Stability problems of steel‐concrete members composed of high‐strength materials

The presented paper deals with the stochastic analysis of the ultimate limit states of steel‐concrete building members. The load carrying capacity of steel‐concrete columns, comprising of steel profiles encased in high strength concrete, in compression is analyzed. The first part of the paper lists assumptions for the determination of the theoretical load carrying capacity of the column. Principles of elasticity and plasticity are used to determine stresses in the concrete and steel sections. Statistical characteristics of input material and geometrical imperfections are listed. Results of the theoretical analysis are then compared with results of experimental research. Statistical characteristics of obtained results of the theoretical analysis were verified using statistical characteristics obtained from experimental research. Numerical simulation LHS and Monte Carlo methods, which take into account the influences of variability of input imperfections, were employed. The influence of the utilization of the plastic reserve in the determination of the load carrying capacity of the analysed strut is shown. The influence of the initial geometric imperfections of initial strut curvature on the load carrying capacity is also presented. Santrauka Straipsnyje pateikta plienbetonio pastatu elementu didžiausiu ribiniu būkliu stochastine analize, analizuojama plienbetonio kolonu, sudarytu iš plieniniu profiliuočiu, padengtu didelio stiprio betonu, laikomoji galia gniuždant. Pirmoje straipsnio dalyje išvardytos kolonos teorines laikomosios galios nustatymo prielaidos. Tamprumo ir plastiškumo principai taikyti itempiams betono ir plieno skerspjūviuose nustatyti. Nustatytos medžiagu ir geometriniu defektu statistines charakteristikos, teorines analizes rezultatai palyginti su eksperimentiniu tyrimu rezultatais. Teorines analizes metu gautu rezultatu statistines charakteristikos patikrintos taikant iš eksperimentiniu tyrimu gautus statistinius rodiklius. Pritaikytas skaitinis modeliavimas LHS ir Monte Karlo metodais, kurie ivertina pradiniu defektu kintamumo itaka. Parodyta plastiškumo atsargos naudojimo itaka, nustatant analizuojamojo statramsčio laikomaja galia, pateikta pradinio statramsčio išlinkio pirminiu geometriniu defektu itaka laikomajai galiai. First Published Online: 10 Feb 2011 Reikšminiai žodžiai: medžiagos, plienas, betonas, struktūra, defektai, susilpnejimas, patikimuma

Fatigue Resistance and Durability of New Mechanical Connections of Currently Developed Temporary Steel Footbridges and Railway Bridges

On the workplace of paper authors, the experimental studies of the fatigue behaviour and fatigue resistance of several new types of steel mechanical connections have been performed recently. The problems of mechanical connections mentioned above have been solved in the past within the projects of the development of new types of advanced temporary steel bridges and footbridges, with the support of the programme of applied research, development and innovations of the Technology Agency of the Czech Republic. These newly developed connections represent the assembly joints based on the bolts and pins together with plates. Within this investigation, fatigue tests of connections have been performed. The experimental studies have been oriented to the verification of the behaviour of those connections and especially, the fatigue strength, and subsequently the fatigue resistance and durability of the structural detail according to the configuration and structural design.On the workplace of paper authors, the experimental studies of the fatigue behaviour and fatigue resistance of several new types of steel mechanical connections have been performed recently. The problems of mechanical connections mentioned above have been solved in the past within the projects of the development of new types of advanced temporary steel bridges and footbridges, with the support of the programme of applied research, development and innovations of the Technology Agency of the Czech Republic. These newly developed connections represent the assembly joints based on the bolts and pins together with plates. Within this investigation, fatigue tests of connections have been performed. The experimental studies have been oriented to the verification of the behaviour of those connections and especially, the fatigue strength, and subsequently the fatigue resistance and durability of the structural detail according to the configuration and structural design

Experimental Analysis of Actual Behaviour of Fiber Cement Boards

The paper is focused on analysis of limit states and actual behaviour of the great size fibre cement boards that are produced without autoclaving. In this paper the basic information on the testing of the fibre cement boards is summarized, but its main goal is the utilization of acquired specification and data for the elaboration of backgrounds for direct determining of the defined load carrying capacity of boards for basic cases of loading, span and support conditions. The elaborated solutions and results follow the contemporary approach of the structural design method and reliability verification based on the concept of limit state design using the partial safety factors

Shear transfer behavior in composite slabs under 4-point standard and uniform-load tests

The 4-point bending test, prescribed by most standards, is the conventional test used to determine the shear resistance of steel-concrete composite slabs, whereas loading requirements are commonly specified in terms of uniform load in standard codes. This article shows a comparison between the results of these two load arrangements. This comparison has been made through both experimental tests and FEM simulations points of view. Both approaches show that the 4-point load arrangement provides higher shear strength than uniform load. The cause of this difference has been studied by means of a realistic FEM approach focusing on the slip mechanics and the 3D contact forces in the steel-concrete interface: longitudinal (shear), transversal (interlocking) and vertical (clamping). It has been concluded that the distribution of contact forces is different from the one load arrangement to the other, mainly because of differences in the distribution of concrete cracks. This article is the result of cooperation between UPC-BarcelonaTech, where the 4-point bending tests and the FEM models were developed, and AdMaS-BUT where the uniform load tests were carried out by means of a vacuum system. The slabs were made with conventional open-rib trapezoidal profile and the Eurocode-4 provisions have been followed in both testing procedures.Peer ReviewedPostprint (author's final draft

Shear transfer behavior in composite slabs under 4-point standard and uniform-load tests

The 4-point bending test, prescribed by most standards, is the conventional test used to determine the shear resistance of steel-concrete composite slabs, whereas loading requirements are commonly specified in terms of uniform load in standard codes. This article shows a comparison between the results of these two load arrangements. This comparison has been made through both experimental tests and FEM simulations points of view. Both approaches show that the 4-point load arrangement provides higher shear strength than uniform load. The cause of this difference has been studied by means of a realistic FEM approach focusing on the slip mechanics and the 3D contact forces in the steel-concrete interface: longitudinal (shear), transversal (interlocking) and vertical (clamping). It has been concluded that the distribution of contact forces is different from the one load arrangement to the other, mainly because of differences in the distribution of concrete cracks. This article is the result of cooperation between UPC-BarcelonaTech, where the 4-point bending tests and the FEM models were developed, and AdMaS-BUT where the uniform load tests were carried out by means of a vacuum system. The slabs were made with conventional open-rib trapezoidal profile and the Eurocode-4 provisions have been followed in both testing procedures.Peer Reviewe