The research conducted in this project is related to hybrid wall systems. Additional research is need on hybrid wall systems in the following areas: (1) development of new and innovative hybrid wall connections and systems; (2) parametric evaluation of the seismic behavior of hybrid wall systems. This project addresses these needs.
The broad objective of this research is to analytically investigate the seismic behavior and design of a new type of hybrid coupled wall which uses unbonded post-tensioning to couple the walls. Compared with current industry practice and current research, the use of unbonded post tensioning, in a hybrid coupled wall system is significant innovation. The proposed system consists of reinforced concrete walls and steel coupling beams. It is expected t hat by using unbonded post-tensioning, the detailing of the coupling beams and the walls can be simplified. Furthermore, it is anticipated that by using unbonded post tensioning the coupling beams can be designed to remain essentially "damage-free" during a "design" level ground motion, with most of the damage occurring in certain selected components of the beam-to-wall connections which can be replaced after the ground motion.
The research task include (1) developing and analytical models for the hysteric behavior of unbonded post-tension hybrid coupled walls; (2) performing a parametric seismic response evaluation of these walls; (3) developing preliminary seismic design recommendations and practical application guidelines for these walls. Analytical model of the coupled walls in the prototype structures will be developed and a series of parametric nonlinear static and nonlinear dynamic time history analyses of these walls will be conducted. The analytical models will be verified using experimental results obtained at Lehigh University on unbonded post tensioned steel frame subassemblages with connections similar to the coupling beam-to-wall connections used in the proposed system. Based on the results of the nonlinear dynamic time-history analyses, the research will assess the seismic behavior of unbonded post-tensioned hybrid coupled walls and develop practical analysis and design procedures and practical application guidelines.
This project is supported under the 4th year completion of initiative NSF 97-154. Successful completion of the research will provide an analytical foundation on which future experimental research can be built and codified design specifications can be formulated.
