			Home About us Contact

Tall Buildings (tall + building)

Distribution by Scientific Domains

Engineering	60%

Selected Abstracts

A reduced-order modeling technique for tall buildings with active tuned mass damper

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2001
Zu-Qing Qu
Abstract It is impractical to install sensors on every floor of a tall building to measure the full state vector because of the large number of degrees of freedom. This makes it necessary to introduce reduced-order control. A kind of system reduction scheme (dynamic condensation method) is proposed in this paper. This method is iterative and Guyan condensation is looked upon as an initial approximation of the iteration. Since the reduced-order system is updated repeatedly until a desired one is obtained, the accuracy of the reduced-order system resulting from the proposed method is much higher than that obtained from the Guyan condensation method. Another advantage of the method is that the reduced-order system is defined in the subspace of the original physical space, which makes the state vectors have physical meaning. An eigenvalue shifting technique is applied to accelerate the convergence of iteration and to make the reduced system retain all the dynamic characteristics of the full system within a given frequency range. Two schemes to establish the reduced-order system by using the proposed method are also presented and discussed in this paper. The results for a tall building with active tuned mass damper show that the proposed method is efficient for the reduced-order modelling and the accuracy is very close to exact only after two iterations. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Solar Ultraviolet-B Radiation in Urban Environments: The Case of Baltimore, Maryland,,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2004
Gordon M. Heisler
Ultraviolet-B radiation (UV-B, 280,320 nm) has important effects in urban areas, including those on human health. Broadband UV-B radiation is monitored in Baltimore, MD, as part of the Baltimore Ecosystem Study, a long-term ecological research program. We compare broadband UV-B irradiance in Baltimore with UV-B at two nearby locations: a more rural station 64 km southeast and a suburban station 42 km southwest. The monitoring station in Baltimore is on the roof of a 33-m-tall building; there are no significant obstructions to sky view. The U.S. Department of Agriculture UV-B Monitoring and Research Program provided all sensors, which were calibrated at the National Oceanic and Atmospheric Administration Central UV Calibration Facility. UV-B irradiances at the three sites generally were similar. Over all conditions, Baltimore and the suburban site measured 3.4% less irradiance than the rural site. This difference is within the anticipated ±3% calibration uncertainty of the pyranometers. On 59 days with cloud-free conditions at all three sites, average differences in measured UV-B among the three sites were even smaller; Baltimore measured 1.2% less irradiance than the rural site. High aerosol optical thickness strongly reduced daily UV-B dose, whereas [SO2] had no influence. Surface O3 increased with increasing UV-B dose when [NO2] exceeded 10 ppb. [source]

A reduced-order modeling technique for tall buildings with active tuned mass damper

Nurses' perception of disaster: implications for disaster nursing curriculum

JOURNAL OF CLINICAL NURSING, Issue 22 2009
Fung WM Olivia
Aims and objectives., The aims of the study were to identify nurses' perception of disaster, whether they considered some of the events that have occurred in Hong Kong to be disasters and the types of disastrous events that they considered likely in Hong Kong. Background., The frequent occurrence of disasters has caused concern internationally. When disaster strikes, the demands on nursing staff are much higher than those on other healthcare professionals. There is little understanding of the concept of disaster among nurses in Hong Kong. Design., This was a descriptive study. A questionnaire was used to explore nurses' perception of disaster. Method., The questionnaire was distributed to all registered nurses studying in a master's degree programme in a university in Hong Kong. Findings., Only 123 out of the 164 respondents (75%) gave a description of disaster in the open-ended question. Sixty-one per cent of them described unfortunate events with large numbers of victims as disasters. The ,Lan Kwai Fong tragedy , stampede caused by over-crowdedness' (90·9%) and the severe acute respiratory syndrome outbreak (89·6%) were commonly referred to as disasters in Hong Kong. Fires in tall buildings (61·6%), infectious disease outbreaks (61%) and stampedes caused by overcrowding (48·8%) were rated as the events most likely to happen in Hong Kong. Conclusion., Understanding how nurses perceive disaster and the likelihood of disastrous events is the initial step for disaster planning and the development of a disaster nursing curriculum in Hong Kong. Relevance to clinical practice., All nurses around the world should be equipped with knowledge and skills for disaster care. This study provides information and implications for related research and the development of a disaster nursing curriculum to meet the global demand for disaster preparedness. [source]

Knotengestaltung hybrider Fachwerkkonstruktionen , Entwicklung neuartiger Tragwerkskonzepte unter Verwendung von Ultrahochleistungsbeton (UHFB)

BAUTECHNIK, Issue 5 2006
Nguyen Viet Tue Prof. Dr.-Ing. habil.
Fachwerkkonstruktionen zählen zu den leistungsfähigsten raumbildenden Strukturen der Baugeschichte. Rein normalkraftbeanspruchte Bauteile zeichnen sich vor allem durch minimalen Werkstoffaufwand aus. Die Einsatzgebiete von Fachwerken sind so vielgestaltig wie deren Ausführungsformen selbst. Gerade in den letzten Jahren gewinnen Fachwerkkonstruktionen z. B. beim Bau transparenter Hochhäuser oder für Stadien und Veranstaltungsarenen und vereinzelt auch wieder im Brückenbau, verstärkt an Bedeutung. Mit finanzieller Unterstützung der Bilfinger | Berger AG wurde an der Universität Leipzig ein stabförmiges Verbundbauteil aus einem stahlummantelten ultrahochfesten Beton entwickelt. Das neue Tragelement kennzeichnet sich durch seine hohe Tragfähigkeit unter Druckbeanspruchung sowie großer Duktilität. Dieser hybride Verbundstab stellt, einschließlich einer innovativen Knotenlösung, eine sinnvolle, wirtschaftliche und vor allem architektonisch ansprechende Alternative zu den herkömmlich konstruierten Fachwerken, dar. In diesem Beitrag wird über die Besonderheiten dieser Konstruktionsform sowie über die Entwicklung geeigneter Knoten berichtet. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Design of joints for hybrid truss structures. Truss constructions belong to the most efficient spatial structures in building history. Purely longitudinal stressed members are characterized by a minimum material expense. The application areas of truss members are as multiform as their embodiment. Recently, truss constructions increase importance due to their application within transparent tall buildings, stages, arenas, bridges etc. With the financial support of Bilfinger | Berger AG, at the University of Leipzig a bar-shaped composite member was developed using a steel-encased Ultra High Performance Concrete (UHPC). This new structural member is distinguished by its high load carrying capacity under compression stress as well as high ductility. Including an innovative joint solution, this hybrid composite bar is a reasonable, economic, and above all, an architectural appealing alternative to a conventionally designed truss structure. In the following contribution, some features of this member and the development of appropriate joints are described. [source]