Concrete-filled buckling restrained braces (BRBs) was first developed in 1988 in Tokyo, Japan, to prevent the steel plates in the core portion from buckling, leading the steel core to exhibiting a more stable and fully hysteretic loop than conventional steel braces. However, past studies have shown that buckling restrained braced frames (BRBFs) have a large residual deformation after a median or high seismic event due to steel’s residual strain. In order to address this issue, innovative self-centering SMA braces are proposed and installed in the originally unbraced bays in existing BRBFs to become a hybrid frame system where the existing steel BRBs dissipate energy induced by external forces and the newly added self-centering SMA braces restore the building configuration after the steel BRBs yield. A case study of conventional three-story BRBF retrofitted by the proposed self-centering SMA braces is carried out to develop systematic retrofit strategies, to investigate the structural behavior, and to probabilistically assess their seismic performance in terms of interstory drifts, residual drifts, and brace deformation, as compared to the original steel BRB frames. Finally, the developed brace component fragility curves and system fragility curves will be further used for the assessment of downtime and repair cost.

Modular construction is a relatively new technique where prefabricated units are assembled on-site to produce a complete building. Due to detailing requirements for the assembly of the modules, these systems are prone to undesirable failure mechanisms during large earthquakes. Specifically, for multi-story Modular Steel Buildings (MSBs), inelasticity concentration in vertical connections can be an area of concern. Diaphragm interaction, relative displacements between modules and the forces in the horizontal connections need to be investigated. In this study, two 4-story MSBs with two different structural configurations were chosen to be analyzed. In the first model which was introduced in a study by Annan et al. (2009 a), some of the unrealistic detailing assumptions were challenged. To have a more accurate assessment of the structural capacity, in the second model, a more realistic MSB model was proposed. Using OpenSees, Incremental Dynamic Analyses (IDA) have been performed and conclusions were made.

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Modular construction is a relatively new technique where prefabricated units are assembled on-site to produce a complete building. Due to detailing requirements for the assembly of the modules, these systems are prone to undesirable failure mechanisms during large earthquakes. Specifically, for multi-story Modular Steel Buildings (MSBs), inelasticity concentration in vertical connections can be an area of concern. Diaphragm interaction, relative displacements between modules and the forces in the horizontal connections need to be investigated. In this study, two 4-story MSBs with two different structural configurations were chosen to be analyzed. In the first model which was introduced in a study by Annan et al. (2009 a), some of the unrealistic detailing assumptions were challenged. To have a more accurate assessment of the structural capacity, in the second model, a more realistic MSB model was proposed. Using OpenSees, Incremental Dynamic Analyses (IDA) have been performed and conclusions were made.

During 2010 and 2011, a series of major earthquakes caused widespread damage in the city of Christchurch, New Zealand. The magnitude 6.3 quake in February 2011 caused 185 fatalities. In the ensuing months, the government progressively zoned residential land in Christchurch on the basis of its suitability for future occupation (considering damage from these quakes and future earthquake risk). Over 6,000 homes were placed in the ‘red-zone’, meaning that property owners were forced to sell their land to the Crown. This study analysed patterns of residential mobility amongst thirty-one red-zone households from the suburb of Southshore, Christchurch. Drawing on interviews and surveys, the research traced their experience from the zoning announcement until they had moved to a new residence. The research distinguished between short (before the zoning announcement) and long term (post the red zone ‘deadline’) forms of household relocation. The majority of households in the study were highly resistant to short term movement. Amongst those which did relocate before the zoning decision, the desire to maintain a valued social connection with a person outside of the earthquake environment was often an important factor. Some households also moved out of perceived necessity (e.g. due to lack of power or water). In terms of long-term relocation, concepts of affordability and safety were much more highly valued by the sample when purchasing post-quake property. This resulted in a distinct patterning of post-quake housing location choices. Perceived control over the moving process, relationship with government organisations and insurance companies, and time spent in the red-zone before moving all heavily influenced participants’ disaster experience. Contrary to previous studies, households in this study recorded higher levels of subjective well-being after relocating. The study proposed a typology of movers in the Christchurch post-disaster environment. Four mobility behaviours, or types, are identified: the Committed Stayers (CSs), the Environment Re-Creators (ERCs), the Resigned Acceptors (RAs), and the Opportunistic Movers (OMs). The CSs were defined by their immobility rather than their relocation aspirations, whilst the ERCs attempted to recreate or retain aspects of Southshore through their mobility. The RAs expressed a form of apathy towards the post-quake environment, whereas, on the other hand, the OMs moved relative to pre-earthquake plans, or opportunities that arose from the earthquake itself. Possibilities for further research include examining household adaptability to new residential environments and tracking further mobility patterns in the years following relocation from the red- zone.

The Alpine Fault is a major plate boundary structure, which accommodates up to 50-80% of the total plate boundary motion across the South Island of New Zealand. The fault has not ruptured historically although limited off-fault shaking records and on-fault dating suggest large to great (~ Mw 8) earthquakes (every ~100-480 years; most recently in 1717), making it potentially one of the largest onshore sources of seismic hazard in New Zealand. The central section of the Alpine Fault, which bounds the highest elevations in the Southern Alps, is one of the most poorly characterised sections along the fault. On-fault earthquake timing in addition to the amount of dextral slip during major earthquakes was unknown along a 200-km-long section of the central Alpine Fault, while the amount of co-seismic hanging wall uplift was poorly known, prior to the present work. In this thesis I address these knowledge gaps through a combination of light detection and ranging (lidar), field, and stratigraphic mapping along with sample dating to constrain earthquake timing, style of faulting, and hanging wall rock uplift rates. Using lidar data coupled with field mapping I delineated the main trace of the Alpine Fault at Gaunt Creek as a north-striking fault scarp that was excavated and logged; this is part of a 2-km-wide restraining bend dominated by low-angle thrust faulting and without the clear strike-slip displacements that are present nearby (<5 km distant along strike in both directions). Where exposed in this scarp, the fault-zone is characterized by a distinct 5-50 cm thick clay fault-gouge layer juxtaposing hanging wall bedrock (mylonites and cataclasites) over unconsolidated late-Holocene footwall colluvium. An unfaulted peat at the base of the scarp is buried by post-most recent event (MRE) alluvium and yields a radiocarbon age of A.D. 1710–1930, consistent with sparse on-fault data, validating earlier off-fault records that suggest a 1717 MRE with a moment magnitude of Mw 8.1 ± 0.1, based on the 380-km-long surface rupture. Lidar and field mapping also enabled the identification and measurement of short (<30 m), previously unrecognized dextral offsets along the central section of the Alpine Fault. Single-event displacements of 7.5 ± 1 m for the 1717 earthquake and cumulative displacements of 12.9 ± 2 m and 22 ± 2.7 m for earlier ruptures can be binned into 7.1 ± 2.1 m increments of repeated dextral (uniform) slip along the central Alpine Fault. A comparison of these offsets with the local paleoseismic record and known plate kinematics suggests that the central Alpine Fault earthquakes in the past 1.1 ka may have: (i) bimodal character, with major surface ruptures (!Mw 7.9) every 270 ± 70 years (e.g. the 1717 event) and with moderate to large earthquakes (!Mw 7) occurring between these ruptures (e.g. the 1600 event); or (ii) that some shaking data may record earthquakes on other faults. If (i) is true, the uniform slip model (USM) perhaps best represents central Alpine Fault earthquake recurrence, and argues against the applicability of the characteristic earthquake model (CEM) there. Alternatively, if (ii) is true, perhaps the fault is “characteristic” and some shaking records proximal to plate boundary faults do not necessarily reflect plate-boundary surface ruptures. Paleoseismic and slip data suggest that (i) is the most plausible interpretation, which has implications for the understanding of major plate-boundary faults worldwide. Field mapping, geological characterisation, geophysical mapping, and optically stimulated luminescence (OSL) dating of on-fault hanging wall sediments were used to better constrain the geometry and kinematics of Holocene deformation along the rangefront of the Southern Alps at the Alpine Fault near the Whataroa River. The fault here is dextral-reverse, although primarily strike-slip with clear fault traces cutting across older surfaces of varying elevations. Deformational bulges are observed along these traces that are likely thrust-bounded. A terrace of Whataroa River sediments was found on the hanging wall of the Alpine Fault approximately ~ 55-75 m (when considering uncertainties) above the floodplain of the Whataroa River. OSL ages for a hanging wall sediments of 10.9 ± 1.0 ka for the aforementioned terrace, 2.8 ± 0.3 ka for Whataroa River terrace deposits in a deformational bulge, and 11.1 ± 1.2 ka for a rangefront derived fan indicate Holocene aggradation along the rangefront and hanging wall uplift rates of 6.0 ± 1.1 mm/yr. The sub-horizontal, laterally continuous, and planar-bedded Whataroa-sourced terrace deposits suggest that the adjacent bounding faults are steeply-dipping faults without geometries in the shallow subsurface that would tend to cause sedimentary bed rotation and tilting. Using data from the approximately 100-m deep pilot DFDP boreholes together with lidar and field mapping, I present a review of the Quaternary geology, geomorphology, and structure of the fault at Gaunt Creek, and estimate new minimum Late-Pleistocene hanging wall rock uplift rates of 5.7 ± 1.0 mm/yr to 6.3 ± 1.1 mm/yr (without considering local erosion) that suggest that the Southern Alps are in a dynamic steady state here. GPS-derived “interseismic” vertical uplift rates are < 1 mm/yr at the Alpine Fault, so the majority of rock uplift at the rangefront happens during episodic major earthquakes, confirming with on-fault data that slip occurs coseismically. Notably the uplift rates from both Mint and Gaunt Creek are consistent between the two sites although the primary style of faulting at the surface is different between the two sites, suggesting consistent coseisimc uplift of the Southern Alps rangefront along the Alpine Fault in major earthquakes. This thesis collected new on-fault datasets that confirm earlier inferences of plate-boundary fault behaviour. This study of the high-uplift central section of the Alpine Fault provides the first on-fault evidence for the MRE (i.e. 1717) and repeated of dextral slip during the MRE and previous events as well as new hanging wall uplift data which suggests that the majority of rangefront uplift occurs in earthquakes along the Alpine Fault. Because the fault has not ruptured for ~300 years, it poses a significant seismic hazard to southern New Zealand.

A field experiment was conducted at near Lake Coleridge in the Southern Alps of New Zealand, focusing on the kinematic response of bedrock-dominated mountain edifices to seismic shaking. The role of topographic amplification of seismic waves causing degradation and possible failure of rock masses was examined. To study site effects of topography on seismic ground motion in a field situation, a small, elongated, and bedrock-dominated mountain ridge (Little Red Hill) was chosen and equipped with a seismic array. In total seven EARSS instruments (Mark L-4-3D seismometers) were installed on the crest, the flank and the base of the 210 m high, 500 m wide, and 800 m long mountain edifice from February to July 2006. Seismic records of local and regional earthquakes, as well as seismic signals generated by an explosive source nearby, were recorded and are used to provide information on the modes of vibration as well as amplification and deamplification effects on different parts of the edifice. The ground motion records were analyzed using three different methods:comparisons of peak ground accelerations (PGA), power spectral density analysis (PSD), and standard spectral ratio analysis (SSR). Time and frequency domain analyses show that site amplification is concentrated along the elongated crest of the edifice where amplifications of up to 1100 % were measured relative to the motion at the flat base. Theoretical calculations and frequency analyses of field data indicate a maximum response along the ridge crest of Little Red Hill for frequencies of about 5 Hz, which correlate to wavelengths approximately equal to the half-width or height of the edifice (~240 m). The consequence of amplification effects on the stability and degradation of rock masses can be seen: areas showing high amplification effects overlap with the spatial distribution of seismogenic block fields at Little Red Hill. Additionally, a laboratory-scale (1:1,000) physical model was constructed to investigate the effect of topographic amplification of ground motion across a mountain edifice by simulating the situation of the Little Red Hill field experiment in a smallscale laboratory environment. The laboratory results show the maximum response of the model correlates to the fundamental mode of vibration of Little Red Hill at approximately 2.2 Hz. It is concluded that topography, geometry and distance to the seismic source, play a key role causing amplification effects of seismic ground motion and degradation of rock mass across bedrock-dominated mountain edifices.

Hollow-core flooring units are designed as simply supported members. However, frequently in construction, continuity is established between the units and supporting structure by the addition of insitu topping concrete and steel reinforcement. This change in structural form can result in negative bending moments and axial forces being induced in the floor by seismic and other structural actions. Significant negative moments are induced by load combinations that include the effects of seismic forces due to vertical ground motion. The focus of this research was two failure mechanisms possible under these loading conditions, a flexural failure and a shear failure. Both failure mechanisms were investigated analytically and experimentally. A brittle flexural failure was observed experimentally in a sub assembly test that contained starter bars and mesh reinforcement in the insitu topping concrete. The failure occurred at loads lower than those predicted using standard flexural theory. It appears that, due to the prestressing and low reinforcement ratio of the topping concrete, the assumption that plane sections remain plane is not appropriate for this situation. It is proposed that a strain concentration factor be introduced to account for the effects of tension stiffening. This factor improves the correlation between observed and predicted flexural strength. The second failure mode investigated was a flexure shear failure in a negative moment zone. Flexural cracks reduce the shear strength of a reinforced concrete member. Analytical predictions suggest that some hollow-core floor details could be prone to this type of brittle failure. A flexure shear failure was not observed experimentally; however, this does not eliminate the possibility of this failure mode. A summary of other failure mechanisms possible in hollow-core flooring is also presented. All failure modes should to be considered as part of establishing a hierarchy of failure in the design or retrofit of hollow-core floors.

In the central United States, undefined earthquake sources, long earthquake recurrence intervals and uncertain ground motion attenuation models have contributed to an overstatement of regional seismic hazard for the New Madrid Seismic Zone on the National Seismic Hazard Maps. This study examined concerns regarding scientific uncertainties, overly stringent seismic mitigation policies and depressed local economy in western Kentucky through a series of informal interviews with local businessmen, public officials, and other professionals in occupations associated with seismic mitigation. Scientific and relative economic analyses were then performed using scenario earthquake models developed with FEMA’s Hazus-MH software. Effects of the 2008 Wenchuan earthquake in central China and seismic mitigation policies in use there were considered for potential parallels and learning opportunities. Finally, suggestions for continued scientific research, additional educational opportunities for laymen and engineering professionals, and changes in the application of current earthquake science to public policy in the central United States were outlined with the goal of easing western Kentucky economic issues while maintaining acceptable public safety conditions.

This dissertation consists of two parts and investigates the crustal deformation associated with great subduction zone earthquake at two different spatial scales. At the small scale, I investigate the stress transfer along the megathrust during great earthquakes and its effects on the forearc wedge. At the large scale, I investigate the viscoelastic crustal deformation of the forearc and the back arc associated with great earthquakes. Part I: In a subduction zone, the frontal region of the forearc can be morphologically divided into the outer wedge and the inner wedge. The outer wedge which features much active plastic deformation has a surface slope angle generally larger than that of the inner wedge which hosts stable geological formations. The megathrust can be represented by a three-segment model, the updip zone (velocity-strengthening), seismogenic zone (velocity-weakening), and downdip zone (velocity-strengthening). Our dynamic Coulomb wedge theory postulates that the outer wedge overlies the updip zone, and the inner wedge overlies the seismogenic zone. During an earthquake, strengthening of the updip zone may result in compressive failure in the outer wedge. The inner wedge undergoes elastic deformation. I have examined the geometry and mechanical processes of outer wedges of twenty-three subduction zones. The surface slope of these wedges is generally too high to be explained by the classical critical taper theory but can be explained by the dynamic Coulomb wedge theory. Part II: A giant earthquake produces coseismic seaward motion of the upper plate and induces shear stresses in the upper mantle. After the earthquake, the fault is re-locked, causing the upper plate to move slowly landward. However, parts of the fault will undergo continuous aseismic afterslip for a short duration, causing areas surrounding the rupture zone to move seaward. At the same time, the viscoelastic relaxation of the earthquake-induced stresses in the upper mantle causes prolonged seaward motion of areas farther landward including the forearc and the back arc. The postseismic and interseismic crustal deformation depends on the interplay of these three primary processes. I have used three-dimensional viscoelastic finite element models to study the contemporary crustal deformation of three margins, Sumatra, Chile, and Cascadia, that are presently at different stages of their great earthquake cycles. Model results indicate that the earthquake cycle deformation of different margins is governed by a common physical process. The afterslip of the fault must be at work immediately after the earthquake. The model of the 2004 Sumatra earthquake constrains the characteristic time of the afterslip to be 1.25 yr. With the incorporation of the transient rheology, the model well explains the near-field and far-field postseismic deformation within a few years after the 2004 Sumatra event. The steady-state viscosity of the continental upper mantle is determined to be 10^19 Pa S, two orders of magnitude smaller than that of the global value obtained through global postglacial rebound models. / Graduate