Motion based design : solution algorithms to the inverse problem with applications to seismic design
A general solution algorithm to the inverse equilibrium problem is derived. The algorithm finds stiffness coefficients for a given loading and a given set of displacment constraints. Optimization techniques are employed for the statically indeterminate case and for the case of partial displacement specification. The applicability of the method to seismic design of buildings is demonstrated. An inverse eigen-problem is solved for a stiffness distribution that produces a desired fundamental mode shape. The stiffness is then scaled based on the magnitude of the excitation with the use of response spectra. Emphasis is placed on stiffness proportional damping, which can be generated from the physical placement of dampers. Thesis Supervisor: Jerome J. Connor Title: Professor of Civil and Environmental Engineering Acknowledgments I would like to take this opportunity to thank the people to whom I am indebted for this thesis. First of all, I would like to thank my father and mother, Wilfred and Lorraine Gallegos. I would not have had the opportunity to write this thesis, were it not for your financial and emotional support. You have been very supportive of all my efforts without trying to influence any of the decisions I have made. A very heartfelt thanks to my brother and sister, Wilfred Jr. and Anita. You have always been, and will continue to be excellent role models. A special thanks to my advisor Professor Jerome J. Connor for an extremely interesting and challenging research topic. But more importantly, I thank you for helping me find a new direction in life. It was a pleasure working with you. Thanks to Miguel Licona for providing a state space simulator which was used to analyze the designs. I dedicate this thesis to my grandmothers, Corina V. Duran and Lucia Lopez. You provided me with a stable cultural environment and a unique perspective on life. I have always drawn and will continue to draw upon your wise words of wisdom in times of need.
Optimum design and earthquake-response constrained design of elastic shear buildings
The necessary and sufficient conditions for global optimality and the closed form solution are derived for a problem of minimizing a weighted sum of storey stiffnesses of a shear building subject to a fundamental frequency constraint. A set of higher frequency formulae is derived for optimally designed shear buildings with equal masses. It is shown that, if the weight coefficients are regarded as parameters for adjustment, the distribution of the SRSS estimates of the maximum interstorey drifts can be adjusted so as to coincide with a specified one. The base shear–fundamental period formulae and the base shear–design drift formulae are derived semi-analytically for shear buildings with equal masses on the basis of the optimum design formulae and the SRSS estimates of the maximum interstorey drifts. Some numerical examples are presented in order to illustrate the validity of the proposed method of earthquake-response constrained design.
Experimental study of water fluxes in a residential area: 2. Road infiltration, runoff and evaporation
Lack of accurate data has led some hydrologists and city planners to assume that urban infiltration is zero and runoff is 100% of the rainfall. These assumptions lead to an over estimation of road runoff volume and an underestimation of direct recharge to groundwater, which is already rising under some UK cities. This study investigates infiltration and runoff processes and quantifies the percentage of rainfall that contributes to storm drainage, and that which infiltrates through different types of road surface. Access tubes were installed for measuring soil water content using a neutron probe in three car parks, a road and a grass site at the Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford. Storm drainage was recorded at the exit of the Thamesmead Estate in Crowmarsh Gifford, just before the drain joins the River Thames at Wallingford. Rainfall and water table depth were also recorded. Weekly measurements of soil moisture content indicated that the top 40 cm layer is not influenced by water‐table fluctuations and, therefore, positive changes in soil moisture could be attributed to infiltration of rainfall through the surface. Depending on the nature of the surface, subsurface layers, level of traffic, etc., between 6 and 9% of rainfall was found to infiltrate through the road surfaces studied. The storm drainage generated by road runoff revealed a flow pattern similar to that of the receiving watercourse (River Thames) and increased with the increase of infiltration and soil water content below the road surface. The ratio of runoff to rainfall was 0·7, 0·9 and 0·5 for annual, winter (October–March) and summer (April–September) respectively. As the results of the infiltration indicated that 6 to 9% of annual rainfall infiltrates through the road surface, this means that evaporation represents, 21–24% of annual rainfall, with more evaporation taking place during summer than winter. Copyright © 2003 John Wiley & Sons, Ltd.