UC San Diego

Large investments have recently been made for the construction of new medium- and high-rise buildings in California. In many cases performance-based designs have been the preferred method for these buildings. A main consideration in performance-based seismic design is the estimation of the likely development of structural and nonstructural damage limit-states given a hazard level. For this type of buildings efficient modeling techniques are required able to compute the response at different performance states. A research work was conducted at University of California San Diego (UCSD) on the i) seismic design, ii) experimental response and iii) computational modeling of medium- and high-rise reinforced concrete wall buildings. In the first part of this work a displacement-based seismic design method for use within performance-based is developed. Capacity design is used to control the mechanism of inelastic deformation. Based on principles of plastic analysis and structural dynamics the new formulation allows the computation of the effects of system overstrength and of the higher modes of response. Equal emphasis is given to displacement, force and acceleration demand parameters. The ground motion destructiveness potential is also determined. Application of the method to reinforced concrete wall buildings is discussed. The method is validated with the experimental response of a full-scale 7 story building. In addition a dual plastic hinge design concept for improving the performance and optimizing the construction of high-rise buildings is presented. The second part presents the experimental research program, with extensive shake table tests, of a full-scale 7-story reinforced concrete wall building slice, that was conducted at UCSD. The base shear coefficient obtained by the proposed method, of the first part of the research work, described above was 50% of that required by the equivalent static method prescribed by the ASCE-7 code. In spite of the reduced amount of longitudinal reinforcing steel, all performance objectives were met. The response of the building was significantly influenced, as expected, by the interaction of the main lateral force resisting wall with other structural elements (kinematic overstrength) and by the higher modes of response. Finally the third part presents a dynamic nonlinear strut-and-tie modeling approach developed for the analysis and evaluation of damage limit-states in reinforced concrete walls. The modeling approach is verified with the response of the UCSD 7-story building test