Retrofitting and Strengthening Evaluation from Stiffness Variations of a Damaged Building from Ambient Vibration Recordings

Abstract

The rigidity of a six-story shear-wall building, damaged by the May 21, 2003 Boumerdes earthquake (Algeria) has been evaluated before the event, in its damaged state, and after retrofitting, by estimating its natural frequency, damping factor, and modal shape. Pre-event parameters are estimated through a numerical analysis, based on the structure drawings, complemented by an ambient vibration investigation of an identical non-damaged building located on the same site. Parameters of the damaged and retrofitted states were obtained from ambient vibration recordings. Variations of the modal parameters, for the three states of the building, allow evaluating rigidity changes, and thus checking of both the retrofitting and strengthening of the building

Ambient Vibration Recording for Single-Station, Array and Building Studies Made Simple: CityShark II

“…CityShark II has been successfully used in various types of ambient vibration studies: buildings (Figure 9 and [6][7][8][9][10][11]), arrays (Figure 10 and [12][13][14][15]), landslides [15] and single-station (H/V) (Figure 3 and [16][17][18][19][20][21][22]).…”

Dynamic Behavior of Connected Structures

“…In order to determine the fo, modern technologies through the ambient vibration testing allow in a short time (10 to 15 minutes) assessment of the translational dynamic properties of a single building, which then also able to conduct for a large number of constructions with only a limited effort is required [1]. Ambient vibration techniques are very robust to define building dynamic response (natural frequency, modal damping, and modal shape) and stiffness changes of a structure when as decrease of building natural frequencies it is always linked to a loss of stiffness [8]. However, it is important to place the sensors in a right place along the building's bays and floors so that all deformation modes either in translation or torsion could be obtained.…”

Establishing Empirical Period Formula for RC Buildings in Lima, Peru: Evidence for the Impact of Both the 1974 Lima Earthquake and the Application of the Peruvian Seismic Code on High-Rise Buildings

“…The seismometers have been installed using the same protocol in each building, as done, for example, by Dunand et al (2004) and Farsi et al (2009): the northsouth component of the sensor was oriented along the main axis of the building (hereinafter the longitudinal direction) leading to redirect the east-west component of the sensor in the shorter length of the building (hereinafter the transverse direction). Recordings have been performed at the top of the buildings, that is, in most cases the roof (in Lima all roofs are flat due to the absence of rain), and if not accessible at the highest level.…”

“…This crucial parameter can be directly assessed in situ using (1) dynamic methods, such as unbinding, harmonic excitation, or percussion (e.g., Trifunac, 1972;Boutin et al, 2001;Crowley and Pinho, 2004) that are expensive, tedious to install, and generally disturbing, (2) traditional earthquake records (e.g., Dunand et al, 2006;Todorovska, 2009), or (3) passive ambient vibration recordings (e.g., Carder, 1936;Trifunac, 1972;Trifunac et al, 2001a,b;Farsi and Bard, 2004;Michel et al, 2008;Farsi et al, 2009;Michel, Guéguen, El Arem, et al, 2010) or other passive method such as coherent Light Detection and Ranging measurement . The most reliable building dynamic parameter estimates are obtained from earthquake records, but this type of data is quite difficult to obtain, very expensive because of the seismic network deployment and maintenance, and heavily dependent on earthquake occurrence, which may be quite a problem in low-to-moderate seismic regions.…”