Excitation of a building with an eccentric-mass exciter and ambient vibration

A set of acceleration records obtained at specific points of an actual reinforced concrete, four-story building structure subjected to forced vibrations are presented and documented in this project. The structure has vertical setbacks so that it has natural eccentricity along one direction. The tests were initially conducted to study the torsional behavior of the structure subjected to both forced vibrations and ambient vibrations. A mechanical eccentric-mass exciter was used for the forced vibration tests. It was attached to the roof slab at two locations and the resultant force was varied in magnitude, direction and frequency.
Given the characteristics of the building structure and the tests, the generated data can be used for several purposes, as suggested below:
• Building torsion. The exciter resultant force was applied along the direction of the building symmetry axis at two locations: 1) without eccentricity and 2) with an eccentricity of 2 m with respect to the symmetry axis (almost 10% of the building plan dimension along the perpendicular direction of the force). The exciter force was also applied along the perpendicular direction causing building torsion due to the building asymmetry in the perpendicular direction. In a third scheme of load, the resultant force was applied at the center of the roof slab but with an angle with respect to the axis of symmetry.
• Structural identification. Because for each load condition both the load and the corresponding response of some structure points are recorded, several identification techniques can be applied to estimate the dynamic properties of the building structure. The comparison of identification techniques can be assessed since the nominal properties of the building were known at the time of the tests. It is also interesting to further investigate plausible differences of both structural responses and dynamic properties when they are obtained from forced vibrations or ambient vibrations.