Journal of Construction Engineering The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Hard-Hat Detection for Construction Safety Visualization Sun, 01 Feb 2015 08:43:43 +0000 In 2012, 775 fatalities were recorded, and many more were injured at construction sites in the United States. Of these, 415 fatalities (54%) were due to fall, slips, and trips as well as being struck by falling objects. In order to decrease fatalities at construction sites to these types of events, the Occupational Safety and Health Administration (OSHA) provides Fall Prevention and OSHA-10 trainings to construction workers. Moreover, safety personnel monitor whether the workers use personal protective equipment (PPE) properly. Data shows that construction fatalities have decreased by 2% annually since 1994; however, the owners still are not satisfied with this result. Various studies have shown that fall is the biggest contributor for construction fatalities. One study showed that half of the fall fatalities were because the workers either had not used PPEs or had not used them properly. In addition, studies showed that, with proper use of hard hats, the fatalities due to fall, slips, trips, and being struck by falling objects could be reduced. This study developed and tested a hard-hat detection tool that uses image-processing techniques to identify whether workers are wearing hard hats. The tool dispatches warning messages if the workers do not use hard hats. Kishor Shrestha, Pramen P. Shrestha, Dinesh Bajracharya, and Evangelos A. Yfantis Copyright © 2015 Kishor Shrestha et al. All rights reserved. Optimizing Traffic Operation in Designing Specific Upgrades Sun, 18 Jan 2015 14:14:15 +0000 Transport forms one of the primary needs in all categories of the population in modern society; it is of paramount concern for traffic engineers, transport planners, and policy makers to understand and evaluate the quality of service being provided by the transport facilities designed by them. This paper presents an investigation in profile geometric design and traffic flow operation on two-lane two-way highways and provides analyses that will help in a better understanding of traffic operation on these facilities to select the optimum profile configuration. The effects of influencing parameters consisting of grade, length of grade, traffic composition, and traffic volume are evaluated and finally a systematic procedure to evaluate flow rate under the base condition is presented. Finally, based on these achievements an algorithm is introduced to select optimum Finished Ground of profile view. Results show that the percentage of heavy vehicles has a contributing effect on traffic operation so that the optimum profile configuration is incredibly affected by this factor. Source data have been obtained from Highway Capacity Manual (HCM) as a pioneer document in respect of quantifying the concept of capacity for a transport facility. Ebrahim Sangsefidi, Mohammadjafar Rashidbenam, Shahab Kabiri, Hossein Amid, and Maryam Sangsefidi Copyright © 2015 Ebrahim Sangsefidi et al. All rights reserved. Experimental Heat Transfer Study on Green Roofs in a Semiarid Climate during Summer Sun, 18 Jan 2015 09:38:32 +0000 An experimental study was conducted on green roofs under the semiarid summer climatic conditions of West Texas to investigate the effect of soil type, moisture content, and the presence of a top soil grass layer on the conductive heat transfer through the roof. Two soil types were investigated: uniform sand and local silt clay. Tests were also conducted on a control roof. A dual-needle heat-pulse sensor was used to conduct thermal property tests on the soils. The tests reveal that unlike sand, the thermal conductivity of silt clay did not increase continuously with soil moisture. Better heat transfer conditions were achieved when the sand and silt clay roofs were watered to a water depth of 10 mm per day rather than double the amount of 20 mm per day. The roof with silt clay soil had the lowest fluctuation in inner temperature between daytime and nighttime. Green roofs with silt clay soil required more than twice the amount of soil moisture than green roofs with sand to achieve similar roof heat transfer rates. The best net heat flux gains for vegetated green roofs were 4.7 W/m2 for the sand roof and 7.8 W/m2 for the silt clay roof. Roy J. Issa, Kenneth Leitch, and Byungik Chang Copyright © 2015 Roy J. Issa et al. All rights reserved. An Automated BIM Model to Conceptually Design, Analyze, Simulate, and Assess Sustainable Building Projects Thu, 06 Nov 2014 12:41:56 +0000 Quantifying the environmental impacts and simulating the energy consumption of building’s components at the conceptual design stage are very helpful for designers needing to make decisions related to the selection of the best design alternative that would lead to a more energy efficient building. Building Information Modeling (BIM) offers designers the ability to assess different design alternatives at the conceptual stage of the project so that energy and life cycle assessment (LCA) strategies and systems are attained. This paper proposes an automated model that links BIM, LCA, energy analysis, and lighting simulation tools with green building certification systems. The implementation is within developing plug-ins on BIM tool capable of measuring the environmental impacts (EI) and embodied energy of building components. Using this method, designers will be provided with a new way to visualize and to identify the potential gain or loss of energy for the building as a whole and for each of its associated components. Furthermore, designers will be able to detect and evaluate the sustainability of the proposed buildings based on Leadership in Energy and Environmental Design (LEED) rating system. An actual building project will be used to illustrate the workability of the proposed methodology. Farzad Jalaei and Ahmad Jrade Copyright © 2014 Farzad Jalaei and Ahmad Jrade. All rights reserved. Study of the Causes and Magnitude of Wastage of Materials on Construction Sites in Jordan Wed, 29 Oct 2014 08:25:39 +0000 The research aims to study the causes and magnitude of wastage of construction materials on construction projects sites in Jordan. To achieve the research aim, the researcher had prepared a questionnaire form included questions about the causes of wastage and the estimated percentages of wastage of ten most popular kinds of materials used on construction sites in Jordan. Prior to the final formulation of the questionnaire form, a pilot survey was conducted. The form was revised in accordance with the feedback received. The number of causes adopted was 60 distributed on the six major categories. The form was distributed to 240 participants (clients, contractors, and consultants). The study revealed that the most important causes of wastage of materials on construction sites in Jordan are frequent design and client’s changes; rework due to workers mistakes; poor contract documents; wrong and lack of storage of materials; poor strategy for waste minimization; shortage and lack of experience of skilled workers; poor site conditions; damage during transportation; theft and vandalism; and mistakes in quantity surveying and over allowance. In addition the study concluded that the percentage of wastage materials is accounted for by values between 15% and 21% on Jordanian construction sites. Ghanim A. Bekr Copyright © 2014 Ghanim A. Bekr. All rights reserved. Identification and Classification of the Unique Features of Mass Housing Projects Thu, 23 Oct 2014 09:12:18 +0000 Mass housing projects (MHPs) are said to differ significantly from the “one-off” traditional building projects often encountered in the construction industry and thus require unique management skills and approach in MHPs delivery. This unique nature of MHPs contributes to managerial inefficiencies that result in delivery failures when management approaches are not adapted to the project characteristics. However, understanding and knowledge of the unique attributes of MHPs are critical towards improving the organisation, planning, managerial effectiveness, and delivery success of mass housing projects. To date, extensive studies establishing the unique features of mass housing projects are lacking. This study is set out to identify what constitutes the unique features of mass housing projects by comparing mass housing projects to traditional “one-off” building projects. A questionnaire survey was used to establish mass housing practitioners’ perception of the unique characteristics of MHPs. Data analysis involving mean scores and ANOVA revealed 10 unique features of MHP. A clear and systematic understanding of these unique features of MHPs is crucial for evolving effective project management practices and critical competencies towards successful delivery of current and future MHPs. Titus Ebenezer Kwofie, Frank Fugar, Emmanuel Adinyira, and Divine Kwaku Ahadzie Copyright © 2014 Titus Ebenezer Kwofie et al. All rights reserved. Quantitative Analysis of the Sources of Construction Waste Mon, 20 Oct 2014 09:20:45 +0000 The construction industry is traditionally environmentally unfriendly. The environmental impacts of construction waste include soil contamination, water contamination, and deterioration of landscape. Also, construction waste has a negative economic impact by contributing additional cost to construction due to the need to replace wasted materials. However, in order to mitigate waste, construction managers have to explore management options, which include reduction, recycling, and disposal of wastes. Reduction has the highest priority among the waste management options but efficient reduction cannot be achieved without adequate identification of the sources of waste. Therefore, the purpose of this paper is to present a study that was carried out on the contribution rates of nine identified sources of construction waste. Establishing the contribution rates of different waste sources will enhance knowledge-based decision-making in developing appropriate strategy for mitigating construction waste. Quantitative research method, using survey questionnaire, was adopted in this study to assess the frequency and severity of contribution of the sources of waste. As one of the findings of the study, residual waste such as material off-cuts was identified as the highest contributor to construction waste. This study consequently demonstrated that waste has a significant contribution to the cost of construction. Olusanjo O. Fadiya, Panos Georgakis, and Ezekiel Chinyio Copyright © 2014 Olusanjo O. Fadiya et al. All rights reserved. NIDE: A Novel Improved Differential Evolution for Construction Project Crashing Optimization Sun, 19 Oct 2014 09:16:40 +0000 In the field of construction management, project crashing is an approach to shortening the project duration by reducing the duration of several critical project activities to less than their normal activity duration. The goal of crashing is to shorten the project duration while minimizing the crashing cost. In this research, a novel method for construction project crashing is proposed. The method is named as novel improved differential evolution (NIDE). The proposed NIDE is developed by an integration of the differential evolution (DE) and a new probabilistic similarity-based selection operator (PSSO) that aims at improving the DE’s selection process. The PSSO has the role as a scheme for preserving the population diversity and fending off the premature convergence. The experimental result has demonstrated that the newly established NIDE can successfully escape from local optima and achieve a significantly better optimization performance. Nhat-Duc Hoang Copyright © 2014 Nhat-Duc Hoang. All rights reserved. Current State of Off-Site Manufacturing in Australian and Chinese Residential Construction Thu, 25 Sep 2014 09:26:50 +0000 Many techniques have been implemented to make construction industry more productive. The key focus is on reduction of total duration, reduction in construction cost, improvements in the quality, achieving more sustainable development, and safer construction sites. One of the techniques, which is emerging in the last two decades, is the use of off-site manufacturing (OSM) within the construction industry. Several research projects and industry initiatives have reported the benefits and challenges of implementation of OSM. The focus of this paper is Australian and Chinese residential construction industry and the uptake of the OSM concepts. The paper presents a brief review of the current state of OSM in the last five to seven years with the context of the above-mentioned two countries. The paper concludes that the construction industry, both in Australia and China, needs to start walking the talk with regard to OSM adoption. The paper also highlights some of the research gaps in the OSM area, especially within the housing and residential sector. Malik M. A. Khalfan and Tayyab Maqsood Copyright © 2014 Malik M. A. Khalfan and Tayyab Maqsood. All rights reserved. Do Building Information Modelling Applications Benefit Design Teams in Achieving BREEAM Accreditation? Mon, 22 Sep 2014 05:25:35 +0000 Using building information modelling (BIM) within a design team allows for integration of sustainability analysis such as daylighting analysis, water harvesting, and thermal assessment whilst capturing the data which can be used for BREEAM assessment. Therefore, the availability of data compared to traditional methods can be used to design teams, stakeholders, and environmental assessment bodies’ advantage. Since BIM boasts extensive building performance analysis capabilities, design teams should be provided with standard methodologies and guidance into successfully achieving certain BREEAM criteria. This paper highlights gaps in the existing theory to develop a solid understanding for further research in order to achieve BIM integrated BREEAM design team protocol. Further to this and running parallel to the protocol and guidance, an internal conceptual framework existing within BIM software could be instigated from future research. This will require detailed and innovative solutions to link the credits with the software both from an IT and from a software coding perspective; also, there is great merit into analysing design teams’ cultural and behavioural factors towards sustainable design through the BIM model. Josh Harding, Subashini Suresh, Suresh Renukappa, and Sabah Mushatat Copyright © 2014 Josh Harding et al. All rights reserved. Holistic Diagnosis of Rising Damp and Salt Attack in Two Residential Buildings in Kumasi, Ghana Thu, 24 Jul 2014 08:38:53 +0000 Rising damp is one of the most severe phenomena that leads to decay and deterioration of both old and modern types of buildings. This study employed a holistic approach to dampness investigation and sought to examine the problem of rising damp in the walls of two residential apartments in Kumasi, Ghana. The study sought to determine the types of soluble salts and their concentrations in the soils and accumulated percentages in the walls over time and whether there exists any linkage between the salts in the walls and those in the ground. Results from the geotechnical survey of the building sites found that the soils on site 1 consisted of silty sandy gravel with some clay particles and those on site 2 consisted of silty sandy soil with some clay and traces of gravel. The study identified several groups of salts in the walls of the buildings, with the most damaging and dangerous being magnesium sulphate, magnesium chloride, and sodium sulphate salts. Similar salts were identified in the soil samples from the trial pits. The results therefore indicate a linkage between the salts found in the ground and those found in the walls and therefore confirm the presence of rising dampness. Kofi Agyekum, Joshua Ayarkwa, and Christian Koranteng Copyright © 2014 Kofi Agyekum et al. All rights reserved. Investigation of Contemporary Performance Measurement Systems for Production Management of Renovation Projects Mon, 21 Jul 2014 12:10:42 +0000 Renovation projects exhibit complex characteristics due to the presence of constraints that lead to cost and schedule overruns. Numerous researchers have concluded that the performance of renovation projects is typically lower than that of new construction projects. This paper discusses the initial phases of a research conducted at Michigan State University, which focused on developing a framework for production management of renovation projects. The emphasis of this paper is on the findings from literature review and interviews, pertinent to performance measurement in renovation projects that led to the framework development. However, the framework development and the framework itself have not been discussed. This paper primarily addresses two questions: (1) what are the complexities of renovation projects that lead to underperformance in cost, time, and quality? and (2) what are the limitations of state-of-the-art construction performance measurement systems for managing production in renovation projects? Interviews of 10 construction companies were conducted to identify current practices of production management in renovation projects. This research observed a lack of a formal production management process in renovation projects, with a limited use of performance measurement systems. The research identified essential attributes for avoiding schedule and cost overruns on renovation projects. Yash Singh, Tariq Abdelhamid, Tim Mrozowski, and Mohamed A. El-Gafy Copyright © 2014 Yash Singh et al. All rights reserved. Perceptions on Barriers to the Use of Burnt Clay Bricks for Housing Construction Mon, 21 Jul 2014 00:00:00 +0000 Burnt clay bricks can be readily manufactured in Ghana as all ten regions have significant clay deposits with the Ashanti region having the highest estimated deposit of 37.1 million metric tonnes. In recent times, burnt clay bricks have been regarded as old fashioned and replaced by other perceived modern walling units within Kumasi, the metropolitan capital of Ashanti Region, despite its availability, unique advantages (aesthetics, low maintenance cost, etc.), and structural and nonstructural properties. This study involved a questionnaire survey of 85 respondents made up of architects, brick manufacturing firms, and brick house owners or occupants in the Kumasi Metropolis of Ghana and sought to examine their perceptions on barriers to the use of burnt clay bricks for housing construction. The findings revealed that the key factors inhibiting the use of burnt clay bricks for housing construction are low material demand, excessive cost implications, inappropriate use in construction, noncompatibility of burnt clay bricks with other materials, unreliable production, and transportation problems. The findings however provide a platform for stakeholders to address the barriers to enable the extensive use of clay bricks in housing constructions. Bernard K. Baiden, Kofi Agyekum, and Joseph K. Ofori-Kuragu Copyright © 2014 Bernard K. Baiden et al. All rights reserved. Motivating Workers in Construction Wed, 09 Jul 2014 09:04:05 +0000 The study of the motivation of construction workers is limited to a relatively small body of knowledge. Although there is considerable research available regarding motivation and productivity, few researchers have provided a comprehensive analysis on the motivation of construction workers. The research stated that productivity in construction has not improved compared to other industry sectors such as manufacturing. This trend has been echoed in publications throughout the past five decades, and suggested that motivation is one of the key factors impacting productivity. This paper offers a comprehensive review of the published work that directly links the key words—construction and motivation. The findings have been presented in five themes, that is, motivation models, environment and culture, incentives and empowerment, and worker management. This paper concludes with two methods suggested by previous researchers to improve motivation of construction workers: (1) relevant worker incentives (intrinsic or extrinsic) and (2) improved management practices, specifically regarding communication with workers. Jason E. Barg, Rajeev Ruparathna, Daylath Mendis, and Kasun N. Hewage Copyright © 2014 Jason E. Barg et al. All rights reserved. Hybrid Simulation Environment for Construction Projects: Identification of System Design Criteria Sun, 29 Jun 2014 11:39:47 +0000 Large construction projects are complex, dynamic, and unpredictable. They are subject to external and uncontrollable events that affect their schedule and financial outcomes. Project managers take decisions along the lifecycle of the projects to align with projects objectives. These decisions are data dependent where data change over time. Simulation-based modeling and experimentation of such dynamic environment are a challenge. Modeling of large projects or multiprojects is difficult and impractical for standalone computers. This paper presents the criteria required in a simulation environment suitable for modeling large and complex systems such as construction projects to support their lifecycle management. Also presented is a platform that encompasses the identified criteria. The objective of the platform is to facilitate and simplify the simulation and modeling process and enable the inclusion of complexity in simulation models. Mohamed Moussa, Janaka Y. Ruwanpura, George Jergeas, and Tamer Mohamed Copyright © 2014 Mohamed Moussa et al. All rights reserved. A Novel Resource-Leveling Approach for Construction Project Based on Differential Evolution Wed, 21 May 2014 10:41:04 +0000 In construction engineering, project schedules are commonly established by the critical path method. Nevertheless, these schedules often lead to substantial fluctuations in the resource profile that are not only impractical but also costly for the contractors to execute. Therefore, in order to smooth out the resource profile, construction managers need to perform resource-leveling procedures. This paper proposes a novel approach for resource leveling, named as resource leveling based on differential evolution (RLDE). The performance of the RLDE is compared to that of Microsoft Project software, the genetic algorithm, and the particle swarm optimization algorithm. Experiments have proved that the newly developed method can deliver the most desirable resource-leveling result. Thus, the RLDE is an effective method and it can be a useful tool for assisting managers/planners in the field of project management. Hong-Hai Tran and Nhat-Duc Hoang Copyright © 2014 Hong-Hai Tran and Nhat-Duc Hoang. All rights reserved. Feasibility of Using Palmyrah Strips as Reinforcing Material in Cost Effective Houses Mon, 14 Apr 2014 08:24:05 +0000 Construction of cost effective houses is a dilemma among the impoverished population in developing countries. The ever increasing price of traditional building materials results in high capital investments for residential buildings. Palmyrah is a significant economic resource, widely spread all over the northeast region of Sri Lanka. This research explores the technical feasibility of using heartwood of Palmyrah as a reinforcing member in lightly loaded concrete elements. Initially, mechanical properties of Palmyrah were examined through static bending, tensile, and compressive tests. Percentages of water absorption, dimensional stability, and anchorage bond strength were investigated to envisage the suitability of Palmyrah as reinforcement. Next, several short span slabs and beams reinforced with Palmyrah strips were subjected to tests. It was observed that Palmyrah reinforcement enhanced the moment capacity of the slabs and beams compared to unreinforced sections. Experimental failure loads of slabs and beams were higher than theoretically predicted values with Palmyrah reinforcement. Further, Palmyrah reinforced beams and slabs underwent flexural failures. Thus, it is concluded that heartwood of Palmyrah has the potential to be used as reinforcement in lightly loaded slabs and beams. Further research is recommended to investigate the durability and serviceability issues. K. Baskaran, H. E. Mallikarachchi, M. J. P. L. M. Jayasekara, and G. A. T. Madushanka Copyright © 2014 K. Baskaran et al. All rights reserved. An Artificial Intelligence Approach for Groutability Estimation Based on Autotuning Support Vector Machine Thu, 10 Apr 2014 09:43:06 +0000 Permeation grouting is a commonly used approach for soil improvement in construction engineering. Thus, predicting the results of grouting activities is a crucial task that needs to be carried out in the planning phase of any grouting project. In this research, a novel artificial intelligence approach—autotuning support vector machine—is proposed to forecast the result of grouting activities that employ microfine cement grouts. In the new model, the support vector machine (SVM) algorithm is utilized to classify grouting activities into two classes: success and  failure. Meanwhile, the differential evolution (DE) optimization algorithm is employed to identify the optimal tuning parameters of the SVM algorithm, namely, the penalty parameter and the kernel function parameter. The integration of the SVM and DE algorithms allows the newly established method to operate automatically without human prior knowledge or tedious processes for parameter setting. An experiment using a set of in situ data samples demonstrates that the newly established method can produce an outstanding prediction performance. Hong-Hai Tran and Nhat-Duc Hoang Copyright © 2014 Hong-Hai Tran and Nhat-Duc Hoang. All rights reserved. Magnitude of Construction Cost and Schedule Overruns in Public Work Projects Wed, 18 Dec 2013 18:34:23 +0000 This study analyzed 363 Clark County Department of Public Works (CCDPW) projects to determine construction cost and schedule overruns in various types and sizes of the projects. The sample projects were constructed from 1991 to 2008, with a total construction cost of $1.85 billion, equivalent to 2012 cost. A one-factor ANOVA test was conducted to determine whether construction cost and schedule overruns significantly varied based on types and sizes of the projects. The study showed that large, long-duration projects had significantly higher cost and schedule overruns than smaller, short-duration projects. Pramen P. Shrestha, Leslie A. Burns, and David R. Shields Copyright © 2013 Pramen P. Shrestha et al. All rights reserved. Effect of Turf Roof Slabs on Indoor Thermal Performance in Tropical Climates: A Life Cycle Cost Approach Thu, 07 Nov 2013 12:01:54 +0000 Urbanization related to population growth is one of the burning issues that the world is facing today. Parallel to this, there is visible evidence of a possible energy crisis in the near future. Thus, scientists have paid attention to sustainable development methods, and in the field of building construction also, several innovations have been proposed. For example, green roof concept is one of such which is considered a viable method mainly to reduce urban heat island effect, to regain lost land spaces in cities, and to increase aesthetics in cities. The present study was aimed at investigating the impact of green roofs on indoor temperature of buildings, the effect of different types of roofs on the air conditioning loads, and the life cycle cost of buildings with different types of roofing. The study was conducted in several phases: initial small-scale models to determine the heat flow characteristics of roof top soil layers with different thicknesses, a large-scale model applying the findings of the small-scale models to determine temperature fluctuations within a building with other common roofing systems, a computer simulation to investigate air conditioning loads in a typical building with cement fiber sheets and green roof slabs, a comparative analysis of the effect of traditional type roofs and green roofs on the air conditioning loads, and finally an analysis to predict the influence of traditional type roofs and green roofs on life cycle cost of the buildings. The main findings of the study were that green roofs are able to reduce the indoor temperature of buildings and are able to achieve better heat transfer through the roof, and, thus a lower cooling load is necessary for air conditioning and has the possibility of reducing life cycle cost of a building. R. U. Halwatura Copyright © 2013 R. U. Halwatura. All rights reserved. Building Sustainability Assessment throughout Multicriteria Decision Making Mon, 30 Sep 2013 14:32:42 +0000 Opinion and choice strongly influence sustainability concepts. The building construction industry, in particular property developers, has been charged with promoting excess environmental impacts ranging from overuse of resources to pollution generation. This paper presents an application of sustainability concepts to building projects, as well as to the development of practices, methodology, and tools for evaluating existing buildings. This study will detail how current systems to evaluate building performance operate and how to improve them. This approach utilizes the analytic hierarchy process (AHP). AHP is a multicriteria method that evaluates the relative importance of criteria, subcriteria, and families of indicators, used in the proposed system of technical characteristics applied to the local culture. At the same time, AHP makes visible the critical factors involved in evaluation of sustainability of these buildings. A result of the application of this type of modeling is a system for sustainability assessment and evaluation of environmental aspects and socioeconomic perspectives of existing buildings in the state of Rio de Janeiro, Brazil. Lúcio VillarinhoRosa and Assed Naked Haddad Copyright © 2013 Lúcio VillarinhoRosa and Assed Naked Haddad. All rights reserved. A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste Mon, 26 Aug 2013 11:28:43 +0000 This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement) was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage and concrete properties. Concerning mechanical properties, a gradual decrease in compressive, splitting, and flexural strengthn with the increase in recycled aggregate percentage is shown. Mamery Sérifou, Z. M. Sbartaï, S. Yotte, M. O. Boffoué, E. Emeruwa, and F. Bos Copyright © 2013 Mamery Sérifou et al. All rights reserved. Improving the Collaboration between Main Contractors and Subcontractors within Traditional Construction Procurement Mon, 15 Jul 2013 13:30:57 +0000 The inability of subcontractors/specialist contractors to contribute meaningfully to the construction process under the traditional construction procurement hampers the possibilities of improving value on projects and their integration with the rest of the supply chain. In particular, the main contractors and subcontractors in traditional construction procurement projects pursue their self-interests to such an extent that collaborative working has been impossible to achieve. In this research, qualitative and quantitative approaches were used to collect data to explore the problems at the root of the main contractor-subcontractor relationship. Intending to derive innovative ideas to reinvent the delivery process of traditional construction procurement, the principles of integrated project delivery (IPD) and the last planner system (LPS) were studied to seek useful ideas that can be employed to improve collaboration between main contractors and subcontractors. A high point of contention is the debate on the managerial competence of subcontractors; nevertheless, hope is expressed at the possibility of improving collaboration between the main contractor and subcontractor within traditional construction procurement work environment. Obafemi A. Akintan and Roy Morledge Copyright © 2013 Obafemi A. Akintan and Roy Morledge. All rights reserved. Improvement of Bearing Capacity of Shallow Foundation on Geogrid Reinforced Silty Clay and Sand Wed, 19 Jun 2013 18:25:30 +0000 The present study investigates the improvement in the bearing capacity of silty clay soil with thin sand layer on top and placing geogrids at different depths. Model tests were performed for a rectangular footing resting on top of the soil to establish the load versus settlement curves of unreinforced and reinforced soil system. The test results focus on the improvement in bearing capacity of silty clay and sand on unreinforced and reinforced soil system in non-dimensional form, that is, BCR. The results show that bearing capacity increases significantly with the increased number of geogrid layers. The bearing capacity for the soil increases with an average of 16.67% using one geogrid layer at interface of soils with equal to 0.667 and the bearing capacity increases with an average of 33.33% while using one geogrid in middle of sand layer with equal to 0.33. The improvement in bearing capacity for sand underlain silty clay maintaining and equal to 0.33; for two, three and four number geogrid layer were 44.44%, 61.11%, 72.22%, respectively. The finding of this research work may be useful to improve the bearing capacity of soil for shallow foundation and pavement design for similar type of soil available elsewhere. P. K. Kolay, S. Kumar, and D. Tiwari Copyright © 2013 P. K. Kolay et al. All rights reserved. Estimating Strain Changes in Concrete during Curing Using Regression and Artificial Neural Network Sun, 21 Apr 2013 15:36:53 +0000 Due to the cement hydration heat, concrete deforms during curing. These deformations may lead to cracks in the concrete. Therefore, a method which estimates the strain during curing is very valuable. In this research, two methods of multivariable regression and neural network were studied with the aim of estimating strain changes in concrete. For this purpose, laboratory cylindrical specimens were prepared under controlled situation at first and then vibration wire strain gauges equipped with thermistors were placed inside each sample to measure the deformations. Two different groups of input data were used in which variables included time, environment temperature, concrete temperature, water-to-cement ratio, aggregate content, height, and specimen diameter. CEM I, 42.5 R was utilized in set (I) and strain changes have been measured in six concrete specimens. In set (II) CEM II, 52.5 R was employed and strain changes were measured in three different specimens in which the diameter was held constant. The best multivariate regression equations calculated the determined coefficients at 0.804 and 0.82 for sets (I) and (II), whereas the artificial neural networks predicted the strain with higher of 1 and 0.996. Results show that the neural network method can be utilized as an efficient tool for estimating concrete strain during curing. Kaveh Ahangari, Zahra Najafi, Seyed Jamal Sheikh Zakariaee, and Alireza Arab Copyright © 2013 Kaveh Ahangari et al. All rights reserved. Seismic Analysis of Deep Water Pile Foundation Based on Three-Dimensional Potential-Based Fluid Elements Thu, 11 Apr 2013 10:22:24 +0000 This paper investigates the use of three-dimensional (3D) potential-based fluid elements for seismic analyses of deep water pile foundation. The mathematical derivations of the potential-based formulations are presented for reference. The potential-based modeling technique is studied and validated through experimental data and analytical solutions. Earthquake time history analyses for a 9-pile foundation in dry and different water environments are conducted, respectively. The seismic responses are discussed to investigate the complex effect of earthquake-induced fluid-structure interaction. Through the analyses, the potential-based fluid and interface elements are shown to perform adequately for the seismic analyses of pile foundation-water systems, and some interesting conclusions and recommendations are drawn. Kai Wei and Wancheng Yuan Copyright © 2013 Kai Wei and Wancheng Yuan. All rights reserved. Review of Nondestructive Testing Methods for Condition Monitoring of Concrete Structures Thu, 04 Apr 2013 08:20:17 +0000 The deterioration of concrete structures in the last few decades calls for effective methods for condition evaluation and maintenance. This resulted in development of several nondestructive testing (NDT) techniques for monitoring civil infrastructures. NDT methods have been used for more than three decades for monitoring concrete structures; now it has been recognized that NDT plays an important role in the condition monitoring of existing RC structures. NDT methods are known to be better to assess and evaluate the condition of RC structures practically. This paper reviewed several available NDT methods developed and used in the last few decades. Sanjeev Kumar Verma, Sudhir Singh Bhadauria, and Saleem Akhtar Copyright © 2013 Sanjeev Kumar Verma et al. All rights reserved. Thermal Behavior of Green Roofs Applied to Tropical Climate Thu, 10 Jan 2013 08:02:06 +0000 The main goal of this paper is to present results on an experimental field about the green roofs thermal behavior, compared to other traditional roof covering systems. On the one hand, it intends to describe shortly the constructive system of a green roof with a lightweight building system, which has a sustainable building materials character and, on the other, it worries with the water reuse and with the run-off delay. The main methodological procedure adopted to study the thermal behavior of green roof was installing thermocouples to collect surface temperatures and indoor air, later comparing them with existing prototypes in an experimental plot. The thermal behavior analysis of cover systems was assessed by a representative episode of the climate fact, based on the dynamic climate approach. The experimental results from internal air temperature measurements show that the green roofs applied to warm and dry climates also provide an interesting time lag with surface and internal air temperature reduction. Grace Tibério Cardoso and Francisco Vecchia Copyright © 2013 Grace Tibério Cardoso and Francisco Vecchia. All rights reserved.