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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 shaking 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.
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Predicting Floor-Level for 911 Calls with Neural Networks and Smartphone Sensor Data
In cities with tall buildings, emergency responders need an accurate floor level location to find 911 callers quickly. We introduce a system to estimate a victim's floor level via their mobile device's sensor data in a two-step process. First, we train a neural network to determine when a smartphone enters or exits a building via GPS signal changes. Second, we use a barometer equipped smartphone to measure the change in barometric pressure from the entrance of the building to the victim's indoor location. Unlike impractical previous approaches, our system is the first that does not require the use of beacons, prior knowledge of the building infrastructure, or knowledge of user behavior. We demonstrate real-world feasibility through 63 experiments across five different tall buildings throughout New York City where our system predicted the correct floor level with 100% accuracy.
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- Award ID(s):
- 1702952
- PAR ID:
- 10210316
- Date Published:
- Journal Name:
- Sixth International Conference on Learning Representations
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The system under investigation is a 40 story building. Real-time hybrid simulations (RTHSs) were performed on the building, where the entire façade of the structure is subjected to wind loading over a 360 second duration. Nonlinear viscous dampers between the outrigger truss and perimeter columns are placed at stories 20th and 30th. The outcome of the tests is to assess the ability of the damped outrigger system to suppress undesirable floor accelerations. The data collected from the tests can be reused by replaying the real-time hybrid simulation offline, where all of the response quantities of the building can then be retrieved. The data can be reused to study the response of tall buildings with outriggers and passive dampers subjected to wind natural hazards.more » « less
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The system under investigation is a 40 story building. Real-time hybrid simulations (RTHSs) were performed on the building, where the structure is separately subjected to multi-natural hazards consisting of a 110 mph sustained wind storm and 43 second earthquake. Nonlinear viscous dampers between the outrigger truss and perimeter columns are placed at stories 20th and 30th. The outcome of the tests was to assess the ability of the damped outrigger system to suppress undesirable floor wind accelerations and reduce earthquake story drift and damage. The data collected from the tests can be reused by replaying the real-time hybrid simulation offline, where all of the response quantities of the building can be retrieved. The data can be reused to study the response of tall buildings with outriggers and passive dampers subjected to wind and earthquake natural hazards.more » « less
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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 use 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.more » « less
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This study addresses the influence of biaxial interaction of hysteretic restoring forces of base isolation system on wind-induced response of base-isolated tall buildings. Both buildings with and without eccentricity in center of resistance are considered. Response history analysis is carried out to characterize the coupled responses of a square-shaped base-isolated tall building. A comprehensive parameter study is presented which covers a wide range of yielding level, response ratio and correlation of alongwind and crosswind base displacements. The results demonstrate that the biaxial interaction leads to increase in low-frequency component and decrease in resonant component of lower inelastic base displacement. However, the increase of low-frequency component of base displacement does not affect the upper building response relative to base isolation system. As a result, the upper building response is reduced by the influence of biaxial interaction. The biaxal interaction also results in fast growth of time-varying mean alongwind base displacement. The increase of low-frequency component can be significant when the yielding level of higher response is significant and two translational base displacements are quite different in magnitude. The correlation of two translational base displacements enhances the influence of biaxial interaction. For the base-isolated building with eccentricity, the alongwind and crosswind base responses are closer in magnitudes thus are less influenced by the biaxial interaction.more » « less
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