Seismic testing of post-tensioned Pres-Lam core walls using cross laminated timber

Moroder, Daniel; Smith, Tobias; Dunbar, Andrew; Pampanin, Stefano; Buchanan, Andrew

doi:10.1016/j.engstruct.2018.02.075

Cited by 45 publications

(14 citation statements)

References 7 publications

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“…The issue can be addressed using either a careful design of the diaphragm connections (Moroder et al, 2014b) or using an alternative wall configuration which minimizes displacement incompatibilities.…”

Section: Discussionmentioning

confidence: 99%

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Development and Testing of an Alternative Dissipative Posttensioned Rocking Timber Wall with Boundary Columns

2016

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The unbonded post-tensioned rocking and dissipative technology was first developed as the main outcome of the PRESSS (PREcast Seismic Structural Systems) Program in US.After the first developments and significant refinement, the technology was extended to steel and, more recently, timber structures. The timber version, referred to as Pres-Lam (Prestressed laminated) system can be either implemented for timber walls (single or coupled) or frames or combination of the above, with unbonded post-tensioning and supplemental dissipation devices.In unbonded post-tensioned dissipative wall systems a combination of re-centering capacity and energy dissipation leads to a "controlled rocking" mechanism which develops a gap opening at the wall base. This generates an uplift displacement which is transferred to the floor diaphragm. This vertical displacement incompatibility can represent a potential issue if the connection detailing between floor and lateral resisting system is not designed properly.The same issue can be mitigated by adopting an alternative configuration of the rocking/dissipative wall system, based on the use of a column-wall-column post-tensioned connection. This concept, originally proposed for precast concrete walls and referred to as PreWEC (Prestressed Wall with End Column), has been extended and adapted to posttensioned timber structures and validated through experimental testing.

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Section: Discussionmentioning

confidence: 99%

“…Two alternative design strategies can be adopted to mitigate the effects of vertical displacement incompatibility. A series of different connection options and construction details to connect the diaphragm drag beams to the rocking wall have been proposed and experimentally validated by Moroder et al (2014b).…”

Section: Introductionmentioning

confidence: 99%

Development and Testing of an Alternative Dissipative Posttensioned Rocking Timber Wall with Boundary Columns

2016

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“…In concrete rocking walls, precast panels are vertically connected and PT from the top of the wall by an unbonded PT cable anchored to its foundation 5–7, 21 . This solution can be applied also for monolithic cast in place walls 29 or for converting existing traditional monolithic walls to exhibit a rocking behavior 30 ; similarly, this solution has been applied to timber structures 22–24 . In steel structures, the rocking solution was applied to concentrically braced frames (CBFs) to produce the self‐centering concentrically braced frames (SC‐CBF) 14, 26–28 .…”

Section: Introductionmentioning

confidence: 99%

“…20 The rocking mechanism has been adopted for several seismic lateral load resistant systems. This include concrete, [5][6][7]21 timber, [22][23][24] masonry, 25 and steel 14,[26][27][28] structures. In concrete rocking walls, precast panels are vertically connected and PT from the top of the wall by an unbonded PT cable anchored to its foundation.…”

Section: Introductionmentioning

confidence: 99%

Mixed Lagrangian formalism for dynamic analysis of self‐centering systems

Marzok

Lavan

2020

Earthq Engng Struct Dyn

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This paper presents two models for the analysis of self‐centering concentrically braced frames (SC‐CBFs) with multiple rocking sections. Both models are developed within the mixed Lagrangian formalism (MLF). For these models, MLF leads to a quadratic optimization problem at each time step where the internal forces at the end of the time step are the design variables. The first model is more general and explicitly models the truss elements. The second model is simplified and utilizes a macromodel. This model is easier to implement for initial designs, optimization, and parametric studies. For the purpose of formulating the simplified model, a new rotational contact element is developed and added to the MLF to describe the behavior of the rocking sections. Both models are compared to results obtained using the finite‐element method. Although the comparison shows a good agreement, MLF is shown to allow much larger time increments for convergence. This considerably reduces the computational effort and central processing unit time. The simplified model is extended for three‐dimensional analysis of SC‐CBFs. This shows that the proposed models can be easily extended using relatively simple transformation matrices.

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“…Extensive laboratory testing (e.g. Moroder et al, 2018; Newcombe et al, 2008; Sarti et al, 2015; Wanninger and Frangi, 2014) showed that the post-tensioned timber connection has remarkable seismic performance: in fact, it presents negligible residual displacements, negligible structural damage in the timber members, and stable non-degrading hysteretic response. Furthermore, analytical and numerical models (e.g.…”

Section: Introductionmentioning

confidence: 99%

Fragility-based methodology for evaluating the time-dependent seismic performance of post-tensioned timber frames

et al. 2020

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Since 2010, the construction of post-tensioned wooden buildings (Pres-Lam) has been growing rapidly worldwide. Pres-Lam technology combines unbonded post-tensioning tendons and supplemental damping devices to provide moment capacity to beam–column, wall–foundation, or column–foundation connections. In low seismic areas, designers may choose not to provide additional damping, relying only on the post-tensioning contribution. However, post-tensioning decreases over time due to creep phenomena arising in compressed timber members. As a consequence, there is a reduction of the clamping forces between the elements. This reduction affects the seismic response of Pres-Lam buildings in the case of low- and high-intensity earthquakes. Therefore, understanding and accounting for the post-tensioning losses and their uncertainty are paramount for a robust assessment of the safety of Pres-Lam constructions. So far, however, there have been no comprehensive studies which tackle the overall seismic performance of such systems in the presence of time-varying post-tension losses and the associated uncertainty. This study tackles this research gap by introducing a comprehensive seismic evaluation of Pres-Lam systems based on time-dependent fragility curves. The proposed fragility analysis is specifically designed to account systematically for time-varying post-tension losses and the related uncertainty. The method is applied to two case studies, designed, respectively, with and without supplemental damping devices. In terms of structural performance, results show that the use of additional dissipaters mitigates the effect of post-tensioning loss for earthquakes of high intensity. Conversely, performance under low-intensity earthquakes is strongly dependent on the post-tensioning value, as the reduction of stiffness due to the anticipated rocking motion activation would lead to damage to non-structural elements.

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Seismic testing of post-tensioned Pres-Lam core walls using cross laminated timber

Cited by 45 publications

References 7 publications

Development and Testing of an Alternative Dissipative Posttensioned Rocking Timber Wall with Boundary Columns

Development and Testing of an Alternative Dissipative Posttensioned Rocking Timber Wall with Boundary Columns

Mixed Lagrangian formalism for dynamic analysis of self‐centering systems

Fragility-based methodology for evaluating the time-dependent seismic performance of post-tensioned timber frames

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