Installing between-joist bracing can be an economical and effective means of mitigating excessive vibration levels in wood floors associated to human discomfort. Effectiveness of between-joist bracing depends upon its own rigidity that accounts for the location of bracing, geometric arrangement and connection stiffness of installed...
The development of composite mass timber products in the late 20th century continues to generate new developments in the design and production of multi-layer wood products in a wide variety of orientations and for a wide variety of uses. In the US Congress’ Agricultural Act of 2014, provisions were specified in Section 7310 to establish a series of priorities for research into the needs of the forestry sector. Specifically, collaborative research efforts into the increased use of CLT in support of the expansion of this portion of the forest products industry were addressed. Cross laminated timber products have been included in updates to national and international building codes, and new production facilities continue to come online. WoodWorks (2019) reports that 105 CLT based construction projects are in construction or completed, and 200 are in the design process. These projects are scattered across the United States, including in the highest areas of decay potential (Figure 1). Mississippi State University Department of Sustainable Bioproducts has several ongoing projects to investigate the durability of CLT under various conditions. These are partnerships with other investigators, primarily with USDA Forest Products Lab personnel, and are housed at both MSU Department of Sustainable Bioproducts facilities in Starkville, MS as well as Forest Products Lab locations in Madison, WI, McNeill, MS, and Saucier, MS. CLT is being tested in several different formats and in test pieces of different sizes. In an ideal situation, CLT panels would be tested at their full size, however, the time it would take to do so, and the logistics of handling pieces of typical size is prohibitive for rapid assessment of the product. Assessments of CLT to date have focused on examining the durability of CLT when exposed to hazards that occur in the high hazard zones of deterioration, such as fungi, termites, and natural weathering. This report describes the collaborative testing of CLT against termite infestation and damage.
The presented work deals with hygro-thermal numerical simulation and mould growth risk evaluation between concrete foundation and frame of multi-story building made of CLT element modules. Structural CLT modules represent an approach towards wood material utilization in construction as its strength achieves markedly higher values then common structural wooden elements and makes rapid erection of the building possible. Although there are great promises that the novel CLT structures will gain ground in high-rise buildings market with apparent benefits in sustainability and inhabitant comments regarding ambience and acoustics, it is important to analyse their structural health and hygro-thermal conditions. The highest risk of unfavourable hygro-thermal conditions is usually presented in location characterized by thermal bridge, such as foundation, window-wall, wall-roof and wall-floor junctions. It is also of significant importance to analyse junctions between materials, whether wood, composite, mortar or concrete. A certain combination of thermal and humidity conditions in exposed time causes mould growth initiation that may lead to deterioration of structural material and unhealthy indoor environment.
In this case study, the moisture content and air-flow in the junction and open space in structural design details between the first floor (of concrete) housing joint warehouse and technical spaces and the residential upper floors made of CLT modules is analysed. Conditions leading to probable moisture-derived mould issues and design parameters leading to sufficient ventilation according to Mould Index modelling are presented.
Up to now, structural sealant glazing façades have been extensively applied. They are at the cutting edge of technology and meet the highest standards. The objective of several research projects was to develop stiffening glass fronts, which replace expensive frameworks or wind bracings behind the large glass windows. Thus, potential applications...
The outcome of an experimental campaign on the long-term behaviour of timber floors retrofitted with timber-to-timber composite methods is presented. Four diaphragm specimens, 5.2 m long (5 m span) were tested out-ofplane. Each specimen consisted of a solid wood-spruce joist strengthened with a crosslam panel. A layer of timber boards...
Most buildings are designed to accommodate a certain range of movement. In design, it is important for designers to identify locations where potential differential movement could affect structural integrity and serviceability, predict the amount of differential movement and develop proper detailing to accommodate it. To allow non-structural materials to be appropriately constructed, estimate of anticipated differential movement should be provided in the design drawings.
Simply specifying wood materials with lower MC at time of delivery does not guarantee that the wood will not get wet on construction sites and will deliver lower shrinkage amounts as anticipated. It is therefore important to ensure that wood does not experience unexpected wetting during storage, transportation and construction. Good construction sequencing also plays an important role in reducing wetting, the consequent wood shrinkage and other moisture-related issues.
Existing documents such as the APEGBC Technical and Practice Bulletin on 5- and 6-Storey Wood Frame Residential Building Projects, the Best Practice Guide published by the Canadian Mortgage and Housing Corporation (CMHC), the Building Enclosure Design Guide – Wood Frame Multi-Unit Residential Buildings published by the BC Housing- Homeowner Protection Office (HPO) provide general design guidance on how to reduce and accommodate differential movement in platform frame construction.
Serviceability performance studied covers three different performance attributes of a building. These attributes are 1) vibration of the whole building structure, 2) vibration of the floor system, typically in regards to motions in a localized area within the entire floor plate, and 3) sound insulation performance of the wall and floor assemblies. Serviceability performance of a building is important as it affects the comfort of its occupants and the functionality of sensitive equipment as well. Many physical factors influence these performances. Designers use various parameters to account for them in their designs and different criteria to manage these performances. Lack of data, knowledge and experience of sound and vibration performance of tall wood buildings is one of the issues related to design and construction of tall wood buildings.
In order to bridge the gaps in the data, knowledge, and experience of sound and vibration performance of tall wood buildings, FPInnovations conducted a three-phase performance testing on the Origine 13-storey CLT building of 40.9 m tall in Quebec city. It was the tallest wood building in Eastern Canada in 2017.
In this paper finite element analysis of a five layer cross-laminated timber (CLT) rectangular floor is presented. The model was developed using 3D shell elements with linear elastic orthotropic material properties. Support conditions analysed included fully fixed, semi-rigid and simply supported, and both one and two-way span conditions were considered. For each case, the serviceability deflection was determined from a static small displacement analysis and the first three natural frequencies bending and torsional mode shapes, within a 0-80 Hz range, from mode frequency analysis. The analysis shows that the maximum displacement and frequency response are significantly impacted by the support stiffness and the number of edges supported. These results will contribute to determining the optimum fixing configuration with regard to serviceability limit design (SLD) for various CLT floor geometries.