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Steel energy dissipators can be combined with mass timber in integrated seismic lateral force–resisting systems to achieve designs with enhanced seismic performance and sustainability benefits. Examples of such integration include the use of mass timber post-tensioned rocking walls equipped with steel energy dissipation devices. This study proposes a solution using buckling-restrained boundary elements (BRBs) with mass timber walls detailed to pivot about a pinned base. This design allows the walls to rotate with minimal flexural restraint, distributing drift demands more uniformly with building height and reducing crushing damage at the wall base. Experimental quasi-static cyclic tests and numerical simulations were used to characterize the first- and higher-mode behavior of a full-scale three-story building featuring a mass timber gravity system and the proposed mass timber-BRB system. Under first-mode loading, the specimen reached 4% roof drift ratio with stable hysteretic behavior and a nearly uniform story drift profile. While residual drifts were nonnegligible due to the lack of self-centering, analytical estimates indicate realignment is likely feasible at the design earthquake level. Under second-mode loading, the specimen exhibited near-linear behavior with high stiffness. Experimental results were corroborated with numerical simulations for the isolated gravity frame, first-mode-like, and second-mode-like loading protocols. It is expected that results from this study will facilitate greater use of mass timber seismic lateral force–resisting systems. 

A veneer-based engineered wood product known as Mass Ply Panels (MPP) was recently introduced and certified per ANSI-PRG 320. A full-scale three-story mass timber building structure was constructed and tested at Oregon State University to demonstrate the potential of MPP in the design of resilient, structural lateral force-resisting systems. The building structure comprised MPP diaphragms, laminated veneer lumber (LVL) beams and columns, and an MPP rocking wall design. Two opportunistic vibration tests were performed to charac-terize the dynamic properties of the structure. First, an implosion of a stadium within 600 m of the building location was used as the main excitation source, during which bi-directional horizontal acceleration data were collected for approximately 18 seconds. Second, an ambient vibration test was conducted to collect horizontal acceleration data for one hour. In both tests, sixteen accelerometers were used to measure the response of the structure. Modal features were extracted using an output-only method and compared with the estimates from a finite element model. Lessons learned can be used to inform future modeling efforts of a mass timber building to be tested on the Natural Hazards Engineering Research Infrastructure (NHERI) Experimental Facility at the University of California San Diego high-performance outdoor shake table. 

This paper presents the statistical and numerical investigation of the seismic performance of a three-story post-tensioned mass ply panel (MPP) rocking wall lateral force-resisting system prototype whose main components are MPP, U-shaped flexural steel plates (UFPs), and high-strength steel post-tensioned rods. Uncertainties in material properties and geometry of the components are considered in the assessment of the performance of this lateral forceresisting system based on recent experimental data on MPP, experimental data available in the literature for the UFPs and post-tensioning rods, as well as some additional structural design considerations. In the assessment of the seismic performance factors, first, random realizations of the structural design are generated using Monte Carlo simulation. Second, for each realization, a nonlinear finite element model is developed. For each realization, two types of analysis are performed, nonlinear static analyses, and incremental dynamic analyses. Results of the nonlinear static and dynamic analyses are then used to estimate the seismic design factors (e.g., R-factor) and limit state-based fragility functions, the latter being based on exceeding limit states defined for each component based on existing experimental data. 

Mass timber panels are emerging as an innovative alternative for the design of elastic spines due to their high stiffness- and strength-to-weight ratio, among other factors. Recent research has shown that mass timber panels used in conjunction with steel energy dissipators are promising solutions for enhanced seismic performance. However, the available experimental data at the building scale is still minimal, which limits the understanding, adoption, and development of effective seismic design guidelines for these systems. This research addresses this gap through full-scale quasi-static cyclic testing of a three-story mass timber building. Lateral loads are transferred through Mass Ply Panel (MPP) diaphragms to an MPP spine with vertically-oriented unbonded steel buckling-restrained braces (BRBs) as energy dissipating boundary elements in the first story. The only elements designed to dissipate energy in the inelastic range are the BRBs. The building specimen achieved low-structural damage and enhanced-performance goals, being able to reach a 4% roof drift ratio with little loss of strength and stiffness. The proposed pivoting detail was effective in mitigating compressive damage at the wall toe. To support the experimental campaign and future design procedures, a high-fidelity numerical model of the building was developed using OpenSees. 

This paper describes the lateral force resisting system (LFRS) design in a full-scale six-story shake-table test building and presents a comparative cradle-to-grave life-cycle assessment of alternative LFRSs. The test building features the reuse of material from a ten-story shake-table structure comprised of engineered mass timber (MT) products. These include MT floors (cross-, glue-, nail-, and dowel-laminated timber [CLT], [GLT], [NLT], [DLT]); MT posttensioned rocking walls (CLT and mass ply panels [MPP]); and a gravity system consisting of laminated-veneer lumber (LVL) beams and columns. Shake-table testing will benchmark innovative, low-damage design solutions for the LFRSs. To supplement this test, the environmental impact of a MT LFRS is determined relative to design alternatives that use conventional materials. The Athena Impact Estimator for Buildings was used to perform a comparative, cradle-to-grave life-cycle assessment (LCA) of the prototype MT LFRS with respect to an alternative, functionally equivalent reinforced concrete (RC) shear wall design. The LCA results showed reduced environmental impacts across some impact metrics, with a significant reduction in Global Warming Potential for the MT LFRS when accounting for biogenic carbon. 

Mass timber buildings are gaining popularity in North America as a sustainable and aesthetic alternative to traditional construction systems. However, several knowledge gaps still exist in terms of their expected seismic performance and plausible hybridizations with other materials, e.g. steel energy dissipators. This research explores the potential use of mass plywood wall panels (MPP) in spine systems using steel buckling-restrained braces (BRBs) as energy dissipators. The proposed BRB-MPP spine assembly makes up the lateral load-resisting system of a three-story mass-timber building segment that will be tested under cyclic quasi-static loading at Oregon State University. The specimen geometry and material properties result in BRBs that are shorter and of smaller core area than in most common steel structural applications. Small BRBs are prone to exhibit a hardened compressive response and fracture due to ultra-low-cycle fatigue when subjected to repeated cycles of large strain amplitude. These issues, along with the limited availability of test data, make small BRBs difficult to model. To support the experimental testing program, a material model with combined kinematic and isotropic hardening is calibrated against the available experimental data for three BRB specimens to estimate the behavior of BRBs of short length (≤3,500 mm [138 in]) and small core area (≤2,600 mm2 [4 in2]), similar to the ones designed for the test specimen. The calibrated model is used to predict the behavior of the BRB-MPP spine experiment.