Currently, no appropriate standard exists that describes how to determine the in-plane shear stiffness for cross-laminated timber (CLT) panels, meaning that, there is a lack of appropriate and reliable test methods. In this paper, two gross shear test methods are evaluated: a picture frame test and a diagonal compression test, which are intended to measure the shear stiffness of a whole CLT panel. This evaluation aimed to compare the shear modulus, the amount of compression/tension in the diagonal directions of the panels and the deformations of both sides of the panels. The picture frame test and diagonal compression test provides a bi-and uniaxial pre-stress, respectively. A total of 30 non-edge glued CLT panels were tested, 17 3-layer and 13 5-layer panels. The shear modulus for the 3-and 5-layer non-edge-glued panels were measured as 418 and 466 MPa, respectively, in the picture frame test. In the diagonal compression test, the shear modulus was measured to substantially higher values of 530 and 626 MPa for the 3-and 5-layer panels, respectively. In the picture frame test, panels were equally stretched along one of the diagonals as they were compressed along the other diagonal, which was not the case for panels in the diagonal compression test. The test results also showed that measuring only one side incurs a risk of over-or underestimating the in-plane shear modulus. Compared with results from the literature, the picture frame test seems to be a more reliable test method than the diagonal compression test.

No abstract

Cross-laminated timber (CLT) is an engineered wood material that is used in the construction industry, e.g., for floors, walls, and beams. In cases where CLT-elements are used as shear walls, the in-plane-stiffness is an important property. For non-edge glued CLT, in-plane shear stiffness is lower than for edge-glued CLT. To evaluate the non-edge glued CLT panel’s in-plane shear modulus, the diagonal compression test and finite element (FE) simulation was used. FE-models with both isotropic and orthotropic material models were used to calculate the shear stiffness. The FE models using pure shear loads were used as a reference to determine the correct value of the shear modulus. To verify the FE simulations, diagonal compression tests were conducted on 30 CLT samples. A calibration formula was derived using the least square method for calculation of shear modulus. The formula gave accurate results. The results showed that FE simulations can reproduce the same shear stiffness as tests of non-edge glued 3-layer and 5-layer CLT panels.

Purpose -The purpose of this paper is to suggest the application of the line-of-balance (LoB) scheduling technique in combination with a 4D CAD workspace model as a method to improve the management of the flow of resources through locations in construction projects, defined as work flow. Current scheduling methods fail to consistently manage work flow, which can disrupt the construction process, leading to waste such as conflicts in time and space by construction crews. Design/methodology/approach -LoB and 4D CAD are applied to a case study of multi-story timber housing project involving the construction of 95 apartments in five six-storey buildings. Based on the case study results, the benefits and limitations of the combined use of both methods are discussed.Findings -The majority of the problems experienced during the actual construction process quickly become evident from an analysis of a relatively simple LoB diagram. Furthermore, the 4D CAD workspace model provides additional insights in the scheduling of construction activities, such as workspace availability, the spatial context of workspaces and partial overlap of workspaces. Practical implications -Virtual design and construction methods based on principles from lean construction can contribute significantly to the value of the product and the elimination of waste in any construction project. Originality/value -The paper refers to the guiding principles from lean construction in relation to virtual design and construction methods, such as simulations with 4D CAD. Additional research and studies of practical applications are suggested to facilitate the combination of principles from lean construction with virtual design and construction methods.

The majority of companies involved in value delivery in the Swedish housing industry are Small-and Medium-sized Enterprises (SME). An SME is often managed in an informal way with focus on sales and production. Many SME are also financially vulnerable as they are strongly dependent on a few key customers and key products. As variation will always exist, SME should learn to deal with variation instead of try eliminating it. This paper hypothesises that structural flexibility in SME supply chains through horizontal collaboration leads to a regional environment of economical growth from which all active SME will benefit. The hypothesis is examined through two case studies; a Swedish supplier network that has worked together six years and a four year old Norwegian supplier network. A benefit of collaboration is knowledge sharing that lessens the economical strain of keeping up with the "latest". Other examples of collaboration are shared production resources in case of low capacity. Collaboration within supplier tier networks is considered to mark the emergence of a "collective strength" that improves individual suppliers bargaining position towards their customers. This evolution is considered an indication of the emergence of a "Lean Enterprise" within the house building sector.