Osnovni principi stroškovne optimizacije terminskih planov gradbenih projektov

The cost effective project realization represents one of the fundamental goals of the time scheduling in construction. The cost effective time schedule for the construction project is commonly achieved after performed analysis of the network diagram structure, activity durations, project costs, required resources and with trial-and-error testing of different alternative solutions. The minimum total cost time schedule of the construction project is usually selected from the obtained alternative solutions. The analytical approach to the time scheduling is widely used in construction on account of its simple execution and acceptable results. On the other hand, a significantly better results can be obtained by the mathematical programming-based cost optimization of time schedules. In this way, the aim of this paper is to bring forward the basic principles of the cost optimization of time schedules to the wider expert community. The paper presents the two basic methods for the model formulation of the project time scheduling optimization problems, i.e. the arrow diagramming method and the precedence diagramming method. Both methods were used for basic cost optimization model formulations of the project time scheduling optimization problem. An example from the literature was presented at the of the paper to demonstrate the applicability of optimization models for the cost optimization of construction project time schedules.Stroškovna učinkovitost izvedbe projekta predstavlja enega od temeljnih ciljev terminskega planiranja v gradbeništvu. Stroškovno učinkovit terminski plan za gradbeni projekt se običajno določi po opravljeni analizi strukture mrežnega diagrama, časov trajanja aktivnosti, stroškov projekta, potrebnih resursov in s preizkušanjem različnih alternativnih rešitev. Pri tem se izmed ugotovljenih alternativnih rešitev navadno izbere tista različica terminskega plana, s katero je možno doseči najnižje celotne stroške izvedbe gradbenega projekta. Analitični pristop k terminskemu planiranju se v gradbeništvu široko uporablja predvsem zaradi enostavnosti izvedbe in sprejemljivih rezultatov. Po drugi strani je možno doseči bistveno boljše rezultate s stroškovno optimizacijo terminskih planov, ki temelji na pristopu matematičnega programiranja. Tako je osnovni namen pričujočega članka približati osnovne principe stroškovne optimizacije terminskih planov širši strokovni javnosti. V članku sta predstavljeni dve osnovni metodi za formulacijo modelov optimizacijskih problemov terminskega planiranja projektov, to sta: metoda puščičnega diagrama in metoda precedenčnega diagrama. Za problem stroškovne optimizacije terminskega plana projekta je prikazana formulacija osnovnega optimizacijskega modela po obeh metodah. Na koncu članka je predstavljena uporaba optimizacijskih modelov za stroškovno optimizacijo terminskih planov na primeru gradbenega projekta iz literature

An integration of spreadsheet and project management software for cost optimal time scheduling in construction

Successful performance and completion of construction projects highly depend on an adequate time scheduling of the project activities. On implementation of time scheduling, the execution modes of activities are most often required to be set in a manner that enables in achieving the minimum total project cost. This paper presents an approach to cost optimal time scheduling, which integrates a spreadsheet application and data transfer to project management software (PMS). At this point, the optimization problem of project time scheduling is modelled employing Microsoft Excel and solved to optimality using Solver while organization of data is dealt by macros. Thereupon, Microsoft Project software is utilized for further managing and presentation of optimized time scheduling solution. In this way, the data flow between programs is automated and possibilities of error occurrence during scheduling process are reduced to a minimum. Moreover, integration of spreadsheet and PMS for cost optimal time scheduling in construction is performed within well-known program environment that increases the possibilities of its wider use in practice. An application example is shown in this paper to demonstrate the advantages of proposed approach

Using the TSP Solution for Optimal Route Scheduling in Construction Management

This paper presents the optimal route scheduling in construction management by using the solution of the traveling salesman problem (TSP). The TSP is a well-known combinatorial optimization problem which holds a considerable potential for applications in construction management. The aim of this paper is to bring forward the solution of the TSP to the wider expert community. For this purpose, the TSP model formulation, the applicability of the TSP optimization model and the commercially available software for modelling and solving the TSP are presented. An example of the optimal route scheduling by using the solution of the TSP is demonstrated at the end of the paper to show the applicability of the TSP model

Manufacturing cost optimization of composite floor trusses

This paper presents the manufacturing cost optimization of composite floor trusses. The composite floor trusses are designed to be built up of a reinforced concrete slab and steel trusses consisting of cold formed hollow sections. The optimization was performed by the nonlinear programming approach, NLP. An accurate objective function of the manufacturing material, power and labour costs was developed and applied for the optimization. Composite floor trusses were optimized according to Eurocode 4 for the conditions of both the ultimate and the serviceability limit states. A numerical example of the manufacturing cost optimization of a composite floor truss system, presented at the end of the paper, shows the applicability of the proposed approach

A comparison between MILP and MINLP approaches to optimal solution of Nonlinear Discrete Transportation Problem

Finding an exact optimal solution of the Nonlinear Discrete Transportation Problem (NDTP) represents a challenging task in transportation science. Development of an adequate model formulation and selection of an appropriate optimization method are thus significant for attaining valuable solution of the NDTP. When nonlinearities appear within the criterion of optimization, the NDTP can be formulated directly as a Mixed-Integer Nonlinear Programming (MINLP) task or it can be linearized and converted into a Mixed-Integer Linear Programming (MILP) problem. This paper presents a comparison between MILP and MINLP approaches to exact optimal solution of the NDTP. The comparison is based on obtained results of experiments executed on a set of reference test problems. The paper discusses advantages and limitations of both optimization approaches. First published online: 10 Jul 201

Solving the nonlinear discrete transportation problem by MINLP optimization

The Nonlinear Discrete Transportation Problem (NDTP) belongs to the class of the optimization problems that are generally difficult to solve. The selection of a suitable optimization method by which a specific NDTP can be appropriately solved is frequently a critical issue in obtaining valuable results. The aim of this paper is to present the suitability of five different Mixed-Integer Nonlinear Programming (MINLP) methods, specifically for the exact optimum solution of the NDTP. The evaluated MINLP methods include the extended cutting plane method, the branch and reduce method, the augmented penalty/outer-approximation/equality-relaxation method, the branch and cut method, and the simple branch and bound method. The MINLP methods were tested on a set of NDTPs from the literature. The gained solutions were compared and a correlative evaluation of the considered MINLP methods is shown to demonstrate their suitability for solving the NDTPs. First published online: 16 Oct 201

Solving the nonlinear transportation problem by global optimization

The aim of this paper is to present the suitability of three different global optimization methods for specifically the exact optimum solution of the nonlinear transportation problem (NTP). The evaluated global optimization methods include the branch and reduce method, the branch and cut method and the combination of global and local search strategies. The considered global optimization methods were applied to solve NTPs with reference to literature. NTPs were formulated as nonlinear programming (NLP) optimization problems. The obtained optimal results were compared with those got from literature. A comparative evaluation of global optimization methods is presented at the end of the paper to show their suitability for solving NTPs. First published online: 10 Feb 201

Construction procedures for public goods on roads of local interest in Slovenia

This paper deals with the issue of construction procedures for public goods on roads of local interest in Slovenia. The methodological frameworks of construction procedures for investment maintenance works and maintenance works in public interest are proposed for that purpose. A complete flow of activities required for such constructions is presented here, namely from preparation of project documentation through realization and inspection to the final acceptance of executed works. The applicability of the discussed approach is shown on practical examples. The paper is intended to serve as a guide to the local communities in Slovenia as well as an informative material to nearby countries that have similar regulations in considered field. The aim is to improve the local governance related to public goods on road infrastructure as well as to share key information about considered topic with a wider international expert audience for discussion and proposals of improvement