Broadband physics-based simulated earthquake ground motions are utilized to characterize the regional-scale seismic risk to modern reinforced concrete (RC) structures. A highly dense dataset of ground motions covering a 100-km × 40km domain was generated using kinematic fault rupture models with varying rupture characteristics to represent shallow crustal earthquakes and resolved up to frequencies of 5 Hz. Over 40,000 nonlinear response history simulations of short-and mid-rise RC special moment frame buildings were conducted using simulation models that are capable of representing nonlinear behavior and component deterioration effects. The spatial variability of structural risk within a sin-
K E Y W O R D Sforward directivity, ground motion simulations, regional-scale risk, reinforced concrete, shallow basin
INTRODUCTION AND BACKGROUNDCharacterizing the complex variability of risk to engineered structures near active earthquake faults is a challenging problem hindered by the sparsity of observed earthquake ground motion data in the near-source region. Ground motions
Fiber-based elements are commonly used to simulate steel beam-columns, due to their ability to capture P-M interactions and spread-of-plasticity. However, when mechanisms such as local buckling result in effective softening at the fiber-scale, conventional fiber models exhibit mesh dependence. To address this, a two-dimensional nonlocal fiber-based beam-column model is developed and implemented numerically. The model focuses on hot-rolled wide flange (W-) sections that exhibit local buckling-induced softening when subjected to combinations of axial compression and flexure. The formulation up-scales a previously developed nonlocal formulation for "single-fiber" buckling to the full frame element. The formulation incorporates a physical length scale associated with local buckling, along with an effective softening constitutive relationship at the fiber level. To support these aspects of the model, 43 Continuum Finite Element (CFE) test-problems are constructed. These test-problems examine a range of parameters including the axial load, cross-section, and moment gradient. The implemented formulation is validated against CFE models as well as physical steel beam-column experiments that exhibit local bucklinginduced softening. The formulation successfully predicts post-peak response for these validation cases in a mesh-independent manner, while also capturing the effects of P-M interactions and moment gradient. To enable convenient generalization, guidelines for calibration and selection of the model parameters are provided. Limitations are discussed along with areas for future development.
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