Lateral systems for tall buildings

The advances in three-dimensional structural analysis and computing resources have allowed the efficient and safe design of increasingly taller structures. These structures are the consequence of increasing urban densification and economic viability. The modem skyscraper has and will thus continue to feature prominently in the landscape of urban cities. The trend towards progressively taller structures has demanded a shift from the traditional strength based design approach of buildings to a focus on constraining the overall motion of the structure. Structural engineers have responded to this challenge of lateral control with a myriad of systems that achieve motion control while adhering to the overall architectural vision. An investigation was carried out to understand the behavior of the different lateral systems employed in today's skyscrapers. The investigation examined the structural behavior of the traditional moment frame, the braced frame, the braced frame with outriggers and finally the tubular structure. The advantages and disadvantages of all schemes were explored from both an architectural and structural efficiency standpoint. Prior to the computer modeling of each lateral system, each scheme was understood from an analytical standpoint to both verify computer results and to illustrate the importance of hand calculations. The study repeatedly illustrated that motion was the governing condition and this led to the proposal of an approach for the design of braced frames. Thesis Supervisor: Professor Jerome J. Connor Professor of Civil and Environmental Engineering Lateral Systems for Tall Buildings Lateral Systems for Tall Buildings ACKNOWLEDGEMENTS I would like to thank my parents and family for always being unconditionally supportive of my education in the United States. The environment and knowledge gained at both Northwestern University and MIT has been invaluable and has allowed incredibly opportunity unforeseen a few years ago. Thank you. I would also like to acknowledge the professors who have challenged and encouraged me throughout my academic career. Many thanks to Professor Jerome Connor and Professor Edwin Rossow for being the guiding force during my structural engineering studies. Their dedication to the advancement of the field and student focus has been resolute and my gratitude is immense. Thanks to: Tiffany for her sense of humor and going through the ups and downs of the year with me. I hope that I can have the positive impact on you as you had on me when your graduate studies come around. Diego for being supportive and a great buddy. I have learnt many things from you besides that there is no such thing as hard tacos. Midori for her patience and belief You have broadened my horizons far beyond that of only architecture. Mark Chang. Thanks for being a great friend and homework buddy. Our experiences at Northwestern will be with me for a long time to come. Evan for personifying dedication and perseverance. And of course all the M. Eng HPS people who have made the year a great experience. All the best to you all. Lateral Systems for Tall Buildings "Iteration is only for people who don't know what they are doing." Professor Jerome Connor Lateral Systems for Tall Buildings Table of