Development of All-Wood Connections with Plywood Flitch Plate and Oak Pegs

This paper proposes a new method for beam-beam connections, which include plywood as slot-in plates connected by oak pegs. A total of 96 specimens were fabricated for tests to explore the minimum required end distances and spacing between pegs parallel to the grain. A new failure mode, termed shear wedge that is different from those found in previous research, was found. A spring model was also proposed in this study to investigate the stiffness of the connections, and feasibility of EC5 to be applied on the new proposed connections was also examined. The effective number was discussed in this study and modified in accordance to the experimental results. The result of this study shows the new connections proposed do not lead to brittle failure unless failure in plywood occurred

Single step joint: overview of European standardized approaches and experimentations

In the field of the built heritage restoration, engineers have to work with old structures made of badly preserved timber elements. The assessment of timber elements and connections is a major issue for engineers involved in a restoration project. Before thinking about any intervention technics, engineers have to properly understand how the carpentry connections fail, which parameters influence the failure modes (geometry of the joint, mechanical properties of the wood,…) and how the internal forces are distributed into the joint to finally figure out how to design the traditional carpentry connections. The present paper aims to raise those questions focusing on the Single Step Joint design. Even if this common joint between the rafter and the tie beam is geometrically simple, one may pick up three geometrical configurations of Simple Notched Joints from the past till today: the geometrical configuration ideal (GCID), the geometrical configuration perpendicular to the tie beam (GCPTB) and the geometrical configuration perpendicular to the rafter (GCPR). The first one is more recent because it requires a highest accuracy production, and so the use of the new technologies (e.g., CNC). For each one, some general design rules about the geometrical parameters of the Single Step Joint are defined by some European standards (Siem and Jorissen, 2015), but no one details how to design this connection to prevent shear cracks at the heel depth or the compressive crushing at the joint contact surfaces. Hence the design rules and the emergence of failure modes according to the geometrical parameters of the Simple Notched Joint must be defined. In order to check the design equations and the failure modes, lab tests about the three geometrical configurations of the Single Step Joint have been carried out, varying the heel depth, the shear length and the inclination of the rafter

The influences of moisture content variation, number and width of gaps on the withdrawal resistance of self tapping screws inserted in cross laminated timber

A large experimental campaign comprised of 470 withdrawal tests was carried out, aiming to quantify the withdrawal resistance of self-tapping screws (STS) inserted in the side face of cross laminated timber (CLT) elements. In order to deeply understand the “CLT-STS” composite model, the experimental tests considered two main parameters: (i) simple and cyclic changes on moisture content (MC) and (ii) number and width of gaps. Regarding (i), three individual groups of test specimens were stabilized with 8%, 12% and 18% of moisture content and one group was submitted to a six month RH cycle (between 30% and 90% RH). Concerning (ii), different test configurations with 0 (REF), 1, 2 and 3 gaps, and widths equal to 0mm (GAP0) or 4mm (GAP4), were tested. The influences of MC and number of gaps were modeled by means of least square method. Moreover, a revision of a prediction model developed by Uibel and Blaß (2007) was proposed. The main findings of the experimental campaign were: the decrease of withdrawal resistance for specimens tested with MC=18% in most configurations; the unexpected increase of withdrawal resistance as the number of gaps with 0mm increased; and, the surprising increase of withdrawal resistance for REF specimens submitted to the RH cycle.The development of the present work was possible only thanks to the financial support of the 391 Portuguese Science Foundation (Fundação de Ciência e Tecnologia, FCT), through PhD grant SFRH / BD17392 / 79972 / 2011. Further, the valuable partnerships with the Institute of Timber Engineering and Wood393 Technology, at Graz University of Technology (Austria), and Rusticasa are gratefully acknowledged

Fire behaviour of gypsum plasterboard wall assemblies: CFD simulation of a full-scale residential building

New trends in building energy efficiency include thermal storage in building elements that can be achieved via the incorporation of Phase Change Materials (PCM). Gypsum plasterboards enhanced with micro-encapsulated paraffin-based PCM have recently become commercially available. This work aims to shed light on the fire safety aspects of using such innovative building materials, by means of an extensive experimental and numerical simulation study. The main thermo-physical properties and the fire behaviour of PCM-enhanced plasterboards are investigated, using a variety of methods (i.e. thermo-gravimetric analysis, differential scanning calorimetry, cone calorimeter, scanning electron microscopy). It is demonstrated that in the high temperature environment developing during a fire, the PCM paraffins evaporate and escape through the failed encapsulation shells and the gypsum plasterboard's porous structure, emerging in the fire region, where they ignite increasing the effective fire load. The experimental data are used to develop a numerical model that accurately describes the fire behaviour of PCM-enhanced gypsum plasterboards. The model is implemented in a Computational Fluid Dynamics (CFD) code and is validated against cone calorimeter test results. CFD simulations are used to demonstrate that the use of paraffin-based PCM-enhanced construction materials may, in case the micro-encapsulation shells fail, adversely affect the fire safety characteristics of a building. © 2015 Elsevier Ltd. All rights reserved

Review Paper on Road Vehicle Vibration Simulation for Packaging Testing Purposes

Inefficient packaging constitutes a global problem that costs hundreds of billions of dollars, not to mention the additional environmental impacts. An insufficient level of packaging increases the occurrence of product damage, while an excessive level increases the packages' weight and volume, thereby increasing distribution cost. This problem is well known, and for many years, engineers have tried to optimize packaging to protect products from transport hazards for minimum cost. Road vehicle shocks and vibrations, which is one of the primary causes of damage, need to be accurately simulated to achieve optimized product protection. Over the past 50 years, road vehicle vibration physical simulation has progressed significantly from simple mechanical machines to sophisticated computer-driven shaking tables. There now exists a broad variety of different methods used for transport simulation. Each of them addresses different particularities of the road vehicle vibration. Because of the nature of the road and vehicles, different sources and processes are present in the vibration affecting freight. Those processes can be simplified as the vibration generated by the general road surface unevenness, road surface aberrations (cracks, bumps, potholes, etc.) and the vehicle drivetrain system (wheels, drivetrain, engine, etc.). A review of the transport vibration simulation methods is required to identify and critically evaluate the recent developments. This review begins with an overview of the standardized methods followed by the more advanced developments that focus on the different random processes of vehicle vibration by simulating non-Gaussian, non-stationary, transient and harmonic signals. As no ideal method exists yet, the review presented in this paper is a guide for further research and development on the topic

Incidence of cancer in children residing in ten jurisdictions of the Mexican Republic: importance of the Cancer registry (a population-based study)

BACKGROUND: In 1996, Mexico started to register cases of childhood cancer. Here, we describe the incidence of cancer in children, residing in ten Mexican jurisdictions, who were treated by the Instituto Mexicano del Seguro Social (IMSS). METHODS: New cases of childhood cancer, which were registered prospectively in nine principal Medical Centers of IMSS during the periods 1998–2000 (five jurisdictions) and 1996–2002 (five jurisdictions), were analyzed. Personnel were specifically trained to register, capture, and encode information. For each of these jurisdictions, the frequency, average annual age-standardized incidence (AAS) and average annual incidence per period by sex and, age, were calculated (rates per 1,000,000 children/years). RESULTS: In total 2,615 new cases of cancer were registered, with the male/female ratio generally >1, but in some tumors there were more cases in females (retinoblastoma, germ cells tumors). The principal groups of neoplasms in seven jurisdictions were leukemias, central nervous system tumors (CNS tumors), and lymphomas, and the combined frequency for these three groups was 62.6 to 77.2%. Most frequently found (five jurisdictions) was the North American-European pattern (leukemias-CNS tumors-lymphomas). Eight jurisdictions had AAS within the range reported in the world literature. The highest incidence was found for children underless than five year of age. In eight jurisdictions, leukemia had high incidence (>50). The AAS of lymphomas was between 1.9 to 28.6. Chiapas and Guerrero had the highest AAS of CNS tumors (31.9 and 30.3, respectively). The frequency and incidence of neuroblastoma was low. Chiapas had the highest incidence of retinoblastoma (21.8). Germ-cell tumors had high incidence. CONCLUSION: The North American-European pattern of cancers was the principal one found; the overall incidence was within the range reported worldwide. In general but particularly in two jurisdictions (Yucatán and Chiapas), it will be necessary to carry out studies concerning the causes of cancer in children. Due to the little that is known about the incidence of cancer in Mexican children, it will be necessary to develop a national program to establish a cancer registry for the whole of the country

Les écoles savantes en Turquie : sciences, philosophie et arts au fil des siècles : actes des journées d'Ankara 24-29 Avril 1995, Lycée Charles de Gaulle / textes réunis et publiés par Sakina Önen & Christine Proust

Includes bibliographical referencesKonferenzschrif