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Abstract: Advancing the seismic resilience of building systems is an active area of research in earthquake engineering. Ensuring safe egress in and out of buildings during extreme events, such as an earthquake, is essential to supporting this effort. To this end, understanding the seismic response of stairs facilitates the robust design of egress systems to ensure they can remain operable after an earthquake. From prior earthquake events and physical experiments, it is understood that stairs with a flight to landing fixed connection at multiple levels within a building are prone to damage. In addition, the stair system with flight to landing fixed attachments may affect the dynamic behavior of the building. To accommodate seismic inter‐story drifts, a kinematically free connection between the stairs and landing has been proposed. Herein this connection is referred to as a drift‐compatible stair connection. To investigate and aid in the design of such a connection, a unique set of shake table experiments were conducted at the University of Nevada, Reno. In this paper, an overview of these tests is presented, and a high‐fidelity finite element model of the tested stair system is used to predict the responses measured during these experiments. Developed in Abaqus, the robustness of the modeled stair unit is investigated considering a variety of contrasting connections, namely, drift‐compatible connections, fixed ends and one end fixed and the other free. Results from these numerical simulations offer guidance towards development of simplified models of multi‐level stair subsystems. Such models are needed when investigating seismic resilience of building systems across a wider range of hazard levels. Furthermore, best practices observed utilizing the models developed and evaluated herein against experimental data will be useful for subsequent analysis of larger stair tower models, such as the 10‐story stair system implemented in the NHERI Tall Wood mass timber building with post‐tensioned rocking walls, conducted in 2023 at the UC San Diego Large High‐Performance Outdoor Shake Table.

Copyright of Canadian Journal of Hospital Pharmacy / Journal Canadien de la Pharmacie Hospitalière is the property of Canadian Society of Hospital Pharmacists and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Development of a growth factor delivery vehicle providing appropriate temporal-spatial release together with an appropriate preclinical large animal model to evaluate bone formation is critical in the development of delivery strategies for bone tissue regeneration. Smectite nanoclays such as LAPONITE™ possess unique thixotropic and protein retention properties offering promise for use in growth factor delivery in bone repair and regeneration. This study has examined bone formation mediated by a clinically approved growth factor delivery system (InductOs®) in combination with Laponite gel in an aged female ovine femoral condyle defect preclinical model (10 weeks). Two different designs, one containing a low volume of Laponite gel (LLG) in combination with the InductOs® absorbable collagen sponge (ACS), the other in which Laponite gel formed the implant (HLG), were compared against InductOs® alone and an autograft positive control. Thus, five groups: (i) empty defect, (ii) autograft, (iii) BMP2 + ACS, (iv) BMP2 + ACS + LLG and (v) BMP2 + HLG + ACS were examined in 9 mm × 12 mm defects performed bilaterally in the medial femoral condyles of 24 aged (>5 years) sheep. Bone formation within the defect was assessed using micro-computed tomography (micro-CT), digital volume correlation (DVC) for biomechanical characterisation as well as histology. The autograft and InductOs® mediated enhanced bone formation (p < 0001) compared to blank controls, while no significant differences were observed between the Laponite/Collagen/BMP delivery vehicles. However, the current study illustrated the excellent biocompatibility of Laponite and its ability to deliver localised active BMP-2, with the opportunity for improved efficacy with further optimisation. Interestingly, DVC-computed strain distributions indicated that the regenerated bone structure is mechanically adapted to bear external loads from the early remodelling stages of the bone reparation cascade. The current studies of selected nanoclay delivery platforms for BMP, assessed in a clinically relevant large animal model auger well for the development of bone fracture therapeutics for an ageing population. [ABSTRACT FROM AUTHOR]

This paper summarizes the results from a comprehensive experimental program in an effort to better understand the phenomenon of viscous heating of fluid dampers under small-stroke (wind loading) and large-stroke (earthquake loading) motions. Two dampers, one with 15-kip and one with 250-kip force output at peak design velocity, have been instrumented and tested under various amplitudes and frequencies. Temperature histories at different locations along the damper casing and within the silicon fluid that undergoes the shearing action have been recorded. Experimental data under small-stroke motions of the 250-kip damper showed that a single closed-form expression derived from first principles is capable of predicting the temperature rise at different locations of the damper with fidelity. The recorded data under long-stroke motions suggest a two-parameter law of cooling that allows the estimation of the internal temperature of the silicon oil once the external temperature on the damper casing is known. The presented cooling law is an extension of Newton's law of cooling. The study concludes that for both dampers, the same values of the model parameters provide a good approximation of the cooling behavior. The study presents a valuable formula that can be used in practice to estimate the internal fluid temperature of the damper given the external shell temperature. DOI: 10.1061/(ASCE)0733-9399(2007) 133:5(566) CE Database subject headings: Damping; Heating; Monitoring; Earthquake engineering; Parameters; Earthquake resistant structures.

In this paper, the inelastic response of rigid-plastic and elastic-plastic systems subjected to pulse-type excitations is revisited with dimensional analysis. Starting from Newmark's result on the maximum displacement of a sliding mass resting on a base that is subjected to a rectangular acceleration pulse, the paper introduces an energetic length scale of the excitation and the relevant dimension-less [PI]-products that govern the response of yielding structures. The introduction of Buckingham's [PI]-theorem reduces the number of variables that govern the response of the elastic-plastic system from five (5) to three (3). The proposed dimensionless [PI]-products are liberated from the associated elastic system response and are consistent with the incremental evolution from the rigid-plastic to the elastic-plastic system. When the response is presented in terms of the dimensionless [PI]-terms remarkable order emerges. It is shown that for a given value of dimensionless yield displacement the response curves (maximum relative dimensionless displacements) become self-similar and follow a single master curve. The self-similar solutions show clearly how the inelastic response amplifies as the normalized yield displacement increases and that an increase in strength may lead to an increase in inelastic displacements. The main advantage of the analysis presented in this paper is that it brings forward the concept of self-similarity--an invariance with respect to changes in scale or size--which is a decisive symmetry that shapes nonlinear behavior. CE Database subject headings: Seismic response; Earthquake engineering; Dimensional analysis; Nonlinear analysis; Bilinear analysis; Elastoplasticity.

In this paper the response of a bilinear oscillator subjected to pulse-type motions is revisited with dimensional analysis. Using Buckingham's [PI] theorem the number of variables in the response analysis is reduced from six (6) to four (4). When the response is presented in terms of dimensionless [PI] terms remarkable order emerges. It is shown that for a given value of dimensionless strength and dimensionless yield displacement, the response (relative dimensionless displacements and dimensionless base shears) is self-similar regardless of the intensity and duration of the pulse excitation. These self-similar solutions scale better with the peak pulse acceleration rather than with the peak pulse velocity, indicating that peak pulse acceleration is a superior intensity measure of the induced shaking. Most importantly, the paper demonstrates that for relatively small values of strength (larger values of ductility) the value of the normalized yield displacement is immaterial in the response, a finding that shows that the response of the bilinear single-degree-of-freedom oscillator exhibits a complete similarity (similarity of the first kind) in the normalized yield displacement. This finding implies that under a strong earthquake an isolated bridge will exhibit the same maximum displacement regardless if it is supported on lead-rubber bearings or friction pendulum bearings that exhibit the same strength and offer the same isolation period. CE Database subject headings: Seismic response; Earthquake engineering; Dimensional analysis; Nonlinear analysis; Bilinear analysis; Oscillations.

This paper investigates the 'goodness' of peak ground velocity as a dependable intensity measure for the earthquake shaking of civil structures. The paper stresses the importance of distinguishing between acceleration pulses and velocity pulses, and identifies two classes of near-source ground motions: those where the peak ground velocity is the integral of a distinguishable acceleration pulse and those where the peak ground velocity is the result of a succession of high-frequency, one-sided acceleration spikes. It is shown that the shaking induced by the former class is in general much more violent than the shaking induced by the latter class of motions even when motions that belong to the former class may be generated by significantly smaller-magnitude earthquakes. Building on the dimensional analysis introduced in the companion papers this paper shows that both linear and nonlinear structural responses from a variety of records which exhibit distinguishable pulses scale better with the peak pulse acceleration than with the peak pulse velocity, indicating that the peak pulse acceleration is a more representative intensity measure of the earthquake shaking. This conclusion is further supported from the response analysis of linear and bilinear single-degree-of-freedom oscillators subjected to selected records from the 1999 Chi-Chi Taiwan earthquake that exhibit unusually high and long period velocity pulses. The paper shows that these high velocity pulses alone do not impose unusual demands on most civil structures. What is more detrimental are local, distinguishable acceleration pulses that override the long period velocity pulses. CE Database subject headings: Velocity; Ground motion; Seismic response; Earthquake engineering; Dimensional analysis; Nonlinear analysis; Bilinear analysis.

This paper reports on the results from a comprehensive component testing program on a type of buckling-restrained brace known as the Unbonded Brace[TM] The experimental data are used to: (1) verify the results of theoretical predictions on the structural stability of the braces; (2) validate the inelasitc capacity of the braces under severe earthquake demands; and (3) calibrate a macroscopic hysteretic model that is found to predict, with fidelity, the brace force-displacement behavior. The study concludes that the unbonded brace is a reliable and practical alternative to conventional framing systems to enhance the earthquake resistance of new and existing structures; capable of providing both the rigidity needed to satisfy structural drift limits, while delivering a substantial and repeatable energy absorption capability. DOI: 10.1061/(ASCE)0733-9445(2004) 130:6(880) CE Database subject headings: Seismic tests; Buckling; Bracing; Experimental data

Results demonstrate that there is no basic nitrogen atom involvement in the high-affinity binding of cytochrome P450 2D6 to substrates. Data indicate that some substrates bind through a negative charge either by electrostatic interaction or by hydrogen-bonding while others do not share this property.