Ossama Hosny

Solving the Least-Cost Route Cut and Fill Sequencing Problem Using Particle Swarm

AbstractSeveral researchers have attempted to formulate and solve different classes of the earthwork allocation problem. Linear programming (LP) and integer programming (IP) techniques have traditionally been applied to minimize transportation costs and mass-haul distances associated with earthwork processes. However, typical formulations of the earthwork allocation problem do not consider the sequence of equipment movement and are, therefore, limited in their ability to establish a practical and workable hauling plan. A more complex problem, which is formulated and solved in this research, is the least-cost route cut and fill problem (LCRCFP). The primary objective of the LCRCFP is to determine the specific route to be traveled and the quantities of soil that construction equipment must haul to meet the desired grade while minimizing the total distance traveled. In this research, the LCRCFP was formulated as a mixed binary optimization problem and solved using a traditional branch-and-bound method and a ...

Selection of slab formwork system using fuzzy logic

Formwork plays an important role in building construction. The selection of an appropriate formwork system can reduce project cost, improve quality and speed up the construction process. Although the selection of an appropriate formwork system requires years of experience in formwork design, few experienced personnel may be available, especially in small/medium size contracting companies. With the lack of such experts, the costly outsourcing option becomes essential otherwise the selection of a particular formwork system might not be appropriate. A structured approach is developed to help decision makers in small/medium Egyptian construction companies to select the appropriate horizontal formwork system(s) for their projects. This can be achieved by recognizing the project governing factors affecting the selection process. Based on these factors, a knowledge base is developed to facilitate the process. A fuzzy logic system is used to automate the process and overcome ambiguity and uncertainty in the selection process. The system is shown to be useful and accurate in its application to a real-life case. A survey of formwork experts reveals its ease of use. Further research will expand the system to consider vertical formwork selection to ensure full compatibility.

Prequalification of Egyptian construction contractors using fuzzy‐AHP models

Purpose – Contractor prequalification is a typical multiple criteria decision‐making problem that includes both quantitative and qualitative criteria. The conditions surrounding the prequalification decision are often imprecise, subjective and uncertain; assessments are consequently made using linguistic approximations. Fuzzy set theory is specifically designed to handle qualitative and linguistic data based on approximations and provides a method of representing in numerical form the linguistic approximations used to describe the decision‐maker judgments. However, fuzzy set theory has a weakness in identification of the relative weights of the decision criteria. On the other hand, one of the most accurate and easy methods for identifying the relative weights is the analytic hierarchy process (AHP). This paper seeks to address these issues.Design/methodology/approach – The main objective of this paper is to develop a new integrated decision model composed of fuzzy set theory and analytic hierarchy process...

Fuzzy Logic Model for Selection of Vertical Formwork Systems

Formwork systems have a considerable share in building construction costs. Accordingly, selecting an appropriate formwork system that respects project individualities plays an important yet challenging role in achieving significant cost savings. In Egypt, current practice in formwork selection primarily uses the subjective decisions of site engineers. This paper presents a fuzzy logic-based model that supports decision makers in selecting the appropriate vertical formwork system for projects. Ten commercial vertical formwork systems commonly used in Egypt are identified with the most important factors affecting their selection. The data were tabulated to serve as a knowledge-based system (KBS) to guide site engineers in selection. On the basis of the KBS, a fuzzy logic model with five input variables, representing the governing factors, is then developed to automate the selection process. The model is tested by applying it on a real-life case study. Results are acceptable and show a promising role for fuzzy logic in formwork selection. DOI: 10.1061/(ASCE)CO.1943-7862 .0000490.

Decision Support System for Housing Developers in Developing Countries under Uncertain Buyer Behavior

AbstractThe financing of housing projects is an essential component for solving the housing problem in developing countries. Traditional cash flow models for housing developments do not consider the stochastic nature of buyer behavior in terms of the time of purchase, the chosen financing method and the probability of default. This paper presents a decision support system to help developers in planning their projects and to better assess the expected profits and risks involved. The proposed model represents a new approach for assessing the profitability of housing projects by considering the effect of buyer behavior on the cash flow of a project. The system could be particularly useful for developing countries where housing development projects can extend over many years due to the long delivery/construction time frames involved as well as the intermittent nature of sales. A Monte-Carlo simulation model is presented that models the financial interactions over the life cycle of the project. This proposed f...

A Model for Assessing Maximum Overtime Rate in Labor Subcontracting Practices

Despite the rapid development in the construction industry due to the changing new technologies, many projects still fail to meet target deadlines. Shortage in manpower and skilled laborers is one of the main reasons for such delays. Markets with high economic growth and economic expansion (such as Gulf Countries in the Middle East) may have pronounced labor the shortages. Labor subcontracting practices are used sometimes to increase production rates and meet project deadlines. This paper explains and analyses labor subcontracting practices currently being used in many places around the world (and especially in the Gulf Countries) and in particular defines a maximum overtime rate for laborers in the laborer-subcontracting method ensuring that the contractor gains both the time saved during overtime and also reduces the cost per unit produced. The mathematical model used formalizes a closed-form equation for overtime pay in similar situations and as such can be applicable worldwide. Data was collected from representative projects that employed such practices from various trades. Validation of the model and formula has been tested successfully by analyzing historic data. The results prove that contractors often do not reach the optimum use of their practices resulting in a higher cost per unit. The presented model and the analysis should be of interest to many contractors currently involved in the practice or considering its use and to those who wish to find new methods that would help in eliminating as much wastes as possible by allocating their resources in the most efficient way.

Green building design in Egypt from cost and energy perspectives

Sustainable concepts in building designs have potential to enhance building performance and to reduce operating cost. With investors in developing economies overlooking all considerations except profit, this paper aims at promoting green construction in Egypt by presenting possible savings that investors could earn. The paper introduces an integrated framework to allow building design stemming from basic sustainable approaches. The framework can function as an optimization/simulation platform to automatically improve building designs. Following the framework principles, a model was developed that functions through four modules: a System Builder to create various envelope systems alternatives; a Building Integrator to form a complete design; a Design Evaluator to assess costs and energy; and Design Adaptation that allows optimization and simulation. The model represents a comprehensive yet easy application tool for cost and energy trade-off analyses that suits early design stage. A comparative analysis showed that green designs exhibited lifecycle and annual energy savings reaching 16.3% and 50%, respectively. A sensitivity analysis was performed to show the relationship between changes in electricity prices and percentage saving in lifecycle cost, optimum design and payback period. Furthermore, simulation of possible building designs is conducted to offer trade-off comparison between initial and energy costs of different designs.

Structural Deterioration Prediction Modeling for Coastal Protection Structures in Alexandria Eastern Harbor

Limited research has been carried out on artificial-intelligence-based deterioration modeling for coastal structures. An Asset Inventory Database (AID) for Alexandria’s Eastern Harbor coastal assets was developed. Established visual inspection and condition rating procedures were followed to obtain a current Structural Condition Index (SI) and a Structural Condition Matrix (SCM) for each structure, considering a single inspection point. SI’s and SCM’s are classified into severity ranges. Taking the age of structure into account, transition probabilities between each of the deterioration severity ranges were calculated using backward analysis. Such probabilities were then utilized to formulate the structure’s MarkovChain (MC) transition probability matrix, enabling the prediction of future deterioration in case of a No-Action policy. Furthermore, an Artificial Neural Network (ANN) model was constructed using the same backward analysis concept. Comparing the MC and the ANN deterioration forecasts up to year 2050 for the same structures, the results showed very close deterioration trends with an error margin ranging between 5% and 12%. It was concluded that the stochastic MC-based deterioration modeling was more accurate in simulating the deterioration of structures between their year of construction and present. The deterministic ANN model showed promising capability of deterioration prediction depending on the quality of the structure’s design data, historical records, and environmental conditions.

Design Buildings Optimally: A Lifecycle Assessment Approach

This publication is based on the work supported by Award No. KUK-C1-014-12, made by King Abdullah University of Science and Technology (KAUST), Saudi Arabia.

Performance-Based Reliability-Centered Maintenance Planning for Hospital Facilities

AbstractThe deteriorating state of the built environment has affected numerous sectors, and hospitals are no exception. Hospitals are relatively unique compared with other facilities because of the...