Two five-node rectangular elements are developed for analyzing two dimensional infinitesimal elastic strain problems. Several optimization criteria are elaborated, based on strain gradient notation. By utilizing these criteria and satisfying the equilibrium conditions, the SSDD and SSDI elements are formulated. Two additional five-node rectangular elements are also developed by using the traditional displacement approach. The robustness and accuracy of these four elements are assessed via numerical examples. The findings of the paper demonstrate the advantage of the SSDD and SSDI elements over the others. Moreover, these elements are free of the parasitic shear error.
SENSITIVITY OF THE FAO-PENMAN MONTEITHREFERENCE EVAPOTRANSPIRATION EQUATION TO CHANGE IN CLIMATIC VARIABLES IN THE NORTH-WESTERN IRAN
Response modification factor is one of the seismic design parameters to know the nonlinear performance of building structures during strong earthquakes. As such, relying on this factor, many seismic design codes lead to reduce the structural loads. The current paper tries to evaluate the response modification factors of conventional eccentric braced frames (EBFs). Since, the response modification factor depends on ductility and overstrength, the static nonlinear analysis has been performed on building models including type three length of link beam, with 3, 5, 7 and 10 stories and with different brace configurations (open chevron invert V and open diagonal bracing), Further, the linear dynamic and incremental nonlinear dynamic analysis was performed on building models under San Fernando, Cape Mendocino and Northridge strong ground motions for modification of the nonlinear static analysis results. The results indicated that the response modification factors for open diagonal eccentric braced frames were higher than the open chevron eccentric braced one. It was also found that the length of link beam and the height of buildings have had greater effect on the response modification factors.
DEVELOPMENT OF SYNTHETIC UNIT HYDROGRAPH USING PROBABILITY MODELS
Mohammad Ali Ghorbani, Mahsa Hasanpour-Kashani, Saba Zeynali
Use of probability distribution functions (pdfs) in deriving synthetic unit hydrographs (SUHs) has received much attention because of their similarity with unit hydrograph properties. In this study, the potential of four pdfs, i.e., two-parameter Gamma, three-parameter Beta, two-parameter Weibull and one-parameter Chi-square distribution to derive SUH are compared with traditional synthetic methods, i.e., SCS method and Snyder method using field and simulated data in Lighvan catchment, Iran. The distribution parameters are computed using numerical methods by programming in Mathematica. Based on visual comparison as well as statistical measures, such as square root of error (STDER), root mean square error (RMSE), coefficient of determination (R2), and weighted error, it was found that the Gamma and Weibull distributions yield SUHs precisely using the field and simulated data, respectively. The Gamma, Beta and Weibull distributions were more flexible in preserving SUHs shape than the Chi-square. All of the pdfs outperformed the traditional methods.
NEED TO CRITERIA FOR THE EVOLUTION OF PERFORMANCE AND CATEGORIZE MODELS IN HYDROLOGY
Hadi Delafrouz, Abbas Ghaheri, Mohamad Ali Ghorbani
A lot of models have been developed from the past until now to analysis rainfall-runoff process and the complexity of the models are increasing. Artificial Intelligent technique is one of the most developed methods as a branch of computer science. In these methods, ANN is widely used among those which are employed alone or in combination with others. In this study, daily runoff time series of 60 stations from different parts of Iran are simulated using both auto regressive moving-average (ARMA) as a simple and classic model, and ANN as an advanced model. The results indicate that in most of the time series, there is no significant difference between the results of two models. In the absence of clear criteria for evaluating the model performance to prediction, only complexities of the models were added daily. There has been no significant change in the results of the models and both of the models encountered problems with the prediction of some datasets.
NUMERICAL INVESTIGATION OF ANGLED BAFFLE ON THE FLOW PATTERN IN A RECTANGULAR PRIMARY SEDIMENTATION TANK
It is essential to have a uniform and calm flow field for a settling tank with high performance. In general, however, the circulation zones always appear in the sedimentation tanks. The presence of these regions may have different effects. The non-uniformity of the velocity field, the short-circuiting at the surface and the motion of the jet at the bed of the tank that occurs because of the circulation in the sedimentation layer, are affected by the geometry of the tank. There are some ways to decrease the size of these dead zones, which would increase the performance. One is to use a suitable baffle configuration. In this study, the presence of baffle with different position and angle has been investigated by computational modeling. The results indicate that the best position and angle of the baffle is obtained when the volume of the recirculation region is minimized and the flow field trend to be uniform in the settling zone to dissipate the kinetic energy in the tank.
WAVELET BASED NOISE CORRECTIONS OF STRONG GROUND MOTION ACCELEROGRAMS: AN APPLICATION TO EARTHQUAKE DISCRETE TIME SERIES DATA RECORDED FROM THE 2011 JAPAN EARTHQUAKE
The analysis and design of any structure, subjected to earthquake vibration depends on the processed and denoised ground accelerograms. Filtering and Fourier based processing is the traditional processing technique practiced by the seismic and earthquake research community for the past few decades. In recent years wavelet based processing of accelerograms has attracted the researchers of seismology and earthquake engineering community, to use the wavelet processed accelerograms for further earthquake engineering applications. This article aims in processing the highly noisy accelerograms of the Japan Sendai earthquake of magnitude 9.0. Processing of noisy accelerograms of such high magnitude is challenging and wavelet transform has been succeeded in processing such challenging accelerograms. The three acceleration components of the station IBR 003 is used for this study. The accelerograms are processed and analysed for the determination of its magnitude characteristics at all possible levels of decomposition in wavelet domain.