2The research and development of connecting and strengthening timber structural elements with

In the framework of the Cost Action CERTBOND (Reliable roadmap for certification of bonded primary structures), a wide group of researchers from 27 European Countries have had the opportunity to work on the topic of certification of bonded joints for primary structural applications from different engineering sectors such as the aerospace, automotive, civil engineering, wind energy and marine sectors. Since virtual testing and optimization are basic tools in the certification process, one of the key objectives of CERTBOND is to critically review some of the available models and failure theories for adhesive joints. The present paper summarizes the outcome of this task. Nine different models/theories are described in detail. Specifically, reviewed are the Classical Analytical Methods, the Process Zone Methods, Linear Elastic Fracture Mechanics (LEFM), the Virtual Crack Closure Technique (VCCT), the Stress Singularity Approach, Finite Fracture Mechanics (FFM), the Cohesive Zone Method (CZM), the Progressive Damage Modeling method and the Probabilistic methods. Also, at the end of the paper, the modeling of temperature effects on adhesive joints have been addressed. For each model/theory, information on the methodology, the required input, the main results, the advantages and disadvantages and the applications are given.

No abstract

No abstract

Use of timber as a construction material has entered a period of renaissance since the development of high-performance engineered wood products, enabling larger and taller buildings to be built. In addition, due to substantial contribution of the building sector to global energy use, greenhouse gas emissions and waste production, sustainable solutions are needed, for which timber has shown a great potential as a sustainable, resilient and renewable building alternative, not only for single family homes but also for mid-rise and high-rise buildings. Both recent technological developments in timber engineering and exponentially increased use of engineered wood products and wood composites reflect in deficiency of current timber codes and standards. This paper presents an overview of some of the current challenges and emerging trends in the field of seismic design of timber buildings. Currently existing building codes and the development of new generation of European building codes are presented. Ongoing studies on a variety topics within seismic timber engineering are presented, including tall timber and hybrid buildings, composites with timber and seismic retrofitting with timber. Crucial challenges, key research needs and opportunities are addressed and critically discussed.

Ongoing development of timber and timber products made from European hardwoods like ash and beech influences the selection of acceptable methods for connecting these elements and thus demands validation and application of current design methods for softwood and glulam. For the last 20 years, despite many national and international research projects and practical applications of glued-in rods in timber structures, there is still no universal standard with respect to their design. The use of adhesives available for bonding rods and timber is limited to softwood. This work shows the performance of different timber species Norway spruce (Picea abies Karst.), European ash (Fraxinus excelsior L.) and European beech (Fagus silvatica L.) and engineered timber products (laminated veneer lumber made of Norway spruce and European beech) based on comprehensive pull-compression tests of glued-in rods. For characterizing the elastic and elasticplastic behavior, failure loads as well as stiffness and ductility were considered whereby the rod diameter and anchorage length were maintained constant. The aim of the research was to show that glued-in rods cannot only be used in softwoods and glulam members but also in hardwoods and in wood-based products such as LVL.

Cross-laminated timber (CLT)-a state of the art report Cross laminated timber is an innovative plate-shaped product presenting a laminated structure and excellent physicomechanical properties. Due to its high stiffness and in-plane and out-of-plane bearing capacity, it is most often used in form of wall or floor panels. Favourable environmental, aesthetic and energy properties further enhance its qualities. The paper is a summary of CLT research conducted so far, with an emphasis on the need to harmonise existing regulations and include this product in the European standard for timber structures Eurocode 5.

No abstract