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Carpenter L.D.,WHL International Inc | Naeim F.,John A. Martin and Associates Inc. | Lew M.,Amec Foster Wheeler | Youssef N.F.,Nabih Youssef and Associates | And 3 more authors.
Structural Design of Tall and Special Buildings | Year: 2011

After the devastating offshore Maule, Chile earthquake of moment magnitude 8.8 on 27 February 2010, the Los Angeles Tall Buildings Structural Design Council (LATBSDC) organized a reconnaissance team to visit the Santiago, Concepción and Viña del Mar areas. This report summarizes the highlights of the damage observed in the Viña del Mar area on the coast 120 km west-north-west of Santiago and much closer to the subduction rupture zone than Santiago. A significant portion of Viña del Mar is uniquely situated on variable ground conditions, particularly in the area with most of the damaged buildings. The Viña del Mar area also included tall buildings constructed before and damaged by the large 3 March 1985 magnitude 7.8 Offshore Valparaiso earthquake, which were damaged again in the 2010 earthquake. The predominant observation in these buildings was the lack of confinement and ductile detailing of shear walls. The second observation was the high demand in the localized Viña del Mar area. The apparently high demand on buildings clustered in the Viña del Mar area may be an observation based on the damage since most of the taller structures in the area are somewhat clustered in Viña. But significant damage was not reported in Valparasio, which is largely, situated on higher ground which steps downward to a narrow flat area along the ocean. Similarly, significant damage was not reported in new buildings along the coast just North of Viña del Mar. The authors' conclusion based on these observations is that the ground conditions in Viña del Mar relate to the level of demand and the level of demand is higher. Demand is variable geoseismically but with the local history of many earthquakes from the same source zone, the characterization should be regularized. However, structural response is much better defined at least for confined elements with tested and predictable analytical characterization. Regardless, the detailing of reinforcing in reinforced concrete must relate to the expected demand and duration. In addition, the structural system and elements need to be designed and detailed to prepare a building to survive a higher unanticipated demand without collapse. However, despite the apparently large demands due to the large magnitude earthquake with strong aftershocks and the long duration of seismic motions, building collapses did not occur even with limited capability due to non-ductile and non-confined detailing. © 2010 John Wiley & Sons, Ltd.


Lew M.,Amec Foster Wheeler | Naeim F.,John A. Martin and Associates Inc. | Carpenter L.D.,WHL International Inc | Youssef N.F.,Nabih Youssef and Associates | And 4 more authors.
Structural Design of Tall and Special Buildings | Year: 2010

The magnitude 8·8 Offshore Maule, Chile earthquake is a significant event in seismology and earthquake engineering. The earthquake occurred on a convergent plate boundary (subduction zone) and affected a large area that a significant number of tall buildings designed to modern building codes. An understanding of the seismological and tectonic setting of this earthquake, together with understanding of the behaviour of structures, will further research and enhancements in seismic design in similar convergent plate boundary environments, such as the Cascadia subduction zone off the coast of the Pacific north-west in the USA and Canada and other areas around the world. Copyright © 2010 John Wiley & Sons, Ltd.


Saragoni G.R.,University of Chile | Lew M.,Amec Foster Wheeler | Naeim F.,John A. Martin and Associates Inc. | Carpenter L.D.,WHL International Inc | And 4 more authors.
Structural Design of Tall and Special Buildings | Year: 2010

The mega earthquake of 27 February 2010, offshore Maule, Chile with moment magnitude of 8·8 is the fifth largest recorded earthquake in the world and, therefore, is considered to be a mega earthquake. This subduction interplate thrust earthquake occurred at the convergence of the Nazca (oceanic) plate with the South American continental plate. This type of earthquake affects the north-western region of USA and Canada, as well as Alaska. Therefore, it is important to study the characteristics of the recorded accelerograms and their effects on the future behaviour of tall buildings in USA. Although the earthquake produced accelerographic records with very high ground motions in terms of peak ground accelerations and very long duration of ground shaking, the observed damage from this earthquake was more like the level of damage expected from a moment magnitude 8?0 rather than a moment magnitude of 8?8. This may be the result of asperities in the fault rupture surface. Copyright © 2010 John Wiley & Sons, Ltd.


Lew M.,Amec Foster Wheeler | Naeim F.,John A. Martin and Associates Inc. | Carpenter L.D.,WHL International Inc | Youssef N.F.,Nabih Youssef and Associates | And 4 more authors.
Structural Design of Tall and Special Buildings | Year: 2010

The 27 February 2010 Offshore Maule, Chile earthquake is one of the most significant seismic and earthquake engineering events for many reasons but especially for the study of the dynamic behaviour of tall buildings. Because the earthquake occurred on a subduction zone where the convergence of the Nazca plate with the South American plate occurs, there are similarities to large areas of North America with similar conditions such as the Cascadia subduction zone extending from Northern California to British Columbia; major metropolitan areas that could be affected by the Cascadia subduction zone include Portland, OR, Seattle, WA and Vancouver, BC. The abundance of tall buildings in Chile, particularly in Santiago, Viña del Mar and Concepción, allow for significant case histories into the behaviour of tall buildings in Chile, a country that has similar design and construction practices to the USA, where there is also an abundance of tall buildings in major population areas. Copyright © 2010 John Wiley & Sons, Ltd.


Rojas F.,University of Southern California | Rojas F.,University of Chile | Naeim F.,John A. Martin and Associates Inc. | Lew M.,Amec Foster Wheeler | And 4 more authors.
Structural Design of Tall and Special Buildings | Year: 2011

Concepción, near the southern end of the fault rupture zone of the offshore Maule, Chile earthquake, suffered significant damage to all types of structures. Tall reinforced concrete buildings in the region were also affected, some severely. Spectacular collapse and partial collapse were experienced in two buildings, and many buildings had failure of thin shear walls that lacked sufficient boundary element confinement. Concrete spalling and crushing occurred and reinforcing steel buckled and were sometimes fractured. © 2010 John Wiley & Sons, Ltd.

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