Behavior of concrete cylinders confined by carbon composite 2. Prediction of strength

The mechanical behavior of round concrete cylinders confined by a carbon-epoxy composite wrapping is analyzed concerning the increased concrete compression strength due the wrapping. It is shown that the loading trajectories in the normalized stress space fit into a single master curve for all the concrete batches and jacket thicknesses investigated. The loading paths ended at failure of the composite wrapping from the increased internal lateral pressure. The strength of the composite was determined by split-disc tests of composite rings, but the strength of composite jackets realized on concrete specimens did not reach the strength of the rings. Therefore, a coefficient of composite strength reduction was introduced. A simple formula for predicting the strength of confined concrete is derived, and a comparison with fib (fédération internationale du béton) recommendations for strength predictions is given. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 165–178, April–May, 2006.     

Finite-element modeling of the interaction of reinforcement with concrete matrix

A finite-element model of a reinforced concrete beam with rebars modeled by a 3-D deformable body has been developed. An analysis of the stress-strain state of the beam allowed us to determine the stress distribution on cross sections of the rebars and the location of zones with cracks in concrete. It is found that the break of bond between the reinforcement and concrete goes outside the areas of intensely cracked concrete matrix. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 3, pp. 309–316, May–June, 2008.     

Investigations into the fire hazard of a composite made from aerated concrete and crushed expanded polystyrene waste

The study deals with experimental investigations into the fire hazard of a composite of density 150–350 kg/m³ made of aerated concrete and crushed expanded polystyrene waste. The results of fire tests showed that a single-flame source of low heat output (0.07 kW) did not influence the origination and spread of flame on the surface of test specimens, regardless their density. Upon exposing the specimens to a single burning item of moderate heat output (30.0 kW), during the first 600 s of exposure, neither flaming particles nor droplets originated, nor a lateral flame spread on the long specimen wing was observed. In the case of high heat output (112 kW), the specimens of densities 150 and 250 kg/m³ started to burn, but those of density 150 kg/m³, in addition, lost their integrity. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 255–264, March–April, 2008.     

Perfect simulation of processes with long memory: A “coupling into and from the past” algorithm

We describe a new algorithm for the perfect simulation of variable length Markov chains and random systems with perfect connections. This algorithm, which generalizes Propp and Wilson's simulation scheme, is based on the idea of coupling into and from the past. It improves on existing algorithms by relaxing the conditions on the kernel and by accelerating convergence, even in the simple case of finite order Markov chains. Although chains of variable or infinite order have been widely investigated for decades, their use in applied probability, from information theory to bio‐informatics and linguistics, has recently led to considerable renewed interest. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 46, 300–319, 2015