More Like this

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. From Testing to Codification: Post-tensioned Cross Laminated Timber Rocking Walls

   Pei, S. ; Dolan, J. ; Zimmerman, R. ; McDonnell, E. ; Line, p. ; Popovski, P. ( October 2019 , Proceedings of the International Network for Timber Engineering Research (INTER))

   Blass, Hans (Ed.)

   Wood buildings in North American has been predominantly constructed using light-framed wood systems since early 1900’s, with only limited exception of heavy timber construction in some non-residential applications. This situation is likely to change in the future with the growing acceptance of mass timber construction in the region. In fact, a number of mass timber buildings have been constructed in recent years in the U.S. and Canada, including low- to mid-rise mixed-use buildings (e.g. UMass Student Center, T3 building) and tall towers (e.g. Brocks Commons at UBC). Most of these buildings utilized cross laminated timber (CLT) or nail laminated timber (NLT) floors and heavy timber framing systems to support gravity loads, and a non-wood lateral system such as concrete shear walls or a braced steel frame to resist wind and seismic loads. Although CLT material and glulam products have been recognized in the U.S. and Canada (IBC (2018) and NBCC (2015), there is currently no mass timber lateral systems in the U.S. and only one system (platform style panelized CLT shear wall) in Canada that is currently recognized by the building codes. As a result, special design procedures and review/approval processes must be followed for any building intended to usemore »a mass timber lateral system. There is a need to promote codification of mass timber lateral systems in order to help further develop mass timber building market in North American. At the time of this paper, there has been an on-going effort to devel-op seismic design parameters for panelized CLT shear walls in the U.S. (ref) following the FEMA P695 procedure for platform construction. The other lateral system that at-tracted significant attention and research resources is post-tensioned CLT rocking wall system, which has the potential to be applicable to balloon framed low-rise to tall wood buildings. This paper will focus on recent research development on CLT rocking wall system in the U.S. and the effort to develop a seismic design procedure for this system for inclusion in the NDS Special Design Provisions for Wind and Seismic (SPDWS)(2008). While the expensive and time consuming process of the FEMA P695 process would provide the ability to use the equivalent lateral force method for design purposes, this path is not part of the discussion included here.« less
3. Development and Full-Scale Validation of Resilience-Based Seismic Design of Tall Wood Buildings: The NHERI Tallwood Project

   Pei, S. ( April 2017 , Proceedings of the New Zealand Society for Earthquake Engineering Annual Conference, April 27-29, Wellington, New Zealand, 2017)

   With global urbanization trends, the demands for tall residential and mixed-use buildings in the range of 8~20 stories are increasing. One new structural system in this height range are tall wood buildings which have been built in select locations around the world using a relatively new heavy timber structural material known as cross laminated timber (CLT). With its relatively light weight, there is consensus amongst the global wood seismic research and practitioner community that tall wood buildings have a substantial potential to become a key solution to building future seismically resilient cities. This paper introduces the NHERI Tallwood Project recentely funded by the U.S. National Science Fundation to develop and validate a seismic design methodology for tall wood buildings that incorporates high-performance structural and nonstructural systems and can quantitatively account for building resilience. This will be accomplished through a series of research tasks planned over a 4-year period. These tasks will include mechanistic modeling of tall wood buildings with several variants of post-tensioned rocking CLT wall systems, fragility modeling of structural and non-structural building components that affect resilience, full-scale biaxial testing of building sub-assembly systems, development of a resilience-based seismic design (RBSD) methodology, and finally a series of full-scale shakingmore »table tests of a 10-story CLT building specimen to validate the proposed design. The project will deliver a new tall building type capable of transforming the urban building landscape by addressing urbanization demand while enhancing resilience and sustainability.« less
4. 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.
5. Seismic Retrofit of RC Shear Walls Using Selective Weakening and Self- Centering

   Sharma, Sumedh ; Aaleti, Sriram ; Okumus, Pinar ( July 2022 , 12th National Conference on Earthquake Engineering)

   Traditional retrofit methods typically focus on increasing strength/stiffness of the structure. This may increase seismic demand on the structure and could lead to excessive damage during a seismic event. This paper presents an alternative retrofit method which integrates concepts from selective weakening and self-centering (rocking) to achieve low seismic damage for substandard reinforced concrete shear walls. The proposed method involves converting traditional cast-in-place built shear walls into rocking walls, which softens the structure, while allowing re-centering. Laboratory tests were performed to validate the retrofit concept on a benchmark wall specimen designed to pre-1970s standards. Observations from the test showed minimized damage and excellent recentering in the retrofitted wall. Additional testing was carried out to verify a novel anchorage scheme for post-tensioning elements, required to implement the proposed retrofit. Ultra-High-Performance Concrete (UHPC) was judiciously used to minimize damage and optimize the retrofit process.