Search

Drones are becoming indispensable in emergency search and rescue (SAR), particularly in intricate urban areas where rapid and accurate response is crucial. This study addresses the pressing need for enhancing drone navigation in such complex, dynamic urban environments, where obstacles like building layouts and varying wind conditions create unique challenges. Particularly, the need for adapting drone autonomous navigation in correspondence with dynamic wind conditions in urban settings is emphasized because it is important for drones to avoid loss of control or crashes during SAR. This paper introduces a pioneering method integrating multiobjective reinforcement learning (MORL) with a convolutional autoencoder to train autonomous drones in comprehending and reacting to aerodynamic features in urban SAR. MORL enables the drone to optimize multiple goals, whereas the convolutional autoencoder generates synthetic wind simulations with a substantially lower computation cost compared to traditional computational fluid dynamics (CFD) simulations. A unique data transfer structure is also proposed, which fosters a seamless integration of perception and decision-making between machine learning (ML) and reinforcement learning (RL) components. This approach uses imagery data, specific to building layouts, allowing the drone to autonomously formulate policies, prioritize navigation decisions, optimize paths, and mitigate the impact of wind, all while negating the necessity for conventional aerodynamic force sensors. The method was validated with a model of New York City, offering substantial implications for enhancing automation algorithms in urban SAR. This innovation enables the possibility of more efficient, precise, and timely drone SAR operations within intricate urban landscapes. [ABSTRACT FROM AUTHOR]

The Manhattan Bridge is one of the first examples of an urban bridge whose design was impacted by partisan politics and a desire for a more, in the eyes of some, esthetically pleasing suspension bridge. It was the third bridge to be built across the East River and its design resulted in a battle between Leffert L. Buck, his associates R. S. Buck, and O. F. Nichols and Gustav Lindenthal, the Commissioner of Bridges in New York City, appointed after the preliminary design of the bridge had been completed. This paper is about that battle. [ABSTRACT FROM AUTHOR]

This paper presents some findings of the FEMA and SEI/ASCE sponsored studies of structural performance of New York’s World Trade Center (WTC) following the attacks of September 11, 2001, and the Murrah Building following the April 19, 1995, Oklahoma City bombing. The WTC collapses were caused not by aircraft impact alone but by the combination of impact and the resulting fire that weakened structural members and connections. On the other hand, the Murrah Building collapsed as a direct result of the blast. Although these studies call for further research in a number of areas, this report summarizes some of the lessons learned. [ABSTRACT FROM AUTHOR]

Following the collapse of the World Trade Center towers in September 2001, there has been heightened interest among building owners and government entities in evaluating the progressive collapse potential of existing buildings and in designing new buildings to resist this type of collapse. The General Services Administration and Department of Defense have issued general guidelines for evaluating a building’s progressive collapse potential. However, little detailed information is available to enable engineers to confidently perform a systematic progressive collapse analysis satisfying these guidelines. In this paper, we present four successively more sophisticated analysis procedures for evaluating the progressive collapse hazard: linear-elastic static; nonlinear static; linear-elastic dynamic; and nonlinear dynamic. We discuss the advantages and disadvantages of each method. We conclude that the most effective analysis procedure for progressive collapse evaluation incorporates the advantageous parts of all four procedures by systematically applying increasingly comprehensive analysis procedures to confirm that the possibility of progressive collapse is high. [ABSTRACT FROM AUTHOR]

The article presents a paper on the concept of accidental demolition, whereby a heavy damage sustained by a level of a building results to the eventual collapse of the upper part to the lower one in a sequence that crushes other levels in the process. It focuses on the treatment of equations of motion where few numbers are quoted relating to physical properties of the World Trade Center (WTC) towers. Comments are included to fill that gap and also to determine the applicability of this concept.

The article focuses on the article published in the July 2002, issue of the "Journal of Engineering Mechanics," on various preventive measures that could have prevented the collapse of World Trade Center. According to the author, when a lateral load hits the intermediate stories of a tall building, the vertical load transmission path gets disrupted. Consequently, the intermediate stories hang on to the undamaged top portion of the building and exert an enormous pull with their massive self-weight. Because of this phenomenon, the WTC towers had a collapse failure and this was aided by the conflagration of the aircraft fuel spilled inside the building. The conflagration due to aircraft fuel in the WTC towers apparently heated the building to a temperature of over 800°C. Obviously, the various energy-absorbing materials considered cannot withstand such a sustained temperature. The author explains the possible constructional features to prevent the collapse of tall buildings like WTC. The article also presents an acknowledgement of thanks from writers of the discussion to the article's writer to clarify their papers.

The article presents an introduction to articles published within the issue is presented, including one on a presentation delivered as part of the Brooklyn Bridge 125th anniversary celebration in 2008, and also the provides the list of 2008 Outstanding Paper Award honored by the American Society of Civil Engineers.

The article focuses on the article published in the July 2002, issue of the "Journal of Engineering Mechanics," on various preventive measures that could have prevented the collapse of World Trade Center. According to the author, when a lateral load hits the intermediate stories of a tall building, the vertical load transmission path gets disrupted. Consequently, the intermediate stories hang on to the undamaged top portion of the building and exert an enormous pull with their massive self-weight. Because of this phenomenon, the WTC towers had a collapse failure and this was aided by the conflagration of the aircraft fuel spilled inside the building. The conflagration due to aircraft fuel in the WTC towers apparently heated the building to a temperature of over 800°C. Obviously, the various energy-absorbing materials considered cannot withstand such a sustained temperature. The author explains the possible constructional features to prevent the collapse of tall buildings like WTC. The article also presents an acknowledgement of thanks from writers of the discussion to the article's writer to clarify their papers.