Estimation of Vertical Floor Displacement Using a Wavelet De-Noising Method

The horizontal response of structural and nonstructural systems during seismic events has been studied for a long time. However, the effect of the vertical response of floors on building contents and nonstructural systems has still remained a topic of concern. A wavelet de-noising method along with the experimental data obtained from a full-scale test at E-Defense is used to estimate the vertical floor displacement of a five-story steel moment frame building in base-isolated and fixed-base configurations. Vertical displacements of slabs and beams are calculated from the experimental data and formulated based on their out-of-plane dominant frequencies. A curve fitting approach is then carried out to estimate vertical displacements at floors and stories. In these tests, partition wall damage such as buckling of studs occurred at slab displacements of about 1 in.     

Seismic Fragility Study of Displacement Demand on Fire Sprinkler Piping Systems

Seismic damage to fire sprinkler piping systems is not only caused by inertial forces or interstory drifts, but also by impact with surrounding objects. The collision of constituents of piping systems with nearby objects increases the chance of damage to the piping itself and to adjacent objects. In this study, the probability of seismic damage to fire sprinkler systems due to impact is quantified by obtaining seismic fragility parameters for large diameter pipes passing through walls and floors, as well as small diameter pipes that typically interact with suspended ceilings. The results of two shaking table experiments conducted at the University of Nevada, Reno and E-Defense test facility, and a high-fidelity numerical model of a hospital piping system are used to evaluate the displacement demands. Piping interaction fragility curves are generated based on clearances between adjacent objects and pipes. The probability of piping interactions and damage to piping systems subjected to different levels of peak floor acceleration is compared for different clearances. It is found that the probability of damage due to impact is comparable with the probability of exceeding other limit states, like the leakage in fittings, when a 1 in or 2 in gap is provided around large and small diameter pipes, respectively.     

Capacity Evaluation of Typical Stud-Track Screw Connections in Nonstructural Walls

A series of component-level experiments have been conducted aiming to evaluate the force and displacement capacities of typical stud-track screw connections (STCs) in steel-framed partition walls. The variables considered in these experiments included screw-edge distances, loading protocols (monotonic or cyclic), and stud and track thicknesses. The experimental data was then utilized to develop different capacity fragility curves for STCs in terms of displacements. A series of analytical STC hinge models were also proposed and validated using this data. The hinge models can be adopted in future studies to develop a comprehensive analytical model for a typical partition wall assembly.