Mario Galić

Methodology and algorithm for asphalt supply chain optimization

In this paper authors suggest and test evolutionary algorithm of multiple criteria solver (MCS) for asphalt supply chain optimization. On the basis of the defined imperfection of the basic mathematical model authors made an algorithm and conducted simulations of transportation problems cases generated from the given realistic input intervals in order to determine the constraints and possibilities for improvement of the original model of the transportation problem of large amounts of asphalt mixture. Results have shown that the suggested model verifies and eliminates the lack of the original model. As well, it is shown in which scenarios of transportation problem and to which extent the suggested methodology contributes to the total transportation costs savings and insurance of the program’s optimality.

PROCESS MODELING AND SCENARIO SIMULATION IN CONSTRUCTION USING ENTERPRISE DYNAMICS SIMULATION SOFTWARE

Modeling and simulation of organizational processes are established methodologies and tools in most industries. In civil engineering, however, this is

Scenario simulation model for optimized allocation of construction machinery

Metode optimizacije imaju veliku važnost pri sužavanju izbora resursa na konacni i pri alokaciji resursa u svim fazama projekata. To se narocito odnosi na složena projektna okruženja gdje je potrebno provesti alokaciju resursa (strojeva) na vise građevinskih projekata u njihovim raznim fazama i prioritetima. U radu se predlaže model koji se zasniva na algoritmu visekriterijske optimizacije i rangiranja scenarija suboptimalnih programa serijskog visekanalnog rada građevinskih strojeva pri konacnom broju strojeva za izbor, te izlucivanje presjeka optimalnih programa i/ili scenarija programa u složenom okruženju.Metode optimizacije imaju veliku važnost pri sužavanju izbora resursa na konacni i pri alokaciji resursa u svim fazama projekata. To se narocito

Pervious concrete mix optimization for sustainable pavement solution

In order to fulfill requirements of sustainable road construction, new materials for pavement construction are investigated with the main goal to preserve natural resources and achieve energy savings. One of such sustainable pavement material is pervious concrete as a new solution for low volume pavements. To accommodate required strength and porosity as the measure of appropriate drainage capability, four mixtures of pervious concrete are investigated and results of laboratory tests of compressive and flexural strength and porosity are presented. For defining the optimal pervious concrete mixture in a view of aggregate and financial savings, optimization model is utilized and optimal mixtures defined according to required strength and porosity characteristics. Results of laboratory research showed that comparing single-sized aggregate pervious concrete mixtures, coarse aggregate mixture result in increased porosity but reduced strengths. The optimal share of the coarse aggregate turn to be 40.21%, the share of fine aggregate is 49.79% for achieving required compressive strength of 25 MPa, flexural strength of 4.31 MPa and porosity of 21.66%.

Impact of changes in a project team structure on the team performance

Structuring a project team is highly sensitive task, so numerous methods which address the problem have emerged. One of the most effective methods is structuring teams by the team members’ affinities and talents presented as team roles. In this paper, we applied Belbin’s Self-Perception Inventory in order to investigate the following questions: Which are the most engaged team roles? How does the absence of the most engaged team members affect the team’s efficiency? How does this change of the team environment affect the member? Our results show that, even in small project teams, changes in team structure will surely have a negative effect on the team’s organizational culture in a short run, and even more importantly they decrease the team’s overall productivity. Also, the changes had a negative effect at the individual level ; teams had trouble integrating new members, and individuals had trouble integrating themselves in new teams.

CONSTRUCTABILITY-BUILDABILITY-IZGRADIVOST

Izgradivost je koncept koji jos nije ostvario znacajniji utjecaj u građevinskoj praksi u Hrvatskoj, kao sto je to slucaj u zemljama poput SAD-a, Kanade, UK i Australije. Ovim se radom nastoji prihvacenu definiciju, ciljeve i output koncepta izgradivosti približiti sudionicima u građevinskim projektima, no i utvrditi sto pojedine interesne strane smatraju kljucnim problemom u eventualnom provođenju koncepta, ali i koji su uzroci problema na relaciji projektiranje-izvođenje-koristenje opcenito.

Finite Element Mesh Size Optimization for Steel Bolted Connection

Bolted connections are important components of steel structures and they must be based on good design, with analytical descriptions of failure mechanisms that are thoroughly researched. A robust and reliable analytical description of a failure mode requires a large base of results, collected experimentally or numerically, usually via FEA. The modelling procedure in FEM simulations can significantly influence result accuracy, and one of the most important parameters is spatial discretization. Mesh size presents a delicate balance between accuracy, efficiency and convergence issues, especially in bolted connection analysis with contact, material and geometric nonlinearity. Due to increased complexity, sensitivity studies are difficult to interpret and time expensive, which is why in this study a mesh size optimization procedure is presented. This optimization is based on a previously verified and validated numerical model parametric study of a single-bolt lap connection. The first step included forming of an optimization model based on an artificial neural network, through which results were extrapolated and compared to experimental. However, estimated solving wall time was significantly longer. In the second step, a nonlinear optimization model was structured to determine a mesh size for which the difference between experimental and optimization results would be equal, whilst having a minimal solving wall time. The optimization model provided insights into mesh size quality to efficiency ratios and rendered that the minimal difference between experimental and numerical results is 1.57%, while having a solving wall time of 1.3 h, instead of the step one optimization modelling estimated 36 h.

Survey Of Accomplishments in BIM Implementation in Croatia, The Czech Republic, Germany and Slovenia

Building information modelling (BIM) may currently be considered the fastest developing concept in the field of construction management, aiming to become a global standard. Although the roots of the concept date back to the mid-1970s, some original expectations are still missing from its implementation. There has been a time gap between its theoretical and practical implementations. While the simultaneous development of information technologies is one reason for the implementation delay, other reasons remain unclear. This paper analyzes the gaps between theoretical and practical BIM application, as well as the legislation regarding BIM implementation in four countries (in alphabetical order: Croatia, the Czech Republic, Germany, and Slovenia). The paper additionally presents a survey of current practical BIM applications as well as general and theoretical feedback from construction projects that implemented BIM.

Application of “Einstein's riddle” in solving construction machine allocation problems

“Einstein’s riddle” is a popular example of constraints satisfaction problem. Since its introduction, different forms and variations of the riddle have been presented. Regardless of the variant of the riddle, its solution is considered a tough challenge for humans. Researchers have developed and are still developing mathematical models, as well as computational simulation models for solving it. In this article, the authors have modified a previously published mathematical model and developed a computational spreadsheet model for solving the riddle, which provides a unique solution for the riddle. The model was also tested in a small and medium-scaled form for solving constraint satisfaction problems regarding the allocation of construction machines. The authors have also highlighted the model’s limitations for solving such problems and made suggestions regarding necessary modifications in the model to solve more complex problems in the same domain.

Scenarijski simulacijski model za optimalnu alokaciju građevinskih strojeva

Metode optimizacije imaju veliku važnost pri sužavanju izbora resursa na konacni i pri alokaciji resursa u svim fazama projekata. To se narocito odnosi na složena projektna okruženja gdje je potrebno provesti alokaciju resursa (strojeva) na vise građevinskih projekata u njihovim raznim fazama i prioritetima. U radu se predlaže model koji se zasniva na algoritmu visekriterijske optimizacije i rangiranja scenarija suboptimalnih programa serijskog visekanalnog rada građevinskih strojeva pri konacnom broju strojeva za izbor, te izlucivanje presjeka optimalnih programa i/ili scenarija programa u složenom okruženju.Metode optimizacije imaju veliku važnost pri sužavanju izbora resursa na konacni i pri alokaciji resursa u svim fazama projekata. To se narocito