Structural Analysis Programme Based on the Equivalent Column＇s Method

The focus of this article is to accomplish a program using MatLab software, which will determine the global behavior of the structure, the stress, stability and frequency of the tall building with ＂n＂ levels. The program starts with the global analyses based on the equivalent column theory. The central core consists of reinforced concrete shear walls of the elevator＇s tubes and of the staircase, design to resist the lateral loads. Applying the equivalent column＇ s theory, the bracing system will be replaced by an equivalent column, considered to be a vertical cantilever fixed at the base and the loads will be applied in the shear center axis. The program using mathematical and physical relations, has as input dates the geometrical and stiffness characteristics of the plan of the building and as output dates the critical load, the fundamental frequency, the maximum stresses and deformations of the structure.

Damage detection of frames using the increment of lateral displacement change

The method proposed in this paper is based on the fact that the damage in different types of structural members has distinctive influence on the structural stiffness. The intrinsic mechanical property of the structure is tapped and fully utilized for damage detection. The simplified model of the flexibility of frames treats the individual storeys as springs in series and the frame as an equivalent column. It fully considers the main deformation of all beams and columns in the frame. The deformation property of the simplified model accorded well with that of the actual frame model. The obtained increment of lateral displacement change (IOLDC) at the storey level was found to be very sensitive to the local damage in the frame. A damage detection method is pro- posed using the IOLDCs as the damage identification parameters. Numerical examples demonstrate the potential applicability of this method.

Estimating water storage changes and sink terms in Volta Basin from satellite missions

The insufficiency of distributed in situ hydrological measurements is a major challenge for hydrological studies in many regions of the world. Satellite missions such as the Gravity Recovery and Climate Experiment （GRACE） and the Tropical Rainfall Measurement Mission （TRMM） can be used to improve our understanding of water resources beyond surface water in poorly gauged basins. In this study we combined GRACE and TRMM to investigate monthly estimates of evaporation plus runoff （sink terms） using the water balance equation for the period from January 2005 to December 2010 within the Volta Basin. These estimates have been validated by comparison with time series of sink terms （evaporation plus surface and subsurface runoff） from the Global Land Data Assimilation System （GLDAS）. The results, for the period under consideration, show strong agreement between both time series, with a root mean square error （RMSE） of 20.2 ram/month （0.67 mm/d） and a correlation coefficient of 0.85. This illustrates the ability of GRACE to predict hydrological quantities, e.g. evaporation, in the Volta Basin. The water storage change data from GRACE and precipitation data from TRMM all show qualitative agreement, with evidence of basin saturation at approximately 73 mm in the equivalent water column at the annual and semi-annual time scales.

The equivalent circuit of ultrasonic coupling vibration of a longitudinally-excited short column

On the basis of apparent elasticity method, we derived the equivalent circuit of coupling vibration of a short column and discussed its frequency equation and the effects of the load impedance on the resonant frequency of the short column. By the equivalent circuit, we calculated the input mechanical impedance of the longitudinally-excited short column and the curves of the apparent vibration velocity ratio versus the geometrical dimensions of the column. It shows that the equivalent circuit method is a simple and convenient one to analyze and calculate the coupling vibration of the short column.