The Total Costs of Seismic Retrofits: State of the Art.

This article presents the current state-of-practice with respect to quantifying the total cost to retrofit an existing building. In particular, we combine quantitative, qualitative, and heuristic data to provide a taxonomy for understanding the direct and indirect costs associated with seismic risk mitigation. Much of the literature to date has focused on estimating structural retrofit costs, the costs of retrofitting the structural elements of a building. In contrast, there is very little research or data on the remaining cost components of the total cost. We propose using structural cost as the foundation for approximating the remaining cost components and the total cost itself. To validate our findings, we compare the proposed approximations with actual cost estimates developed by engineering professionals.

A Predictive Modeling Approach to Estimating Seismic Retrofit Costs.

This paper presents a methodology for estimating seismic retrofit costs from historical data. In particular, historical retrofit cost data from FEMA 156 is used to build a generalized linear model (GLM) to predict retrofit costs as a function of building characteristics. While not as accurate as an engineering professional's estimate, this methodology is easy to apply to generate quick estimates and is especially useful for decision makers with large building portfolios. Moreover, the predictive modeling approach provides a measure of uncertainty in terms of prediction error. The paper uses prediction error to compare different modeling choices, including the choice of distribution for costs. Finally, the proposed retrofit cost model is implemented to estimate the cost to retrofit a portfolio of federal buildings. The application illustrates how the choice of distribution affects cost estimates.

Social and Economic Components of Resilient Multi-Hazard Building Design.

In 2017, U.S. damages from natural hazard events exceeded $300B, suggesting that current targets for building performance do not sufficiently mitigate loss. The significant costs borne by individuals, insurers, and government do not include impacts from social disruption, displacement, and subsequent economic and livelihood effects. In 2016, Congress mandated the National Institute of Standards and Technology (NIST) develop a report (NIST SP 1224) describing the research needs, implementation activities, and engineering principles necessary to improve the performance of residential and commercial buildings subjected to natural hazards. An Immediate Occupancy Performance Objective (IOPO) could help preserve building and social functions post event, minimizing physical, social, and economic disaster. The stakeholder-informed NIST report sets forth items needed for multi-hazard building design that can support enhanced resilience decision-making. This paper highlights the social and economic considerations that require additional research, particularly with regard to feasibility and potential impacts from an IOPO. These topics must be considered prior to and throughout the IOPO technical development and community implementation processes to ensure better outcomes after natural hazard events.

Increasing Community Resilience Through Improved Lifeline Infrastructure Performance.

The concept of community resilience is complex and multidimensional, relying on engineering and other disciplines to help communities break the cycle of destruction and recovery and reduce the impacts of earthquakes and other hazards. This article presents proposed prioritized actions to improve lifeline infrastructure resilience based on an assessment of lifeline infrastructure performance commissioned and funded by the National Institute of Standards and Technology (NIST).

A accurate means to assess coupled lateral torsional motion of single story structures in the Central and Eastern U.S

An analytical procedure is developed that in part enables design engineers utilizing code planar force methods to acuurately acount for the additional lateral response for torsion in irregular structures subjected to seismic motion. Furthermore, a dynamic factor is devepoled which modifies the lateral displacements obtained from the code planar force methods to predict the earthquake demands for any seismic zone without requiring a 3 - dimensional dynamic analysis. Hence, the design seismic displacements above. The accuracy of the procedure is verified through example problems (AU)

The need for ductility limits in the development of design criteria

The developemnt of design criteri for typical structures must address the behavior of these systems under seismic excitation. The approach typically used in building codes is to apply some form of reduction factor to the seismic forces directly, or to the design spectrum. This reduction factor is related to, but should not necessaryly be considered equal to the classic ductility factor, it encompasses many factors (AU)