Study On Seismic Damage Mechanism Control And Design Of Rocking Wall-Frame Structures

The control of seismic damage mechanism is of crucial importance for the safety of building structures subjected to strong earthquakes. The research in this dissertation makes a contribution in both the system design philosophy and the seismic demand analysis by studying the seismic performance of rocking wall-frame structure and proposing a damage mechanism control-based seismic design methodology. Major achievements of the dissertation are as follows:1. Uniaxil hysteretic models for steel rebars and concrete are developed for fiber beam elements and implemented in a finite element software ABAQUS. Calibrated with existing experimental data, the model is proved applicable in simulating the nonlinear seismic response of reinforced concrete frame structures.2. Commonly-used methods of selecting earthquake ground motion records for nonlinear dynamic analysis are evaluated and compared through case studies. The influence of the equivalent period of damaged structure on the effectiveness of different selection methods is presented. Earthquake strong ground motion suites appropriate for evaluating the seismic performance of various building structures are established.3. The relationship between the extent of story drift concentration and the stiffness of rocking wall in a rocking wall-frame structure is studied, based on which a practical equation for determining the stiffness demand for rocking wall is proposed. The superior seismic performance of rocking wall-frame structures over moment-resisting frames is demonstrated though comprehensive analysis of a typical rocking wall-frame structure with emphasis on its well-controlled deformation pattern and more uniformly distributed damage. A simplified rocking wall-frame structure is proposed for the use in less-developed earthquake prone regions.4. Substitute structure analysis (SSA) as a method of predicting the nonlinear seismic peak responses of building structures is studied. As a basis, a new equivalent linear model for single-degree-of-freedom system is proposed based on comprehensive discussions, both conceptually and quantitatively, in the influence of various structural parameters on equivalent linear parameters. The procedure of substitute structure analysis is completed and errors studied. The performance of substitute structure analysis in predicting the nonlinear seismic peak responses of building structures is proved adequate for seismic design practice through several case studies. The wide applicability and high computational efficiency of SSA are demonstrated.5. In determining the seismic demands of building structures, a damage mechanism control-based seismic design procedure is proposed with SSA as its analysis basis. The seismic damage mechanism is expected to be under control by means of explicitly determining the required strength and deformability of structural members with different seismic performance objectives. A moment resisting frame and a rocking wall-frame structure with similar structural layouts are designed using the proposed procedure to prove its rationality.