a more general scenario of multiple-debris impacts has not been studied experimentally. To address this need, experimental studies were performed, considering the effect of debris orientation and the number of debris field components on peak impact and damming forces on coastal structures. These forces are evaluated both qualitatively and quantitatively to provide insight into the nature of these impacts. For a few selected cases, a number of trials were conducted and an initial statistical study of the debris field collision phenomena performed. Observed forces and results are presented in terms of normalized quantities using analytical equations commonly used to calculate impact or drag forces. The lessons from this work provide an initial data set that can be used to guide further experimental and numerical studies on debris-laden tsunami flows. [ABSTRACT FROM AUTHOR]

Connections in mass timber structural systems transfer lateral forces from mass timber elements such as shear walls to floor diaphragms. Cross-laminated timber (CLT) is a prominent engineered mass timber material used to manufacture walls and floor assemblies. Fire performance research of CLT walls and floors has been abundant in recent years in an effort to develop an understanding of the performance of structural members under fire. Some fire-protected structural elements, including connections, may not be directly exposed to flames in a fire event but will experience elevated temperatures. There is limited research on elevated temperature performance of CLT connections, and consequently a lack of understanding of their fire performance in CLT structures. To aid in bridging this knowledge gap, in this study a series of cyclic shear tests were conducted on a CLT wall-to-floor bracket connection assembly to characterize thermal degradation according to a matrix of 28 exposure duration–temperature combinations. Two different methods were employed to develop force-displacement backbone models from the experimental hysteresis data. Models from both methods indicate an overall degradation of the connection performance in terms of load carrying capacity, elastic stiffness, ductility, and energy dissipation with increasing exposure to elevated temperatures. [ABSTRACT FROM AUTHOR]

A large-scale physical model was constructed in the Large Wave Flume of Hinsdale Wave Research Laboratory (HWRL) at Oregon State University to develop a dataset of measured pressures and forces acting on an elevated, coastal structure, representing a two-story building with an elevated foundation, due to tsunami-like wave impacts. Two wave cases, unbroken and broken long waves, were investigated by changing the still water level, resulting in cases without and with an air gap between the still water level and the bottom of the test specimen, while maintaining the base of the test specimen at the same elevation. Horizontal and vertical pressures and forces were measured on the faces of the test specimen and between the test specimen and its supports, respectively. Three pressure gauge layouts were used to measure the distribution of pressures around the test specimen for each wave case. Regression surfaces of the pressure gauge measurements illustrate the shape of the pressure distributions on the test specimen. The maximum vertical forces were measured during the unbroken-wave case. However, the streamwise, horizontal force was maximized when the structure was subjected to the broken wave. The findings and data presented here are intended for use by numerical modelers for future validation analyses that can be used toward enabling tsunami-resistant designs of coastal elevated building structures. [ABSTRACT FROM AUTHOR]

Connections in mass timber structural systems are critical for transferring lateral forces from mass timber elements such as shear walls and diaphragms. Cross-laminated timber (CLT) is a prominent mass timber material used to manufacture these wall and floor assemblies. Although research exists that investigated the fire performance of CLT walls and floors, very little investigation has been devoted to the thermal performance of the connection systems themselves. This void in the data and knowledge surrounding CLT connections is an impediment for modeling the elevated temperature performance of CLT structures. Therefore, a series of shear tests were conducted on a CLT L-bracket connection assembly to characterize the thermal degradation of peak loads and initial stiffness as a function of exposure duration at a given temperature. A total of 116 specimens, including four control specimens, were tested according to a matrix of 28 exposure duration-temperature combinations. Two analytical models are developed to explain the thermal degradation—one assuming a mechanism based on first-order kinetics and the second using a statistical regression. The results of this work indicate that the degradation of peak load and initial stiffness with respect to exposure duration occurred at a linear rate and depended on temperature, according to the Arrhenius activation energy theory. This research is a step toward a holistic evaluation of elevated temperature modeling of CLT structures. [ABSTRACT FROM AUTHOR]

Although pre-Northridge earthquake steel moment resisting frame buildings have been shown to be susceptible to brittle connection failures, they still represent a large fraction of the existing steel buildings in the United States of America. In this study, the performance of the 3- and 9-story Los Angeles pre-Northridge SAC buildings are analyzed considering ductile and brittle beam-column connection failures, and their uncertainty. This paper contributes to understanding the influence of uncertainty associated with connections brittle fracture on building interstory deformation capacity and its impact on bias and variability of fragility functions and loss assessment. The results show that considering brittle connections leads to significantly larger drift demands and to higher repair costs, particularly under intense ground shaking. New fragility curve parameters are derived that account for the effect of the uncertainty of the strength and deformation capacity of brittle connections. [ABSTRACT FROM AUTHOR]

A three-dimensional nonlinear modeling strategy for simulating the seismic response of slender reinforced concrete structural walls with different cross-sectional shapes is presented in this paper. A combination of nonlinear multi-layer shell elements and displacement-based beam-column elements are used to model the unconfined and confined parts of the walls, respectively. A uniaxial material model for reinforcing steel bars that includes buckling and low-cyclic fatigue effects is used to model the longitudinal steel bars within the structural walls. The material model parameters related to the buckling length are defined based on an analytical expression for reinforcing steel bars embedded in reinforced concrete elements, which are developed based on beam-on-springs model, and validated with experimental tests of boundary elements of structural walls available in the literature. Six experimental case studies of reinforced concrete walls with rectangular-shape, T-shape, and U-shape cross-section are used to validate the structural wall numerical modeling strategy. [ABSTRACT FROM AUTHOR]

In this paper, unreinforced masonry (URM) and retrofitted masonry walls are modeled experimentally and computationally. The walls were subjected to in-plane loading to assess on the effectiveness of a retrofit solution that makes use of near surface mounted (NSM) reinforcing steel bars. A laboratory testing campaign was performed that included pull-out tests, diagonal compression tests, and in-plane cyclic tests of URM and NSM retrofitted physical models. The experimental results indicate that the NSM reinforcing steel bars are effective in improving the deformation capacity of the URM walls. A computational modeling approach that makes use of the applied element method is proposed and the computational results are validated using the experimental tests presented. Results from computational models indicate that a good correlation with the test results is achieved in terms of load-displacement response as well as failure mechanisms observed. [ABSTRACT FROM AUTHOR]

Large earthquakes and tsunamis can damage or lead to the collapse of lifeline bridges, resulting in human and socioeconomic losses as well as prolonged recovery times. Although many simulation models are available for the individual effects of earthquake and tsunami hazards on bridges, there are limited modeling approaches for predicting damage from sequential earthquake and tsunami hazards. A bridge modeling approach, which includes soil-foundation-structure interaction effects, is developed within the finite-element framework OpenSees to quantify sequential earthquake and tsunami-induced damage. Multihazard interaction diagrams that relate earthquake and tsunami intensity measures to bridge system damage show that the residual effects of earthquake loading on the bridge system reduce resistance to subsequent tsunami loading. [ABSTRACT FROM AUTHOR]

Probabilistic Tsunami Hazard Analysis (PTHA) can be used to evaluate and quantify tsunami hazards for planning of integrated community-level preparedness, including mitigation of casualties and dollar losses, and to study resilient solutions for coastal communities. PTHA can provide several outputs such as the intensity measures (IMs) of the hazard quantified as a function of the recurrence interval of a tsunami event. In this paper, PTHA is developed using a logic tree approach based on numerical modeling for tsunami generated along the Cascadia Subduction Zone. The PTHA is applied to a community on the US Pacific Northwest Coast located in Newport, Oregon. Results of the PTHA are provided for five IMs: inundation depth, flow speed, specific momentum flux, arrival time, and duration of inundation. The first three IMs are predictors of tsunami impact on the natural and built environment, and the last two are useful for tsunami evacuation and immediate response planning. Results for the five IMs are presented as annual exceedance probability for sites within the community along several transects with varying bathymetric and topographic features. Community-level characteristics of spatial distribution of each IM for three recurrence intervals (500, 1000, 2500 year) are provided. Results highlight the different pattern of IMs between land and river transects, and significant magnitude variation of IMs due to complex bathymetry and topographic conditions at the various recurrence intervals. IMs show relatively higher magnitudes near the coastline, at the low elevation regions, and at the harbor channel. In addition, results indicate a positive correlation between inundation depth and other IMs near the coastline, but a weaker correlation at inland locations. Values of the Froude number ranged 0.1-1.0 over the inland inundation area. In general, the results in this study highlight the spatial differences in IMs and suggest the need to include multiple IMs for resilience planning for a coastal community subjected to tsunami hazards. [ABSTRACT FROM AUTHOR]

Summary: Reliable and robust probabilistic assessment of structures requires explicit consideration of all relevant sources of uncertainty, both aleatory and epistemic. This paper proposes a formulation to incorporate model class uncertainty in probabilistic seismic demand assessment (PSDA) of structures, where model class uncertainty relates to the use of different structural analysis models used to predict the physical response of structural systems. The application of the proposed formulation is illustrated through the assessment of a recent code‐designed reinforced concrete (RC) frame building with unreinforced masonry (URM) infills, which is a prevalent form of construction worldwide. The model class uncertainty analyzed in this paper is related to the potential selection of one of three state‐of‐the‐art masonry infill strut models. In the application example, nonlinear static pushover (NSP) analyses and tornado sensitivity analyses are performed to identify the important parameters of infill strut models affecting the seismic response of the infilled RC frame. A hybrid stripe analysis (HSA) approach is adopted to perform nonlinear response history analyses (NRHAs) of the example RC frame. To account for relevant sources of uncertainty, latin hypercube sampling (LHS) is used to quantify the minimum number of realizations of model parameters necessary to achieve convergence of the coefficient of variation (COV) of the engineering response parameters assessed. Results of the NRHAs indicate that incorporating model class uncertainty significantly affects the estimation of uncertainties of the drift hazard demand. [ABSTRACT FROM AUTHOR]

Finite-length plastic hinge (FLPH) models have shown advantages over the concentrated plasticity hinge (CPH) models. However, empirical phenomenological relationships, such as Modified Ibarra–Medina–Krawinkler (ModIMK) deterioration model, were mainly calibrated for use in CPH models. ModIMK relationships are versatile and have been applied to steel, reinforced concrete, and timber structures. Herein, a calibration procedure of FLPH models and a unified algorithm for use of ModIMK relationships in CPH and FLPH models are presented. Results from included examples validate the proposed algorithms, which were implemented in OpenSees. Additionally, results highlight that FPLH models avoid errors and convergence pitfalls of CPH models. [ABSTRACT FROM PUBLISHER]

Drilled shaft foundations commonly experience torsional loads, in addition to axial and lateral loading. Such cases include loads on mast arm traffic sign and signal poles, or seismically induced inertial loading of foundations supporting skewed or curved bridges. Despite the prevalence of drilled shafts, the understanding of the actual resistance to torsion provided by these deep foundation elements is not well established. To help address this gap in knowledge, two instrumented drilled shafts were constructed to evaluate the torsional capacity and load transfer at full scale. Both monotonic quasi-static and cyclic loading tests were performed. The imposed rotation and corresponding torque was monitored using string potentiometers and load cells, respectively. Strain gauges installed to measure shear strains facilitated computation of the torsional load transfer, which is described in detail. Design procedures for the calculation of the ultimate total and unit torsional resistances of drilled shafts are proposed and resulting estimates compared against the resistances observed in the testing program and other studies reported in the literature. The rational design methodology proposed herein overpredicts or underpredicts the torsional capacity, indicating the need for the development of improved methods for assessing the torsional resistance of drilled shaft foundations. [ABSTRACT FROM AUTHOR]

Tsunamis affect coastal regions around the world, resulting in fatalities and catastrophic damage to communities. Fragility functions form the basis of most risk and resilience analyses at the individual structure level, thereby allowing physical infrastructure components to be included at the community level. For tsunami loading, the vast majority of fragilities that have been developed are based on postevent observations in the field, which are usually specific to the site of the event. In this paper, a methodology to generate physics-based tsunami fragility functions is proposed, using vector intensity measures, such as tsunami flow depth and flow velocity and several combinations thereof. The proposed methodology relies on Monte Carlo Simulation for consideration of material uncertainties and includes epistemic uncertainties in the tsunami force calculation. The ability of different tsunami intensity measures (flow depth, flow velocity, and momentum flux), which are common in the literature, to predict the response of structures are investigated, and a new intensity measure (kinematic moment of momentum flux) that represents overturning moment of a structure for tsunami fragility curves is proposed. The methodology is illustrated using an application example consisting of a steel moment frame structure and fragility functions based on the kinematic moment of momentum flux are presented and shown to be a better predictor with less epistemic uncertainty. [ABSTRACT FROM AUTHOR]

Highway bridges are one of the most vulnerable constituents of transportation networks when exposed to one or more natural hazards, such as earthquakes, hurricanes, tsunamis, and riverine floods. To facilitate and enhance prehazard and posthazard event mitigation and emergency response strategies of transportation systems and entire communities, probabilistic risk and resilience assessment methodologies have attracted increased attention recently. In this context, fragility and restoration models for highway bridges subjected to a range of hazards are essential tools for efficient and accurate quantification of risk and resilience. This paper provides a comprehensive review of state-of-the-art fragility and restoration models for typical highway bridge classes that are applicable for implementation in multihazard risk and resilience analyses of regional portfolios or transportation networks in the United States. An overview of key gaps in the literature is also presented to guide future research. [ABSTRACT FROM AUTHOR]

This paper presents an analytical study evaluating the influence of ground motion duration on structural damage of 3-story, 9-story, and 20-story SAC steel moment resisting frame buildings designed for downtown Seattle, WA, USA, using pre-Northridge codes. Two-dimensional nonlinear finite element models of the buildings are used to estimate the damage induced by the ground motions. A set of 44 ground motions is used to study the combined effect of spectral acceleration and ground motion significant duration on drift and damage measures. In addition, 10 spectrally equivalent short-duration shallow crustal ground motions and long-duration subduction zone records are selected to isolate duration effect and assess its effect on the response. For each ground motion pair, incremental dynamic analyses are performed at at least 20 intensity levels and response measures such as peak interstory drift ratio and energy dissipated are tracked. These response measures are combined into two damage metrics that account for the ductility and energy dissipation. Results indicate that the duration of the ground motion influences, above all, the combined damage measures, although some effect on drift-based response measures is also observed for larger levels of drift. These results indicate that because the current assessment methodologies do not capture the effects of ground motion duration, both performance-based and code-based assessment methodologies should be revised to consider damage measures that are sensitive to duration. Copyright © 2016 John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

This paper presents a new alternative energy dissipation solution to be used with cross-laminated timber (CLT) self-centering walls. CLT is a relatively new building product in North America and could potentially be used for high-rise construction. The development of high-performance seismic design solutions is necessary to encourage innovative structures and the design of these structures to new heights. The objective of this paper is to propose a wall-to-floor connection system that is easy to install and replace (structural fuse) after the occurrence of a large damaging event. The proposed energy dissipators are fabricated following concepts used in developing steel buckling restrained steel braces (BRB), having a milled portion, which is designed to yield and is enclosed within a grouted steel pipe. The connection system is investigated experimentally through a test sequence of displacement-controlled cycles based on a modified version of the test method developed by the American Concrete Institute (ACI) to facilitate development of special precast systems (ACI T1.1-01 Acceptance Criteria for Moment Frames Based on Structural Testing). Digital Image Correlation (DIC) was used to analyze strain behavior of the milled portion, as well as track movement of the panels during quasi-static uniaxial and cyclic testing. The results show the yield behavior and energy dissipation properties of the connection system. Damage was focused primarily in the energy dissipators, with negligible deformation and damage to the CLT panels and connections. [ABSTRACT FROM AUTHOR]

This paper presents the results of a testing program developed to assess the performance of circular RC bridge columns constructed with ASTM A706 Grade 80 [550] high-strength steel (HSS) reinforcement. Two pairs of columns were tested (four columns in total). The columns were subjected to lateral cyclic loading to determine the effects of steel reinforcement grade (yield strength) and of moment-shear span ratio on column performance. Each pair consisted of one column constructed with Grade 80 [550] HSS reinforcement and a control column constructed with Grade 60 [420] reinforcement. The first pair had a moment-shear span ratio of six (6), and the second pair had a moment-shear span ratio of three (3). All four columns were designed to have similar nominal bending-moment capacities. Results indicate that the columns constructed with Grade 80 [550] HSS reinforcement achieve similar resistance, similar maximum lateral displacements, and similar curvature ductility values when compared with the control columns constructed with Grade 60 [420] reinforcement. However, columns constructed with Grade 80 [550] reinforcement exhibited lower hysteretic energy dissipation than the control columns. Results also indicate that, independently of the steel grade, as the moment-shear span ratio decreases, the maximum drift ratio decreases, despite an increase in the displacement ductility. [ABSTRACT FROM AUTHOR]

The development of cross-laminated timber (CLT) technology has opened up new opportunities for low-density hardwood species, which have traditionally not been rated as construction-grade materials for structural engineering applications. Several characteristics of CLT, namely thermal performance, seismic behavior, and speed of construction, have raised interest among designers. The CLT technology has recently been used for residential and nonresidential multistory buildings and it has been identified as one of the ways of achieving tall timber building construction. As CLT gains acceptance in the industry, low-density wood species, not specified in current ANSI standards, need to be investigated for potentially successful use in CLT panels. This paper presents a study that demonstrates the viability of a Forest Stewardship Council (FSC) certified sustainable plantation grown low-density species, hybrid poplar (marketed as Pacific Albus), for use in performance-rated CLT panels by following the ANSI/APA PRG-320-2012: Standard for performance-rated cross-laminated timber shear and bending test guidelines to determine the structural viability of the CLT panels. [ABSTRACT FROM AUTHOR]

ABSTRACT A full-scale seven-story reinforced concrete building section/slice was tested on the Network for Earthquake Engineering Simulation (NEES) shake table at the University of California San Diego during the period of October 2005 to January 2006. Three output-only system identification methods were used to extract the modal parameters (natural frequencies, damping ratios, and mode shapes) of the test structure at different damage states. In this study, the performance of these system identification methods is investigated in two cases: (Case I) when these methods are applied to the measured dynamic response of the structure and (Case II) when these methods are applied to the dynamic response of the structure simulated using a three-dimensional nonlinear finite element model thereof. In both cases, the uncertainty/variability of the identified modal parameters due to the variability of several input factors is quantified through analysis of variance (ANOVA). In addition to ANOVA, meta-models are used for effect screening in Case II (based on the simulated data), which also capture the effects of linear interactions of the input factors. The four input factors considered in Case I are amplitude of input excitation, spatial density of measurements, length of response data used for system identification, and model order used in the parametric system identification methods. In the second case of uncertainty analysis, in addition to these four input factors, measurement noise is also considered. The results show that for all three methods considered, the amplitude of excitation is the most significant factor explaining the variability of the identified modal parameters, especially the natural frequencies. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The use of empirically calibrated moment-rotation models that account for strength and stiffness deterioration of steel frame members is paramount in evaluating the performance of steel structures prone to collapse under seismic loading. These deterioration models are typically used as zero-length springs in a concentrated plasticity formulation; however, a calibration procedure is required when they are used to represent the moment-curvature behavior in distributed plasticity formulations because the resulting moment-rotation response depends on the element integration method. A plastic hinge integration method for using deterioration models in force-based elements is developed and validated using flexural stiffness modifications parameters to recover the exact solution for linear problems while ensuring objective softening response. To guarantee accurate results in both the linear and nonlinear range of response, the flexural stiffness modification parameters are computed at the beginning of the analysis as a function of the user-specified plastic hinge length. With this approach, moment-rotation models that account for strength and stiffness deterioration can be applied in conjunction with force-based plastic hinge beam-column elements to support collapse prediction without increased modeling complexity. [ABSTRACT FROM AUTHOR]