SMIP 2013 Seminar

In this presentation, I will review the results of analyses of ground motions recorded during the large interface subduction zone earthquakes in Maule Chile (M 8.8, 2010) and Tohoku Japan (M 9.0, 2011). I will also describe how these analyses influenced the selection of ground motion prediction equations (GMPEs) for subduction zone regions in the Global Earthquake Model (GEM) project organized through the Pacific Earthquake Engineering Research Center (PEER). The work discussed in this presentation is largely presented in prior publications by Boroschek et al. (2012), Stewart et al. (2013a), and Stewart et al. (2013b).

Many tall buildings in Tokyo metropolitan area were strongly shaken during the Tohoku Earthquake, March 11, 2011. Most of them are less than 40 years old, and experienced the shaking of such a strong level for the first time, although they suffered little damage. The buildings are conventional seismically-resistant buildings, and those constructed after the 1995 Kobe Earthquake are typically supplementally-damped buildings or base-isolated buildings for seismic damage reduction. Some of the tall buildings are instrumented with sensors and their motions recorded during the event. This paper discusses recorded responses of such tall buildings in Tokyo employing the three distinct structural systems. By estimating contributions of multiple vibration modes, various shaking phenomena observed in the tall building are clarified. Characteristics of the distinct systems and their effects on building contents are contrasted based on mode-based analyses.

The April 20, 2013 Lushan earthquake followed the 2008 Great Wenchuan earthquake by almost five years. Although the rupture also started in the Longmenshan fault zone, the Lushan earthquake is not an aftershock. Although similar damage and disruptions to infrastructure and society occurred, it was of a smaller scale and not unexpected due to the short time for the lessons from Wenchuan to be applied. There were some examples of lessons learned and the strong motion dataset obtained in this event will prove valuable in assessing how effective the actions taken have been. The visual observations were made on May 27 and 28, 2013 in Lushan.

Earthquake Early Warning (EEW) is a proven use of seismological science that can give people and businesses outside the epicentral area of a large earthquake up to a minute to take protective actions before the most destructive shaking hits them. Since 2006 several organizations have been collaborating to create such a system in the United States. These groups include the US Geological Survey, Caltech, UC Berkeley, the University of Washington, the Southern California Earthquake Center, the Swiss Federal Institute of Technology, Zürich, the California Office of Emergency Services, and the California Geological Survey.

This paper provides interim results of an on-going investigation of the seismic response and performance of instrumented pile supported wharves at the ports of Los Angeles and Oakland, California. The first phase of the project has focused on the synthesis of geotechnical, structural, and strong motion data at three port sites instrumented by CSMIP. Geophysical investigations performed for this study provide Vs data in unimproved, liquefiable hydraulically-placed fill at a CSMIP strong motion station and in adjacent zones of fill improved with stone columns. Strong motion recordings obtained at the Port of Oakland Berth 36-38 and Port of Los Angeles Berth 404 have been used to validate a practice-oriented 2D nonlinear, effective stress geomechnical model for low- to moderate-levels of ground shaking and structural response.

California Department of Transportation (Caltrans) and California Geological Survey (CGS) have instrumented a number of bridges, and have been collecting their strong motion response measurements for more than two decades (Hipley and Huang, 1997). The deployed instrument sets usually include down hole sensor arrays, and accelerometers installed on piles, pile-caps, and decks. These bridges are located relatively close to faults identified on the Caltrans Seismic Hazard Map (Mualchin, 1996). The intent has been to select different bridge types, ranging from standard ordinary bridges to those such as toll bridges with unique features.

This paper presents three-dimensional global high-fidelity numerical (finite element) models for three representative bridges—namely, a standard ordinary non-skewed bridge, a skewed bridge, and a non-standard long-span bridge. There are multiple sets of acceleration records due to nearby earthquakes for each of the selected bridges. We carefully, albeit heuristically, calibrate the parameters of these models to improve the agreement between the measured and predicted responses. Upon model calibration, the calculated displacement responses of the simulation models match remarkably well with those obtained from the acceleration records at major locations on the specimen bridges.

Seismic instrumentation can provide valuable insight into performance of structures and help us assess the validity, or lack thereof, of assumptions used and methods applied. It is precisely for this reason that the Los Angeles Tall Building Structural Design Council (LATBSDC) mandates extensive seismic instrumentation of tall buildings designed according to the provisions of its alternative analysis and design procedure that has been adopted by the Department of Building and Safety of the city of Los Angeles. This paper describes 2011 LATBSDC seismic instrumentation requirements and provides an example of their application.

This paper reviews the recent accomplishments and current status of the California Strong Motion Instrumental Program. With the completion of the instrumentation of the new San Francisco Oakland Bay Bridge, all major bridges in California will have been instrumented, as well as the BART tube, two tunnels and a new series of hospitals and new geotechnical arrays. New approaches to instrumentation in recent years are discussed. The current state of instrumentation accomplished by the program is summarized.

Strong-motion data from the United States and other seismically active countries are served to engineers, seismologists, and public safety authorities through the Center for Engineering Strong Motion Data (CESMD) at www.strongmotioncenter.org. The CESMD is a joint effort between the US Geological Survey and the California Geological Survey, in cooperation with US and international strong-motion seismic networks and data centers. The transfer of operational and maintenance responsibilities for the COSMOS Virtual Data Center from its original home at UC Santa Barbara to the CESMD have been completed, along with software upgrades and improvements in the virtual links to worldwide data providers. Two search options are now available at the CESMD: US structural and ground response data at the Engineering Data Center (EDC), and worldwide ground response data at the Virtual Data Center (VDC).