Forced vibration testing and analytical modeling of a four-story reinforced concrete frame building.

摘要

A series of force vibration tests and ambient vibration measurements were performed on a four-story reinforced concrete building, which was damaged in the 1994 Northridge earthquake. A unique dataset of low noise, high-density spatial resolution and low to moderate amplitude vibration was produced. Broadband low-amplitude vibrations from the linear shaker excitation were collected for an efficient assessment of modal properties of the test building. During relatively high-amplitude sinusoidal vibrations obtained by synchronized operation of two large capacity eccentric mass shakers, local behaviors of some structural members (curvature distributions of floor slabs and columns) as well as the global structural response (interstory drifts and story accelerations) were monitored. In addition to forced vibration testing, ambient vibrations were measured before and after each test to investigate potential drifts of modal properties resulting from the forced vibrations. Detailed system identification analyses as well as investigations of detailed component behavior were conducted using collected data for accurate characterization of the building properties.; A FE model updating procedure using both frequency response function and modal data was implemented. To enhance the numerical stability and convergence, absolute and relative constraints as well as weighting factors were added to the conventional iterative least-squares solution procedure. Using implemented updating procedure, a FE model for the test building capable of reproducing experimental results accurately and consistent with observed building damage was obtained.; A testing method to induce seismic excitations that are consistent with earthquake induced shaking at the structure base was proposed. This testing method uses linear shaker for simulation, and addressed two challenges associated with implementation in the context of linear elastic seismic response for structures. These challenges were (a) identifying a linear shaker input motion which produces a structural response similar to that of the building shaken from the base by an actual earthquake, and (b) pre-correcting the input motion to account for control-structure interaction effects.