No abstract

No abstract

The Shanghai Tower, currently being constructed in Shanghai, China, is a supertall building with a height of 632 m. The Shanghai Tower will be the tallest skyscraper in China after its completion. This structure consists of a core wall inner tube, an outer mega-frame, and a total of six levels of outriggers that connect the tube and the frame.The structure needs comprehensive full-scale investigation to understand its structural performance when subjected to dead loads, strong winds, earthquakes, and temperatures, given its supertall height and complex structural configuration. A sophisticated structural performance monitoring system that consists of more than 400 sensors is designed for both in-construction and in-service real-time monitoring of the skyscraper. This is the Pre-Published Version.This paper reports the structural system and provides details on the performance of the monitoring system. The key features of the monitoring system are the following: (1) simultaneous installation of sensors and data acquisition systems with structural construction to record initial values; (2) measurement of structural settlement and displacement at different construction stages; (3) direct measurement of wind loads on structure facades through 27 wind pressure sensors; and (4) measurement of structural inclination and derivation of structural sway at different heights using 40 inclinometers.Preliminary monitoring data, which include deformation and strain/stress up to the present construction stage, are also presented and discussed.

No abstract

A nonlinear dynamic model of a spur gear transmission system is developed with consideration of gear mesh stiffness, backlash, internal and external excitation. Lagrange equation is used which is derived for the vibration of the drive system differential equations. Time process diagram, frequency spectrum and phase diagram of the spur gear pair system are obtained by using the numerical method. The gear dynamic behaviors are analyzed and the influences of backlash and damping coefficient are given quantitatively. The statistic analysis shows that: the response of the drive system amplitude increases, the enhancement of vibration with the increase of backlash. The solution to the problem provides a reference for inherent characteristic and dynamic response for wind turbine gearbox transmission system.

No abstract

Excessive and unexpected settlement of supertall buildings during the construction stage may affect structural safety. Floor settlement monitoring is imperative during the structural construction. The current practice is to measure floor settlement within a specific time frame and then compensate for the elevation error in the next construction stage. This posterior manner is inaccurate because it does not take account of measurement error and the real settlement in the next construction stage. This paper presents a Kalman filter based settlement monitoring approach with the aid of forward construction stage analysis. The settlement of floors in the next stage is predicted with the forward construction stage analysis. Consequently the elevation of the floor to be constructed can be pre-determined. The proposed method is demonstrated through construction settlement monitoring of the 632-m tall Shanghai Tower. The structure will be the tallest supertall building of China upon completed in 2014. It shows that this method can improve the accuracy of pre-determined elevation of supertall buildings.

No abstract