Sökning: "shrinkage"

Visar resultat 11 - 15 av 225 avhandlingar innehållade ordet shrinkage.

1. 11. Constitutive Modelling and Finite Element Analysis of Concrete Structures with Regard to Environmental Influence

   Författare :Ola Dahlblom; Byggnadsmekanik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Finite Elemente Method; Constitutive model; Concrete; Environment; Moisture; Drying; Temperature; Fracture; Fictitious crack model; Smeared Crack; Creep; Shrinkage; Pickett Effect;

   Sammanfattning : A constitutive model for concrete is formulated. Tensile fracture is described using a smeared crack approach where the fracrure energy is considered and the shear stiffneess in the cracked region is gradually reduced as crackling develops. LÄS MER

3. 12. Principles of Biomass Pyrolysis with Emphasis on the Formation of the Nitrogen-Containing Gases HNCO, HCN and NH3

   Författare :Karl-Martin Hansson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; pyrolysis; depolymerisation; NH3; HCN; crack formation; fragmentation; combustion time; pyrolysis time; HNCO; biomass; shrinkage;

   Sammanfattning : This thesis investigates some aspects of the pyrolysis and combustion of biomass. The emphasis of the work is on the formation of nitrogen-containing species under pyrolysis. LÄS MER

4. 13. Thermal Crack Risk Estimation and Material Properties of Young Concrete

   Författare :Anders Hösthagen; Jan-Erik Jonasson; Mårten Larson; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Thermal cracking risk; young concrete; Equivalent Restraint Method; strength development; heat of hydration; creep; shrinkage; thermal dilation; modeling; field observations; Structural Engineering; Konstruktionsteknik;

   Sammanfattning : This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. LÄS MER

5. 14. Analyses of shotcrete stress states due to varying lining thickness and irregular rock surfaces

   Författare :Andreas Sjölander; Anders Ansell; Richard Malm; Fredrik Johansson; Jan Alemo; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Shotcrete; cracking; shrinkage; block load; varying thickness; numerical simulations; fibre reinforcement; Byggvetenskap; Civil and Architectural Engineering;

   Sammanfattning : Shotcrete is sprayed concrete applied pneumatically under high pressure and was invented in the beginning of the 1900's. This new technique decreased the construction time and since steel fibres were introduced in the shotcrete during the 1970's, shotcrete has been the primary support method for tunnels. LÄS MER

7. 15. Multiphysical analysis methods to predict the ageing and durability of concrete

   Författare :Tobias Gasch; Anders Ansell; Richard Malm; Erik Nordström; Max Hendriks; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Ageing; Cracking; Creep; Concrete; Durability; Finite Element Method; Multiphysics; Shrinkage; Beständighet; Betong; Finita elementmetoden; Krypning; Krympning; Multifysik; Sprickbildning; Åldring; Civil and Architectural Engineering; Byggvetenskap;

   Sammanfattning : With the societal demand for sustainability and the increasing age of infrastructure, a crucial task for the civil engineering community is to improve the durability of concrete structures. This thesis aims to contribute to such development through theoretical studies using mathematical modelling and numerical simulations. LÄS MER