Analysis of Strain State and Cracking of Cocnrete Sleepers

Prestressed concrete sleepers are the most common type of the sleepers used on the railroad. They serve as rail supports and absorb loads induced by trains. Sleepers are important for the durability and safety of the railroad and are exposed to various loads and an agressive environment during exploitation. Therefore, different types of appearing damage can determine their reliability. The article briefly discusses possible causes of damage and the deterioration of prestressed concrete sleepers. End cracking and damage at the rail seat was determined during the inspection of used sleepers. Therefore, the strain state and cracking of the rail seat of the sleeper was analysed under static and dynamic loads. The paper provides the obtained results of experimental research of used and new sleepers

CALCULATION METHODS ANALYSIS OF CRACKED REINFORCED CONCRETE BENDING ELEMENTS CURVATURES / SUPLEIŠĖJUSIŲ LENKIAMŲJŲ GELŽBETONINIŲ ELEMENTŲ KREIVIŲ SKAIČIAVIMO METODŲ ANALIZĖ

This paper describes three methods of curvatures calculating, which are used in STR, EC2 and EMM. Describes, what influence for the average curvature of cracked elements have cracked and uncracked sections in the different methodologies. There are given range of variation of empirical coefficients when long-term loads are acting. According to constructions design and test data the reinforcement, concrete class and pre-stressed force influence is determined. Santrauka Darbe nagrinėjami trys kreivių skaičiavimo metodai, taikomi STR, EC2 ir EMM. Aprašyta, kokią įtaką vidutiniam supleišėjusio elemento kreiviui turi ruožai tarp plyšių ir per plyšius, kai taikomi skirtingi metodai. Pateiktos empirinių koeficientų kitimo ribos, esant ilgalaikėms apkrovoms. Pagal konstrukcijų skaičiavimo ir bandymo duomenis nustatyta armavimo, betono klasės, išankstinio apspaudimo jėgos įtaka. Raktiniai žodžiai: kreivis, lenkiamas elementas, plyšiai, armavimas, betono klas

The Analysis of Reinforced Concrete Box Girder Viaduct Defects and Their Estimation

The article describes the main damages of box girder viaducts constructed in Lithuania and discusses the reasons for their occurrence. Several viaducts are examined in more detail with regard to their design data and experimental results. Using finite element software “Midas Civil” the distribution of the main stresses was determined in the box and reduced girders of the Pareizgupis viaduct caused by symmetrical and asymmetrical loads. The widths of flexural cracks in the Pareizgupis viaduct are analyzed evaluating the behaviour of prestressed reinforcement suffered from corrosion. The above mentioned program was used to calculate the deflection of viaduct when damage of reinforcement is estimated. The paper examines the possibility to evaluate viaduct durability using the probability methods based on the initial investigation data