JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2006 | Volume:32 | Issue:1 (42) CIVIL ENGINEERING|Papers Count:6

The main fraction of embankment dam settlement occurs during construction and first impounding period. Estimation of magnitude of this settlement, prior to construction, is highly important in design and safety control of embankment and appurtenant structures. In order to evaluate the precision and accuracy of Mohr- Coulomb and soft soil creep models in estimation of embankment settlement, Alavian dam was selected as a well constructed and monitored case. The features of mentioned models and the dam under study have been explained in brief. The parameters required for analyses were provided screening laboratory and field test results. Then the during construction settlement profiles were established using Mohr- Coulomb and soft soil creep models through PLAXIS software and compared with those of obtained by direct field measurements with settlement meters. It was disclosed that, in general, the estimated settlement profiles are in agreement with that of field measurements. The predicted maximum settlement using both models, occur at 1/3 of embankment height which is coincident with field measurements. With Mohr-Coulomb model acceptable agreement is observed between the predicted and field measured settlements in short term. However, as time passes the field measured profiles precede the predicted values. With soft soil creep model, however, agreement between the predicted and field measured values is quite encouraging all through the construction period.

One of the most significant problems in the dynamic behaviour of industrial structures is the effect of impulsive loading of industrial machinery on the instability of these structures. In design codes, the effects of impulsive loading have been represented by appropriate coefficients in order to transform the dynamic loads into the equivalent static loads. However due to the dynamic nature of impulsive loads, investigation into the instability behaviour of these structures should be undertaken considering the dynamic instability criteria. In the present paper, dynamic instability behaviour of three dimensional industrial space structures subjected to the impulsive loading of industrial machinery, set up in the first floor of these buildings, have been investigated using (geometric and material) nonlinear dynamic analysis. The half- sine- wave, triangular and rectangular impulsive loads with different time duration as well as step loading have been used to apply the impulsive effects of industrial machinery on this type of structures. The obtained results from the nonlinear dynamic analyses have been used to compare with the design criteria presented by design codes and some recommendations have been suggested to modify the design of these structures.

In this research, hydraulic effects of canal control - gates operations have been simulated using hydrodynamic model. A few tests were performed with four slide gates in the laboratory canal equipped by sensitive instruments for measuring and saving the time variation of the water depths. The measured depths were compared with the hydrodynamic model simulation results. Average error of the model estimation along the canal was 0.60% for gradually opening changes and 3.74% for sudden opening changes of the control gates. The results showed that the hydrodynamic model based on the implicit F.D.M of the unsteady flow equations would be able to simulate the gradually operation of control gates with good accuracy. This model can be used for different purposes such as design of control systems in water conveyance canals.

Use of waterglass in concrete is limited to shotcrete for vertical faces and over head in tunnels. This material influences the time of setting and also the strength of concrete. In this study, the compressive and tensile strength and the modulus of elasticity for 7, 28 and 90 days old concrete specimens were determined. A total of 216 concrete cylindrical 150×300 mm specimens using 12 different concrete mixes with water- to- cement ratios of 0.4, 0.5 and 0.6 and waterglass- to- cement ratios of 0.0, 0.03, 0.06 and 0.09 were tested. Due to chemical reaction between sodium silicate (waterglass) and concrete ingredients, adhesion of concrete mix occurred before initial set of concrete. It was observed that adding waterglass to concrete causes a reduction in compressive and tensile strength, however the ultimate strain at failure increases, leading to a more ductile concrete.

Because of importance of bridges in lifelines, damage evaluation of bridges in earthquakes and strengthening methods is most important object in scientific researches. This study is intended to evaluate and compare two methods that provided by FEMA 273 guidelines and UCSD test results. These two methods was compared in two models (steel & concrete bridge) with analytical procedure (using nonlinear static procedure/capacity spectrum method). Analysis was performed using two levels of seismic load intensities: Design Base Earthquake (DBE) & Maximum Considerable Earthquake (MCE). In final, NSP method compared with nonlinear time history analysis that is most accurate procedures for evaluation of nonlinear response of structures.

The deep and correct education of rainfall- runoff modeling can be a reliable way to overcome on huge risk of flood disaster. In this paper after introducing liquid analog model as a new hydrological analog model in which is established on the basis of linear reservoir model, the circumstances of its scaling and construction in the laboratory are originally described, then its applications for laboratory simulation of Nash’s rainfall- runoff model, the effect of the watershed shape on the output hydrograph and the response of a watershed to the storm movement direction are extensively discussed. Consequently, due to simple structure, visible property and convenient operation of liquid model, it can be considered as an educational instrument in hydrology.