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Hellesland, Jostein
(2019).
2. ordens beregninger av staver og rammer -- Generelt og etter Eurokode 2 (NS-EN 1992-1-1).
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Hellesland, Jostein
(2017).
2. ordens beregninger av staver og rammer - Generelt og etter Eurokode 2 (NS-EN 1992).
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Hellesland, Jostein
(2016).
Second order structural analysis of members and systems -- Revised proposal for EC2-5.8 (CEN Document TG6/N107).
-
Hellesland, Jostein
(2016).
Preliminary global stiffness proposal (for second order global system analysis) (Doc. TG6/N77).
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Hellesland, Jostein
(2016).
Second order analysis of members and systems -- Revised and updated proposal for EC2-5.8 (Doc.TG6/N82).
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Hellesland, Jostein
(2015).
Flexural stiffness for slender columns -- A collection of published research (Doc. TG6/N61).
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Hellesland, Jostein
(2015).
Comments on EI-values in the moment-magnifier procedure of EC2, and in Dutch rules (Doc.TG6/N48).
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Hellesland, Jostein
(2014).
Principles and basis for nominal stiffness and curvature (doc. TG6/N37).
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Hellesland, Jostein
(2014).
Discussion of proposal for Second order structural analysis of members and systems (doc. TG6/14).
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Hellesland, Jostein
(2014).
Second order analysis of members and systems -- Proposal for EC2-5.8 (doc.CEN/TC250/SC2/WG1/TG6 N14).
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Brubak, Lars; Hareide, O. J. & Hellesland, Jostein
(2014).
On Application of a Semi-Analytical Approach for Vibration Analysis of Irregularly Stiffened Plates.
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Hellesland, Jostein
(2013).
Second order structural analysis of members and systems -- Preliminary comments towards revising EC2:2004-sect.5.8.
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Brubak, Lars; Hellesland, Jostein & Hareide, Ole J.
(2013).
Vibration analysis of plates with arbitrary stiffener arrangement using a semi-analytical approach.
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Hareide, Ole J.; Brubak, Lars; Steen, Eivind & Hellesland, Jostein
(2012).
Approximate buckling model for steel-elastomer sandwich plates.
Vis sammendrag
The paper describes the development of a semi-analytic buckling model for steel-elastomer sandwich plates using the Rayleigh-Ritz method. The model includes transverse shear deformations which are important in this type of plate. The unknowns - the deflections and cross-sectional rotations -are approximated by Fourier series. All combinations of in-plane tensile, compressive and shear loads are allowed. Pre-stressing of the plate and elastic springs on the boundary are also included. The model has been implemented in a FORTRAN programme and the results have been compared with results from the finite element programme ABAQUS.
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Challamel, Noël & Hellesland, Jostein
(2012).
Buckling of Imperfect CDM Structural Systems.
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Challamel, Noël & Hellesland, Jostein
(2012).
Post-buckling and post-failure of CDM structural systems.
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Andersen, Håkon S.; Hellesland, Jostein & Brubak, Lars
(2010).
On strength criteria for stiffened plates with a free or stiffened edge.
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Brubak, Lars & Hellesland, Jostein
(2010).
On response propagation analysis of imperfect stiffened plates with a free or flexible edge using a semi-analytical method.
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Hellesland, Jostein
(2009).
Closure to "Mechanics and Slenderness Limits of Sway-Restricted Reinforced Concrete Columns" by Jostein Hellesland.
Journal of Structural Engineering.
ISSN 0733-9445.
135(11),
s. 1431–1433.
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Brubak, Lars; Hellesland, Jostein & Steen, Eivind
(2009).
Approximate postbuckling analysis of imperfect stiffened plates with a free edge.
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Hellesland, Jostein
(2009).
Lineære og ikke-lineære beregningsmetoder -- 2. ordens virkninger.
-
Hellesland, Jostein
(2009).
Lineære og ikke-lineære beregningsmetoder -- 2. ordens virkninger.
-
Hellesland, Jostein
(2009).
Lineære og ikke-lineære beregningsmetoder -- 2. ordens virkninger.
-
Hellesland, Jostein
(2009).
Lineære og ikke-linære beregningsmetoder-- 2. ordens lastvirkninger.
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Hellesland, Jostein
(2008).
NS-EN 1992, Eurokode-2 -- Lineære og ikke-lineære beregningsmetoder; 2. ordens lastvirkninger.
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Hellesland, Jostein
(2008).
NS-EN 1992 Lineære og ikke-lineære beregningsmetoder - 2. ordens lastvirkninger.
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Brubak, Lars & Hellesland, Jostein
(2007).
Strength criteria in stiffened plate analysis using semi-analytical, large deflection methods.
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Brubak, Lars & Hellesland, Jostein
(2005).
Computational buckling strength analysis of stiffened plates with varying thickness.
I Bergan, P.; Garcia, J.; Onate, E. & Kvamsdal, T. (Red.),
Computational Methods in Marine Engineering.
International Center for Numerical Methods in Engineering (CIMNE).
ISSN 84-95999-63-3.
s. 355–364.
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Brubak, Lars & Hellesland, Jostein
(2005).
Computational buckling strength analysis of stiffened plates with varying thickness.
-
Hellesland, Jostein
(2005).
Buckling of plates, slenderness limits of columns, etc. -- Research overview.
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Hellesland, Jostein & Brubak, Lars
(2005).
Stability of Stiffened Orthotropic Plates: Performance Based Design.
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Osnes, Harald & Hellesland, Jostein
(2004).
Faststoff-/konstruksjonsmekanikk ved UiO.
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Brubak, Lars & Hellesland, Jostein
(2004).
Knekningsanalyse av plater med vilkårlig orienterte stivere.
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Brubak, Lars & Hellesland, Jostein
(2004).
Approximate buckling strength analysis of plates with arbitrarily oriented stiffeners.
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Andersen, Alfred; Osnes, Harald & Hellesland, Jostein
(2000).
Computational analysis of computational joints.
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Hellesland, Jostein
(1999).
Slanke konstruksjonsdeler.
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Hellesland, Jostein
(1999).
Slanke konstruksjonsdeler.
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Hellesland, Jostein
(1999).
Structural engineering for the largest petroleum exploration structure in the North Sea,
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Hellesland, Jostein
(1999).
Bridge design and construction in Norway.
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Hellesland, Jostein; Kanstad, Terje; Sørensen, Svein & Ålstedt, Erik
(1998).
Anvendelse av elementmetodeprogram på slanke plater, vegger og skall,
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Hellesland, Jostein
(1998).
Trykkstaver i rammesystem--Knekklengder,
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Hellesland, Jostein
(2019).
Approximate end and maximum moment formulations for slender columns in frames with sway.
Matematisk institutt, Universitetet i Oslo.
ISSN 0801-9940.
Fulltekst i vitenarkiv
Vis sammendrag
Based on a study of isolated restrained columns, and two-column panel frames, the often complicated mechanics of moment formations in the members are studdied using elastic second-order theory for the purpose of establishing a base on
which procedures for moments due to sidesway can be evaluated. A distinction is made between moment developments in “supporting (bracing) sway columns” and “supported (braced) sway columns”. The primary objective is to derive improved slender column design expressions that are suitable in approximate design code formats. Both shear, end moments and maximum moments, applicable over the full range of axial loads, are considered. Proposals are presented that will
allow more economical designs of framed columns with sway. Extended application to load combinations that include both gravity and sideways loading are also suggested.
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Hellesland, Jostein
(2019).
Mechanics of columns in sway frames -- Derivation of key characteristics.
Matematisk institutt, Universitetet i Oslo.
ISSN 0801-9940.
Fulltekst i vitenarkiv
Vis sammendrag
Columns in sway frames may be divided into laterally ``supporting (bracing) sway columns'', which can resist applied lateral shears, and ``supported (braced) sway columns'', which must have negative shears from the rest of the frame to support them. The supported sway column acts like a braced column with an initial displacement of one end
relative to the other. The maximum moment will occur at the end of a supporting sway column, but may occur between the ends of a supported sway column. Mechanics of such columns, single or part of panels, are studied using elastic second-order theory. The main objective is to establish simple, explicit expressions for characteristic points in
the moment versus axial load space. Such results may be useful in teaching, in design practice to assist in the assessment of the often complicated column response, and also useful as a supplement to full, second-order structural analyses.
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Brubak, Lars & Hellesland, Jostein
(2010).
Semi-analytical large displacement analysis of stiffened imperfect plates with a free or stiffened edge.
Universitetet i Oslo.
ISSN 0809-4403.
Fulltekst i vitenarkiv
-
Hellesland, Jostein
(2009).
Konstruksjonsmekanikk MEK3500/4500--Ekasamensoppgaver med løsningsforslag.
Avd. for mekanikk, Matematisk institutt.
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Hellesland, Jostein
(2009).
Todimensjonal elastisitetsteori for tynne plater--Introduksjon.
Avd. for mekanikk, Matematisk instittt.
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Hellesland, Jostein
(2008).
Extended second order approximate sway and critical load analysis of frames with sway-braced column interaction.
Dept. of Mathematics, Univ. of Oslo.
ISSN 0801-9940.
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Hellesland, Jostein
(2008).
Approximate second order analysis of unbraced frames reflecting inter-storey interaction in single curvature regions.
Mechanics Division, Dept. of Mathematics, Univ. of Oslo,.
ISSN 0801-9940.
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Brubak, Lars & Hellesland, Jostein
(2007).
Strength criteria in local and global semi-analytical, large deflection analysis of arbitrarily stiffened plates.
Matematisk institutt, Universitetet i Oslo.
ISSN 0809-4403.
-
Brubak, Lars & Hellesland, Jostein
(2006).
Semi-analytical buckling strength analysis of arbitrarily stiffened plates with varying thickness.
Matematisk institutt, Universitetet i Oslo.
ISSN 0809-4403.
-
Brubak, Lars & Hellesland, Jostein
(2006).
Computational postbuckling and strength analysis of arbitrarily stiffened plates in local and global bending.
Matematisk institutt, Universitetet i Oslo.
ISSN 0809-4403.
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Hellesland, Jostein
(2005).
Comments to Proposed Changes to ACI 318-02 Slender Column Provisions.
Mechanics Division, Dept. of Mathematics, University of Oslo.
ISSN 0801-9940.
-
Hellesland, Jostein
(2005).
Analysis of second order effects with axial loads, EN 1992-1-1-2004 (E), 5.8 -- Nasjonalt tillegg (NA).
Avd. for mekanikk.
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Brubak, Lars; Hellesland, Jostein & Steen, Eivind
(2005).
Semi-analytical buckling strength analysis of plates with arbitrary stiffener orientations.
Matematisk institutt, Universitetet i Oslo,.
ISSN 0809-4403.
Vis sammendrag
Buckling of plates with arbitrarily oriented, sniped stiffeners are
studied. The main objective is to present and validate an
approximate, semi-analytical computational model for such plates
subjected to in-plane loading. Estimation of the buckling strength
is made using the von Mises' yield criterion for the membrane stress
as the strength limit. The formulations derived are implemented in
a Fortran computer code, and numerical results are obtained for a
variety of plate and stiffener geometries. The model may handle
complex plate geometries, by using inclined stiffeners to enclose
irregular plate shapes. The method allows for a very efficient
analysis. Relatively high numerical accuracy is achieved with low
computational efforts. The results are, in most cases, found to be
conservative compared to fully nonlinear finite element analysis
results.
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Mari, Antonio & Hellesland, Jostein
(2003).
When can second order effects in columns be neglected?
Department of Construction Engineering, Universitat Politecnica de Catalunya,.
ISSN 84-87691-27-7.
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Hellesland, Jostein
(2003).
Non-slender RC Column Limits.
Matematisk institutt, Universitetet i Oslo.
ISSN 82-553-1389-3.
Vis sammendrag
Structural frame systems may be analyzed and designed based on forces from conventional first order theory when second order effects of axial forces on displacements in the compression members of the system are negligible. This is often the case. Slenderness limits at which this is the case are studied in this paper. Existing limits are reviewed and major factors that affect such limits are investigated. A new slenderness measure, labeled normalized slenderness, is defined based on a reduced stiffness concept. In addition to the geometrical slenderness, the normalized slenderness is a function of axial force and reinforcement. Slenderness limit predictions are obtained from numerical nonlinear analyses for unbraced (sway) members and for transversely loaded braced members. For such members, new slenderness limits are proposed and verified against the nonlinear results. They are generally found to be more reliable than existing lower limit formulations. Braced compression members subjected to end moments only are dealt with in a separate paper.
-
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Hellesland, Jostein
(2002).
Lower slenderness limits for unbraced and transversely loaded braced r.c. compression members.
Avd. for mekanikk, Matematisk institutt, Univ. i Oslo, Oslo.
ISSN 82-553-1355-9.
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Hellesland, Jostein
(2002).
Lower slenderness limits for braced, end loaded r.c. compression members.
Avd. for mekanikk, Matematisk institutt, Univ. i Oslo, Oslo.
ISSN 82-553-1356-7.
Vis sammendrag
--
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Hellesland, Jostein; Osnes, Harald & Skeie, Geir
(2000).
Proceedings of the 13th Nordic Seminar on Computational Mechanics.
Dept. of Mathematics, Univ. of Oslo,.
ISSN 82-553-1257-9.
Vis sammendrag
These proceedings contain the papers presented at the 13th Nordic
Seminar on Computational Mechanics (20-21 October, 2000). The seminars
are organized annually under sponsorship of the Nordic Association for
Computational Mechanics (NoACM), whose member countries are the Nordic
and the Baltic countries. The papers cover a wide range of subjects
within computational mechanics.
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Hellesland, Jostein
(1998).
Kommentarer og forslag til endringer i NS 3473, pkt.A.9.4.4 (4.utg.,1992) vedr. rotasjonsbehov og rotasjonskapasitetsberegninger,
7Letras.