This thesis develops and explores two methodologies to assess earthquake ground shaking in southwestern British Columbia based on 1D soil layering and 3D basin structure. To assess site response based on soil layering, microtremor array measurements were conducted at two sites of contrasting geology to estimate Rayleigh-wave dispersion curves. A Bayesian inversion algorithm is developed to invert the dispersion data for the shear-wave velocity (VS) profile together with quantitative uncertainty estimates, accounting rigorously for data error covariance and model parameterization selection. The recovered VS profiles are assessed for reliability by comparison with invasive VS measurements at each site with excellent agreement. Probabilistic site response analysis is conducted based on a sample of VS profiles drawn from the posterior probability density of the microtremor inversion. The quantitative uncertainty analysis shows that the rapid and inexpensive microtremor array method provides sufficient resolution of soil layering for practical characterization of earthquake ground motion. To assess the effects of 3D Georgia basin structure on long-period (> 2 s) ground motion for large scenario earthquakes, numerical 3D finite difference modelling of viscoelastic wave propagation is applied. Both deep (> 40 km) subducting Juan de Fuca plate and crustal (5 km) North America plate earthquakes are simulated in locations congruent with known seismicity. Simulations are calibrated by comparing synthetic waveforms with 36 selected strong- and weak-motion seismograms of the 2001 MW 6.8 Nisqually earthquake. The ratio between predicted peak ground motions in models with and without Georgia basin sediments is applied as a quantitative measure of basin amplification. Steep edges in the upper 1 km of the northwest and southeast extents of the basin are coincident with the appearance of surface waves. Focussing of north-to-northeast propagating surface waves by shallow (< 1 km) basin structure increases ground motion in a localized region of southern Greater Vancouver. This effect occurs for both types of earthquakes located south-southwest of Vancouver at distances greater than ~80 km. The predicted shaking level is increased up to 17 times and the duration of moderate shaking (> 3.4 cm/s) is up to 16 times longer due to the 3D Georgia basin structure. / Graduate

<div>Observations from experiments and post-earthquake surveys have shown that drift is the key parameter for identifying potential damage of a structure during ground motions (Sozen, 1981). These observations suggest that drift should govern seismic design and evaluation of structures.</div><div><br></div><div>In this study, three methods for estimating drift demands were considered: 1) the method proposed by Sozen (2003) referred to in this study as Velocity of Displacement (VOD), 2) the Coefficient Method and 3) Nonlinear Dynamic Analysis (NDA). The reliability of each method was evaluated by comparing estimates of roof and maximum story drift ratios with measurements from 46 reinforced concrete structures with initial periods shorter than 3 seconds.</div><div><br></div><div>Measurements from long-period structures (with periods longer than 3 seconds) were not available. To produce data to evaluate the reliability of the three mentioned methods for</div><div>long-period structures as well as understand the displacement and base-shear response of such structures, seven scaled Multi-Degree-of-Freedom (MDOF) specimens with an initial period of approximately 1.2 seconds were tested with five scaled base motions of varying intensities. Each motion was scaled in time such that its scaled spectral shape near the initial period of the specimen was similar to the spectral shape of the unscaled motions for periods ranging from approximately 1 to 10 seconds. A total of 118 tests were conducted.</div><div><br></div><div>The effect of loading history on drift demands and drift estimates was also evaluated by quantifying changes in drift demands of structures subjected to repeats of the same ground motion. Data from 1) experimental tests of structures subjected to repeated ground motions, and 2) numerical analyses of Single-Degree-of-Freedom (SDOF) oscillators subjected to multiple sequences of ground motions of varying intensities were used.</div><div><br></div><div><div>Based on comparisons of measured and calculated drifts as well as data from the experimental program, the following observations were made:</div></div><div><br></div><div>1) For structures with periods shorter than 3 seconds, all three methods for estimating drift demands produced estimates of both roof and maximum story drifts of similar</div><div>quality despite large differences in the effort required to use each method.</div><div><br></div><div>2) For structures with periods longer than 3 seconds, NDA produced drift estimates close to the mean of measured values while VOD overestimated measured values, on average, by approximately 30%. The Coefficient Method produced estimates that were, on average, smaller than measurements by approximately 40%.</div><div><br></div><div>3) For structures (not susceptible to decay in lateral strength) subjected to sequences of ground motions of similar intensities, the relative increase in drift demands was,</div><div>on average, no more than 20%. Larger increases in drift demands were observed for structures where the first motion (in a pair of repeated motions) was mild enough</div><div>not to cause cracking and/or yielding, and the second motion was preceded by larger intensity motions that did cause cracking and/or yielding.</div><div><br></div><div>4) For test structures with periods longer than 3 seconds, drifts in the nonlinear range of response were generally smaller than linear estimates, and maximum base-shear</div><div>demands were as much as three times those calculated assuming a linear lateral load distribution.</div>

<p>Masonry infills historically have increased in-plane stiffness and reduced drift demands of reinforced concrete frames. An inherent risk remains during intense ground motions that unreinforced masonry infills can develop shear cracks, fail out-of-plane, or lead to the formation of captive-column conditions. This study explored the use of full-bay, plywood panel infills in non-ductile reinforced concrete frames as a novel seismic retrofit. Wood infills were constructed from layers of APA 3/4” Rated Sheathing plywood panels. Infills were tested using two single-bay, single-story concrete frames at 1/3 scale, with initial periods between 0.1 and 0.3 seconds once infilled. External post-tensioning was provided to the columns during all series to prevent column shear failure and doubled as dowel connections between the concrete frame and wood panel infill. Test series were performed on a uniaxial earthquake simulator with the frame bay parallel to the direction of ground motion. Wood infills were approximately 0.36∗𝑏, 0.18∗𝑏, and 0.09∗𝑏 thick, where b is the column width. Multi-layer infills were screw-laminated via a 6” square grid. Infills were tested in previously damaged and nominally pristine frames.</p> <p>During similar ground motions, masonry infills reduced the effective period of the pristine bare frame by approximately 50%. In nominally pristine frames, one-panel plywood infills reduced the bare frame period by a maximum of 50%, and two-panel infills by 60%. One and two-panel wood infills reduced drift demands in comparison to the pristine bare frame by a factor of 1√2∗𝑛 in previously damaged frames and by 12∗𝑛 in nominally pristine frame, where n is the number of panels of plywood across the infill thickness. There was no extra reduction in drift demands resulting from increasing the wood infill thickness beyond two panels. One-panel wood infills failed via out-of-plane buckling causing splitting at a drift demand of approximately 1.5%.</p> <p>The results of this study confirm that wood panel infill retrofits are structurally viable alternatives to stiffen non-ductile reinforced concrete frames. Plywood panel infills reduced drift demands more efficiently per unit thickness and unit weight than masonry infills; the resilience and ease of construction of wood infills suggest expanded use should be explored. Experimental study of full-scale wood infills is needed before this retrofit method could become field deployable.</p>

Fires following earthquake (FFE) have historically produced enormous post-earthquake damage and losses in terms of lives, buildings and economic costs, like the San Francisco earthquake (1906), the Kobe earthquake (1995), the Turkey earthquake (2011), the Tohoku earthquake (2011) and the Christchurch earthquakes (2011). The structural fire performance can worsen significantly because the fire acts on a structure damaged by the seismic event. On these premises, the purpose of this work is the investigation of the experimental and numerical response of structural and non-structural components of steel structures subjected to fire following earthquake (FFE) to increase the knowledge and provide a robust framework for hybrid fire testing and hybrid fire following earthquake testing. A partitioned algorithm to test a real case study with substructuring techniques was developed. The framework is developed in MATLAB and it is also based on the implementation of nonlinear finite elements to model the effects of earthquake forces and post-earthquake effects such as fire and thermal loads on structures. These elements should be able to capture geometrical and mechanical non-linearities to deal with large displacements. Two numerical validation procedures of the partitioned algorithm simulating two virtual hybrid fire testing and one virtual hybrid seismic testing were carried out. Two sets of experimental tests in two different laboratories were performed to provide valuable data for the calibration and comparison of numerical finite element case studies reproducing the conditions used in the tests. Another goal of this thesis is to develop a fire following earthquake numerical framework based on a modified version of the OpenSees software and several scripts developed in MATLAB to perform probabilistic analyses of structures subjected to FFE. A new material class, namely SteelFFEThermal, was implemented to simulate the steel behaviour subjected to FFE events.