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1. Experimental Seismic Test of Drywall Partition Walls with Improved Detailing for Damage Reduction

   Ryan, K. ; Hasani, H. ( July 2020 , The 17th World Conference on Earthquake Engineering)

   Drywall partition walls are susceptible to damage at low-level drifts, and hence reducing such damage is key to achieving seismic resiliency in buildings. Prior tests on drywall partition walls have shown that slip track connection detailing leads to better performance than other detailing, such as fully-fixed connections. However, in all prior testing, partition wall performance was evaluated using a unidirectional loading protocol (either in-plane or out-of-plane) or in shake table testing. Moreover, all details are susceptible to considerable damage to wall intersections. Two phases of the test have been performed at the Natural Hazards Engineering Research Infrastructure (NHERI) Lehigh Equipment Facility to develop improved details of drywall partition walls under bidirectional loading. The partition walls were tested alongside a cross-laminated timber (CLT) post-tensioned rocking wall subassembly, wherein the CLT system is under development as a resilient lateral system for tall timber buildings. In the Phase 1, the slip behavior of conventional slip-track detailing was compared to telescoping detailing (track-within-a-track deflection assembly). In the Phase 2, two details for reducing the wall intersection damage were evaluated on traditional slip-track C-shaped walls. First, a corner gap detail was tested. This detail incorporates a gap through the wall intersection to reduce the collisionmore »damage at two intersecting walls. Second, a distributed gap detail was tested. In this approach, the aim was to reduce damage by using more frequent control joints through the length of the wall. All walls were tested under a bidirectional loading protocol with three sub-cycles: in-plane, a bi-directional hexagonal load path, and a bi-directional hexagonal load path with an increase in the out-of-plane drift. This loading protocol allows for studying the bidirectional behavior of walls and evaluating the effect of out-of-plane drift on the partition wall resisting force. In the Phase 1, the telescoping detailing performed better than conventional slip track detailing because it eliminated damage to the framing. In Phase 2, the distributed gap detailing delayed damage to about 1% story drift. For the corner gap detailing, the sacrificial corner bead detached at low drifts, but the wall itself was damage-free until 2.5% drift. Bidirectional loading was found to have an insignificant influence on the in-plane resistance of the walls, and the overall resistance of the walls was trivial compared to the CLT rocking.« less
2. PRE-TEST SEISMIC EVALUATION OF DRYWALL PARTITION WALLS INTEGRATED WITH A TIMBER ROCKING WALL

   Hasani, H ; Ryan, K ; Amer, A ; Ricles, J ; Sause, R. ( June 2018 , Proceedings of the U.S. National Conference on Earthquake Engineering)

   Drywall partition walls (DPW) could considerably affect the seismic resilience of tall cross-laminated timber (CLT) buildings due to cost and building downtime associated with repair. These drift sensitive components are susceptible to damage at low shaking intensities, and thus controlling or eliminating such damage in low to moderate earthquakes is key to seismic resilience. Conversely, post-tensioned CLT rocking walls have been shown to be a resilient lateral load resistant system for tall CLT building in high seismic areas. A series of tests will be performed at the NHERI Lehigh EF to compare the performance of DPWs with conventional slip-track detailing and alternative telescoping slip-track detailing (track-within-a-track deflection assembly), and to evaluate different approaches for minimizing damage at the wall intersections through the use of gaps. Moreover, a configuration is examined with partition wall encapsulating the rocking wall for fire protection. This paper presents a summary of pre-test studies to design the best configuration of DPW to improve the overall resiliency of the structure.
3. Phase 2: Gap Detailing in Drywall Partition Walls with Return Walls

   https://doi.org/10.17603/ds2-k8jn-yy03  

   Hasani, Hamed ; Ryan, Keri ; Amer, Alia ; Marullo, Thomas ; Ricles, James ( January 2021 )

   Abstract

   Two partition walls with return walls at both ends and traditional slip-track detailing were investigated. Special gap details were evaluated to reduce damage at the wall intersection. The first detail utilized a large gap in the wall intersection, while the other detail utilized distributed gaps along the wall. The walls were tested under a bidirectional loading protocol, to provide better insight into the wall intersection behavior under bidirectional loading.
4. Stability of Fluid Flow through a Channel with Flexible Walls

   https://doi.org/10.1155/2021/8825677  

   Shubov, Marianna A. ; Edwards, Madeline M. ( March 2021 , International Journal of Mathematics and Mathematical Sciences)

   Solovjovs, Sergejs (Ed.)

   In the present paper, we summarize the results of the research devoted to the problem of stability of the fluid flow moving in a channel with flexible walls and interacting with the walls. The walls of the vessel are subject to traveling waves. Experimental data show that the energy of the flowing fluid can be transferred and consumed by the structure (the walls), inducing “traveling wave flutter.” The problem of stability of fluid-structure interaction splits into two parts: (a) stability of fluid flow in the channel with harmonically moving walls and (b) stability of solid structure participating in the energy exchange with the flow. Stability of fluid flow, the main focus of the research, is obtained by solving the initial boundary value problem for the stream function. The main findings of the paper are the following: (i) rigorous formulation of the initial boundary problem for the stream function, ψ x , y , t , induced by the fluid-structure interaction model, which takes into account the axisymmetric pattern of the flow and “no-slip” condition near the channel walls; (ii) application of a double integral transformation (the Fourier transformation and Laplace transformation) to both the equation and boundary and initial conditions,more »which reduces the original partial differential equation to a parameter-dependent ordinary differential equation; (iii) derivation of the explicit formula for the Fourier transform of the stream function, ψ ˜ k , y , t ; (iv) evaluation of the inverse Fourier transform of ψ ˜ k , y , t and proving that reconstruction of ψ x , y , t can be obtained through a limiting process in the complex k -plane, which allows us to use the Residue theorem and represent the solution in the form of an infinite series of residues. The result of this research is an analytical solution describing blood flowing through a channel with flexible walls that are being perturbed in the form of a traveling wave.« less
5. Indoor Wireless Channel Properties at Millimeter Wave and Sub-Terahertz Frequencies

   https://doi.org/10.1109/globecom38437.2019.9013236  

   Xing, Yunchou ; Kanhere, Ojas ; Ju, Shihao ; Rappaport, Theodore S. ( May 2019 , 2019 International Conference on Communications)

   This paper provides indoor reflection, scattering, transmission, and large-scale path loss measurements and models, which describe the main propagation mechanisms at millimeter wave and Terahertz frequencies. Channel properties for common building materials (drywall and clear glass) are carefully studied at 28, 73, and 140 GHz using a wideband sliding correlation based channel sounder system with rotatable narrow-beam horn antennas. Reflection coefficient is shown to linearly increase as the incident angle increases, and lower reflection loss (e.g., stronger reflections) are observed as frequencies increase for a given incident angle. Although backscatter from drywall is present at 28, 73, and 140 GHz, smooth surfaces (like drywall) are shown to be modeled as a simple reflected surface, since the scattered power is 20 dB or more below the reflected power over the measured range of frequency and angles. Partition loss tends to increase with frequency, but the amount of loss is material dependent. Both clear glass and drywall are shown to induce a depolarizing effect, which becomes more prominent as frequency increases. Indoor propagation measurements and large-scale indoor path loss models at 140 GHz are provided, revealing similar path loss exponent and shadow fading as observed at 28 and 73 GHz. The measurementsmore »and models in this paper can be used for future wireless system design and other applications within buildings for frequencies above 100 GHz« less