This paper is a companion to "Displacement-Based Method of Analysis for Regular Reinforced-Concrete Wall Buildings: Application to a Full-Scale 7-Story Building Slice Tested at UC-San Diego" and presents key results obtained from a full-scale 7-story reinforced concrete building slice built and tested on the George E. Brown Jr. Network for Earthquake Engineering Simulation Large Outdoor High-Performance Shake Table at the University of California, San Diego. The building was tested in two phases. This paper discusses the main test results obtained during Phase I of the experimental program. In this phase, the building had a rectangular load-bearing wall acting as the main lateral force-resisting element. The building was subjected to four historical California input ground motions, including the strongintensity near-fault Sylmar record, which induced significant nonlinear response. The test addressed the dynamic response of the building, including the interaction between the walls, the slabs, and the gravity system as well as four issues relevant to construction optimization: (1) reduction in the longitudinal reinforcement; (2) use of a single curtain of reinforcement to transfer shear; (3) constrain of plasticity in the first level of the wall using capacity design; and (4) use of resistance-welded reinforcement in the boundary elements of the first level of the walls. The building responded very satisfactorily to the ground motions reproduced by the shake table and met all performance objectives. The effects of kinematic system overstrength and higher modes of response in the experimental response were important; this verified to a large extent the displacement-based method of analysis presented in the companion paper.

SUMMARYThis paper explores the notion of detailing reinforced concrete structural walls to develop base and midheight plastic hinges to better control the seismic response of tall cantilever wall buildings to strong shaking. This concept, termed here dual-plastic hinge (DPH) concept, is used to reduce the effects of higher modes of response in high-rise buildings. Higher modes can significantly increase the flexural demands in tall cantilever wall buildings. Lumped-mass Euler-Bernoulli cantilevers are used to model the case-study buildings examined in this paper. Buildings with 10, 20 and 40 stories are designed according to three different approaches: ACI-318, Eurocode 8 and the proposed DPH concept. The buildings are designed and subjected to three-specific historical strong near-fault ground motions. The investigation clearly shows the dual-hinge design concept is effective at reducing the effects of the second mode of response. An advantage of the concept is that, when combined with capacity design, it can result in relaxation of special reinforcing detailing in large portions of the walls.

A full-scale seven-story reinforced concrete building slice was tested on the unidirectional UCSD-NEES shake table during the period October 2005 -January 2006. A rectangular wall acted as the main lateral force resisting system of the building slice. The shake table tests were designed to damage the building progressively through four historical earthquake records. The objective of the seismic tests was to validate a new displacement-based design methodology for reinforced concrete shear wall building structures. At several levels of damage, ambient vibration tests and low amplitude white noise base excitations tests were applied to the building which responded as a quasi-linear system with dynamic parameters evolving as a function of structural damage. Six different state-of-the-art system identification algorithms including three output-only and three input-output methods were used to estimate the modal parameters (natural frequencies, damping ratios, and mode shapes) at different damage levels based on the response of the building to ambient as well as white noise base excitations, measured using DC-coupled accelerometers. The modal parameters estimated at various damage levels using different system identification methods are compared in order to: (1) validate/crosscheck the modal identification results and study the performance of each of these system identification methods, and (2) investigate the sensitivity of the identified modal parameters to actual structural damage. For a given damage level, the modal parameters identified using different methods are found to be in good agreement indicating that these estimated modal parameters are likely to be close to the actual modal parameters of the building specimen.

No abstract