The behaviour of actual prestressed concrete beams under static load up to failure has been experimentally investigated. The experimental testing includes five types of precast concrete beams with different ratios of prestressed and classical reinforcements (only prestressed reinforcement, dominant prestressed reinforcement and classical reinforcement, equal prestressed and classical reinforcements, dominant classical reinforcement and prestressed reinforcement, and only classical reinforcement) i.e. with different levels of prestressing force. Twenty-three beams were tested. The total amount of reinforcement in each beam was selected to provide approximately equal ultimate bending bearing capacity. The deflections, concrete stresses, stresses in classical and prestressed reinforcements and concrete cracks were monitored until the beams collapsed. It was concluded that by increasing the level of prestressing, the serviceability limit state of the beams was improved. The optimal level of prestressing should be selected based on the relevant criteria for each individual structure.

Firstly, a discussion about the application of beam-column (1D) and plane (2D) finite elements in the numerical analysis of the planar concrete frames is presented. Then, briefly are presented two numerical models for nonlinear static analysis of planar concrete frames, first based on beam-column (1D) elements and second on plane (2D) finite elements, which can simulate their main nonlinear effects. The presented models are verified on two experimental test results. Good agreement was obtained between the experimental and the numerical results, which confirm the possibility of practical application of both presented numerical models. However, their further verifications are necessary.

Static and dynamic analysis of the old stone bridge in Mostar The static and dynamic analysis results for the arch stone bridge in Mostar are presented. The analysis is based on the numerical model previously developed by the author for static and dynamic analysis of various types of masonry structures. Two bridge geometry models, with micro and macro modelling of masonry, are considered. The influence of vertical load, temperature change, and real earthquake action, is analyzed. The design deflections and crack zones in arch correspond well to the real life situation, which confirms reliability of the numerical model used. It is emphasized in the paper that the damage to the renovated stone arch should be remedied as soon as practicable.