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Eva Labašová

shear modulus for the samples circular and hollow circular cross-section. In: Materials Science Forum. Novel Trends in Production Devices and Systems III. Special topic volume with invited peer reviewed papers only , Vol. 862. pp. 298-304. ISSN 0255-5476 9. VLK, M., HOUFEK, L., HLAVOŇ, P., KREJČÍ, P., KOTEK, V., KLEMENT, J., 2003. Experimental mechanics. Brno, 147 p. Information on [1.12.2016] http://ean2011.fme.vutbr.cz/img/fckeditor/file/opory/Experimentalni_mechanika.pdf 10. Quantum X, Operating manual, Information on [1.12.2016] http

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Karel Vojtasík, Eva Hrubešová, Marek Mohyla and Jana Staňková

References Bulytchev, N. C. Mechanika podzemnych sooruženij. (1982) Moskva : NEDRA, 270. ALDORF, J., HRUBEŠOVÁ, E., VOJTASÍK, K., ĎURIŠ, L. Alternativní výpočet tuhosti betonového ostění vyztuženého válcovými prvky. Informace Českého svazu stavebních inženýrů. ročník XV. (2009), č. 1, 27-31. ISSN 1213-4112. VOJTASÍK, K., HRUBEŠOVÁ, E., MOHYLA, M., STAŇKOVÁ, J. Determination of development of elastic modulus value for primary steel concrete reinforcement according to cooperative

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Nadeem Anwer Quresh and Bilal Khurshid

REFERENCES AASHTO (1993). “Guide for design of pavement structures”. American Association of State Highway and Transportation Officials, Washington, DC, USA. Barksdale, R. D., Alba, J., Khosla, N. P., Kim, R., P. C. Lambe, P. C., and Rehman, M. S. (1997). “Laboratory Determination of Resilient Modulus for Flexible Pavement Design.” NCHRP Web Document 14 (Project 1-28): Contractor’s Final Report , TRB, National Research Council, Washington, D.C., USA. Kandhal, P. S., and Mallick, R. B. (1997). “Pavement Recycling Guidelines for State and Local

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Arkadiusz Tomczak

section of the tree stem and selected biometric traits of the Scots pine (Pinus sylvestris L.). Baltic Forestry, 13(1): 116-125. Tomczak A., Pazdrowski W., Jelonek T., Stypuła I. 2006. Selected biometric traits of Scots pine tree stems developer in conditions of the fresh coniferous forest as the basis of the evaluation of juvenile wood volume. Annals of Warsaw Agriculture University - SGGW, Forestry and Wood Technology, 59: 311-315. Tomczak A., Pazdrowski W., Jelonek T., Stypuła I. 2007b. Vertical variability of selected macrostructural

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Anguel Baltov and Ana Yanakieva

Abstract

Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model’s plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).

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Angel S. Mladensky and Victor I. Rizov

Abstract

Mixed mode II/III crack investigation in cantilever bilayered unidirectional fiber reinforced composite beam is reported. The crack is situated between the layers. The two crack arms have different widths. Formula for the strain energy release rate is obtained by the linear elastic fracture mechanics methods using the magnitude of the applied forces, geometrical characteristics of the cross-section, and the elastic moduli of the layers. An equivalent shear modulus of the un-cracked beam portion is used. Several diagrams illustrating the results of parametrical analysis of the strain energy release rate are presented. The paper is a part of a research in the field of fracture behaviour of composite beams.

Open access

W. Żórawski, M. Makrenek and A. Góral

Abstract

Nanostructured and composite WC-12Co coatings were prepared by means of the supersonic spray process (HVOF). The microstructure and composition of WC-12Co nanostructured powder were analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Investigations revealed nano grains of WC with the size in the range of 50-500 nm. The nanostructured sprayed coating was analysed by SEM and phase composition was investigated by X-ray diffractometer (XRD). A denser coating structure with higher hardness was observed compared to conventional coating with a small amount of W2C, WC1−x, W and some amorphous phase. Young’s modulus and hardness were determined by depth sensing indentation in HVOF sprayed WC-12Co nanostructured coatings. Results were compared to conventional coatings and the relevance of the nanostructure was analyzed. An indentation size effect was observed on the polished surface and cross-section of both coatings. Data provided by indentation tests at maximum load allow to estimate hardness and elastic modulus. Enhanced nanomechanical properties of conventional coating in comparison to nanostructured one were observed. Nanostructured coatings WC-12Co (N) revealed significantly better corrosion resistance.

Open access

Rafał F. Obrzud, Sébastien Hartmann and Krzysztof Podleś

Abstract

This paper analyzes two approaches to serviceability limit state (SLS) verification for the deep excavation boundary value problem. The verification is carried out by means of the finite element (FE) method with the aid of the commercial program ZSoil v2014. In numerical simulations, deep excavation in non-cohesive soil is supported with a diaphragm wall. In the first approach, the diaphragm wall is modeled with the Hookean material assuming reduced average stiffness and possible concrete cracking. The second approach is divided into two stages. In the first stage, the wall is modeled by defining its stiffness with the highest nominal Young’s modulus. The modulus makes it possible to find design bending moments which are used to compute the minimal design cross-section reinforcement for the retaining structure. The computed reinforcement is then used in a non-linear structural analysis which is viewed as the “actual” SLS verification.

In the second part, the paper examines the same boundary value problem assuming that the excavation takes place in quasi-impermeable cohesive soils, which are modeled with the Hardening Soil model. This example demonstrates the consequences of applying the steady-state type analysis for an intrinsically time-dependent problem. The results of this analysis are compared to the results from the consolidation-type analysis, which are considered as a reference. For both analysis types, the two-phase formulation for partially- saturated medium, after Aubry and Ozanam, is used to describe the interaction between the soil skeleton and pore water pressure.

Open access

Grzegorz Trzciński, Paweł Kozakiewicz and Rafał Selwakowski

References BN-64/8931-02 Drogi samochodowe. Oznaczanie modułu odkształcenia nawierzchni podatnych i podłoża przez obciążenie płytą [Road car. Determination of modulus of flexible pavements and the substrate by the load plate]. Warszawa. Polski Komitet Normalizacyjny. DZIKOWSKI J., SZARŁOWICZ A., BURZYŃSKI S., RAJSMAN M., SATOŁA J., WIĄZOWSKI Z. 2006. Drogi leśne - Poradnik techniczny [Forest roads: Technical guide] [online]. Warszawa, Bedoń. ORWLP, DGLP pp. 136. [Access 30.05.2017]. Available at: http

Open access

Paola Dalla Valle and Nick Thom

Abstract

This paper presents the results of a review on variability of key pavement design input variables (asphalt modulus and thickness, subgrade modulus) and assesses effects on pavement performance (fatigue and deformation life). Variability is described by statistical terms such as mean and standard deviation and by its probability density distribution.

The subject of reliability in pavement design has pushed many highway organisations around the world to review their design methodologies, mainly empirical, to move towards mechanistic-empirical analysis and design which provide the tools for the designer to evaluate the effect of variations in materials on pavement performance. This research has reinforced this need for understanding how the variability of design parameters affects the pavement performance.

This study has only considered flexible pavements. The sites considered for the analysis, all in the UK (including Northern Ireland), were mainly motorways or major trunk roads. Pavement survey data analysed were for Lane 1, the most heavily trafficked lane. Sections 1km long were considered wherever possible.

Statistical characterisation of the variation of layer thickness, asphalt stiffness and subgrade stiffness is addressed. A sensitivity analysis is then carried out to assess which parameter(s) have the greater influence on the pavement life.

The research shows that, combining the effect of all the parameters considered, the maximum range of 15th and 85th percentiles (as percentages of the mean) was found to be 64% to 558% for the fatigue life and 94% to 808% for the deformation life.