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Driven by demand for sustainable buildings and a reduction in construction time, mass timber buildings, specifically cross-laminated timber (CLT), is being more widely used in mid-rise buildings in the US. Low damage post-tensioned self-centering (SC) CLT shear walls (SC-CLT walls) provide an opportunity to develop seismically resilient CLT buildings. Previous research focused primarily on the lateral-load response under unidirectional loading of isolated self-centering timber walls, without considering the interaction with the adjacent building structural components, i.e., the floor diaphragms, collector beams, and gravity load system. Buildings response under seismic loading is multidirectional and there are concerns that multidirectional loading may be more damaging to SC-CLT wall panels and the adjacent building structural components than unidirectional loading, which affects the potential seismic resilience of buildings with SC-CLT walls. A series of lateral-load tests of a 0.625-scale timber sub-assembly was conducted at the NHERI Lehigh Large-Scale Multi-Directional Hybrid Simulation Experimental Facility to investigate the the lateral-load response and damage of SC-CLT walls and the capability of the adjacent building structural components i.e., the floor diaphragms, collector beams, and gravity load system to accommodate the building response and the controlled-rocking of the SC-CLT walls under multidirectional lateral loading. 

The system under investigation is a 2-story reinforced concrete building. Nonlinear viscous dampers were placed at the 1st and 2nd stories. The building was subjected to the maximum considered earthquake hazard levels. The outcome of the tests is to assess a newly developed explicit non-iterative formulation for the nonlinear viscous damper model and the ability of the unscented Kalman filter to identify and update the damper parameters in order to improve the model’s prediction of the damper force. 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 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. 

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. 

This study presents a finite element model for a hybrid self-centering damper considering the rate and temperature effects and explores the effects of different design parameters on the damper response. The damper, called as superelastic friction damper (SFD), consists of superelastic shape memory alloy (SMA) cables and a frictional energy dissipation mechanism. The experimental response of the SMA cables, frictional unit and overall damper at different loading frequencies and temperature are used to develop numerical model of the damper. Once a validated numerical model is obtained, parametric studies are carried out to evaluate force-displacement response of the damper when the design parameters are altered. The effects of damper design parameters on the equivalent stiffness, dissipated energy, equivalent viscous damping and self-centering capabilities of the damper are analyzed. Based on the findings, the recommendations for the design of the damper are presented.

 

Protecting both the essential building contents and the structural system—as well as facilitating and accelerating the post-event functionality of business operations—is a major concern during natural hazards. Floor isolation systems (FIS) with rolling pendulum bearings along with nonlinear fluid viscous dampers (NFVD) have been proposed to mitigate damage and enhance the resiliency of non-structural and structural systems, respectively. These devices are designed to decrease vibrations under dynamic loading conditions. In this poster, we introduce research using tridimensional nonlinear cyber-physical experimental testing (i.e., real-time hybrid simulations) to validate the performance of these response modification devices placed in structural systems under wind and earthquake loading conditions. The effects of soil-structure-foundation and fluid-structure interactions were also accounted for. The novelty of the project is the use of multi-directional large-scale real-time hybrid simulations of complex nonlinear systems under wind and earthquake demands to combine experimental structural modification passive devices with analytical multi-story buildings considering soil-foundation interaction via neural network. Results show that the FIS and NFVD can significantly reduce the demand on non-structural and structural systems of buildings subjected to natural hazards whose response can be also significantly affected by soil-foundation-structure interaction. A product of this research is the data (which is linked in Related Works), which can be used to compare with new studies using the same experimental techniques and structural modification devices or with alternative approaches. Researchers interested in multi-natural hazards resilience and mitigation, state-of-the-art structural experimental techniques, and the use of machine learning as a tool to improve modeling efficiency will benefit from its results. Also, companies dedicated to the commercial development of structural response modification devices, as well as policymakers working or with interest in economic and social resilience.