Department of Architecture and Civil Engineering

Creep of structural timber adhesives

At a glance

Funding body: Malaysian Government
Principal investigator: Martin Ansell
Co-investigator: Richard Harris
Researcher: Adlin SM Roseley
Industry partner: Rotafix Ltd
Dates: 2008-2011

Abstract

The serviceability of adhesively bonded connections within timber structures has been widely researched, particularly their ability to withstand static loads. However, whilst adhesively bonded joints have been used in timber structures little attention has been paid to long-term deformation under static creep loads in adverse environments.

No information is available in the literature or in standards, including Eurocode 5, for the design of adhesively bonded connections under creep loads at elevated temperatures and relative humidities. Major concerns are the lack of understanding of creep behaviour of adhesive bonded joints close to the adhesive’s glass transition temperature and the durability of the wood to adhesive interface and the adhesive itself. In order to explore the basic characteristics of adhesive joints it is necessary to develop research methods in order to obtain relevant and meaningful mechanical test data.

Appropriate mechanical test specimens, geometries and testing procedures will be evaluated and test environments will be considered. The creep resistance of the adhesive alone, adhesively bonded timber to timber connections and bonded-in pultruded reinforced plastic rods will be evaluated. Numerical models will be developed to model the creep deformation. Prediction of service life in a full-scale bonded structure may be included, for example a bonded-in repair in a heritage structure in the South West of England.

The main purpose of this study is to conduct an investigation of wood adhesives (epoxies) and their ability to form coherent joints in structural timber connections under static creep loads in adverse environments. This study will include examination of microstructure and nanostructure and thermal analysis of the adhesives and evaluation of mechanical properties of timber connection in relation to their creep performance.

The research will quantify creep and develop creep-resistant adhesive formulations for wood in conjunction with the company Rotafix Ltd who have an extensive track record in bonded timber connections. Research will be aimed at applications in Malaysia and the UK.