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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. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

There are many modern tall buildings in Santiago that were subjected to the 27 February 2010 earthquake in Chile. Although there was not widespread damage in Santiago, there was notable damage to some tall concrete buildings that may have resulted from lack of proper detailing, the absence of 135? seismic hooks and inadequate confinement of walls in the boundary zones. These caused buckling of the main bars and tension compression failure of the walls. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Three of the tall buildings that members of the Los Angeles Tall Buildings Structural Design Council visited after the 27 February 2010 Chilean moment magnitude 8.8 earthquake were reviewed. The three buildings discussed in this paper are located in the Greater Concepción area in the Biobió Region (Region VIII) of Chile. Two of the buildings (Bosquemar and Olas) are located on the west side of the Bio-Bio River in San Pedro de La Paz, while the third building (Pedro de Valdivia) is located on the east side of the river south of the downtown area of the city of Concepción. The tower at Bosquemar was the most thoroughly investigated, although the observations from the damage at all three structures offer important insight that can be applied to current and future earthquake engineering practice. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY It is a pleasure to present the eighth annual issue developed by the Los Angeles Tall Buildings Structural Design Council. Each year in the December issue of the journal, readers can look forward to a collection of excellent papers written by structural engineers that have received special recognition for their contributions to tall building design. These annual combinations of paper topics are especially timely to structural engineering by authors that are leaders of the structural engineering profession. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]