Geology topics

A. Sanli

Publications and source records attributed to A. Sanli.

4 recordsLinked to original sources

USGS2004

Real-time seismic monitoring needs of a building owner - And the solution: A cooperative effort

A recently implemented advanced seismic monitoring system for a 24-story building facilitates recording of accelerations and computing displacements and drift ratios in near-real time to measure the earthquake performance of the building. The drift ratio is related to the damage condition of the specific building. This system meets the owner's needs for rapid quantitative input to assessments and decisions on post-earthquake occupancy. The system is now successfully working and, in absence of strong shaking to date, is producing low-amplitude data in real time for routine analyses and assessment. Studies of such data to date indicate that the configured monitoring system with its building specific software can be a useful tool in rapid assessment of buildings and other structures following an earthquake. Such systems can be used for health monitoring of a building, for assessing performance-based design and analyses procedures, for long-term assessment of structural characteristics, and for long-term damage detection.

Earthquake Spectra↗

USGS2003

Seismic monitoring instrumentation needs of a building owner and the solution: A cooperative effort

A specific case whereby the owner of a building, in collaboration with another federal agency with expertise in seismic monitoring of buildings, private consulting engineers, and a supplier, facilitated development of a seismic monitoring system for a 24-story building in San Francisco, California. The unique aspects of this monitoring systems include: the monitoring system must relate to rapid assessment of the building following an earthquake and the monitoring system must deliver the data in relatively short time, if not in real-time. The system has the standard recording capability at the site server PC. It has the capability to calculate select number of drift ratios, specific to the building.

California↗

USGS2002

GPS in pioneering dynamic monitoring of long-period structures

Global Positioning System (GPS) technology with 10-20-Hz sampling rates allows scientifically justified dynamic measurements of relative displacements of long-period structures. The displacement response of a simulated tall building in real time and permanent deployment of GPS units at the roof of a building are described. To the authors' best knowledge, this is the first permanent deployment of GPS units (in the world) for continuous dynamic monitoring of a tall building. Data recorded from the building during a windy day is analyzed to determine the structural characteristics. When recorded during extreme motions caused by earthquakes and strong winds, such measurements can be used to compute average drift ratios and changes in dynamic characteristics, and therefore can be used by engineers and building owners or managers to assess the structural integrity and performance by establishing pre-established thresholds. Such information can be used to secure public safety and/or take steps to improve the performance of the building.

Earthquake Spectra↗

USGS2001

Main shock and aftershock records of the 1999 Izmit and Duzce, Turkey earthquakes

The August 17, 1999 Izmit (Turkey) earthquake (M w =7.4) will be remembered as one of the largest earthquakes of recent times that affected a large urban environment (U.S. Geological Survey, 1999). This significant event was followed by many significant aftershocks and another main event (M w =7.2) that occurred on November 12, 1999 near Duzce (Turkey). The shaking that caused the widespread damage and destruction was recorded by a handful of accelerographs (~30) in the earthquake area operated by different networks. The characteristics of these records show that the recorded peak accelerations, shown in Figure 1, even those from near field stations, are smaller than expected (Çelebi, 1999, 2000). Following this main event, several organizations from Turkey, Japan, France and the USA deployed temporary accelerographs and other aftershock recording hardware. Thus, the number of recording stations in the earthquake affected area was quadrupled (~130). As a result, as seen in Figure 2, smaller magnitude aftershocks yielded larger peak accelerations, indicating that because of the sparse networks, recording of larger motions during the main shock of August 17, 1999 were possibly missed.

Duzce↗