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Kaiser, A., Larsson, M. & Girhammar, U. A. (2019). From file to factory: Innovative design solutions for multi-storey timber buildings applied to project Zembla in Kalmar, Sweden. Frontiers of Architectural Research, 8(1), 1-16
Open this publication in new window or tab >>From file to factory: Innovative design solutions for multi-storey timber buildings applied to project Zembla in Kalmar, Sweden
2019 (English)In: Frontiers of Architectural Research, ISSN 2095-2635, E-ISSN 2095-2643, Vol. 8, no 1, p. 1-16Article in journal (Refereed) Published
Abstract [en]

A “file-to-factory” process of computer technology is a way to both maximise efficiency throughout the building process, increase a building׳s performance, and be able to add interesting architectural possibilities throughout the design phase. The authors investigate a novel approach that produces a set of building trajectories rather than a set of buildings, yet yields a series of build-able examples of those trajectories. This paper evaluates how this series of stacked multi-storey timber buildings can be both incorporated within a file-to-factory process, and give rise to creating new innovative solutions throughout the entire design and manufacturing process. This process is applied to a real Swedish project called Zembla. It redefines the notion of sprawl, turning it into a progressive tactics for linking the city fabric to rural areas. It is a post-sustainable file-to-factory-produced timber ground-scraper; soaring above ground and water, suggesting a new way of making city-sized buildings for the future. A plug-in grid-shell structure is designed to contain a minimal amount of timber elements, beams make up the lattice, cross-laminated panels add structural support, surfaces come together to form the living capsules. Having the structure undulate across the topography and touching the ground in as few places as possible uses the dichotomy between landscape and urbanism, bringing the city to the people living in less densified areas. Each living unit is customised to its topological conditions within the grid.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Multi-storey timber buildings, File-to-factory, Modular systems, Grid shells, Slotting, Living capsules
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-72871 (URN)10.1016/j.foar.2018.12.001 (DOI)000461995600001 ()
Note

Validerad;2019;Nivå 2;2019-04-11 (oliekm)

Available from: 2019-02-12 Created: 2019-02-12 Last updated: 2019-04-11Bibliographically approved
Huber, J. A., Ekevad, M., Girhammar, U. A. & Berg, S. (2019). Simulation of Alternative Load Paths After a Wall Removal in a Platform-Framed Cross-Laminated Timber Building. In: Tomas K. Bader, Josef Füssl, Anders Olsson (Ed.), CompWood 2019 Book of Abstracts: . Paper presented at CompWood 2019 - International Conference on Computational Methods in Wood Mechanics- from Material Properties to Timber Structures, June 17-19, 2019.
Open this publication in new window or tab >>Simulation of Alternative Load Paths After a Wall Removal in a Platform-Framed Cross-Laminated Timber Building
2019 (English)In: CompWood 2019 Book of Abstracts / [ed] Tomas K. Bader, Josef Füssl, Anders Olsson, 2019Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

An increasing number of multi-storey timber buildings use cross-laminated timber (CLT) for their bearing structure. Platform-framed CLT buildings consist of vertical repetitions of floors resting upon one-storey tall walls, squeezing-in the floor panels between the walls. Tall buildings need to be structurally robust because many lives would be at stake in case of a disproportionate collapse. Robustness is the ability of a system to survive the loss of components. For collapse resistance, it poses the last line of defence, after an unforeseen exposure (e.g. accident, terrorism) has already occurred and after the exposed components could not resist failure. A robust building offers alternative load paths (ALPs) which come into action when a part of the bearing structure has been removed [1].

Many alternative load path analyses (ALPA) have been conducted for tall concrete and steel buildings using the finite element method (FEM), but for timber, ALPA are still scarce. ALPs depend on the behaviour of the connections after a loss [1]. Studies on timber so far have accounted for connections in a simplified manner by lumping their aggregate behaviour into single points. Our goal is to elicit the ALPs after a wall removal in a platform-framed CLT building, study their development and quantify their capacity, to determine whether they can prevent a collapse.

We investigated a corner bay of an 8-storey platform-framed CLT building (see Figure 1) and removed a wall at the bottom storey. We studied the ALPs of each storey by pushing down the walls above the gap in a non-linear quasi-static analysis in the FE software Abaqus. We accounted for contact and friction, considered plastic timber crushing, and accounted for brittle cracking in the panels. We modelled single fasteners with connector elements which simulated the elastic, plastic, damage and rupture behaviour. We recorded the force-displacement curves, i.e. pushdown curves, for each storey and used them to conduct a dynamic analysis of the entire bay in a simplified model, as suggested by [2].

The results show that the structure could engage the following ALPs after a wall removal: I) arching action in the outer floor panels, II) arching action of the walls, III) quasi-catenary action in the floor panels, and IV) hanging action from the roof panels. The ALPs were limited by various parameters, but they sufficed to resist a collapse of the bay. We observed that the inter-storey stiffness influenced the load-sharing among storeys, which affected the structural robustness. In the compressed connections, friction, and not the fasteners, transferred most of the horizontal loads. Future research should test the squeezed-in platform joint experimentally, to quantify its capacity for transverse shear loads. We also advise to assess the inter-storey stiffness to estimate the capacity for load-sharing among storeys.

National Category
Wood Science
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-74893 (URN)978-91-88898-64-7 (ISBN)
Conference
CompWood 2019 - International Conference on Computational Methods in Wood Mechanics- from Material Properties to Timber Structures, June 17-19, 2019
Available from: 2019-06-24 Created: 2019-06-24 Last updated: 2019-09-06
Huber, J. A., Ekevad, M., Girhammar, U. A. & Berg, S. (2018). A Review of Structural Robustness with Focus on Timber Buildings. In: 40th IABSE Symposium: Tomorrow’s Megastructures. Paper presented at 40th IABSE Symposium in Nantes 2018: Tomorrow's Megastructures; Nantes; France; 19 - 21 September 2018. International Association for Bridge and Structural Engineering (IABSE), Article ID S32-17.
Open this publication in new window or tab >>A Review of Structural Robustness with Focus on Timber Buildings
2018 (English)In: 40th IABSE Symposium: Tomorrow’s Megastructures, International Association for Bridge and Structural Engineering (IABSE) , 2018, article id S32-17Conference paper, Published paper (Refereed)
Abstract [en]

With an increasing number of storeys, timber buildings require closer attention to structuralrobustness. If a building can survive unforeseen events (e.g. accidents, terrorism), lives can be saved.The literature appears to be rather limited concerning robustness of timber buildings. This paperaims to give a brief review on robustness in general and design guidelines for timber in specific. Theresults indicate that connection design is a key aspect for robustness. Like in seismic design, by usingthe ductile capacity of connectors, the brittleness of timber can be controlled. For light timber-framebuildings, more guidelines exist than for posts and beams and cross-laminated timber, which bothseem to be similar to steel frames and precast concrete respectively regarding robustness.

Place, publisher, year, edition, pages
International Association for Bridge and Structural Engineering (IABSE), 2018
Keywords
robustness, timber, disproportionate collapse, progressive collapse, alternative load path
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70959 (URN)9783857481611 (ISBN)
Conference
40th IABSE Symposium in Nantes 2018: Tomorrow's Megastructures; Nantes; France; 19 - 21 September 2018
Funder
VINNOVA, Bioinnovation 4.4
Available from: 2018-09-24 Created: 2018-09-24 Last updated: 2019-01-14Bibliographically approved
Atashipour, S. R., Girhammar, U. A. & Challamel, N. (2018). A weak shear web model for deflection analysis of deep composite box-type beams. Engineering structures, 155, 36-49
Open this publication in new window or tab >>A weak shear web model for deflection analysis of deep composite box-type beams
2018 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 155, p. 36-49Article in journal (Refereed) Published
Abstract [en]

Deep box-type beams, consisting of framing members and sheathings, are sensitive to shear deformations and hence appropriate refined theories or complicated magnification factors are needed to be used to obtain accurate results. For sheathings or webs between the framing members that are weak in shear, additional shear deformations occur corresponding to the relative axial displacement between the framing members. These sandwich-type or partial interaction-type of in-plane shear behaviour between the framing members, needs to be taken into account, especially when the web shear stiffness is very low. The composite box-type beam treated here is composed of three framing members with sheathings on both sides. To incorporate effects of the sheathings shear deformations between the framing members on the deflection, the sheathings, here called web interlayers, are modelled as shear media with equivalent slip moduli corresponding to a partially interacting composite beam model. Governing equilibrium equations of the model are obtained using the minimum total potential energy principle and solved explicitly. The obtained results are compared with those based on different conventional beam theories and 3-D finite element (FE) simulations. It is shown that the model is capable of predicting accurately the deflection for a wide range of geometry and property parameters. It is demonstrated that the deflection of such deep box-type beams can be expressed as the summation of three different effects, namely bending deformations, conventional shear deformations in the framing members and sheathings, and additional in-plane shear deformations or shear slips of the weak web causing relative axial displacements between the framing members.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-59992 (URN)10.1016/j.engstruct.2017.10.073 (DOI)000419409800004 ()2-s2.0-85033432970 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-13 (andbra)

Available from: 2016-10-27 Created: 2016-10-27 Last updated: 2018-06-11Bibliographically approved
Huber, J. A., Ekevad, M., Berg, S. & Girhammar, U. A. (2018). Assessment of Connections In Cross-Laminated Timberbuildings Regarding Structural Robustness. In: : . Paper presented at 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018.
Open this publication in new window or tab >>Assessment of Connections In Cross-Laminated Timberbuildings Regarding Structural Robustness
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Cross-laminated timber makes timber buildings with an increasing number of storeys achievable. Withmore storeys, structural robustness needs more attention to make a building survive unforeseen events (e.g. accidents,terrorism) and save lives. For steel and concrete buildings, design methods for robustness focus on connection details.The assessment of joints in cross-laminated timber buildings regarding robustness is rather limited in the literature. Theobjective of this paper is to conduct an initial assessment of the connectors after the removal of a wall in a platformcross-laminated timber building. We used the finite element method and the component method for the analysis of acase building. The results indicate that the wall-to-wall and the floor-to-floor connectors may fail at low deflectionlevels leading to high shear loads in the floor panel above the removed wall, which might induce cracking. The removalanalysis was only partially completed, but we identified an indication of the deformation behaviour of the case building.Testing and refined modelling of the connections is needed in the future to verify the results. This study may facilitatefuture investigations regarding robustness of multi-storey cross-laminated timber buildings.

Keywords
Robustness, Connection, Component method, Cross-laminated timber, Finite element method, Disproportionate collapse
National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70599 (URN)
Conference
2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018
Projects
Bioinnovation 4.4
Funder
VINNOVA
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2019-03-27Bibliographically approved
Atashipour, S. R. & Girhammar, U. A. (2018). Influence of Grain Inclination Angle on Shear Buckling of Laminated Timber Sheathing Products. Structures, 13, 36-46
Open this publication in new window or tab >>Influence of Grain Inclination Angle on Shear Buckling of Laminated Timber Sheathing Products
2018 (English)In: Structures, ISSN 2352-0124, Vol. 13, p. 36-46Article in journal (Refereed) Published
Abstract [en]

Recent advances in timber production industries have enabled production of new innovative laminated timber products having layers with grain inclination angle. This paper is aimed to study influence of grain inclination angle in the laminated veneer lumber (LVL) and plywood sheathings on their shear buckling loads. Two extreme edge conditions of simply supported and clamped edges are considered. First, an accurate differential quadrature (DQ) computational code is developed using MAPLE programming software to obtain eigen buckling values and their corresponding eigen mode shapes. Next, for convenience of engineering calculations, approximate algebraic formulae are presented to predict critical shear buckling loads and mode shapes of LVL and plywood panels having layers with grain inclination angle, with adequate accuracy. Furthermore, finite element (FE) modelling is conducted for several cases using ANSYS software to show validity and accuracy of the predicted results for the problem. It is shown that the highest shear buckling loads of LVL sheathings is achievable when the inclination angle of about 30° with respect to the shorter edges is considered for production of LVL panels, whereas the same angle with respect to the long edges of the LVL sheathings results in a relatively lower buckling load. Considering similar inclination angle with respect to any edges of a plywood sheathings will also results in its highest pre-buckling capacity. It is also demonstrated that, under optimal design and certain loading circumstances, LVL shows a higher shear buckling capacity compared to a similar plywood sheathing.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-66675 (URN)10.1016/j.istruc.2017.10.003 (DOI)2-s2.0-85034242984 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-21 (andbra)

Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2018-06-11Bibliographically approved
Huber, J. A., Ekevad, M., Girhammar, U. A. & Berg, S. (2018). Structural Robustness of Timber Buildings. In: : . Paper presented at 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018.
Open this publication in new window or tab >>Structural Robustness of Timber Buildings
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The number of storeys in timber buildings are increasing. With more storeys, structural robustness needsmore attention, to make a building survive unforeseen events (e.g. accidents, terrorism) and save lives. The state of theart regarding robustness of concrete and steel buildings seems to be rather refined, but for timber buildings, theliterature appears to be quite limited. This study aims to review the design methods for robustness of timber buildings.First, the terminology and definitions are introduced. Then, the state of the art for design methods for robustness ingeneral are presented. Finally, the design methods for timber buildings are discussed and compared to those from otherbuilding materials. The results indicate that the guidelines for light timber-frame buildings are more refined than thosefor post and beam and cross-laminated timber buildings. Regarding robustness, the latter two construction types exhibitcertain similarities to steel frames and precast concrete buildings respectively. For timber, ductile connections can beused to avoid brittle timber failure after local damages, which resembles the approach of seismic design. Future researchin robustness should focus on the connection details in multi-storey timber buildings.

Keywords
Robustness, Timber buildings, Disproportionate collapse, Progressive collapse, Alternative load paths
National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-70593 (URN)
Conference
2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23 2018
Projects
Bioinnovation 4.4
Funder
VINNOVA
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-31Bibliographically approved
Caprolu, G., Girhammar, U. A. & Källsner, B. (2017). Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics (ed.). Wood Material Science & Engineering, 12(3), 165-188
Open this publication in new window or tab >>Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics
2017 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 3, p. 165-188Article in journal (Refereed) Published
Abstract [en]

Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls. For such walls, the leading stud is not fully anchored against uplift and tying down forces are developed in the sheathing-to-framing joints and the bottom rail will be subjected to crosswise bending, leading to possible splitting failure of the rail. In order to use these plastic design methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. In two earlier experimental programmes, the splitting failure capacity of the bottom rail has been studied. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the side surface of the bottom rail. In this article, a fracture mechanics approach for the two failure modes is used to evaluate the experimental results. The comparison shows a good agreement between the experimental and analytical results. The failure mode is largely dependent on the distance between the edge of the washer and the loaded edge of the bottom rail. The fracture mechanics models seem to capture the essential behaviour of the splitting modes and to include the decisive parameters. 

Place, publisher, year, edition, pages
Taylor & Francis, 2017
National Category
Building Technologies Other Mechanical Engineering
Research subject
Timber Structures; Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-15998 (URN)10.1080/17480272.2015.1075228 (DOI)000399667800006 ()2-s2.0-84941334544 (Scopus ID)f951919b-af7e-4d7f-ba90-8edc444e7b12 (Local ID)f951919b-af7e-4d7f-ba90-8edc444e7b12 (Archive number)f951919b-af7e-4d7f-ba90-8edc444e7b12 (OAI)
Note

Validerad; 2017; Nivå 2; 2017-04-24 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-11-15Bibliographically approved
Atashipour, S. R., Girhammar, U. A. & Al-Emrani, M. (2017). Exact Lévy-type solutions for bending of thick laminated orthotropic plates based on 3-D elasticity and shear deformation theories. Computers & structures, 163, 129-151
Open this publication in new window or tab >>Exact Lévy-type solutions for bending of thick laminated orthotropic plates based on 3-D elasticity and shear deformation theories
2017 (English)In: Computers & structures, ISSN 0045-7949, E-ISSN 1879-2243, Vol. 163, p. 129-151Article in journal (Refereed) Published
Abstract [en]

Exact solutions for static bending of symmetric laminated orthotropic plates with different Lévy-type boundary conditions are developed. The shear deformation plate theories of Mindlin-Reissner and Reddy as well as the three-dimensional elasticity theory are employed. Using the minimum total potential energy principle, governing equilibrium equations of laminated orthotropic plates and pertaining boundary conditions are derived. Closed-form Lévy-type solutions are obtained for the governing equations of both theories using separation of variables method and different types of classical boundary conditions, namely simply-supported, clamped and free edge, are exactly satisfied. Thereafter, 3-D elasto-static equations for orthotropic materials are solved for bending analysis of laminated plates using two different approaches. First, the method of separation of variables is utilized and an exact closed-from solution is achieved for simply-supported laminated orthotropic plates. Next, a combined Fourier-Differential Quadrature (DQ) approach is employed to present a semi-numerical solution for bending of laminated orthotropic plates with Lévy-type boundary conditions based on the three-dimensional elasticity theory. High accuracy of the presented solutions are proven and comprehensive comparative numerical results are provided and discussed. Presented comparative numerical results can serve as benchmark for investigating the correctness of new solution methods which may be established in the future.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-60002 (URN)10.1016/j.compstruct.2016.12.026 (DOI)000393931800012 ()2-s2.0-85006741906 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-01-09 (andbra)

Available from: 2016-10-27 Created: 2016-10-27 Last updated: 2018-09-13Bibliographically approved
Girhammar, U. A., Gustafsson, P. J. & Källsner, B. (2017). Modeling of shear walls using finite shear connector elements based on continuum plasticity. Frontiers of Structural and Civil Engineering, 11(2), 143-157
Open this publication in new window or tab >>Modeling of shear walls using finite shear connector elements based on continuum plasticity
2017 (English)In: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 11, no 2, p. 143-157Article in journal (Refereed) Published
Abstract [en]

Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Other Mechanical Engineering
Research subject
Wood Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-62947 (URN)10.1007/s11709-016-0377-3 (DOI)000401744300002 ()2-s2.0-85017186171 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-05-30 (rokbeg)

Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2018-07-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0336-6433

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