Wyniki wyszukiwania - Biblioteka Nauki

1

Mechanisms of load capacity and stability decline

100%

Burawska I.

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tom 77

EN

Mechanisms of load capacity and stability decline. Article deals with failures of constructions with considerations of static work states. Analysis of bent beams and compressed columns was made, as most important elements of wooden structural works. Most common structural members failures causes were described, as design and manufacturing errors as well as local weakening caused by wood structural defects. Because of subject challenging, it is purposeful to take a detailed look into the problem, in aim to determine cracks propagation in dependence on type and placement of the defect.

PL

Mechanizmy utraty nośności i stateczności konstrukcji. W artykule dokonano przeglądu stanów awaryjnych konstrukcji, uwzględniając charakter pracy statycznej konstrukcji. Dokonano analizy belek zginanych oraz ściskanych słupów, jako elementów o największym znaczeniu dla konstrukcji drewnianych. Wskazano najczęstsze przyczyny zniszczenia elementów konstrukcyjnych, wśród których można wymienić błędy projektowe i wykonawcze, jak również lokalne obniżenie wytrzymałości wskutek obecności naturalnych wad drewna. Ze względu na złożony charakter zagadnienia, celowa wydaje się konieczność dalszego zgłębiania tematu, m.in. określenie sposobu propagacji zniszczenia w zależności od rodzaju i usytuowania wady.

2

Influence of glueline parameters on the mechanical behaviour of CFRP reinforced wood - numerical analysis

63%

Burawska I. , Tarasovs S.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2014

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tom No. 87

18--24

EN

Influence of glueline parameters on the mechanical behaviour of CFRP reinforced wood – numerical analysis. This work presents numerical investigation of wood strengthening technique in the aspect of glueline parameters. Described reinforcement method consists in application of CFRP tape (Carbon Fibre Reinforced Polymer) of a certain length in aim to increase load capacity and stiffness of reinforced wooden element. CFRP tape is bonded to the tensile area of bent beam with a glue, creating a system composed of wooden beam, glueline and reinforcement. However, depending on the parameters of the bond (rigid, elastic), differences in mechanical behaviour of the composite can be observed. Usage of the glue bond characterized by elastic properties leads to lower stress concentration within the composite, therefore the effectiveness of reinforcement could be increased.

3

Influence of the length of CFRP tape reinforcement adhered to the bottom part of the bent element on the distribution of normal stresses and on the elastic curve

51%

Burawska I. , Tomusiak A. , Beer P.

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2011

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tom 73

EN

Influence of the length of CFRP tape reinforcement adhered to the bottom part of the bent element on the distribution of normal stresses and on the elastic curve. The paper analyses the influence of reinforcements made of CFRP tape on the distribution of normal stresses and on the elastic curve of a wooden beam that is being bent. It was a numerical analysis made in the Solidworks Simulation environment. The local reinforcement of the element permitted to reduce the elastic curve by up to 20% and to reduce the maximum normal stresses by 80% in the proximity of the opening, by using a 50 cm long CFRP tape. It has been concluded that CFRP tapes may be useful for local reinforcement of the tensed areas of bent wooden beams that are weakened due to openings produced by knots that fell out or rotted.

PL

Wpływ długości wzmocnienia w postaci taśmy CFRP przyklejonej od dołu zginanego elementu na rozkład naprężeń normalnych oraz ugięcie. W pracy badano wpływ wzmocnienia w postaci taśm CFRP na rozkład naprężeń normalnych i ugięcie zginanej belki drewnianej. Analizę przeprowadzono numerycznie w środowisku Solidworks Simulation. Dzięki miejscowemu wzmocnieniu elementu uzyskano redukcję ugięć sięgającą nawet 20%, oraz 80% redukcję maksymalnych naprężeń normalnych w okolicy otworu przy zastosowaniu taśmy CFRP o długości 50cm. Stwierdzono, że taśmy CFRP mogą być przydatne do miejscowego wzmacniania stref rozciąganych zginanych belek drewnianych, osłabionych na skutek występowania otworów, jako pozostałości po sękach wypadłych lub zepsutych.

4

Local reinforcement of naturally defected structural lumber

51%

Burawska I. , Jachowicz P. , Zbiec M. , Grzeskiewicz M.

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2014

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tom 87

5

Local reinforcement of naturally defected structural lumber

51%

Burawska I. , Jachowicz P. , Zbieć M. , Grześkiewicz M.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2014

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tom No. 87

25--34

EN

Local reinforcement of naturally defected structural lumber. Paper presents local reinforcement of structural lumber, reducing negative impact of natural wood defects (especially knots), on strength parameters. Local repair engineering allows usage of structural members of decreased strength caused by natural defects, which was previously impossible because of legal regulations and risk of collapse. Strengthening procedures may also be used in existing, especially overloaded structures, renewing their initial strength and load capacity. Effectiveness of local reinforcement was determined by analysis of load capacity and deformation. Glass and carbon fibre composites were used as reinforcing materials. Various shapes of local reinforcement were tested, while maintaining constant length of strengthening in the tension zone of bent element. All tested types of reinforcement showed statistically significant increase in MOR and ultimate force. The highest strength gain was reached with X-shape reinforcement. Statistically significant MOE increase was obtained for X-shape glass fabric reinforcement (315g/m2 and 385g/m2 basis weight).