Search

Successful construction projects are those to be completed within the planned time, cost and quality, in addition to minimizing waste, pollution and energy consumption. It is believed that adopting lean principles in the construction industry can help a lot in achieving these goals. This research aims at studying the benefits, obstacles and readiness to adopt lean construction in Iraq and the actions needed. A questionnaire was designed based on extensive review of relevant literature and then directed to (123) professionals involved in the Iraqi construction industry. The results were statistically analyzed and tested and found to be valid and reliable. Contradictions of very few aspects were then discussed and clarified through direct interviews with (10%) of the questionnaire respondents . The research revealed that the Iraqi construction industry is in need of all potential benefits that lean construction can provide through value maximization and using modern construction techniques. The research also revealed that the main obstacles are lack of expertise, skills, awareness and knowledge in lean principles and poor culture related to waste identification and control. Concerning the readiness success factors, more emphasis was made to the integration of design, manufacture and construction and life-cycle engineering. Finally, proactive actions were suggested on national and institutional scales taking into account that the major role to shift to lean construction rests with the government and the construction sector leaders. Keywords: Lean Thinking, Lean Production, Lean Construction, Construction Industry, Construction Projects

In this paper, the effect of footing shape resting on dry sand when subjected to machine dynamic loading is experimentally investigated. A laboratory set-up was prepared to simulate the case at different operating frequencies. Nine models were tested to examine the effects of the combinations of two parameters, including different frequencies of (0.5, 1, and 2 Hz) and different footing shapes (circular, square and rectangular). The tests were conducted under a load amplitude of (0.25 ton) using sand with medium and dense relative densities corresponding to (R.D. = 50% and 80%) having unit weights of (17.04 and 17.96 kN/m3) respectively. A shaft encoder and a vibration meter were used to measure the strain and amplitude displacement, while the stress in the soil at different depths was measured using flexible pressure sensors. It was found that the shape of footing has a considerable influence on the bearing capacity of the supporting soil under dynamic loading. For instance, the strain of dry sand under a circular footing was nearly (41%) higher, the amplitude displacement was nearly (17%) higher, and stress was nearly (12%) higher than square and rectangular footings, under the same conditions.

Experimental model was done for pile model of L / D = 25 installed into a laminar shear box contains different saturation soil densities (loose and dense sand) to evaluate the variation of pore water pressure before and after apply seismic loading. Two pore water pressure transducers placed at position near the middle and bottom of pile model to evaluate the pore water pressure during pullout tests. Seismic loading applied by uniaxial shaking table device, while the pullout tests were conducted through pullout device. The results of changing pore water pressure showed that the variation of pore water pressure near the bottom of pile is more than variation near the middle of pile in all tests. The variation of pore water pressure after apply seismic loading is more than the variation before apply seismic loading near the middle of pile and near the bottom of pile and in loose and dense sand. Variation of pore water pressure after apply seismic loading and uplift force is less than the variation after apply seismic loading in loose sand at middle and bottom of pile.

This paper focuses on the response of circular machine foundation resting on different soils (sand and clay) through studying the variation of soil shear strength parameters and strain with the number of cycles. The objective of the current study is to explore the results related to the parameters of the dynamic load (number of loading cycles and frequency of load) related to the circular footing of a machine on the dynamic shear strength parameters (for sand soil (ϕ˚dyn) and for clay soil (Cudyn)) in addition to the amplitude strain foundation. A special setup was designed and manufactured to simulate the vertical vibration of a circular machine foundation. A steel circular machine foundation with a diameter of 150 mm was used to represent the footing. A total of 6 cases were examined to take into account the effects of different parameters including different frequencies (0.5, 1, and 2 Hz); state of sand (medium and dense) which corresponded to relative densities of (50 and 80%), while the state of clay (medium and stiff) corresponded to undrained shear strengths (50 and 70 kPa). All tests were carried out under load amplitude of 2.5 kN. It was found that the rate of increase in shear strength parameters for the soil under a circular machine foundation decreases remarkably when increasing the frequency for both types of soil under the footing. While little change in the shear strength parameters, or even no change was observed under the effect of other locations. Moreover, the amplitude strain decreased when increasing the frequency for both types of soil.

To ensure safe design of structures against settlement, it is necessary to determine the compressibility parameters of the underneath soil especially compression and rebound indices. In this paper, an approach to forecast the compressibility parameters of gypseous soils based on index parameters was developed using Artificial Neural Networks technique. Two equations were developed to estimate compression and rebound indices using back propagation algorithm to train multi-layer perceptron, in which good agreements were achieved. The input parameters used were: the depth, gypsum content, liquid limit, plastic limit, plasticity index, passing sieve No.200, dry unit weight, water content and initial void ratio. Two output parameters were determined including compression index and rebound index. A parametric study was also conducted to investigate the generalization and robustness of both models. The findings indicate that both models were reliable within the range of utilized data. It was found that gypsum content has the highest effect on the compressibility index followed by water content, plasticity index, dry unit weight and plastic limit, while other parameters have lower effect. The gypsum content has the highest effect again on the rebound index followed by passing sieve No.200, initial void ratio, plastic limit and plasticity index, while other parameters have lower effect.

In this study a computerised management system was developed to aid major contractors in improving cost control performance in construction projects. The system was developed by synthesising all construction cost-related functions into a comprehensive framework, taking into account both cost overrun factors and mitigating measures. These factors and measures were based on the findings of previous studies by the authors, in which 10 cost factors were specified as the most potentially controllable by contractors of an observed 59 influential factors identified in construction projects in Iraq. The system was then developed using Python programming language to incorporate the material, labour, and equipment costs of each construction activity. The system was then compared to in real life implementations in seven types of construction projects undertaken by the State Company for Project Execution of the Ministry of Transport, a major contracting company in Iraq, with the results showing that the system can be successfully utilised by major contractors for cost control during construction.

Horan Dam H4 is an earth dam located 18 km northeast Rutba town in Anbar province in Iraq. The main objective for dam construction is to save rainfall for agriculture purposes and some household uses. In this study, a mathematical model is developed to analyze water seepage through the dam under steady state. The upstream and downstream slopes stability of the dam are also evaluated by using four methods which are: Bishop, Janbu, Morgenstern-Price, and Ordinary method. In addition, a two-dimensional finite element model was developed using GeoStudio program. The results of seepage analysis clearly show that Horan Dam H4 is safe against failure. Furthermore, the obtained factor of safety of upstream and downstream slopes stability proves that the dam body is stable based on Janbu’s method of minimum value. Moreover, it was found that the soil shear strength parameters highly influence the dam stability in steady state condition.

In this paper, the influence of the following parameters on different modes of vibration response of model footings on sand is studied: (vertical, rocking and pitching load amplitude and frequency). To achieve the objective of this study, the model footing was selected to be rectangular footing with an aspect ratio (L/B= 1.33) i.e (L= length and B= width). A physical model was manufactured to simulate a steady-state harmonic dynamic load applied at different operating frequencies with the same load amplitude (0.5 ton). A total of (9) cases was performed taking into account different parameters. The loading frequency ranged from (0.5) to (2) Hz and the footing was rectangular with an aspect ratio (L/B = 1.33). The soil type used was dry sand having a relative density of (50%). The behavior of the soil underneath the footing was examined by measuring the strain using a shaft encoder and the amplitude of displacement using a vibration meter. It was found that the change in vibration mode made little effect of the final strain values under the same frequency and the amplitude of displacement in (Z) direction, while the amplitude of displacement in (Y) is higher, occuring under rocking vibration and higher value amplitude of displacement in (X) direction under pitching vibration under the same frequency.

The effect of the embedment depth of a circular footing resting on dry sand and subjected to dynamic load on the amplitude of soil displacement (Az) was investigated the present study. In order to simulate the conditions occurring in the field, a special testing apparatus with accessories was designed and manufactured to study the effect of dynamic load on soil. A total of 18 cases were examined to take into account the effects of different parameters, including different frequencies (0.5, 1, and 2 Hz); relative densities (medium sand, R.D=50% and dense sand, R.D=80%); and corresponding unit weights (17.52 kN and 18.33 kN). All tests were carried out under load amplitude of 0.5 tons. The behaviour of the soil underneath the footing was examined by measuring the amplitude of displacement AZ using a vibration meter placed at a set depth (B) under the footing. It was found that when the embedment depth is changed from zero (at surface) to 0.5 B and then to B the value of amplitude of the displacement Az is reduced. The percentage of reduction in Az was about 4 to 39 % at depth 0.5 B, and about 37-77 % at depth B.

The aim of this research is to create a fuzzy logic model that can aid in assessing payment problems encountered in construction projects in Iraq. The model was created based on the findings of a previous study of the authors in which (67) causes of payment problems in construction projects in Iraq were identified. The causes were ranked by (72) professionals from (38) Iraqi firms based on the frequency and severity of causes. All causes were employed in the model after categorizing them in four groups: owner-related, contractor-related, consultant-related and external causes. The model was constructed using MATLAB Program Software Version 2. Finally the model was tested against (10) real life projects and found to be appropriate to aid owners and contractors in the Iraqi Construction Industry to early assess payment problems in order to take preventive actions.

The Ministry of Education in Iraq is confronting a colossal deficiency in school buildings while stakeholders of government funded school buildings projects are experiencing the ill effects of extreme delays caused by many reasons. Those stakeholders are particularly worried to know ahead of time (at contract assignment) the expected completion time of any new school building project. As indicated by a previous research conducted by the authors, taking into account the opinions of Iraqi experts involved with government funded school building projects, nine major causes of delay in school building projects were affirmed through a questionnaire survey specifically are; the contractor's financial status, delay in interim payments, change orders, the contractor rank, work stoppages, the contract value, experience of the supervising engineers, the contract duration and delay penalty. In this research, two prediction models (A and B) were produced to help the concerned decision makers to foresee the expected completion time of typically designed school building projects having (12) and (18) classes separately. The ANN multi-layer feed forward with back-propagation algorithm was utilized to build up the mathematical equations. The created prediction equations demonstrated a high degree of average accuracy of (96.43%) and (96.79%) for schools having (12) and (18) classes, with (R2) for both ANN models of (79.60%) and (85.30%) respectively. It was found that the most influential parameters of both models were the ratio of the sum of work stoppages to the contract duration, the ratio of contractor's financial status to the contract value, the ratio of delay penalty to the total value of contract and the ratio of mean interim payments duration to the contract duration.