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Visar resultat 1 - 5 av 107 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Local variation in bending stiffness in structural timber of Norway spruce : for the purpose of strength grading

   Författare :Min Hu; Marie Johansson; Linnéuniversitetet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; digital image correlation; fibre angle; high resolution; laser scanning; local stiffness; MOE profile; mode shape curvature; strain field; strength grading; structural timber; tracheid effect; Digital image correlation; fibervinkel; laserskanning; lokal styvhet; MOE-profil; töjningsfält; hållfasthetssortering; konstruktionsvirke; trakeideffekt; Forestry and Wood Technology; Skog och träteknik;

   Sammanfattning : Most strength grading machines on the European market use an averagemodulus of elasticity (MOE), estimated on a relatively large distance along awood member, as the indicating property (IP) to bending strength. Theaccuracy of such grading machines in terms of coefficient of determination israther low at R2 ≈ 0.5. LÄS MER

3. 2. Local variability in chemical and physical properties of spruce wood fibers

   Författare :Anna Bergander; KTH; []
   Nyckelord :cell walls; chemical composition; elastic constants; elastic strength; Fiber properties; Fibril angles; Mathematical models; Microscopy techniques; Picea Abies; Stiffness; Tensile properties; Wood polymers; Wood;

   Sammanfattning : Wood is well known to be a heterogeneous native materialwith large variations in its composite properties, includingvariations whose origins have not yet been completelyidentified. Traditionally, the macroscopic variations in woodhave received the most attention; for example, the variation indensity from the pith to the bark in trees. LÄS MER

4. 3. Modeling the effects of knots in Structural Timber

   Författare :Christina Foley; Avdelningen för Konstruktionsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material technology; Byggnadsteknik; Building construction; three-dimensional fiber paradigm; fiber deviation; knots; annual growth layer; material matrix; knot bump; structural timber; load carrying capacity; Materiallära; critical knot; knot distance ratio; local principal material directions; stiffness; materialteknik;

   Sammanfattning : The main purpose of the pursued research is to increase knowledge of the effects of knots in structural timber so that characteristics of weaker timber may be determined and applied to improve current grading techniques. In the process, a three-dimensional fiber paradigm was established, which describes variations of local principle material axes in timber containing knots. LÄS MER

5. 4. On inelastic local flange buckling

   Författare :Mikael Möller; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik; Steel Structures; Stålbyggnad;

   Sammanfattning : This thesis deals with inelastic local buckling of I-beam flanges made of steel. The main focus is on the theoretical description of the buckling process, and the influence of various parameters, e.g. the plastic modulus, yield plateau, yield stress etc. LÄS MER

7. 5. Assessment of existing concrete bridges : bending stiffness as a performance indicator

   Författare :Markus Bergström; Paulo J. de S. Cruz; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Structural Engineering; Konstruktionsteknik;

   Sammanfattning : Optimizing the use of existing civil reinforced concrete (RC) structures could be interpreted in such a way as to say that the capacity should be used and taken care of in an effective manner, both from a technical and economical point of view, keeping the safety in mind. Achieving this requires thorough understanding of the structure and also of the tools used for assessing current and future capacity and needs. LÄS MER