OasisLMS

Abstract: Seismic evaluations of structures are more frequently being performed in Los Angeles and other jurisdictions in California due to seismic retrofit ordinances and the desire of building owners to limit losses in the event of major earthquakes. The most common guideline used for evaluation of seismic performance of existing buildings is the ASCE 41 standard. There are uncertainties associated with evaluation of existing foundations, and uncertainties of soil properties are evaluated using the coefficient of variation of properties to develop best estimate, lower bound, and upper bound values of strength and stiffness. Available geotechnical data at an example site is used to perform a probabilistic evaluation of the soil properties; determination of strength and stiffness parameters require an understanding of the uncertainty of empirical relations and the dataset of soil properties. A Monte Carlo simulation is conducted to evaluate the likelihood of possible strength and stiffness parameters. Therefore, the soil bearing capacity, lateral capacity, and seismic lateral earth pressure can be examined in a probabilistic manner, consistent with the methodology of ASCE 41. The evaluation can also be performed using analytical solutions via convolution of distributions for linear combinations and approximated using numerical integration where analytical convolution is intractable; we derive these solutions as well and validate the Monte Carlo simulations with the results. A comprehensive probabilistic evaluation provides the basis for a complete understanding of variability of the behavior of a structure.

Dr. MARTIN B. HUDSON; Dr. Kenneth Stewart Hudson

Annual Conference Proceedings