Proceedings of Faculty of Civil Engineering

Impressum

Martina Vivoda Prodan — 2024-12-03

Foreword

Martina Vivoda Prodan — 2024-12-03

A Word from the Dean

Mladen Bulić — 2024-12-03

Comparation of flow calculations using the population load coefficient method and population distribution by individual sections of the water supply network

Mauro Košuta — 2024-12-03

The paper presents a comparison and analysis of the flow calculation using the population load coefficient method K and population distribution by individual sections of the branched water supply network. The hydraulic design is based on the laid water supply network for the community of Ližnjan in Istria. Using the population coefficient load method K, a characteristic section of the water supply network is defined, and then the population load coefficient is defined for the remaining sections. After that, the virtual lengths and specific flow for sections of the water supply network are defined in l/s/m, based on which the own flows for individual sections of the water supply network are calculated. The second method defines the number of inhabitants on individual sections of the water supply network, based on which the specific flow for sections of the water supply network is defined in l/s/inhab. After that, own flows are calculated for individual sections of the water supply network. Hydraulic design is made based on the calculated total flows covered by the given methods, and also the comparison and analysis of total flows, pipe diameters, velocities and pressures on individual sections and nodes of the water supply network is given. The conducted comparisons of hydraulic calculations did not reveal any significant differences in the flows, and therefore not in the pipe diameters and velocities in individual sections of the system, nor in the pressures calculated in the calculation nodes of the water supply network. When used properly, both methods give reliable results.

Excavation protection of the Paromlin city library construction pit in Zagreb

Barbara Rukavina — 2024-12-03

The choice for the construction pit protection is extremely important in order to ensure the safety of workers, neighboring buildings and the environment during construction. The specific conditions of the construction site, geological conditions, the depth of the pit and the nearby infrastructure are crucial for the selection of the stabilization method of the construction pit. The paper provides an insight into several variant solutions for securing the construction pit of the Paromlin city library in Zagreb, for which a calculation was made in the PLAXIS 2D software package based on numerical analysis, i.e. the finite element method, taking into account the geotechnical characteristics of the soil determined by investigation work, the depth of the pit, environmental conditions, project requirements, legal and safety aspects, and economic feasibility. In order to choose the most suitable method of pit stabilization, a calculation was carried out for seven variant solutions on the relevant cross-section, all of which can be classified into three types of the construction pit protection: steel sheet piles, pilot rock design, and reinforced concrete diaphragm design.

Testing sand strength with ring shear apparatus

Nika Kamenar — 2024-12-03

This paper describes the determination of the shear strength parameters of sand using a ring shear apparatus (RSA). The paper presents the concept, the design of the apparatus and the test procedure in the apparatus, and offers the description of the soil sample. The tests were performed on samples of uniformly graded sand in drained conditions at normal effective stresses in the range of 32 to 200 kPa. The resistance of the seal inside the device itself was also taken into account. Consolidation was performed as part of the test, and then the sample was sheared with back pressure and a constant increase in shear displacement. Test results were used to determine the peak and residual parameters of the Mohr-Columb sand strength criterion.

Genesis and development phases of coastal settlements on the example of Milna on Brač

Duje Poklepović — 2024-12-03

The paper analyses the development of the urban structure of coastal settlements on the example of Milna on Brač, whose prosperity was marked by shipbuilding. The development stages of the place that gave Milna its characteristic features were examined, which can be observed in the changes in the settlement's fabric. Given the rapid increase in the built environment of almost all coastal settlements, including Milna on Brač, it is imperative to investigate the development processes and changes in the morphology of these settlements to preserve their characteristic features and develop quality guidelines for further development.

Modeling the inflow and outflow dynamics of retention/detention basin

Monika Greblo — 2024-12-03

The paper presents a calculation method that can be used to model the dynamics of emptying and filling retention basins intended for the temporary retention of water, i.e. to achieve the necessary transformation of the flood wave hydrograph. The calculation method is based only on the principle of mass conservation and is therefore very simple and attractive for practical application (assuming that dynamic phenomena can be reasonably neglected). To verify the effectiveness of retention for the relevant hydrological extreme conditions, the temporal change in water level must be determined by solving the mass conservation equation, which correlates the resulting change in water volume in the retention and the difference in mass flows at the inlet and outlet of the retention in the same time period. The presented procedure takes into account the inflow of water from the surface flow and the inflow of water resulting from precipitation above the retention basin. Therefore, for water flows at the outlet, the following are taken into account: the water flow under pressure through the outlet, the water flow over the spillway crest and the infiltration flow at the bottom of the retention basin. The calculation method was reduced to a simple numerical solution of an ordinary and non-linear differential equation of the first order.

Optimisation of traffic in the City of Opatija based on traffic microsimulation model

Edin Fatić — 2024-12-03

In this paper traffic and construction solution for converting the main city street in Opatija, Maršala Tita Street, from a two-way street to a one-way street with additional longitudinal parking and diverting traffic to the parallel corridor, state road D66 (Ulica Nova cesta), is presented. The solution was analyzed using the traffic model created in the VISSIM software package. It turned out that such a solution would have a negative impact on the traffic flow on the state road D66.

Rain garden drainage dynamics modeling by using the Green-Ampt model

Stefan Jakac — 2024-12-03

The paper presents a relatively simple calculation procedure for modeling the drainage dynamics of rain gardens, i.e. adequately designed infiltration surfaces that are used in urbanized areas for the temporary retention of rainwater. To that end, it is necessary to quantify the infiltration of water into the porous soil, which in general can be very demanding because the hydraulic process in question is described by Richards' partial differential equation, the numerical integration of which is a very challenging task (due to the nonlinearity between the hydraulic conductivity and the degree of saturation determined by its solution). At the same time, relying on several working assumptions stated in the paper, the mathematical description of the subject process can be reduced to the solution of one non-linear algebraic equation, which then creates a relatively simple calculation procedure that can be applied in everyday professional work (if the introduced assumptions can be justified). The calculation procedure is reduced to the integration of Darcy's law, which leads to the Green-Ampt model. The paper presents the argumentation for the aforementioned, calculation procedure intended for practical work, and also offers a numerical example.

Analytical solution for the problem of pure bending of orthotropic micropolar plate

Damjan Jurković — 2024-12-03

When analysing the problem of pure bending of a plate, it can be noticed that, for cylindrical bending, a spatial problem collapses into a plane-strain problem. For such a boundary-value problem of the Cosserats' continuum, three engineering parameters are required: Young’s modulus, Poisson’s ratio and the characteristic length for bending. Here we consider an orthotropic form of such a problem, whereby two Young’s moduli, four Poison’s ratios and one characteristic length for bending are found to be sufficient to propose a mathematical model of this problem. General equations of the isotropic micropolar continuum are introduced, and the analytical solution for the pure bending of an isotropic micropolar plate is generalized to the case of orthotropic microstructure. By defining the ratio of a distributed force and a distributed moment boundary conditions required for the pure-bending state, a closed-form solution to this problem is obtained in terms of displacement, strains and stress functions. It is shown that the derived results reduce to the isotropic ones if a material isotropy is assumed.

Detection of a characteristic length in 2D orthotropic micropolar continuum

Damjan Jurković — 2024-12-03

With the aim of obtaining several micropolar engineering parameters, a numerical and experimental analysis of an artificially generated orthotropic microstructure is performed. Young’s moduli and Poisson's ratios of the microstructure are determined using homogenisation by asymptotic analysis. Four-point bending experiments are performed on the aluminium beams with the described microstructure. The same experiments are also performed numerically. Using the previously derived analytical expression for the strains in a plane orthotropic micropolar continuum, one characteristic length is determined. This length corresponds to the characteristic bending length in the isotropic continuum and is one of the four characteristic lengths of the planar orthotropic continuum. Experimental and numerical values agree well, despite the slight scatter of the experimental results. The methodology presented here can be used for further determination of bending lengths.

Experimental determination of the hydraulic jump characteristics behind the wide threshold spillway

Elvis Žic — 2024-12-03

The paper presents an experimental determination of the occurrence of a hydraulic jump behind the spillway of a wide threshold, within which a hydraulic analysis of the dependence of the change in the opening of the upper and lower sluice gates with the values of conjugate depths, the length of the hydraulic jump, the Froude number, the level of the lower water and other physical quantities that arise as a result of the phenomenon itself is given. For the purposes of experimental testing, a physical model of a small hydraulic channel was used. Tests were performed for three different variants of input parameters at different degrees of sluice gates opening.

Experimental and theoretical analysis of beam deformation at large displacements

Leo Škec — 2024-12-03

Euler-Bernoulli beam theory, which is traditionally used to solve engineering problems in construction, assumes that displacements and rotations of beams in the deformed state are relatively small. Such an assumption, apart from being completely justified for most engineering problems in construction, leads to a linear form of the kinematic equations of the problem, so the simplified mathematical formulation becomes very practical for use. However, in situations where the stiffness of the beam is such that it allows linear-elastic behaviour at relatively large deformations, the Euler-Bernoulli beam theory is no longer applicable. In this paper, expressions are derived for determining the deformed line of a cantilever beam loaded with a concentrated force at the free end at large displacements and rotations based on the work of Bishopp and Drucker. In the solution, which is significantly more complex than the one according to the Euler-Bernoulli beam theory, elliptic integrals appear, which were determined in the paper using Wolfram Mathematica software. For the purpose of validating the theoretical model, an experiment was conducted with a flexible bar made of plastic whose displacements were determined by optical measurement using Digital Image Correlation (DIC) technology. It was found that the theoretical model can accurately describe the deformed line of the cantilever even for very large displacements of the free end of the beam.

Dynamic response of large-span frame structures to multiple support seismic excitation

Paolo Fabijan — 2024-12-03

The dynamic response of long structures is the result of varying excitation of distant supports, which can increase the contribution of asymmetrical oscillation modes. Experimental-numerical research was carried out - in the experiments, the excitation was applied by shaking tables perpendicular to the longitudinal axis of the model, and the behavior was monitored optically, while the numerical model is based on linear FEM and numerical time integration.

Graduated Students

Nilda Zelenika — 2024-12-03

Defended Doctoral Theses

Martina Vivoda Prodan — 2024-12-03

Student Awards and Acknowledgements

Martina Vivoda Prodan — 2024-12-03

Employee Awards and Acknowledgements

Martina Vivoda Prodan — 2024-12-03

Retired Employees

Sanja Dugonjić Jovančević — 2024-12-03

New Scientific-teaching Staff

Martina Vivoda Prodan — 2024-12-03

In Memoriam

Elvis Žic — 2024-12-03

Presentation of companies from the Professional Base of the University of Rijeka - Faculty of Civil Engineering

Elvis Žic — 2024-12-03