Journal of Engineering and Sustainable Development (JEASD)

Sometimes in building and construction projects, the sub-contractor may bring a claim made by the main contractor or the employer against the contractor, and then the latter will often seek to settle this claim. The case "John F Hunt Demolition Ltd v ASME Engineering Ltd [2007] EWHC 1507 (TCC)" , which was under the Joint Contracts Tribunal (JCT), provides an example of this situation when the contractor (as sub-contractor in this case) settles the employer’s or main contractor’s claim, and then claims against his sub-contractor (as sub-subcontractor in this case) to recover these sums. This research is undertaken to discuss contractual issues connected to the above mentioned case, and to appraise the legal liabilities that associated with its contractual failure, and then it will appraise those liabilities under the NEC3 form of contract in order to enhance an interpretation of the NEC contracts and provide evaluation of legal implications under different legal provisions.

In this paper, the position control of frame work( disk-drive system) using proportional-derivative fuzzy sliding mode is proposed. First, the mathematical model of D.C motor and related components of the whole system is derived, model reduction technique is used to simplify the transfer function, then a designed classical controllers, like proportional-derivative(PD), linear quadratic regulator(LQR) are investigated, finally PD-fuzzy sliding mode control is derived with minimal rules for fuzzy is derived to compensate the uncertainties , which occur in the control, in which fuzzy logic control is used to compensate the chattering from applying the sliding mode control. The numerical validation results of the proposed scheme have presented good performance in transient and steady-state behavior (improving settling time and maximum overshoot) compared to the conventional controllers. So sliding mode fuzzy control is superior when compared with other controllers in terms of control performance. Various control schemes are then compared with each other. Simulations are carried out by using MATLAB.

The need to produce high performance concrete led the researches to try to exploit the potentialities of natural or artificial materials in order to modify the performance of cement and concrete by adding steel slag to cement .Slag has been used as addition materials to cement in ratio (20%, 40%, 60%, 80%) of cement weight, since its main oxides are similar to those of cement. In this investigation, the effect of steel slag in physical and mechanical properties of mortar was studied including finesses, consistency, initial and final setting time as well as compressive strength of mortar in 7, 28 days and absorption in (28,7)days. Results demonstrated that the addition 40% slag of total weight of cement to mortar showed increase in compressive strength and superior performance at 40% slag adding to total weight of cement. Where the compressive strength after (90) days becomes (52MPa) and the reduction in water absorption in all case except at 80% of slag addition case becomes approximate equal to reference mortar.

The article presents an experimentally investigation on turbulent flow and heat transfer behaviors in a dimple square duct fitted with inline angled baffles having a constant length for two pitch ratio , (PR= PB/a=0.83and 1.66), and three attack angle, α=45◦,60◦ and 90◦. The inline angled baffles are mounted on the lower channel walls to create longitudinal vortex flows throughout the test duct . The tested duct has a constant wall heat flux condition. The experiments are carried out by varying airflow rate in terms of Reynolds number ranging from 3900 to 18750. The experimental results are compared between the duct with inclined baffles and the dimple smooth duct. The duct fitted baffle gives higher heat transfer rate and friction factor than the smooth duct. The experimental results reveal that the maximum heat transfer is at PR= 0.83. For the given conditions, the maximum thermal performance enhancement factor (TEF) of the inline -angled baffle with 30◦ is found to be about 2.4 at PR= 0.83 and Re= 3900.

This research is an experimental study to evaluate the effect of lap splice of high-strength steel bars in reactive powder concrete beams exposed to repeated loading. Seven Reactive Powder Concrete (RPC) beams whose tension steel bars were spliced at mid-span and one RPC beam without lap splice were casted and tested. These beams were simply supported and tested up to failure under the action of two point loads (two beams exposed to monotonic load and five beams exposed to repeated load). The studied parameters were : the repeated loading regime (two different repeated loading regime depending on the minimum to maximum applied load),the lap splice length ( 20 and 30 times diameter of bar diameter), the concrete cover thickness (30mm and 40mm) and adding steel stirrups within the lap splice region. The mid span deflection as well as cracks propagation were recorded for each load step in tested beam. The main results showed that the adopted spliced length of tension steel bars was sufficient in monotonic load but insufficient under the action of greater number of cycles of the repeated load.

This work is concentrate on removal of some environmentally relevant contaminants, such as nickel ions from simulated wastewater by sawdust low- cost natural sorbents. Sorption batch tests were investigated in the removal process at initial concentration of nickel ions (100 mg/l). Equilibrium, kinetics and thermodynamic studies were investigated for the removal process. Parameters affect as pH, amount of sawdust, contact time and temperature were studied. The uptake capacity was 12.5 mg/g; also FTIR demonstrated that carboxyl and hydroxyl groups were involved in the adsorption of the metal ions. The results indicated that adsorption is an endothermic process and rate of removal increased with increase temperature.

Ten T section reinforced concrete beams by use Reactive Powder Concrete (RPC) beams with square and circular web perforation tested under pure torsion . The geometry and main reinforcement of all specimens are same. The main parameters taking into account in present paper are circular opening size, location of openings and number of openings. The torque caused the ultimate crack was recorded, and the angle of twist generated from these torques is calculated. Test results indicate that, torque that causes failure (ultimate) is affected by opening size, opening locations, opening numbers, the presence of web cut – outs reduces ultimate torque capacity of section, such that the increase in web opening size reduces the ultimate torque, when the web openings increase that leads to reduction in the torque capacity، the opening eccentricity makes no uniformity of shear stress distribution through web and leads to reduce the torque capacity. Then, angle of twist depends on the opening location at crack or ultimate stages, the twisted angle depends on torque magnitude because of beam span, shear modulus and geometry of T sections which are the same and the cracks start from support and then take a spiral shape around the beams up to flange so the number of cracks increases as the presence of openings.

The Iraqi construction remains challenging because of lack of basic amenities and is associated with enormous risks and terrorist actions. This status compels clients to wisely select the most efficient contractor that complies with both standard and special circumstances. This study aims to investigate the impact of choosing incompetent contractor on project schedule. The criteria of selection contractor that satisfy Iraqi construction industry were also investigated. Data were collected using an extensive historical data of 352 projects from the database of Diyala Governorate as well as conducting structured interviews with construction professionals from public organizations. Analysis of data showed that the current bidding process significantly impacts the performance of projects. In addition, the analysis revealed that the five most important criteria for selecting Iraqi contractors are: security and safety management, financial stability, past performance, relevant experience, and plant and equipment. Results would enhance the awareness of managers to the importance of tenders’ evaluation based on transparency and fairness.

This study presents an experimental investigation on one type of embedded shearhead called ( collar head reinforcement) as shear reinforcement for tow type of reinforced concrete flat plate with presence of opening on punching shear strength. This type of shearhead is one of the structural solution that are used to increase the shear strength of flat slab . In the present research , ten specimens are tested with dimensions (1000x1000x75 mm) which are divided into two groups; the first group is a normal strength concrete with a compressive strength 30MPa; the second group is modified reactive powder concrete with a compressive strength 90MPa. Each group consists of five slabs. By using collar shearhead around the column sides and extended to the opening NSC4, the cracking load can be increased to 100% solid flat slab without collar head. For serviceability of flat plate with opening, the deflection and crack width can be reduced by using collar head around the column sides extended to the opening. The reduction can be continued by increasing the compressive strength of the concrete.

In this work, an experimental investigation has been done for steady-state free heat convection into a heated externally horizontal open ends circular tube with and without internal ring fins. The tests are carried out for five different aluminum tubes in aspect ratios. Another four tubes are used providing internal ring fins with varying fin spacing and constant aspect ratio . Wide levels of the wall heat fluxes (254 - 2267) W/m2 are used. The influence of aspect ratio , heat flux , ring fins , fin spacing on the free-convection through a heated tube are analyzed and discussed. The experimental results indicate that the local Nusselt number increases with decreasing the aspect ratio. Also the results appear that the free heat convection performance through the tube in terms of local Nusselt number improved with internal fins about 25% higher than without fins. An experimental correlations of local and average Nusselt numbers as a function of Rayleigh number for a wide range of aspect ratios under uniform wall heat flux condition are concluded.

The portal method is one of the common approximate methods in the analysis of statically indeterminate structures. This method is used to analyze the frames which subjected to lateral loadings such as wind, earthquake, and blast loadings. The portal method is still used in the planning phase of projects, preliminary designs, and quick checking for analysis. In this paper an improvement is presented to make the portal method analysis more closer to the accurate analysis for one bay frames. In this work, the analysis by using the finite element method is carried out for a twenty seven building frames with various numbers of bays and stories. The outputs indicate that some improvements in the portal method will be useful to make this method more accurate. The improvements have been written in a new "modified portal method". In order to compare the results of the analysis after improvement, a typical five frames have been analyzed by using three methods: namely, portal method, modified portal method (presented in this paper), and the finite element method via SAP2000 V14.

Using polymers to modify mortar improve the workability, adhesion, strength, durability of the cement besides improving cure characteristics. Two mixtures of cement-sand were prepared without water. The first is 1:2 cement: sand and the other ratio was 1:1 cement: sand mixture. Unsaturated polyester was added to the two mixtures at different ratios (30:70, 40:60, and 50:50) polymer to cement- sand mixture. The effect of unsaturated polyester was studied on both mixtures by calculating the density besides measuring the hardness and compressive strength of specimens .The addition of unsaturated polyester showed an improvement in these properties and showed that the increase in the unsaturated polyester percent improve the mechanical properties.

This research aimed to forecasting of an expected outcome for the planning periods (2014-2026) based on the numbers of traffic accidents, as well as projection long term trend graphically for (Dead and non-dead accidents, numbers of deaths, and numbers of injuries), in Iraq throughout applying an optimal statistical models. Methodology: Data are selected from annuls statistical reports of traffic accidents registered and published by Ministry of Planning for the time periods (2002-2013). Five criteria had been applied, such that (MSE, MAE, MAPE, ME, and MPE), the first three statistics measuring the magnitude of the errors. A better model will give a smaller value. The last two statistics measure bias. A better model will give a value close to zero. Results and Findings: Several forecasting models are suggested, and among that are nominated (Linear trend, Brown’s Linear Exponential Smoothing, and Moving Average of order (1) i.e. MA (1)), since recorded significant autoregressive, and goodness of fit tests. Conclusions: For the three-time series, (Dead accidents, no. of deaths, and no. of injuries), it will be increases significantly at the projection of planning periods, while time series, concerning (Non Dead accidents) according to the magnitude of residuals by applying studied indicators, shows stability status along the projection periods at the general mean line.

FRP-concrete- steel is a new hybrid composite structural member combines the privileges confined compressive strength of concrete and the ductility of steel to produce a lighter in weight member with considerable carrying capacity. In this research the FRP hybrid member was utilized as a pile which is a special case of FRP concrete filled pile with a hollow steel tube inside. F.E modeling were carried out for this new hybrid pile using the computer program ABAQUS, in which confined concrete model was included through the Concrete Damage Plasticity model. Verification of the model was implemented through the simulation of experimentally tested specimens, good agreement were achieved between experimental and F.E results. The F.E model was considered in studying the effects of FRP tube thickness, steel tube thickness, Hollowness ratio and stiffness of concrete. The results were presented in terms of axial load-axial strain curves. It has been found that the axial strength ratio increased as the stiffness of concrete, steel, and FRP increased while it decreased with the increase of hollowness ratio.

Laboratory model tests have been carried out to explore the behavior of piles subjected to lateral soil movement in sand. The results of a single pile test and ten tests on of group piles arranged in a row (perpendicular to the direction of soil movement) are presented. Different parameters were utilized in these tests, (e.g., pile spacing, number of piles within a group and pile head condition). Group effect was calculated using group factor (Fm) which is defined in terms of the measured maximum bending moments of an individual with group and that of the single pile. The results showed that the maximum bending moment of group piles decreases from the single pile with decreasing pile spacing and the pile behaves essentially the same as a single pile when the pile spacing is 7d or more. The maximum reduction of the maximum bending moments of about (17%) and (28%) as compared with that for the standard single pile may be observed for a pile spacing of 3d for the free and capped headed condition, respectively.