Quantities Of Construction Materials Research Articles

Economic analysis and environmental impact of flat plate roof mounted solar energy systems

The flat plate solar water heating system and solar photovoltaic (PV) system are two mature technologies available in the commercial market, which can decrease the residential energy requirement substantially. Several research organizations are working on solar PV/T system to make it competitive to solar thermal system and solar PV system. Innovative designs over the decades have improved the performance of the solar PV/T collector significantly. However, the choice of material-of-construction play a vital role in reducing the mass, cost, embodied energy and embodied CO2 emissions of the solar PV/T collector. In this paper, a solar PV/T based water heating system was compared with a solar PV system and a flat plate solar water heating (SWH) system based on economic evaluation and environmental assessment. Results obtained show that due to the higher overall efficiency, the solar PV/T system has better benefit-to-ratio compared to solar PV system, while being competitive to solar thermal system. Also, it makes the best use of the available domestic roof-space, minimizes quantity of construction materials and payback period. Further, the embodied energy and embodied CO2 emission of the PV/T collector is less than the other two solar energy systems combined.

A hybrid methodology to estimate construction material quantities at an early project phase

Preliminary project cost estimates are the first serious estimates made on a project. They play an important role during the decision-making process, and are the benchmark with which future estimates are expected to agree. This paper concentrates on the estimation of construction material quantities (CMQs) and presents a methodology to accurately estimate them during an early project phase. We make use of existing data and utilize regression analysis, neural networks and case-based reasoning to provide accurate results. It encompasses data collection, model development and evaluation, and the integration of different techniques. The use of the methodology is demonstrated by estimating CMQs of relevant structures. The accuracy of the methodology is investigated and compared with three state-of-practice approaches. The results obtained show a significant improvement over the state of the practice, and would improve the accuracy of preliminary project costs estimates. Through partial automation, it would likely reduce the time required to make estimates.

Preliminary Resource-based Estimates Combining Artificial Intelligence Approaches and Traditional Techniques

The fate of many construction projects is determined using preliminary project cost estimates. These estimates play a key role during the conceptual phase of projects; as in many cases they are the primary element used to decide their viability. The lack of information and the high levels of uncertainty during the conceptual phase, make it infeasible to have reliable building information models that could be used to generate quantity takeoffs for preliminary cost estimates (known in the industry as 5D BIM), in line with a Level 2 BIM maturity. This paper presents a way to combine artificial intelligence (case-based reasoning and neural networks), with traditional techniques (regression analysis), to develop accurate estimates of the resources needed in a project (e.g., construction material quantities). These estimates of resources can then be coupled with unit cost information to make preliminary resource-based cost estimates. The clear division between the technical and financial components of such an estimate gives improved decision support to project managers and decision makers. This enhances the tracking and control mechanisms which could be used to check the estimates prepared in subsequent project phases. The combination of case-based reasoning with regression analysis and the use of neural networks has shown an improved performance in the estimation of the amount construction material quantities. The proposed combination was used to estimate the amount of concrete, reinforcement, and structural steel required for the construction of tall-frame structures. The results show lower errors (overall mean absolute percentage error-MAPE) for the combined models (2.55%) when compared to the regression models (12.01%), neural network models (5.84%), and case-based reasoning models (9.30%).

Investigation of the Case-based Reasoning Retrieval Process to Estimate Resources in Construction Projects

Case-based reasoning (CBR) is a methodology that is seeing increasing use to make predictions during the early phases of a project. It allows estimators to exploit existing knowledge to make predictions that are considerably better than without its use. All CBR, however, is not identical, and variations in how CBR is done can affect the accuracy of the predictions. One particular area of sensitivity is the retrieval phase, i.e. the way in which the CBR determines the closeness between the new and the existing cases.In this paper, CBR is used to make estimates of resources for construction projects, and the use of the nearest neighbor technique to identify the similarity for the retrieval phase to predict the construction material quantities (CMQs) in concrete structures is investigated. Two types of distances, i.e. 1) the City-block distance and 2) the Euclidean distance, and four different types of weights, based on regression analysis and feature counting, to account for the relative importance of the different parameters, are investigated. The four different types of weights used were 1) the adjusted unstandardized coefficients from the regression models, 2) the unadjusted unstandardized coefficients from the regression models, 3) the standardized coefficients from the regression models, and 4) equal weights (i.e., feature counting), in which the weights applied are 1/k, and k is the number of parameter being compared to determine the distance.The mean absolute percentage error (MAPE) was used to evaluate each combination investigated. It was found that for a similarity threshold of 90%, the CBR methodology using the City-block distance with the adjusted unstandardized coefficients from the regression analysis models using the transformed (LN) dataset as weights, gave the best results, with a MAPE of 8.16%. The worst results were obtained from the CBR methodology using the Euclidean distance with feature counting weights, with a MAPE of 28.40%.

A Process for the Development and Evaluation of Preliminary Construction Material Quantity Estimation Models Using Backward Elimination Regression and Neural Networks

During the early stages of a project, it is beneficial to have an accurate preliminary estimate of its cost. One way to make those estimates is by determining the amount of construction material quantities that are required and then multiplying the estimated construction material quantities by the corresponding unit cost. One advantage of making estimates in this way is that it allows for the segregation of quantities and costs. This way they can be updated separately as new information becomes available. They can also be tracked separately allowing decision makers to make better decisions about the project during its conceptual phase. There are several techniques that can be used to develop estimation models. The most common include regression analysis and artificial intelligence, such as neural networks. Work has been done, however, in a non-standardized way, leaving practitioners without guidance as to how to develop and evaluate models for their specific purposes. This can be seen in particular in the...

CONSTRUCTION AND MAINTENANCE OF EMBANKMENTS USING HIGHLY ERODIBLE SOILS IN THE PILBARA, NORTH-WESTERN AUSTRALIA

Many soils and sediments in the Pilbara region of north-western Australia are highly susceptible to erosion. Large quantities of construction materials are required as iron ore mining and the extensive railway lines used to transport ore to port continue to be developed in the region. Simply avoiding the use of highly erodible materials is often considered to be too high a cost where alternatives are scarce. Constructing embankments to survive the cyclonic wet season from material highly susceptible to erosion, is a major challenge. Highly erodible materials encountered in the Pilbara include some bedrock shales, dispersive alluvial silts and sands and slaking clays and mudstones. Dispersive materials can erode internally by the formation of pipes or tunnels. Piping erosion can be difficult to detect and can cause severe internal damage to embankments before being detected. Similarly, slaking material can undergo compaction during wetting and drying cycles resulting in unexpectedly large settlements. The effect of erosion, in general, is controlled by appropriate embankment design and construction, in particular compaction standards. Erosion controls include sacrificial batters, surface protection, encapsulation and stabilisation. For many mining projects achieving short-term construction deadlines is a high priority and adding erosion control measures after construction may be preferred. Predicting the time by which erosion control needs to be installed or rehabilitated should be a part of the embankment design process. Material selection has direct implications for the on-going asset management of embankment structures.

First record of Osteopilus septentrionalis on Guana Island, British Virgin Islands

Cuban treefrogs are native to Cuba, the Cayman Islands, and the Bahamas, but are increasingly recorded from other locations (Lever, 2003). The species was first collected in the British Virgin Islands (BVI) in 1990 (Owen et al., 2005) and has since spread, with about one new island record per year in the BVI (Owen et al., 2005, 2006; Perry and Gerber, 2006) and new localities in the United States Virgin Islands (Waddle et al., 2005; Platenberg and Boulon, 2006; Perry and Platenberg, 2007). Perry and Gerber (2006) mentioned that the species had been sighted on Guana Island, BVI, but did not provide any information that would allow the significance or circumstances of the event to be evaluated. Those details are provided herein. At about 2000 h on 21 October 2005, I collected an adult male (SVL = 72 mm) with small nuptial pads, foraging at a night light within the hotel complex on Guana Island. Guana Island is a private wildlife preserve. In the 12 months prior to the reported event, the small hotel on the island had imported relatively large quantities of construction materials and ornamental plants. However, hotel staff had made extensive attempts to prevent the arrival of the Cuban treefrog and other invasive species. These include manual searches of all arriving plants and other materials while still on the barges bringing them to the island, and on-island fumigation within an enclosure into which arriving materials and engine exhaust were introduced (Perry et al., 2006). No additional Cuban treefrogs have been seen on Guana since removal of that individual, despite extensive searches in 2006 and 2007. Guana Island offers RA P.1 (1-2) APHE:m v 1.24 Prn:7/01/2009; 14:03 aphe1161 by:Daiva p. 1

A STUDY ON THE EFFECTIVE CONSTRUCTION MANAGEMENT USING EARNED VALUE MANAGEMENT SYSTEM

The construction process has a long lifecycle, involving; a planning phase, investigation phase, designing phase, tendering & contracting phase, construction phase, maintenance and renovating phase. Within this lifecycle, the construction phase particularly requires the use of significant quantities of construction materials, machines, manpower and capital within relatively short period. Therefore, to ensure outputs are optimized, and all expectations of project proponents are achieved, effective and efficient management strategies and methodologies must be adopted.An Earned Value Management System (EVM) is an integrated concept which can be applied to manage construction cost and time as conceived by the Department of Defense (USA), and subsequently widely adopted throughout the world by many governmental organizations andprivate enterprises. The use of EVM has also been made more available through the providers of mainstream project management software, such as “Primavera Project Planner” and “MS Project”, by the inclusion of EVM functions within their systems.Our paper considers on the relationship between construction resources and programme through analysis of a resourced network model and application of Graph Theory “between-ness index” to determine important key activities. The output from our analysis has then been applied as a prototype on an oversea project, to weight the planned value of the EVM in line with the identified key activities. The practical effectiveness of our proposed EVM was thereafter monitored verified and validated through a series of extensive and robust physical site trials, with positive results and conclusions.

Four-Dimensional Visualization of Construction Scheduling and Site Utilization

Four-dimensional ~4D! models link three-dimensional geometrical models with construction schedule data. The visual link between the schedule and construction site conditions is capable of facilitating decision making during both the planning and construction stages. The emphases of these 4D developments have often been placed at the level of construction components. Practical features assisting site management are at times lacking in the following areas: ~1! generation of site usage layouts; ~2! estimation of quantities of construction materials; and ~3! cost evaluation. In order to pinpoint these deficiencies, the objective of this work is to enable visual study of the effects of job progress on the logistics and resource schedules. This paper presents a 4D visualization model that is intended both to help construction managers plan day-to-day activities more efficiently in a broader and more practical site management context and to thereby add to our knowledge and understanding of the relevance of modern computer graphics to the responsibilities of the construction site manager. A brief site trial of the software is described at the conclusion of the paper.

Various problems in lunar habitat construction scenarios

Many papers describing the lunar base construction have been published previously. Lunar base has been considered to be a useful facility to conduct future scientific programs and to get new nuclear energy resource, namely 3He, for defending the environmental collapse on Earth and also to develop lunar resources such as oxygen and nitrogen for extending human activities in space more economically. The scale of the lunar base and the construction methods adopted are determined by the scenario of a lunar utilization program but constrained by the availability of the established space transportation technologies. As indicated in the scenarios described in papers regarding lunar base construction, the first steps of lunar missions are the investigation of lunar itself for conducting scientific research and for surveying the lunar base construction sites, the second steps are the outpost construction for conducting man-tended missions, for more precise scientific research and studying the lunar base construction methods, and third steps are the construction of a permanent base and the expansion of this lunar base for exploiting lunar resources. The missions within the first and second steps are all possible using the ferry (OTV) similar to the service and command modules of Apollo Spacecraft because all necessary weights to be landed on the lunar surface for these missions seem to be under the equivalent weight of the Apollo Lunar Lander. On the other hand, the permanent facilities constructed on the lunar surface in the third step requires larger quantities of construction materials to be transported from Earth, and a new ferry (advanced OTV) having higher transportation ability, at least above 6 times, compared with Apollo Service and Command Modules, are to be developed. The largest problems in the permament lunar base construction are related to the food production facilities, 30–40 m 2 plant cultivation area per person are required for providing the nutrition requirement and the necessary electric power per person for producing high energy foods, such as wheat, rice and potato, are now estimated ranging from 30 to 40 kW. The extension program of crew numbers under the limitation of usable transportation capability anticipated at present and the construction scenarios, including the numbers of facilities to be constructed every year, are to be determined based upon the requirements of plant cultivation area and of electric power for producing necessary and sufficient foods in order to accelerate the feasibility studies of each subsystem to be installed in the permanent lunar base in future.