DOI: 10.17603/ds2-fzdf-cn82
title: Phase 1: Single-Story Testing for Development of Floor Acceleration Simulation Methodology, in Advancing Knowledge on the Performance of Seismic Collectors in Steel Building Structures: Shake Table Tests

description: NHERI @ UCSD large scale shake table tests on steel seismic collector project. Testing was conducted one story structural steel collector sensitive specimen representing an upper floor of a building structure. Special length steel column with pinned base were employed to provide appropriate inter story drift. Added mass was attached to the floor slab to get the appropriate tributary collector force. This was followed by a testing of two story collector sensitive specimen with a steel composite deck floor system for the first elevated level and a unfilled bare steel deck roof. A testing methodology involving transfer functions was used to create the appropriate loading for the one story specimen. The two story building structure was subjected to service level, design basis, and maximum considered earthquake ground motions. The structure employed cantilever columns for the primary vertical seismic force resisting system (SFRS). The collector line included all flange weld connection, top flange weld connection, and shear tab connection. Testing concluded with a failure of the roof diaphragm at the metal deck side lap seam.
description: Phase 1 used a single-story steel test building with a composite slab and perimeter collectors to develop and validate a Floor Acceleration Simulation Testing (FAST) methodology intended to reproduce multistory floor accelerations in a single-story test frame. White-noise and impulse tests were used to identify dynamic properties, followed by earthquake simulation tests at 20%, 50%, and 100% Design Earthquake (DE) levels to observe collector axial force, slab participation, and connection rotation.

White-noise tests: White-noise excitation was applied at low amplitude to identify the natural frequencies, damping ratios, and stiffness characteristics of the structure. These tests were typically conducted before and after earthquake events to track changes in dynamic properties as damage accumulated.

Impulse tests: Single-pulse excitation was applied through the shake table to evaluate the transient dynamic characteristics of the structure and to supplement the system-identification testing performed using white-noise input.

Floor Acceleration Simulation Testing (FAST): In FAST, the objective was to reproduce realistic multistory floor acceleration demands in a single-story test building. Target floor-acceleration histories were obtained from nonlinear response-history analyses of a 12-story BRBF prototype building (SDII). A transfer-function approach in the frequency domain was then used to compute the shake-table input motion required for the single-story specimen to generate these target accelerations. This approach allowed the specimen to respond essentially elastically while reproducing the amplitude and frequency content of multistory floor accelerations.

Earthquake simulation tests: Earthquake events consisted of acceleration time histories based on the 1994 Northridge Earthquake record (Beverly Hills-14145 Mulhol.), scaled to different Design Earthquake (DE) intensity levels. Motions were applied in both direct and sign-reversed directions. These events were used to evaluate collector forces, slab parti