Improved Frame Stability Analysis with Effective Lengths

Hellesland, Jostein; Bjorhovde, Reidar

doi:10.1061/(asce)0733-9445(1996)122:11(1275)

Cited by 43 publications

(27 citation statements)

References 4 publications

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“…They used the same assumptions as the traditional effective length method, but considering the true boundary conditions at far ends of the top and bottom columns. Hellesland and Bjorhovde [7,8] suggested a "method of means" to consider the story interaction in sway and no-sway frames. Wood [9] put forward a stiffness distribution process by which the rotational rigidity at each end of the column is determined, and the joint moment equilibrium equations are established, these equations are solved for critical loads.…”

Section: Introductionmentioning

confidence: 99%

Column effective lengths considering inter-story and inter-column interactions in sway-permitted frames

Tong

Wang

2006

Journal of Constructional Steel Research

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Section: Introductionmentioning

confidence: 99%

Column effective lengths considering inter-story and inter-column interactions in sway-permitted frames

Tong

Wang

2006

Journal of Constructional Steel Research

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“…Hellesland and Bjorhovde [11] also show the importance of fully considering the contributions of adjacent elements to rotational stiffnesses. They propose a 'weighted mean' approach to determining frame buckling from individual element analyses, and importantly applied this method to frames in which column stiffnesses change significantly between storeys.…”

Section: Frame Stabilitymentioning

confidence: 99%

The effective length of columns in multi-storey frames

Webber

Orr

Shepherd

et al. 2015

Engineering Structures

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a b s t r a c tCodes of practice rely on the effective length method to assess the stability of multi-storey frames. The effective length method involves isolating a critical column within a frame and evaluating the rotational and translational stiffness of its end restraints, so that the critical buckling load may be obtained.The non-contradictory complementary information (NCCI) document SN008a (Oppe et al., 2005) to BS EN 1993-1 (BSI, 2005) provides erroneous results in certain situations because it omits the contribution made to the rotational stiffness of the end restraints by columns above and below, and to the translational stiffness of end restraints by other columns in the same storey.Two improvements to the method are proposed in this paper. First, the axial load in adjoining columns is incorporated into the calculation of the effective length. Second, a modification to the effective length ratio is proposed that allows the buckling load of adjacent columns to be considered. The improvements are shown to be effective and consistently provide results within 2% of that computed by structural analysis software, as opposed to the up to 80% discrepancies seen using the NCCI (Oppe et al., 2005).

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“…where the value of c is assumed to be 4.8 as specified by Hellesland (2007) and Hellesland and Bjorhovde (1996). The k B is defined as E I b /2t.…”

Section: Parametric Study Of Single Storey Concentric Braced Framementioning

confidence: 99%

Equivalent viscous damping for steel concentrically braced frame structures

Wijesundara

Nascimbene

Sullivan

2011

Bull Earthquake Eng

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The direct displacement based seismic design procedure utilises equivalent viscous damping expressions to represent the effect of energy dissipation of a structural system. Various expressions for the equivalent viscous damping of different structural systems are available in the literature, but the structural systems examined in the past have not included concentrically braced frame structures. Thus, this study describes the development of an equivalent viscous damping equation for concentrically braced frame structures based on the hysteretic response of 15 different single storey models. Initially, equivalent viscous damping is calculated based on the area based approach and then corrected for the earthquake excitation. An iterative procedure is adopted to calibrate the equivalent viscous damping expression to the results of inelastic time history analyses using a number of spectrum-compatible real accelerograms. From the results of this research, a new damping expression is developed as a function of the ductility and the non dimensional slenderness ratio.

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Improved Frame Stability Analysis with Effective Lengths

Cited by 43 publications

References 4 publications

Column effective lengths considering inter-story and inter-column interactions in sway-permitted frames

Column effective lengths considering inter-story and inter-column interactions in sway-permitted frames

The effective length of columns in multi-storey frames

Equivalent viscous damping for steel concentrically braced frame structures

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