JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2003 | Volume:28 | Issue:3 (30) Civil Engineering|Papers Count:7

In the present study, stream tube model for alluvial river simulation has been applied for reservoir sedimentation of storage dams and a case study has been performed on kardeh dam reservoir. The obtained results have been compared with the hydrography survey held in 1995 on the site of this dam reservoir and also compared with results obtained by the Hec-6 model. The comparsion has shown that the model has efficiency and characteristics of a one dimensional mathematical models and it is more accurate because of considering semi two dimensional conditions of the flow. Also in the application of this model for reservoirs the nonequilibrium sediment transport has been used because of the importance of spatial - delay and/or time-delay. The high sensivity of this model has been shown for recovery factor of deposition and entrainment. The calibration of the model with the performed hydrography in the reservoir of kardeh dam has been shown. If the sedimentation process continues in this manner during the next, 30 years period, 70 percent of the reservoir capacity will be filled with sediment.

In this paper the most important character of saddlebag type connection which is the moment - rotation relation has been driven based on the dimensions of its constitutive angles. An analytical model with three parameters has been chosen to present the moment - rotation relationship. The two first parameters are respectively the initial stiffness and ultimate moment capacity of the connection, the third one (shape parameter) has been determined by the least square method. Finally considering the test results and mathematical equations a practical method is proposed to determine the rigidity of all saddlebag type connection.

Dynamic soil-structure interaction problem during earthquakes is a very important topic in the analysis of the dynamic behaviour of civil engineering structures. A suitable method is the finite and infinite elements coupled model. In this method the seismic waves propagating from far field (epicenter) are transformed into nodal dynamic loads acting on the common boundary between finite and infinite elements where the reflected waves from foundation surface and structure can be transmitted back into the far field through the finite and infinite elements coupled system. In this paper the method of damage analysis of masonry structures during earthquakes and obtained results are presented. In this investigation the masonry structure is discretised into finite elements. These elements are coupled with infinite elements that are used to model the infinite soil medium. The examples presented indicate the usefulness of the present method in engineering practice.

Sediment transport considerations IS an Important part of analysis and design of any open channel hydraulic system Sediment transport can change the hydraulic system considerable:- and often dictate special design conditions. Many transport features, such as aggradations, degradation and scouring have been investigated by numerous researchers and many empirical relationships and formulas have been developed. In this research a mathematical model is presented for studying aggradations and degradation in alluvial channels. One – dimensional, unsteady, gradually varied flow equations (Saint- Venant equations) and the sediment continuity equation are solved numerically by the second – order, accurate, explicit finite difference scheme developed by Mac Cormak. All three governing equations are solved simultaneously during any computational time step so that the water - flow equations and sediment continuity equation are coupled. For this purpose Adji -chai rivers data in the Nahand station, with three Sediment discharge equations (Engelund -Hansen, Hassanzadeh, and Graf) are used and finally some results about the capability of model are obtained.

Waterhammer phenomenon caused by pump failure and the sudden change of discharge and consequently the flow velocity, creates the sudden variation of pressure and initiates the upsurges and downsurges along the pipeline. If this abnormal pressure change does not control and adjust with an appropriate equipment, it may occur the destructive problems along the unprotected system. In this paper, by developing a computer program and using the method of characteristics, the governing equations of waterhammer phenomenon, on Nahand - Tabriz pumping station, as a case study, have been analyzed and the appropriate dimension of air chamber to control the surges has been calculated. It is shown that without using this control device, due to path convexity of discharge pipeline, the cavitation phenomenon may occur intensively along the pipeline.

Sediment accumulation in reservoirs of storage dams and methods of sediment removal are significant for reservoir operation planning and increase of the dam useful life. Flushing of sediments in reservoirs is considered as one of the most important methods of sediment removal because the energy of the water flow is utilized to remove accumulated deposits. In this paper a one-dimensional mathematical model has been developed to simulate the process of sediment flushing. The model is able to predict reservoir bed profile variation during the process of flushing. The developed differential equation has been solved by the finite difference method using the control volume approach. The calibration of the model has been done by using results obtained by other researchers and then it was validated for the reservoir of Dashidaira dam. The agreement of the results obtained from the developed model has been compared with those obtained from other models.