[Truncated abstract] Perth is the capital city of Western Australia (WA) and the home of more than three quarters of the population in the state. It is located in the southwest WA (SWWA), a low to moderate seismic region but the seismically most active region in Australia. The 1968 ML6.9 Meckering earthquake, which was about 130 km from the Perth Metropolitan Area (PMA), caused only minor to moderate damage in PMA. With the rapid increase in population in PMA, compared to 1968, many new structures including some high-rise buildings have been constructed in PMA. Moreover, increased seismic activities and a few strong ground motions have been recorded in the SWWA. Therefore it is necessary to evaluate the seismic risk of PMA under the current conditions. This thesis presents results from a comprehensive study of seismic risk of PMA. This includes development of ground motion attenuation relations, ground motion time history simulation, site characterization and response analysis, and structural response analysis. As only a very limited number of earthquake strong ground motion records are available in SWWA, it is difficult to derive a reliable and unbiased strong ground motion attenuation model based on these data. To overcome this, in this study a combined approach is used to simulate ground motions. First, the stochastic approach is used to simulate ground motion time histories at various epicentral distances from small earthquake events. Then, the Green's function method, with the stochastically simulated time histories as input, is used to generate large event ground motion time histories. Comparing the Fourier spectra of the simulated motions with the recorded motions of a ML6.2 event in Cadoux in June 1979 and a ML5.5 event in Meckering in January 1990, provides good evidence in support of this method. This approach is then used to simulate a series of ground motion time histories from earthquakes of varying magnitudes and distances. ... The responses of three typical Perth structures, namely a masonry house, a middle-rise reinforced concrete frame structure, and a high-rise building of reinforced concrete frame with core wall on various soil sites subjected to the predicted earthquake ground motions of different return periods are calculated. Numerical results indicate that the one-storey unreinforced masonry wall (UMW) building is unlikely to be damaged when subjected to the 475-year return period earthquake ground motion. However, it will suffer slight damage during the 2475-return period earthquake ground motion at some sites. The six-storey RC frame with masonry infill wall is also safe under the 475-year return period ground motion. However, the infill masonry wall will suffer severe damage under the 2475-year return period earthquake ground motion at some sites. The 34-storey RC frame with core wall will not experience any damage to the 475-year return period ground motion. The building will, however, suffer light to moderate damage during the 2475-year return period ground motion, but it might not be life threatening.

This dissertation describes the analytical research as part of a comprehensive research program to develop a new floor anchorage system for seismic resistant design, termed the Inertial Force-limiting Floor Anchorage System (IFAS). The IFAS intends to reduce damage in seismic resistant building structures by limiting the inertial force that develops in the building during earthquakes. The development of the IFAS is being conducted through a large research project involving both experimental and analytical research. This dissertation work focuses on analytical component of this research, which involves stand-alone computational simulation as well as analytical simulation in support of the experimental research (structural and shake table testing). The analytical research covered in this dissertation includes four major parts: (1) Examination of the fundamental dynamic behavior of structures possessing the IFAS (termed herein IFAS structures) by evaluation of simple two-degree of freedom systems (2DOF). The 2DOF system is based on a prototype structure, and simplified to represent only its fundamental mode response. Equations of motions are derived for the 2DOF system and used to find the optimum design space of the 2DOF system. The optimum design space is validated by transient analysis using earthquakes. (2) Evaluation of the effectiveness of IFAS designs for different design parameters through earthquake simulations of two-dimensional (2D) nonlinear numerical models of an evaluation structure. The models are based on a IFAS prototype developed by a fellow researcher on the project at Lehigh University. (3) Development and calibration of three-dimensional nonlinear numerical models of the shake table test specimen used in the experimental research. This model was used for predicting and designing the shake table testing program. (4) Analytical parameter studies of the calibrated shake table test model. These studies include: relating the shake table test performance to the previous evaluation structure analytical response, performing extended parametric analyses, and investigating and explaining certain unexpected shake table test responses. This dissertation describes the concept and scope of the analytical research, the analytical results, the conclusions, and suggests future work. The conclusions include analytical results that verify the IFAS effectiveness, show the potential of the IFAS in reducing building seismic demands, and provide an optimum design space of the IFAS.

Joint probability methods for assessing storm surge flood risk involve the use of a collection of hydrodynamic storm simulations to fit a response surface model describing the functional relationship between storm surge and storm parameters like central pressure deficit and the radius of maximum wind speed. However, in areas with a sufficiently low probability of flooding, few storms in the simulated storm suite may produce surge, with most storms leaving the location dry with zero flooding. Analysts could treat these zero-depth, “non-wetting” storms as either truncated or censored data. If non-wetting storms are excluded from the training set used to fit the storm surge response surface, the resulting suite of wetting storms may have too few observations to produce a good fit; in the worst case, the model may no longer be identifiable. If non-wetting storms are censored using a constant value, this could skew the response surface fit. The problem is that non-wetting storms are indistinguishable, but some storms may have been closer to wetting than others for a given location. To address these issues, this thesis proposes the concept of a negative surge, or “pseudo-surge”, value with the intent to describe how close a storm came to causing surge at a location. Optimal pseudo-surge values are determined by their ability to improve the predictive performance of the response surface via minimization of a modified least squares error function. We compare flood depth exceedance estimates generated with and without pseudo-surge to determine the value of perfect information. Though not uniformly reducing flood depth exceedance estimate bias, pseudo-surge values do make improvements for some regions where <40% of simulated storms produced wetting. Furthermore, pseudo-surge values show potential to replace a post-processing heuristic implemented in the state-of-the-art response surface methodology that corrects flood depth exceedance estimates for locations where very few storms cause wetting.

A fragility function quantifies the probability that a structural system reaches an undesirable limit state, conditioned on the occurrence of a hazard of prescribed intensity level. Multiple sources of uncertainty are present when estimating fragility functions, e.g., record-to-record variation, uncertain material and geometric properties, model assumptions, adopted methodologies, and scarce data to characterize the hazard. Advances in the last decades have provided considerable research about parameter selection, hazard characteristics and multiple methodology for the computation of these functions. However, there is no clear path on the type of methodologies and data to ensure that accurate fragility functions can be computed in an efficient manner. Fragility functions are influenced by the selection of a methodology and the data to be analyzed. Each selection may lead to different levels of accuracy, due to either increased potential for bias or the rate of convergence of the fragility functions as more data is used. To overcome this difficulty, it is necessary to evaluate the level of agreement between different statistical models and the available data as well as to exploit the information provided by each piece of available data. By doing this, it is possible to accomplish more accurate fragility functions with less uncertainty while enabling faster and widespread analysis. In this dissertation, two methodologies are developed to address the aforementioned challenges. The first methodology provides a way to quantify uncertainty and perform statistical model selection to compute seismic fragility functions. This outcome is achieved by implementing a hierarchical Bayesian inference framework in conjunction with a sequential Monte Carlo technique. Using a finite amount of simulations, the stochastic map between the hazard level and the structural response is constructed using Bayesian inference. The Bayesian approach allows for the quantification of the epistemic uncertainty induced by the limited number of simulations. The most probable model is then selected using Bayesian model selection and validated through multiple metrics such as the Kolmogorov-Smirnov test. The subsequent methodology proposes a sequential selection strategy to choose the earthquake with characteristics that yield the largest reduction in uncertainty. Sequentially, the quantification of uncertainty is exploited to consecutively select the ground motion simulations that expedite learning and provides unbiased fragility functions with fewer simulations. Lastly, some examples of practices during the computation of fragility functions that results i n undesirable bias in the results are discussed. The methodologies are implemented on a widely studied twenty-story steel nonlinear benchmark building model and employ a set of realistic synthetic ground motions obtained from earthquake scenarios in California. Further analysis of this case study demonstrates the superior performance when using a lognormal probability distribution compared to other models considered. It is concluded by demonstrating that the methodologies developed in this dissertation can yield lower levels of uncertainty than traditional sampling techniques using the same number of simulations. The methodologies developed in this dissertation enable reliable and efficient structural assessment, by means of fragility functions, for civil infrastructure, especially for time-critical applications such as post-disaster evaluation. Additionally, this research empowers implementation by being transferable, facilitating such analysis at community level and for other critical infrastructure systems (e.g., transportation, communication, energy, water, security) and their interdependencies.

<div>Ensuring the resilience of a state’s transportation network is necessary to guarantee an acceptable quality of life for the people the network serves. A lack of resilience in the wake of a seismic event directly impacts the states’ overall safety and economic vitality. With the recent identification of the Wabash Valley Seismic Zone (WBSV), Department of Transportations (DOTs) like Indiana’s have increased awareness for the vulnerability of their bridge network. The Indiana Department of Transportation (INDOT) has been steadily working to reduce the seismic vulnerability of bridges in the state in particular in the southwest Vincennes District. In the corridor formed by I-69 built in the early 2000s the bridge design is required to consider seismic actions. However, with less recent bridges and those outside the Vincennes District being built without consideration for seismic effects, the potential for vulnerability exists. As such, the objective of this thesis is to develop a robust seismic vulnerability assessment methodology which can assess the overall vulnerability of Indiana’s critical bridge network. </div><div><br></div><div>A representative sample of structures in Indiana’s bridge inventory, which prioritized the higher seismic risk areas, covered the entire state geographically, and ensured robust superstructure details, was chosen. The sample was used to carry a deterministic seismic vulnerability assessment, applicable to all superstructure-substructure combinations. Analysis considerations, such as the calculation of critical capacity measures like moment-curvature and a pushover analysis, are leveraged to accurately account for non-linear effects like force redistribution. This effect is a result of non-simultaneous structural softening in multi-span bridges that maintain piers of varying heights and stiffnesses. These analysis components are incorporated into a dynamic analysis to allow for the more precise identification of vulnerable details in Indiana’s bridge inventory.</div><div><br></div><div>The results of this deterministic seismic assessment procedure are also leveraged to identify trends in the structural response of the sample set. These trends are used to identify limit state thresholds for the development of fragility functions. This conditional probabilistic representation of bridge damage is coupled with the probability of earthquake occurrence to predict the performance of the structure for a given return period. This probabilistic approach alongside a Monte Carlo simulation is applied to assess the vulnerability of linked bridges along key-access corridors throughout the state. With this robust seismic vulnerability methodology, DOTs will have the capability of identifying vulnerable corridors throughout the state allowing for the proactive prioritization of retrofits resulting in the improved seismic performance and resiliency of their transportation network.</div>

This study focuses on non-ductile reinforced concrete (RC) frames built outside current practices. These structures are quite vulnerable to collapse during earthquakes. One option to retrofit buildings with poorly detailed RC columns is to construct full-height masonry infill walls to provide additional means to resist loads caused by gravity and increase lateral stiffness resulting in a reduction in drift demand. On the other hand, infill can cause reductions in drift capacity that offset the benefits of reductions in drift demand. Given these two opposing effects, this investigation addresses the following question: are poorly detailed RC frames with masonry infill walls any safer than similar RC frames without infill walls?

Seismically-induced liquefaction has been the cause of significant damage to infrastructure and is a serious concern in current civil engineering practice. Several methods are available for assessing the risk of liquefaction at a given site, each with its own strengths and limitations. One probabilistic method has been shown to provide more consistent estimates of liquefaction risk and can be tailored to the specific needs of a given project through hazard-targeted (i.e. based on return periods or likelihoods) results. This type of liquefaction assessment is typically called “performance-based,” after the Pacific Earthquake Engineering Research (PEER) Center's performance-based earthquake engineering framework. Unfortunately, performance-based liquefaction assessment is not easily performed and can be difficult for practicing engineers to use on routine projects. Previous research has shown that performance-based methods of liquefaction assessment can be simplified into an approximation procedure. This simplification has successfully been completed for the Cetin et al. (2004) empirical, probabilistic standard penetration test -based liquefaction triggering model. Until now, such a simplification has not been performed for another popular liquefaction triggering model developed by Boulanger and Idriss (2012). As some engineers either wish to use or are required to use the Boulanger and Idriss (2012) model in their liquefaction assessments, there is a need for a simplified performance-based method based on this model to supplement that based on the Cetin et al. (2004) model. This thesis provides the derivation of a simplified performance-based procedure for the assessment of liquefaction triggering using the Boulanger and Idriss (2012) model. A validation study is performed in which 10 cities across the United States are analyzed using both the simplified procedure and the full performance-based procedure. A comparison of the results from these two analyses shows that the simplified procedure provides a reasonable approximation of the full performance-based procedure. This thesis also describes the development of liquefaction loading maps for six states and a spreadsheet that performs the necessary correction calculations for the simplified method.

This research consists of full-scale shake table tests to investigate liquefaction of sandy soils. Consideration of the potential and consequences of liquefaction is critical to the performance of any structure built in locations of high seismicity underlain by saturated granular materials as it is the leading cause of damage associated with ground failure. In certain cases the financial losses associated with liquefaction can significantly impact the financial future of an entire region. Most liquefaction triggering studies are performed in the field where liquefaction has been previously observed, or in tabletop laboratory testing. The study detailed herein is a controlled laboratory test performed at full scale to allow for the measurement of field-scale index testing before and after cyclic loading. Testing was performed at the Parson’s geotechnical and Earthquake Laboratory at Cal Poly San Luis Obispo on the 1-dimensional shake table with a mounted flexible walled testing apparatus. The testing apparatus, originally constructed for soil-structure interaction experiments utilizing soft clay was retrofitted for the purpose of studying liquefaction. This research works towards comparing large-scale simple-shear liquefaction testing to small-scale simple-shear liquefaction testing of a #2/16 Monterey sand specimen. The bucket top was modified in order to apply a vertical load to the soil skeleton to replicate overburden soil conditions. Access ports were fitted into the bucket top for instrument cable access and to allow cone penetration testing before and after cyclic loading. A shear-wave generator was created to propagate shear waves into the sample for embedded accelerometers to measure small strain stiffness of the sample. Pore-pressure transducers were embedded in the soil sample to capture excess pore water pressure produced during liquefaction. Displacement transducers were attached to the bucket in order to measure shear strains during cyclic testing and to measure post-liquefaction volumetric deformations. The results of this investigation provide an empirical basis to the behavior of excess pore water production, void re-distribution, shear wave velocity, shear strain and cone penetrometer tip resistance of #2/16 Monterey sand before, during, and after liquefaction in a controlled laboratory environment at full-scale.

This dissertation discusses the potential for using a conventional main lateral-force resisting system, combined with the reserve strength in the gravity framing, and or auxiliary collapse-inhibiting mechanisms deployed throughout the building, or enhanced shear tab connections, to provide adequate serviceability performance and collapse safety for seismic and wind hazards in the central and eastern United States. While the proposed concept is likely applicable to building structures of all materials, the focus of this study is on structural steel-frame buildings using either non-ductile moment frames with fully-restrained flange welded connections not specifically detailed for seismic resistance, or ductile moment frames with reduced beam section connections designed for moderate seismic demands. The research shows that collapse prevention systems were effective at reducing the conditional probability of seismic collapse during Maximum Considered Earthquake (MCE) level ground motions, and at lowering the seismic and wind collapse risk of a building with moment frames not specifically detailed for seismic resistance. Reserve lateral strength in gravity framing, including the shear tab connections was a significant factor. The pattern of collapse prevention component failure depended on the type of loading, archetype building, and type of collapse prevention system, but most story collapse mechanisms formed in the lower stories of the building. Collapse prevention devices usually did not change the story failure mechanism of the building. Collapse prevention systems with energy dissipation devices contributed to a significant reduction in both repair cost and downtime. Resilience contour plots showed that reserve lateral strength in the gravity framing was effective at reducing recovery time, but less effective at reducing the associated economic losses. A conventional lateral force resisting system or a collapse prevention system with a highly ductile moment frame would be required for regions of higher seismicity or exposed to high hurricane wind speeds, but buildings with collapse prevention systems were adequate for many regions in the central and eastern United States. / Ph. D.

Millions of lives have been lost over the years as a result of the effects of earthquakes. One of these devastating effects is slope failure, more commonly known as landslide. Over the years, seismologists and engineers have teamed up to better record data during an earthquake. As technology has advanced, the data obtained have become more refined, allowing engineers to use the data in their efforts to estimate earthquakes where they have not yet occurred. Several methods have been proposed over time to utilize the earthquake data and estimate slope displacements. A pioneer in the development of methods to estimate slope displacements, Nathan Newmark, proposed what is now called the Newmark sliding block method. This method explained in very simple ways how a mass, in this case a rigid block, would slide over an incline given that the acceleration of the block surpassed the frictional resistance created between the bottom of the block and the surface of the incline. Because many of the assumptions from this method were criticized by scientists over time, modified Newmark sliding block methods were proposed. As the original and modified Newmark sliding block methods were introduced, the need to account for the uncertainty in the way soil would behave under earthquake loading became a big challenge. Deterministic and probabilistic methods have been used to incorporate parameters that would account for some of the uncertainty in the analysis. In an attempt to use a probabilistic approach in understanding how slopes might fail, the Pacific Earthquake Engineering Research Center proposed a performance-based earthquake engineering framework that would allow decision-makers to use probabilistically generated information to make decisions based on acceptable risk. Previous researchers applied this framework to simplified Newmark sliding block models, but the approach is difficult for engineers to implement in practice because of the numerous probability calculations that are required. The work presented in this thesis provides a solution to the implementation of the performance-based approach by providing a simplified procedure for the performance-based determination of seismic slope displacements using the Rathje & Saygili (2009) and the Bray and Travasarou (2007) simplified Newmark sliding block models. This document also includes hazard parameter maps, which are an important part of the simplified procedure, for five states in the United States. A validation of the method is provided, as well as a comparison of the simplified method against other commonly used approaches such as deterministic and pseudo-probabilistic.