Fuzzy Estimation Of Activities Duration In Construction Projects

Abstract

During implementation of construction projects, durations of activities are affected by various factors. Because of this, both during the planning phase of the project as well as the construction phase, managers try to estimate, or predict, the length of any delays that may occur. Such estimates allow for the ability to take appropriate action in terms of planning and management during the execution of construction works. This paper presents the use of the non-deterministic concept for describing the uncertainty of estimating works duration. The concept uses the theory of fuzzy sets. The author describes a method for fuzzy estimations of construction works duration based on the fact that uncertain data is an inherent factor in the conditions of construction projects. An example application of the method is presented. The author shows a fuzzy estimation for the duration of an activity, taking into consideration the distorting influence caused by malfunctioning construction equipment and delivery delays of construction materials.

The Alternative Net Model with the Fuzzy Decision Node for the Construction Projects Planning

“…The possibility of analysis and calculation making depends directly on the choice of the mathematical tool. The fuzzy set theory invented by L.A. Zadeh [26] seems a very good, suitable choice, as it is successfully applied in modelling variety of processes in the construction industry [1], [6][7][8], [12], [20][21][22][23]. Considering the type of the input data, modelling linguistic variables with fuzzy numbersaccording to the author's opinion -is justified.…”

“…Nevertheless finding the probability distribution of any hypothetic event, in a real, single construction project it is very difficult. For these reasons, occupancy of any risk factor is uncertain [6][7], [11], [14][15][16], [18][19][20][21]. The assumption made by the decision maker (the manager) about the probability distribution should make him aware of the negative effects of the divergence between assumptions made and the real circumstances.…”

Neuro-fuzzy predictions of construction site completion dates

“…▶ the center of gravity method [7] (labeled as A): -the value of the output variable for i fuzzy set, μ(x i ) -the membership function of the output variable for i fuzzy set, i -number of fuzzy set of n fuzzy sets, ▶ the weighted average method modified (labeled as D) where only two fuzzy sets were taken into account: medium always, and the other set with higher predicted μ (μ S or μ L ), then formula (7) is applied. The modification of method B was based on the fact that delays calculated for teaching ANN set of data are represented by three numbers (as shown in tab.…”

Studies on the Microstructure of Epoxy-Cement Composites

“…The scientific basis for the improvement of PCC performance are similar to those for the other composites. On the one hand, the statistical methods of optimization are developed, the same way as it is observed in theory of structures and managing [16,17]; the advanced methods are employed, like using the artificial neural networks or fuzzy logic [18]. On the other hand, the efficient modification is possible if reliable model of the microstructure formation is available, including such questions as interaction between polymer and cement and creation of continuous polymer film [19].…”