This study tested ultra-high molecular weight polyethylene (UHMWPE) ropes for log load securement. Destructive testing of used rope samples done in a previous project found that the strength of these ropes decreased with use. To address this problem, the diameter of the synthetic rope was increased. In addition, a different type of rope with a UHMWPE inner core covered with a polyester protective jacket was tested. The outer jacket protected the inner core from dirt and abrasion which may help mitigate the loss in strength that occurs with use. Wrappers were put into service and tested for breakage after three and six months of use.
Cette étude a évalué des câbles en polyéthylène de poids moléculaire ultra élevé (PEPMUE) pour sécuriser des chargements de billes. Des tests destructifs d'échantillons de câbles usagés effectués dans un projet précédent avaient révélé que la résistance de ces câbles diminuait avec l'utilisation. Pour résoudre ce problème, le diamètre du câble synthétique a été augmenté. De plus, un autre type de câble avec une âme intérieure en PEPMUE recouverte d'une gaine de protection en polyester a été testé. La gaine extérieure protégeait le câble intérieur de la saleté et de l'abrasion, ce qui peut aider à atténuer la perte de résistance qui se produit avec l'utilisation. Les câbles ont été mis en service et testés pour la résistance à la rupture après trois et six mois d'utilisation.
The objective of this project is to establish fundamental fire performance data for the design and specification of NLT assemblies; this project specially addresses determining FSRs for NLT. The goal of this project is to confirm that NLT, when used as a mass timber element, has a lower FSR than standard thickness SPF boards when tested individually and flatwise. The project also considers how the surface profiles, design details, and the direction of an assembly might influence flame spread. This includes the evaluation of typical architectural features, such as a ‘fluted’ profile.
Having this technical information will support project approvals for the use of NLT elements in larger and taller wood buildings, as well as provide scientific justification for Authorities Having Jurisdiction (AHJ) to review and accept this construction method. This research will provide the evidence for designers to demonstrate their design have met or exceeded fire safety requirements. Ultimately the intent is to expand the adoption of manufactured solid timber construction for larger and taller buildings, as well as for non-traditional wood markets (such as institutional or commercial buildings).
Other aspects of this project (in separate reports) include evaluating fire resistance of NLT, and assessing how NLT charring rates might be affected by gaps between boards.
The objective of this work is to generate fire performance data for NLT assemblies to address gaps in technical knowledge. This project aims to study how the size of gaps between NLT boards might affect charring of an assembly and its overall fire performance. This research will support designers and builders in the use of mass timber assemblies in larger and taller buildings, by ensuring fire safe designs.
The objective of this work is to generate fire resistance data for NLT assemblies to address significant gaps in technical knowledge. This research will support designers and builders in the use of mass timber assemblies in larger and taller buildings, as well as provide scientific justification for Authorities Having Jurisdiction (AHJ) to review and accept this construction method. The intent is to demonstrate that NLT construction can meet or exceed NBCC fire safety requirements for use in buildings of mass timber construction.
The data could be used towards the inclusion of an NLT fire resistance calculation methodology into Annex B of CSA O86 – Engineering Design for Wood , which currently addresses only glue-laminated timber (GLT), structural composite lumber (SCL) and cross-laminated timber (CLT).
Nail-Laminated Timber (NLT) and box beam are efficient and economical engineered wood products. Although NLT has been used in North America for more than a century, only in recent years it has gained renewed interests as they have been seen as the most economical panel products used in mass timber buildings. Box beams, on the other hand, are lightweight and generally possess higher strength and stiffness than comparable-sized solid timber and are more efficient than solid timber for large spans and loads.
In this report, existing design provisions and their limitations for the design and construction of NLT and box beam in Canadian standards are reviewed. For NLT, there is a general lack of information related to manufacturing, design and construction to ensure consistent manufacturing and installation practices. Therefore, it is difficult to research and document with confidence the full range of performance that can be achieved with NLT. It is therefore recommended that a North American product standard and design information on structural performance, floor vibration, fire resistance, acoustic performance, and construction risk mitigation measures (e.g. moisture and fire) be developed.
In CSA O86, design methods are limited to box beams with flanges and webs bonded with glue. As the flanges and webs of a box beam can be assembled by either glue or mechanical fasteners, it is recommended that design provisions for box beam with mechanical joints be also developed. With the information in Eurocode 5 and relevant supporting research papers, it is ready to be implemented.
Single-storey non-residential buildings form a large proportion of the building inventory of Canada. Such buildings may be used for industrial, commercial, recreational or institutional purposes and often have a large footprint. Their common structural framing is comprised of steel deck roof diaphragm supported by the vertical system that may consist of steel braced frames, masonry or concrete shear walls. Although, wood panels, lumber and other engineered wood products can be used as materials for the diaphragms (roofs) of such buildings, wood has not been the material of choice so far in Canada. One of the reasons is the lack of knowledge of the performance of these, in general very flexible diaphragms, that are sometimes significantly more flexible than the vertical lateral force resisting elements. As a result, the seismic response of such buildings is strongly influenced by the flexibility of the diaphragms and the seismic provisions of codes, which are generally suitable for the design of buildings with rigid diaphragms, are not applicable to the design of buildings with flexible diaphragms. Flexibility of the diaphragm affects the period of the building and hence its response to seismic forces. Flexibility also affects the distribution of shears and moments in the diaphragm.
The present study examines the effect of diaphragm flexibility on the building period and reviews the methods currently recommended for classifying the diaphragm as flexible, rigid, or semi rigid. A simplified method of obtaining a better estimate of the period of a building with flexible diaphragm is also suggested. In addition the effect of diaphragm flexibility on the distribution of shear forces and bending moments is examined through time history analysis of a building with flexible diaphragm subjected to an earthquake ground motion.
Des facteurs de correction sont disponibles lors d’essais de flexion aux tiers points afin de prendre en compte le fait d’avoir une section de l’échantillon testé qui soit en porte-à-faux. Ces facteurs sont disponibles pour les pièces aux dimensions nominales courantes mais pas pour le 2’’x5’’. Le but était donc de pallier à ce manque.
Duration of load (DOL) and creep effects characterize rheological behaviour of wood and are of critical importance to timber engineering. These effects are accounted for in the engineering design codes with adjustment factors for structural wood and wood-based products. Various methods are used worldwide for the evaluation of DOL and creep effects and for determination of appropriate adjustment factors. A review of the major international codes for engineering design in wood was carried out to understand how DOL and creep are taken into account in these codes and provide recommendations on how to level out the main differences between the codes. It is recommended to adopt an internationally recognized method for evaluation of DOL and creep, and suggestions for the contents of such a method are provided.
Statisticians were engaged to evaluate the damage accumulation models used in wood industry for assessing DOL and creep effects of wood products. The research undertaken yielded answers to whether the mathematical models can be improved, if times-to-failure for ramp and constant load tests can be approximated by Weibull or log-normal distributions, and whether some model parameters can be assumed constant and other treated as random effects. An experimental study was carried out to support the statistical work. The results of the study were used in statistical simulations to estimate the parameters used in the damage accumulation models in an attempt to refine the current models.
A new design Section on Lateral Load Resisting Systems (LLRSs) was introduced in the 2009 edition of Canadian Standard for engineering Design in Wood (CSA O86). The activities presented in this report (development of technical papers, development of technical polls and attending various code committees) have a goal to continue the work in this field by further improving the new Section on LLRSs by implementing additional design information for other wood-based structural systems and assemblies. During the last two years, several technical polls and papers were developed and presented to various code committees for future code implementation. These activities will help design engineers to use timber in structural systems in residential and non-residential buildings in Canada and the US.