CKI-26: TALL BUILDING BEHAVIOR DURING THE 3 MARCH 1985 CHILEAN EARTHQUAKE
• Raul D. Bertero
• Vitelmo V. Bertero
The main objective of this report is to review and evaluate the performance of tall buildings during the 3 March, 1985, Chilean earthquake in order to improve the seismic design of high-rise reinforced concrete buildings, particularly when they have to be built on soft soil.
This report is divided into seven chapters. The Introduction describes the general goal of the report as well as the partial objectives of each chapter.
The second chapter, Seismic Characteristics of the Region, has two objectives: a) to evaluate the return period of a ground motion with the severity of the 3 March 1985 earthquake at Vina del Mar, intending to classify it as a serviceability, damageability, or survivability ground motion for the city; and b) to evaluate ground motion characteristics (peak instrumental values. Arias intensity, linear elastic response spectra, effective peak acceleration and velocity. Hausner intensity, and strong motion duration) and to compare their severity with those corresponding to El Centro, which is traditionally considered as a severe ground motion.
The third chapter, Structural Engineering Practice in Chile, studies different aspects of Chilean practice that affect the design and behavior of tall buildings in Vina del Mar. Seismic code, design concepts, construction materials with nominal and real properties, structural and nonstructural details are summarized with a view to emphasizing the most peculiar aspects of Chilean practice.
The fourth chapter, Tall Buildings in Vina del Mar, studies specific aspects of the tall buildings in Vina del Mar: configuration, structural lay-out, structural systems and foundations. Also summarized are: the tall building inventory; analysis of its periods and damping, periods comparison with Mexico, Japan and US; and geotechnical characteristics of soil in Vina del Mar (soil profile, standard penetration tests, depth of the soil deposit to bedrock and the characteristic period site).
The fifth chapter, Effects of the 3 March 1985 Earthquake in Vina del Mar, has three objectives.
a) To evaluate the accuracy of the recorded ground motion in Vina del Mar as input for the studied tall buildings.
b) To evaluate the damage potential of the ground motion in Vina del Mar, computing linear elastic and elasto-plastic strength demand, linear elastic and elasto-plastic displacement demand, cumulative ductility demand, and hysteretic energy demand spectra. Also, interstory drift, accelerations, and damage indices of buildings designed according to Chilean practice are evaluated and compared with observed structural and nonstructural damage of tall buildings. Using these data, an estimation of the average overstrength of tall buildings in Vifia del Mar is obtained.
c) To evaluate the effect of the soil-structure interaction on the response of tall buildings in Vina del Mar.
In the sixth chapter, Evaluation of Four Buildings in Vina del Mar, studies of design. analysis, and performance during the 3 March 1985 earthquake [mainly based on a report by Wallace and Moehle (1989)] are presented for four buildings in Vina del Mar. Both damaged and undamaged buildings of similar construction were selected to determine the differences between the buildings, and to correlate the differences with observed damage.
Finally, in the last chapter, Implications of the March 3 1985 Chilean Earthquake on Tall Building Design, the lessons of the behavior of tall buildings during the 1985 Chilean earthquake are summarized and the main conclusions for tall building design are stressed.
2. Seismic Characteristics of the Region
3. Structural Engineering Practice in Chile
4. Tall Buildings in Vina Del Mar
5. Effects of the 3 March 1985 Earthquake in Vina Del Mar
6. Evaluation of Four Tall Buildings in Vina Del Mar
7. Implications of the 3 March 1985 Chilean Earthquake for Tall Building Design
July 15, 1991 - January 14, 1993