Development of optimal location and design capacity of wastewater treatment plants for urban areas: a case study in Samawah city

Water, and related wastewater structures, are critical factors in the existence and the improvement of civilizations. Wastewater gathering and management has a considerable effect on the climate and economy at both regional and global level, and, accordingly, it is appropriate to advance actions that guarantee effective management for wastewater, particularly in urban areas. This research thus examined the environmental and economic aspects of proposed locations for wastewater treatment plants. Samawah city, located in the southern part of Iraq, was selected as a case study for the research methodology, and for research purposes, the studied city was divided into three main zones (1, 2, and 3) of sixteen areas. The Google Earth tool was used to calculate the lowest elevations in the studied zones in order to assess the suggested positions of treatment plants. Additionally, the WinQSB program was utilised to select the most appropriate positions for treatment plants based on data obtained from local government departments. These data include population, water consumption, and required lengths and subsequent cost of pipes. This research thus developed a new strategy for assigning the locations of wastewater treatment plants

Optimum design of composite prestressed concrete girder railway bridges

This paper deals with the formulation of design optimisation of pretsressed concrete bridges. The bridge is of a slab-on-girder type, hence modeled as an equivalent orthotropic plate. The whole bridge system is considered as a simply supported right angle plate. Following linear elastic behaviour, the governing fourth order differential equation of the plate for patch load is solved in order to find out load distribution on the girders forming the bridge as well as the deflections and internal forces at critical sections of the whole bridge. The optimisation problem is formulated for various cross sectional geometries including rectangular, symmetrical I, unsymmetrical I, box, T and inverted T sections. The design variables are the main cross sectional dimensions, prestressing force and tendon eccentricity. The objective function comprises the cost of concrete material, formwork and prestressing steel tendons. The constraint functions are set to satisfy design requirements as per British Standards for bridges (BS 5400). Nonlinear optimisation method based on sequential unconstrained minimisation technique (SUMT) is employed to achieve optimum bridge configuration for specific design parameters of span length, concrete compressive strength and railway loading patterns. A purpose built computer program is set up to carry out the solution of the design optimisation problem efficiently in terms of time and effort. A typical example of unsymmetrical I-section having a small bottom flange as compared to the top flange width with composite deck effect is presented. The results show that the total cost increases as the span increases due to the increase of the initial prestressing force. Furthermore, the total cost decreases as the concrete compressive strength increases in spite of the increasing of the prestressing force. This is due to decrease of the overall depth, top and bottom flange widths, hence leading to a smaller girder size. Such finding will encourage engineers to adopt high strength concrete for bridges as it will help reducing not only the initial cost but also the life cycle cost of the bridge over its entire life