Head of the project: Ing. Zahuranec Michal

Research team: doc. Ing. Koteš Peter, PhD., doc. Ing. Odrobiňák Jaroslav, PhD.

Duration: November 2019 – march 2021

The project is dealing with shear contact between original reinforced concrete and fibre concrete for using different methods of roughing surface. Concrete structures are influenced by degradation, overloading, the thawing and freezing cycles, abrasive damage, corrosion of reinforced bars etc.. All this mentioned influencing decreasing load-carrying capacity. These structures should be repaired or strengthened so fulfil ultimate limit states and serviceability limit states. Concrete structures as vertical columns are usually strengthened by using the concrete encasement of member’s. The main emphasis is put on the interaction of the original reinforced concrete and new concrete. The main factors are cohesion and adhesiveness, which are influencing the resistance of the cross-section. The member´ resistance is changed by the modification of surface. In the frame of the project will be done an experimental measurements taking into account the different methods of the modifications of surface. Subsequently, the results will be compared. The experiment will consist of 15 samples with dimensions 150x150x400mm. These samples will be encasement of the fibre concrete with thickness 35mm. So, the samples for so called push-test will be created. The pressure tests are going to be performed on the samples. The results will be treated and presented in the school round of SVOČ.

Head of the project: Ing. Kraľovanec Jakub, PhD.

Research team: prof. Ing. Moravčík Martin, PhD., doc. Ing. Odrobiňák Jaroslav, PhD.

Duration: September  2020 – August 2021

As part of the research, four prestressed concrete beams will be examined to verify indirect methods for determining of prestressing force in specific time. In the case of two specimens, the prestressing force will be transferred into the concrete through the bond between concrete and prestressing steel. Another two specimens are designed with transfer only in bearings at the end anchorages. Prestressing will be provided by single prestressing strand LS 15,7 / 1860 MPa / 1660 MPa placed in duct of diameter 48 mm. First, based on general knowledge the specimens are designed in compliance with Eurocodes. To avoid the impact of shear stresses, four-point loading scheme is chosen for the test. For numerical analysis, a 2D finite element model with the assumption of nonlinear material behaviour will be used. The numerical analysis will be performed in ATENA software, Idea StatiCa and SCIA Engineer. Later, the results obtained in the laboratory will be compared to those of an analytical calculation. In order to quantify the residual prestress force theoretically, parameters influencing the prestress loses must be taken into account. Subsequently, the influence of the reduction of the stiffness due to cracking the concrete during the loading will be discussed. Finally, we intend to find the correlation between the width of cracks, deflections, strains and the decrease of prestressing force.

Page 3 of 3

© 2021 Department of Building Structures and Bridges. All rights reserved.