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Although dynamic contributions from higher modes are known to influence the force demands in mass timber rocking walls, higher-mode force and acceleration demands have not been formally addressed in a design procedure incorporating limit states at multiple intensity levels. This study assessed the design and dynamic response of posttensioned (PT) mass ply panel (MPP) rocking walls with buckling-restrained boundary elements (BRBs), referred to as MPP-BRB walls. A design approach using multiple modes to estimate system-level dynamic demands was adopted for the design of MPP-BRB walls and assessed via shake-table testing of a full-scale, six-story, mass timber building at the National Hazards Engineering Research Infrastructure (NHERI) Large High-Performance Outdoor Shake Table (LHPOST6) at the University of California, San Diego (UCSD). To meet global and local performance criteria at service, design, and risk-targeted maximum considered earthquake ( ${\mathrm{MCE}}_{\mathrm{R}}$ ) seismic intensity levels, the test specimen was designed using a modal combination rule, which assumes the higher modes superimpose with a first mode governing the nonlinear response. The modal combination rule was validated through comparison of modal estimates for peak response derived using the test specimen’s modal properties identified in white-noise testing and measured story drift, story force, and floor acceleration demands. The testing program utilized ground motion records scaled to the ${\mathrm{MCE}}_{\mathrm{R}}$ design spectrum for a hypothetical Seattle site, where ground motions were chosen to demonstrate the potential for higher-mode effects in the rocking system. After 18 tests with ground motion intensities ranging from 10% MCE_Rto 110% MCE_R, the building exhibited negligible observable residual drifts. The MPP-BRB system behaved as intended, with the rocking wall enforcing a near-uniform distribution of story drift and the posttensioning enabling recentering. The design approach was able to represent the distribution and peak values of the experimentally observed responses, including posttensioning force stability, wall uplift, story drifts, floor accelerations, and force demands. 

Abstract Rapid restoration of access to essential goods and services has long been regarded as paramount for community recovery. Yet, there remains ambiguity in how access should be defined, measured, or operationalized. Defining accessibility as the ability to use available goods and services with a reasonable level of effort and cost requires evaluating it across six dimensions (proximity,availability,adequacy,acceptability,affordability, andawareness) while considering the perspective of both users and providers in the evaluation. But common distance-based metrics that focus solely on physical access and travel time often fall short of fully capturing these requirements, overlooking the user's perception. This paper introduces a new spatio-temporal accessibility metric that combines four out of these six dimensions, including proximity, acceptability, adequacy, and availability. The metric considers uncertainty in measuring each dimension and addresses both user and provider perspectives in measuring the acceptability and adequacy dimensions. The variation in the metric across the disaster timeline serves as a proxy for community recovery. The metric aligns with common engineering-oriented functionality-based resilience frameworks as the functionality level of the providers has been incorporated in its development. Operating at the household level, the metric determines the ratio of post-disruption access time to the intended good or service against its pre-disruption access time and yields a unitless ratio between zero and one, with zero expressing a total loss in accessibility and one signifying the same level of accessibility as pre-disruption. The proposed metric, while being scientifically principled, is a practical tool whose output is easily understood even by non-expert individuals. The metric is illustrated for schools and pharmacies using the Lumberton Testbed and data collected following the 2016 flood in Lumberton, North Carolina after Hurricane Matthew. Findings provide new insight into recovery plan prioritization and can be used to trigger protective actions. The paper concludes by discussing issues and barriers related to developing and validating accessibility metrics while highlighting areas for future research. 

Abstract The utilization of mass timber engineered wood products has increased for new buildings aiming to reduce environmental impacts. Whole-building life-cycle assessment (WBLCA) has been used to quantify the environmental impacts for a building’s lifespan. While mechanisms for calculating the cradle-to-grave impacts of a single building are well established, there are few examples of WBLCA applied for buildings in their first and second life that can be used to inform perspectives and pathways related to the circular economy and lead to informed decision making. This work presents a case study WBLCA to examine the effect of overlapping system boundaries and alternative end-of-life pathways for a building structure in its first and second life. This case study analyzed a ten-story mass timber shake-table specimen that was partially deconstructed and reused as a six-story shake-table building structure. Environmental impacts were analyzed in terms of global warming potential (GWP) calculated as the sum of fossil carbon, biogenic carbon, and avoided impacts. When examining reuse and landfill pathway alternatives using current standards and practices, results show that reusing material causes a positive GWP trend in the first system boundary and negative GWP trend in the second boundary. These results could indicate that it is not advantageous to reuse the ten-story building structure, running against principles of waste hierarchy, although the interpretation should be considered with caution. Future analyses could be improved by considering additional criteria such as demand on forest stocks, economic incentives, and even social impacts for a more complete representation of sustainability. 

Numerical analyses can aid design exploration, but there are several computational approaches available to consider design options. These range from “brute-force” search to optimization. However, the implementation of optimization can be challenging for the complex, time-intensive analyses required to assess seismic performance. In response to this challenge, this study tests several optimization strategies for the direct displacement-based design of a lateral force-resisting system (LFRS) using mass timber panels with U-shaped flexural plates (UFPs) and post-tensioning high-strength steel rods. The study compares two approaches: (1) a brute-force sampling of designs and data filtering to determine acceptable solutions; and (2) various automated optimization algorithms. The differential evolution algorithm was found to be the most efficient and robust approach, saving 90% of computational cost compared to bruteforce sampling while producing comparable solutions. However, every optimization formulation did not return best range of design options, often requiring reformulation or hyperparameter tuning to ensure effectiveness.