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Temporal Evolution of Local Scour Depth around Side-by-side Piers Original Article, C13 Movahedi,.N, Dehghani, A. A., Arabi, M.J., Zahiri, A.R Journal. Civil Eng. Urban. 3(3): 82-86. 2013 ABSTRACT:Due to geotechnical and economic considerations, bridge designs often lead to use complex piers or pier groups. The estimation of temporal evolution of scour around bridge pier is important for design of bridge foundation. This study focuses on temporal variation of scour depth around two side-by-side piers with various distances between piers. Based on experimental data, an equation was developed based on new definition of equivalent pier diameter in Kothyari et al. (2007) equation for estimating the time evolution of scour depth by taking into account the effect of space between the piers. The results show that good agreement exists between proposed equation and measured scour data. It is also revealed that by increasing the distance between piers, the equilibrium scour depth around side by side piers decreases and close to values of single pier and scour depth reached to the isolated pier when G/D=6. Keywords:Temporal Evolution; Scour Depth; Side By Side Piers, Equivalent Pier Diameter منبع: [Hidden Content] دانلود: [Hidden Content] JCEU-C3-14.pdf

Determination of the Most Important Parameters on Scour at Coastal Structures Original Article, B12 Yeganeh-Bakhtiary A, Ghorbani MA and Pourzangbar A. Journal. Civil Eng. Urban. 2(2): 68-71. 2012. ABSTRACT: Scour at coastal structures is one of the major problems that may lead to their failure. Therefore, predicting accurate scour depth at coastal structures is important. Extensive laboratory studies have been conducted predicting the maximum scour depth. These studies have developed their formulas using the limited set of effective input parameters. This study presents an alternative to the conventionally regression-based equations in the form of genetic programming (GP) in order to predict the maximum scour depth at coastal structures under the action of breaking waves. To determine the effective parameters, different models with various combinations of input parameters were considered. Parameters such as reflection coefficient, relative water depth at the toe of the structure, the serf similarity parameter, Shields parameter and breaking wave steepness and the wave breaking depth were found to be best inputs. 46 data sets compiled from published literatures were used to train and test the networks or evolve the models. Statistical parameters including the root mean square error, determination coefficient, scatter index and BIAS are used to measure their performance. The results indicate that relative water depth at the toe of the structure plays a crucial role in the scour process. Keywords: Coastal structures; breaking waves; Genetic programming; Scour depth; Regression-based equations. منبع: [Hidden Content] دانلود: [Hidden Content].,B12-68-71.pdf J. Civil Eng. Urban.,B12-68-71.pdf