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Abstract
This dissertation presents a research project conducted at the University of Nebraska under the auspices of the U.S.-Japan coordinated Precast Seismic Structural Systems (PRESSS) Phase II program. Primary objectives of the research are to investigate the behavior of a mid-rise precast office building under moderate seismicity and to develop design recommendations for similar buildings.
The centerpiece of the project is a six-story building with a floor-to-floor height of 13 ft and plan dimensions of 102 x 224 ft. Gravity loads are resisted by interior frames which utilize shallow and wide precast/prestressed beams, and lateral loads are taken by shear wall panels and perimeter frames.
A full-scale precast beam-column joint subassemblage is subjected to cyclic loads. Results of the experimental study show that the joint dissipates little energy and suffers modest strength and stiffness degradation under two percent drift.
Inelastic dynamic analysis of the lateral load resisting system is performed using the DRAIN-2DX program. Models of an elastic, a monolithic, and four precast concrete systems are investigated. These models are subjected to four ground acceleration records down-scaled to represent Uniform Building Code Seismic Zone 2 events. Analytical results of the monolithic system and the precast systems are compared.
Findings of the analytical study are as follows: (1) Base shear of precast systems is smaller, but their fundamental period is higher than that of a monolithic system, (2) Story drift of precast systems is larger but their maximum values are within design limits, (3) Behavior of the wall panel-panel horizontal joint connection plays a definitive role in the response of the precast systems, and (4) The monolithic system appears to have a larger stiffness while the precast systems exhibit a better energy dissipation characteristic.
Based on this study, it is concluded that the seismic performance of a precast system is at least equal to and can be improved to exceed that of a monolithic system by fine-tuning the connections to behave as desirable.
