京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21365号 / 工博第4524号 / 新制||工||1705(附属図書館) / 京都大学大学院工学研究科建築学専攻 / (主査)教授 西山 峰広, 教授 竹脇 出, 教授 河野 広隆 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Taiwan is located in a highly seismic zone and the historical “Dieh-Dou” timber buildings, constructed without following any code or standard, are prone to collapse under earthquake. These buildings are unique and represent the culture, heritage and art of Taiwan, therefore need to be preserved while minimizing unnecessary intervention that could damage their authenticity. <br /> This research comprises a thorough investigation on the parameters influencing the seismic vulnerability of the Dieh-Dou timber frames in Taiwan, and propose a methodology of assessment and a strategy for strengthening validated through experimental testing and numerical analysis. <br /> After review existing literature and post-earthquake surveys, the failure modes of the buildings are identified, showing that the dislocation of the elements of the frame from the joints is the primary source of damage. An experimental investigation is carried out comprising both rotational and translational tests on full scale joint specimens which, together with a parametric study undertaken with an appropriate FE simulation, demonstrates how both the rotational and translational stiffness of the joints play a key role in defining the behaviour of these structures. <br /> Lateral force, response spectrum, and step-by-step pushover analyses are performed and compared with the post-earthquake survey of two Dieh-Dou buildings seriously affected by the 1999 Chi-Chi earthquake. The results show that the proposed FE modelling can successfully be employed to assess the vulnerability of the frames. <br /> Based on a damage level approach, an assessment methodology is suggested that would allow to optimisation of the strengthening strategy, permitting protection these precious structures from future earthquakes while avoiding unnecessary interventions.

Numerous reinforced concrete buildings vulnerable to earthquake induced collapse have been constructed in seismic zones prior to the 1970s. A major contributor to building collapse is the loss of axial load carrying capacity in non-seismically detailed columns. Experimental investigations have shown that non-seismically detailed columns will only experience axial failure after shear failure and subsequent lateral shear strength degradation have occurred. Therefore, column shear failure and degrading behavior must be modeled accurately before axial collapse algorithms can be properly implemented. Furthermore, accurate modeling of the degrading lateral-load behavior of columns is needed if lateral load sharing between structural elements is to be assessed with reasonable accuracy during seismic analyses. A calibrated analytical model was developed that is capable of estimating the lateral strength degrading behavior of RC columns prone to shear failure. Existing analytical models poorly approximate nonlinear column behavior and require several nonphysical damage parameters to be defined. In contrast, the proposed calibrated model provides the engineering community with a valuable tool that only requires the input of column material and geometric properties to simulate column behavior up to loss of lateral strength. In developing the model, a database of RC columns was compiled. Parameters extracted from database column-tests were scrutinized for trends and regression models relating damage parameters to column physical properties and boundary conditions were produced. The regression models were implemented in the degrading analytical framework that was developed in this project. Two reinforced concrete columns exhibiting significant inelastic deformations prior to failing in shear were tested in support of the analytical work. A newly developed Vision System was used to track a grid of targets on the column face with a resolution of three-thousands of an inch. Surface column deformations were measured to further the understanding of the fundamental changes in column behavior that accompany shear and axial failure and validate the proposed analytical model. This research provides the engineering community with an analytical tool that can be used to perform nonlinear dynamic analysis of buildings that are at risk of collapse and help engineers improve retrofit techniques. Further insight into shear behavior attained through this project is an important step toward the development of better shear and axial degradation models for reinforced concrete columns. / text

La investigación realizada se enfoca en la evaluación del pabellón B del Hospital Luis Negreiros Vega con planos modificados aplicando disipadores de fluido viscoso en la disposición chevron diagonal y horizontal. En el modelo numérico se aplicaron disipadores lineales y no lineales de acuerdo con las expresiones del FEMA, 356, con el fin de realizar una comparación de la disposición y valor de exponente de velocidad óptimo para una deriva objetivo y amortiguamiento efectivo planteado para cada dirección. Los resultados con los cuales se evaluó esta efectividad, son mejores reducciones de distorsiones, menores fuerzas de disipación, y reducción de la irregularidad torsional que presentaba la estructura inicialmente en la dirección Y. Finalmente, entre los resultados que presenta esta investigación, son que los disipadores chevron horizontales no lineales son los más recomendables, debido a que requieren menores valores de coeficiente de amortiguamiento, reducen distorsiones en mayor medida que los otros modelos, presentan menores valores de fuerzas de disipación y reducen la irregularidad torsional en los pisos inferiores. / The research carried out focuses on the evaluation of pavilion B of the Luis Negreiros Vega Hospital with modified planes applying viscous fluid dissipators in the diagonal and horizontal chevron arrangement. In the numerical model, linear and non-linear dissipators were applied according to the FEMA expressions, 356, in order to make a comparison of the arrangement and value of the optimum speed exponent for a target drift and effective damping proposed for each direction. The results with which this effectiveness was evaluated are better reductions of distortions, lower dissipation forces, and reduction of torsional irregularity that the structure initially presented in the Y direction. Finally, among the results presented by this research, are that the Non-linear horizontal chevron heatsinks are the most recommended, because they require lower values of damping coefficient, reduce distortions to a greater extent than other models, present lower values of dissipation forces and reduce torsional irregularity in the lower floors. / Trabajo de investigación