Stability and ultimate behaviour of prestressed stayed beam-columns

Wu, Kaidong; Wadee, M. Ahmer; Gardner, Leroy

doi:10.1016/j.engstruct.2019.109723

Cited by 17 publications

(36 citation statements)

References 25 publications

(56 reference statements)

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“…This enables the main beam-column component to be pre-cambered which would counteract the effect of the self-weight by a controlled extent. As determined in the work presented in [28], two of the three zones of mechanical behaviour, which were initially discovered in [6] for prestressed stayed columns are each sub-divided into two further sub-zones of behaviour owing to the effect of the self-weight.…”

Section: Crossarm Elementmentioning

confidence: 96%

“…Following the recent study on the zonal behaviour, the linear optimum prestressing forces, determined in [28], are used as the bases in the present study.…”

Section: Crossarm Elementmentioning

confidence: 99%

“…However, this force, alongside the self-weight, is no longer taken into account explicitly owing to their effects counteracting each another. In steps 1-3, all stays are assumed to remain straight; T 0 is the force within the lower stays in step 1; w w,m is the midspan vertical displacement after applying self-weight and T l,w = T l1,w = T l2,w are the prestressing forces within the lower stays to counteract the midspan self-weight deflection; T u,i = T u1,i = T u2,i and T l,i = T l1,i = T l2,i are the prestressing forces applied within the upper and lower stays respectively to increase structural capacity, and T u,i sin β u = T l,i sin β l [28]; P is the compressive axial load; T l,R = T l1,R = T l2,R are the residual tensions within the lower stays when the system buckles.…”

Section: Analytical Modellingmentioning

confidence: 99%

“…However, there is a potential demand for very long struts to be used in the horizontal plane, for example to support excavation works in the construction of large scale foundations. As discussed in recent work [28], current practice for propping large excavations relies on so-called 'super struts'; constructed from heavy tubular steel cross-sections, these struts need to withstand earth pressures axially in conjunction with their considerable self-weight under bending. It has been demonstrated in the aforementioned research work that the most effective stayed columns can provide an increase in load-carrying capacity of a conventional column by an order of magnitude when compared to corresponding unstayed systems.…”

Section: Introductionmentioning

confidence: 99%

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Interactive buckling in prestressed stayed beam-columns

Wadee

Gardner

2020

International Journal of Mechanical Sciences

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The instability of beam-columns with crossarms and externally prestressed cable stays is studied analytically, where the combination of bending and compression is assumed to be derived from the system self-weight acting orthogonally to the applied axial load. A nonlinear analytical model for prestressed stayed beam-columns with doubly-symmetric and mono-symmetric configurations, based on the Rayleigh-Ritz method, is presented that captures modal interactions for perfect geometries explicitly for the first time. It is demonstrated that the theoretical compressive strength enhancements under certain configurations can only be obtained at the expense of triggering a sequence of destabilizing bifurcations. This can give rise to severely unstable interactive post-buckling behaviour including the so-called 'mode jumping' phenomenon. Moreover, for mono-symmetric stayed beam-columns, it is shown that the varying levels of prestress within the stays can lead to different buckling modes which all have their own characteristic post-buckling responses. The analytical model is verified using a nonlinear finite element model formulated within the commercial code ABAQUS and excellent comparisons are obtained.

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Section: Crossarm Elementmentioning

confidence: 96%

“…Following the recent study on the zonal behaviour, the linear optimum prestressing forces, determined in [28], are used as the bases in the present study.…”

Section: Crossarm Elementmentioning

confidence: 99%

Section: Analytical Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interactive buckling in prestressed stayed beam-columns

Wadee

Gardner

2020

International Journal of Mechanical Sciences

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“…A notable contribution to the investigation of PSCs by Hafez et al (1979) identified an equation for the calculation of the amount of prestress that will result in the highest critical buckling load for a particular geometry, known as the optimal prestress. Several subsequent studies have utilised numerical modelling to investigate the behaviour of these structures under axial loading (Chan et al, 2002; Hyman et al, 2018; Li et al, 2016, 2018a, 2018b; Osofero et al, 2013; Saito and Wadee, 2008, 2009a, 2009b, 2010; Wang et al, 2019; Wong and Temple, 1982; Wu et al, 2019; Yu and Wadee, 2017b). The majority of previous studies have focused on PSCs under axial loading, when in reality these structures may be used in such a way that there is eccentricity in the loading.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of eccentrically loaded prestressed stayed columns with circular hollow sections

Hyman

Osofero

2020

Advances in Structural Engineering

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The behaviour of axially loaded prestressed stayed columns is a commonly studied area. Despite the fact that load eccentricity in columns is commonplace in practice, the amount of investigation into these systems under eccentric loading is limited. This study employed finite element analysis to investigate the interactive post-buckling behaviour of prestressed stayed columns. Critical imperfection combination with respect to the load carrying capacity was established and a comparison of a planar and a three-dimensional model was carried out to investigate key differences in the models. In this work, it has been shown that the load carrying capacity of eccentrically loaded columns can be significantly reduced when buckling in interactive mode is observed. Furthermore, it was established that increase in eccentricity results in a decrease in load carrying capacity of columns for both planar and three-dimensional models. However, a major difference between the models is the twisting effect exhibited in the three-dimensional model under out-of-plane eccentric loading. This work highlights the importance of carefully designing prestressed stayed columns’ connections to minimise loading eccentricity as it has been shown that the benefit of employing these systems over unstayed columns reduces with increasing load eccentricity.

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Prestressed stayed beam-columns: Sensitivity to prestressing levels, pre-cambering and imperfections

Wadee

Gardner

2021

Engineering Structures

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The behaviour and structural performance of imperfect beam-columns with crossarms and externally prestressed cable stays are studied numerically, where the combination of bending and compression is assumed to be derived from the system self-weight acting orthogonally to the applied axial load. Both doubly-symmetric and mono-symmetric systems are studied. Sensitivity of the structural response to varying prestressing levels, pre-cambering and initial imperfections is investigated. Different initial imperfection levels and combinations are considered to facilitate the exploration of interactive buckling. The optimum prestressing force in terms of ultimate resistance and two structural efficiency indicators is also studied. It is found that relatively small crossarm lengths, stay diameters and crossarm length ratios should be avoided. Moreover, mono-symmetric cases are more sensitive to the level of pre-cambering than their doubly-symmetric counterparts. Considering both load-carrying capacity and structural efficiency, doubly-symmetric cases perform best with zero pre-cambering, but mono-symmetric cases perform best with upward precambering. As for the true optimum prestressing levels, these are recommended to be significantly above the linearly obtained optimum to maximize the structural efficiency.

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Stability and ultimate behaviour of prestressed stayed beam-columns

Cited by 17 publications

References 25 publications

Interactive buckling in prestressed stayed beam-columns

Interactive buckling in prestressed stayed beam-columns

Behaviour of eccentrically loaded prestressed stayed columns with circular hollow sections

Prestressed stayed beam-columns: Sensitivity to prestressing levels, pre-cambering and imperfections

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