Applied Mechanics and Materials Vol. 821

Abstract: The approach slab is the structural member of transition zones, which compensates a different settlement of bridge abutment and a road embankment. The main reason of different settlement is the consolidation of soil under the slab and the abutment. The geometry of approach slab, its length and the thickness is defined on the basis of differential settlement of embankment and the abutment. The static behaviour of slab is defined as a slab on elastic soil. The reinforced concrete slab is supported with the line rigid support on the one edge, and the rest of slab area interacts with the soil. The civil engineers design the reinforcement in those slabs based on the simplified structural scheme, without considering the elastic area support. This scheme is the simple supported slab on the both ends. The paper is dealing with the comparing of different structural models of the reinforced concrete approach slabs. The complex models of transition zones with the brick elements of the soil and the interaction with the reinforced concrete slab with the soil embankment are compared with the simplified models used by civil engineers. The analysis was performed on the transition zone of highway bridge from Slovakia based on its geometry and the subsoil consistence. In the parametric study was compared 8 soil stiffness’s on 10 structural models.

Abstract: The European Standard [1] for design of concrete compressed slender members shows a significant deficit in global reliability for the design method based on non-linear analysis. The experimental investigation at the Faculty of Civil Engineering SUT in Bratislava was planned for slender concrete columns made of different concrete strength classes - C45/55, C70/85 and C100/115. A basic aim of the analysis was to design concrete columns subjected to bending moment and axial force where the stability failure proceeds at the compression strain 1.5 ‰. The first of three series of experimental and numerical analyzed columns is presented in the paper. The experiments were realized at the Faculty of Civil Engineering SUT in Bratislava with cooperation of ZIPP Bratislava LTD Company.

Abstract: The current structural design provisions are prevalently based on experience and on the assumption of stationary meteorological conditions. However, the observations of past decades and advanced climate models show that this assumption is debatable. Therefore, this paper examines the historical long-term trends in ground snow load maxima, and their effect on structural reliability. For this purpose, the Carpathian region is selected, and data from a joint research effort of nine countries of the region are used. Annual maxima snow water equivalents are taken, and univariate generalized extreme value distribution is adopted as a probabilistic model. Stationary and five non-stationary distributions are fitted to the observations utilizing the maximum likelihood method. Statistical and information theory based approaches are used to compare the models and to identify trends. Additionally, reliability analyses are performed on a simple structure to explore the practical significance of the trends. The calculations show decreasing trends in annual maxima for most of the region. Although statistically significant changes are detected at many locations, the practical significance - with respect to structural reliability - is considerable only for a few, and the effect is favourable. The results indicate that contrary to the widespread practice in extreme event modelling, the exclusive use of statistical techniques on the analysed extremes is insufficient to identify practically significant trends. This should be demonstrated using practically relevant examples, e.g. reliability of structures.

Abstract: Results of the latest experiments have revealed that the maximum punching resistance defined from crushing of concrete struts at the perimeter of a column in EC2 is an insufficient criterion for limitation of maximum shear forces at the vicinity of the columns. Therefore further limitation has been introduced in TC 250 SC2 and also included in NA of Eurocodes.

Abstract: This paper is aimed at the reliability analysis of an existing reinforced concrete bridge from 1908. The load bearing capacity is assessed in accordance with valid standards using the partial factor method and probabilistic approach. Load bearing capacities obtained by these methods are critically compared. The application of probabilistic method leads to 40 % higher load bearing capacity then the partial factor method used for structural design.

Abstract: Overview of values and definitions of material partial factors γ_M0 and γ_M1 used in all 20 parts of Eurocodes EN 1993 Design of steel structures [1] and in all 5 parts of EN 1999 Design of aluminium structures [2]. Applications of the γ_M0 and γ_M1 partial factors values and definitions in all clauses of EN 1993. Comparison of safety levels of former Czechoslovak standards (ČSN) with current Eurocodes. Proposals for correction of definitions and applications of γ_M0 and γ_M1 partial factors in all clauses of EN 1993. The overview and corrections enable to do better choice from five official options aiming to change current value γ_M1 = 1,0 valid in EN 1993-1-1 for buildings, which were presented at CEN/TC250 SC3 meetings in October 24^th 2014 and in March 19^th 2015 in Berlin.

Abstract: The paper focuses on the assessment of cast-iron columns in industrial heritage structures. For cast-iron structures it is difficult to verify metallurgical composition and processing technology, which directly affect the geometry of cross-sections. The crucial issue of reliability of cast-iron structures is their brittle fracture in tension at higher slenderness ratios. The load carrying capacity of columns is affected by their stability and cast-iron strength in compression and tension. Outcomes of two recently proposed analytical models are compared with extensive experimental data and model uncertainty is quantified. It appears that the model is in a good agreement with experimental data and provides reasonably conservative estimates of load carrying capacity. Outcomes of the study may provide basis for foreseen improvements in calculating buckling coefficient according to ČSN 730038:2014.