Civil Engineering

A simplified travel demand model that uses routinely collected traffic ground counts to forecast traffic volumes on a street system is described. It is an internal volume forecasting (IVF) model based on a model first proposed by Low in 1972, and incorporates improvements suggested by Smith and McFarlane in 1978. The model is applied to the city of Spokane, Washington. Results from this application indicate that routinely collected traffic counts in a base year can be used to estimate traffic volumes in a horizon year with reasonable accuracy. By eliminating the need for a home-interview survey, the model provides an inexpensive, quick, and transparent technique for forecasting travel in small and medium-sized cities. The model is also suggested for use in cities of less developed and developing countries because of its simplicity and low cost. The output from this model is essentially trips for all purposes. Home-based, non-home-based, and other trip categories could also be obtain...

The planning of crowded pedestrian facilities involves providing adequate capacity for all walkways, as well as designing effective schemes for crowd management. PEDSTREAM is a mesoscopic simulation-based dynamic trip assignment model for large-scale pedestrian networks. The model can represent temporospatial distribution of pedestrians and associated service levels over the network and can predict pedestrian responses to changes in design, operational conditions, and crowd management strategies. The model was used to develop a simulation platform for the Al-Mashaa'er corridor in Makkah, Saudi Arabia, which served about 3 million pilgrims in a peak period that lasted several hours. Use of the platform is illustrated for the evaluation of design alternatives under future pedestrian demand levels and proposed crowd management strategies.

This paper describes work being carried out at Nottingham University, Department of Civif Engineering towards the automating of the production of schedules of work for construction projects. An outline of the method is given followed by a detailed discussion of how the system develops the work to be carried out from the finished work which appears on construction drawings. The knowledge base used is described and results of experiments to test the system are presented. An introduction to the logical ordering of the work and the final scheduling is included but no detail is given.

The construction industry is a complex high risk business, in which the probability of conflicts is very high in comparison to other industries. The variables and unknowns are numerous, having a direct impact on the number and intensity of conflicts arising during the life span of a project. The investment in construction is too big to be left to the unknowns. Conflicts, which could sometimes be predicted, but mostly unpredictable, are a major threat to the investment of money, time, technology and reputation. Finding a simple method of analyzing the possibility and intensity of conflicts in a construction project could help decision makers on judging the feasibility of proceeding with a project. This paper describes a Conflict Forecast Model (CFM). The model presents a tabulated guideline that evaluates and studies the possibility of developing conflict in any construction project. The variables of the construction environment and the major elements of a construction project were considered throughout the defined five phases of the project life cycle.

Jeddah wastewater multi-port outfall was analyzed using CORMIX2 for average ambient conditions. The numerical analysis of the outfall shows that the near-field mixing extends 187.5 m downstream of the diffuser and the dilution at the end of near-field reaches 1,047.8. The concentration of the plume drops sharply from 100 at the exit point to 0.0954 at the end of near-field zone. In the far-field zone the reduction in concentration is gradual and will reach 0.0061 at a distance of 20,000 m downstream of the diffuser, while dilution exceeds 16,440 at this point. The plume rises rapidly due to the buoyancy and touches the water surface at a distance of 187.5 m downstream. The thickness of the plume reaches a maximum value of 37.5 m at the interface of nearfield and far-Field zones, and then it starts spreading horizontally maintaining a thickness of about 13 m over a distance of about 4 km. As the plume mixes with ambient sea water, it starts spreading again in vertical direction and fills the entire water depth at a distance of 18,927 m down stream. The plume maintains nearly a constant width in the near-field zone but spreads progressively horizontally in the far-field zone till the plume touches the left bank at a distance of 18,482.52 m downstream. The plume spreads at a distance of 2,069 m from the coastline at the end of simulation zone. It can be concluded from numerical results that if the discharged water meets local and international standards for treated wastewater, the plume will not pose any threats to the local venerable environment as the dilution is considerably high due to high exit momentum and favorable cross current.

Background A new coupled global climate model (CGCM) has been developed at the Center of Excellence for Climate Change Research (CECCR), King Abdulaziz University (KAU), known as Saudi-KAU CGCM. Purpose The main aim of the model development is to generate seasonal to subseasonal forecasting and long-term climate simulations. Methods The Saudi-KAU CGCM currently includes two atmospheric dynamical cores, two land components, three ocean components, and multiple physical parameterization options. The component modules and parameterization

— This contribution presents a numerical simulation of water temperature fluctuations in overhead water tanks commonly used in intermittent water supply systems. Two types of over head tanks with different sizes were modeled; fiberglass tank and galvanized steel tanks. The numerical calculations were based on the actual outside tank temperature measured during the summer of 2009 in the city of Jeddah, Saudi Arabia. The numerical and measured water temperatures were in a good match in both tanks. The field and numerical investigations indicate that the water temperature in overhead tanks exceeds safe and comfortable temperature range for regular use in midday hours and it is expected that a considerable amount of valuable water will be wasted as the residents draining out the hot water from the plumbing system. Besides it is quite possible that scalding in sensitive skins may occurs to some consumers. This valuable water can be saved and possible scalding can be avoided by changing t...

A 3-D finite element (FE) numerical model was used to analyze structurally a proposed subsurface concrete dam to serve as a strategic water supply storage for the Holy city of Makkah, S audi Arabia. The work was done mainly to show the behavior of the subsurface dam under the subjecting loads. The plastic concrete was chosen for the construction of the cutoff wall required for the reservoir. Three-dimensional finite element analyses were made for three thicknesses of the cutoff walls: 0.6 to 0.8 m, 0.8 to 1.0 m and 1.0 to 1.2 m for the alluvium depths of 30, 50 and 70 m, respectively. The change in soil rigidity with depth was taken into account. The vertical and horizontal boundary conditions were designed to simulate the proper behavior of the structure It was found that increasing the thickness of the wall improves the distribution of the mobilized passive pressure opposite to the water pressure acting on the upstream face of the cutoff wall, while, the vertical and horizontal stresses developed in the wall due to the applied loads increased. In addition, stresses in the wall increase incrementally with the increase of wall height. The maximum horizontal and vertical stresses developed in proportion to the 1/6 bottom height of the wall. In the lower part of the wall, the mix with rich cement content must be used. It is recommended also to use vertical reinforcement imbedded by the anchorage length in the lock of the wall inside the bedrock and extended 1/20 the wall height. Results showed that the two vertical boundaries in the FE mesh must be placed at minimum distance equaling twice the height of the alluvium deposits from the centerline of the cutoff wall.. Index Termsubsurface dam analysis, cutoff wall analysis, underground dam analysis, structural analysis of dams. I.

155705-2828-IJCEE-IJENS ©October 2015 IJENS I J E N S Abstract-Chlorination is one of the frequently used water disinfection methods in water distribution system. It has been successfully used to inactivate harmful micro-organisms and prevent the regrowth or recontamination of pathogens that might be present. However, maintaining residual chlorine besides keeping it below a certain level is essential because of concerns about formation of carcinogenic disinfection byproducts within the distribution system. The stochastic twostate random walk model is employed to solve the advectionreaction transport equation and predicts how the concentration of dissolved chlorine varies in time and space in a water distribution network. Linear non-equilibrium particle transfer from water bulk phase (State 1) to pipe wall phase (State 2) is handled using a two-state Markov-chain process with absorbing state. The model was successful when applied to a single pipe. In the current study, New Haven’s ne...

As the construction industry evolved, the need for more durable, long lasting infrastructure increased. Therefore, more efforts have been put to find new methods to improve the properties of the concrete to prolong the service life of the structural elements. One of these methods is the use of lightweight aggregate as an internal curing agent to help reducing self-desiccation and shrinkage. This research studied the effects of using locally available lightweight aggregate (expanded clay), as a partial replacement of normal weight aggregate in the concrete matrix. The concrete mixtures contained lightweight aggregate with a replacement percentage of 12.5, 25, 37.5, and 50 percent by volume. Fresh properties as well as compressive strength, modulus of rupture, and drying shrinkage were measured. While was effective in reducing drying shrinkage, the use of lightweight aggregate resulted in slightly reducing both the compressive strength and modulus of rupture.

This work investigates the possibility of improving the corrosion resistance of reinforced concrete against corrosive mediums mainly represented by chloride and sulfate ions by using polyaniline (PANi) coating. The polyaniline layer was formed using the galvanostatic technique and investigated for its composition by using X-Ray Photoelectron Spectroscopy (XPS). The potentiodynamic technique was used for investigating the corrosion resistance of the PANi coated steel while coupled with stainless steel and used for reinforcing a layer of concrete, containing different concentrations of corrosive materials such as NaCl and H 2 SO 4 the corrosion current was measured against Ag/AgCl reference electrode. The main variables investigated were the initial concentration of both Cl -and SO4 -2 and the time interval from 0 to 28 days (initial hardening period). The results showed that using polyaniline coating has improved the corrosion resistance of reinforced concrete against Cl -by a factor...

Twenty high-strength plain concrete deep beams were tested under torsion. The variables were concrete strength and depth/width (aspect) ratio; Concrete strengths of 51.01, 58.53, 76.60 and 83.66 MPa and depth/width (aspect) ratios varying from 1 to 5 were used. The tested beams failed suddenly and violently along a smooth surface. The crack inclinations on the beam surfaces were influenced by the concrete strength and aspect ratio. Test results show that by increasing the concrete strength or by reducing the aspect ratio, the torsional capacity and the beam stiffuess increases while the angle of twist decreases. A modification has been suggested to the strength equation of the ACI Code 318-8~ for normal-strength concrete shallow beams under torsion to include the effect of high-strength concrete for deep beams. The proposed equation gave .a good estimate of the experimental torsional strength. NOMENCLATURE Concrete compressive strength, psi or MPa. Modulus of rupture, psi or MPa. Splitting tensile strength, psi or MPa. The tensile strength of concrete, psi or MPa. Center-to-center span in mm or in. Span/depth ratio. Elastic failure torque, kN.m. Experimental torsional strength, kN .m. Nominal torsional strength of plain concrete beam, kN.m. Plastic failure torque, kN .m. Theoretical torsional strength, kN .m. The width and depth of the rectangular section, respectively, mm or in. Depth/width (aspect) ratio. St. Venant's coefficient which depends on Y/X and varies from 0.208 to 0.333.