Dissertations/Theses - Department of Civil Engineering
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Item Investigation of the behaviour of soil-steel structure(Department of Civil Engineering, 1985-06) Rezaul Karim, Md.; Azadur Rahman, Dr. M.For abstract please see full textItem Effect of metal strip reinforcement on bearing capacity of strip footing on sand(Department of Civil Engineering, 2003-05) Rezaul Karim, Md.; Saiful Alam Siddiquee, Dr. Md.This study has been carried out to investigate the effect of metal strip reinforcement on bearing capacity of strip footing resting upon sand deposit. The sand bed consists or horizontally placed metal strip reinforcement in one layer, two layers and three layers. Model tests were conducted to investigate the bearing capacity and settlement or strip footing in two different speed of loadings. The experimental set-up has been modified and re-modeled. All of the measuring devices were connected to a computer through the data-Logger. The out of plane deformation or the loading frame was eliminated by using vertical-ball-bearing system at the mid-level guide-beam. Tests were carried out in a tank on beds or sand having average densities varying from 14.67 kN/m3 to 15.78 kN/mJ . The sand bed thickness was maintained to 3.<) times the least dimension of the footing. Strain controlled vertical loads were applied on the footing placed on the surface or sand bed. The effect of number of reinforced layer, effect of speed on bearing capacity arc studied. The results arc established, discussed and compared among different layers or reinforcement and two rates of speeds. From the experimental result for the case or reinforced sand bed, it is observed that the bearing capacity of the footing increases significantly compared to an unreinforced bed. In most or the tests, it is observed that with the increase in number of the layers of reinforcement, bearing capacity has been improved. Due to change in speed of loading the bearing capacity and settlement have been affected. The results also indicate that for slow speed, bearing capacity was or higher value than that of higher speed of loading. On the other hand, settlement due to slow speed or loading is lower than that or higher speed of loading. In most of the cases, the bearing capacity II1creases with the increase or metal strip reinforcell1enl. In some cases the results show, opposite trend. For unreinforced bed, failure outcrop arises on the sides which distance of 2B to 3B from the edges of footing. III the case of reinforced bed or sand, failure pattern was not very e1ear at 20%, settlements.Item Development of a water quality model using finite segment method(Department of Civil Engineering, 1996-09) Rezaul Karim, Md.; Badruzzaman, Dr. A. B. M.Mathematical models have gained wide acceptance as invaluable tools to support the effective management of impacted rivers and lakes. Simulation of water and pollutants kinetics and movement are the key processes in the water quality modelling. The process has proved to be a reliable and economic method of assessing water quality of surface water. The basic concept underlying the development of a water quality model is the formulation of appropriate mass transport equations. In this study, the finite segment method was used to develop the one dimensional water quality model. The advective dispersive transport phenomenon of the mass transport equation was addressed by the well-established Water Quality Analysis Simulation Program (WASP), developed by the USEPA. The kinetic phenomenon involving phytoplankton, nitrogen, phosphorus and dissolved oxygen in the water column was developed in a kinetic module using FORTRAN 77 computer language. The basis of the kinetic transformations was adopted from literature. The model was applied to the lower reach of the river Sitalakhya to test the model performance. The model was calibrated and verified for the low flow period. Field data were collected to substantiate the calibration and verification process. However, the lack of recorded data during that period prompted the use of a hydrodynamic model to simulate the ".. low flow hydrodynamics. The model reproduced the system behavior reasonably, thereby substantiating the validity of the model. Sensitivity of the model was analyzed to determine the effects of different key kinetic parameters on the spatial distribution of the water quality constituents. Model results indicate that the river contains an abundance of nutrients. Lower light penetration resulting from high level of turbidity limits the algal growth under low flow conditions. Most concentration profiles do not show much spatial variations in the longitudinal direction. River flows dominate the kinetics in the water column and uniform mixing caused the water quality parameters uniformly distributed along the river. The dissolved oxygen concentration remains above the critical level, indicating that the water is still suitable for the survival of aquatic life including fish. Some water quality parameters. such as ammonia nitrogen, suspended solids and carbonaceous biochemical oxygen demand (BODs) are at a critical state. Although their steady state concentrations remained above the recreational and fishing standards, set by the Department of Environment, immediate pollution control and waste management measures are needed to prevent further deterioration. . The model indicates that the effluent loadings from the major point sources have minor effect on the overall spatial distribution of pollutants. The enormity in the width of the river usually represents a well mixed condition at the mid stream of the river for one-.sided discharge, prompting the need for a well defined three dimensional water quality model for the system. The model can be used for waste load allocation and for addressing policy issues regarding existing and future industrial and urban development. The model is a generalized program addressing nutrient transport and kinetics interaction of phytoplankton, nitrogen, phosphorus and dissolved oxygen in river system. It can be applied to any river system in Bangladesh with appropriate calibration and verification.