Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/issn/15375110 Research Paper: SE—Structures and Environment Experimental study on mechanical performance of all-softwood pegged mortice and tenon connections Jonathan David Shanks a,1 , Wen-Shao Chang b,Ã , Kohei Komatsu c,2 a Buro Happold Ltd, Camden Mill, Lower Bristol Road, Bath BA2 3DQ, UK b Department of Architecture, No. 1, University Road, National Cheng Kung University, Tainan City 701, Taiwan c Research Institute for Sustainable Humanosphere, Kyoto University, Gokasyou, Uji, Kyoto 611-0011, Japan article info Article history: Received 23 September 2007 Received in revised form 10 March 2008 Accepted 27 March 2008 Available online 11 June 2008 A series of 168 pull-out tests were completed on samples of all-softwood pegged mortice and tenon connections fabricated using carpentry practices common to the UK, USA, Japan and Taiwan. Following testing, the connections were dissected to allow observations of the failure mode and the effects of the end distance in the tenon, edge distance in the mortice, peg diameter and cross-section. Relative stiffness of the peg and the surrounding connection material, determined by geometry, was shown to influence the mode of failure and elastic connection behaviour. For the pegged mortice and tenon connections to perform to their full capacity in the softwood base material, 2d and d end distances are required for connections with 12 and 18mm pegs, respectively, where d is the diameter of peg. A minimum of 2d edge distance is recommended to prevent wall failure in the mortice and for joints to perform to their full capacity for both 12 and 18 mm pegged connections. & 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. 1. Introduction Mortice and tenon connections fixed with timber pegs have been used to construct timber shelters worldwide for a long time. The exact form of the connection varies geographically but all connections feature a tenon, a mortice and a number of pegs driven through both the mortice and the tenon. The geometry of mortice and tenon joints commonly adopted in domestic-scale timber framing is similar in the UK, Japan, Taiwan and the USA. However, substantial differences exist in the timber species commonly adopted for the pegs, the mortice and the tenon. These variations can lead to noticeable differences in connection behaviour, both in stiffness and failure mode, which may be either brittle or ductile. The brittle failure of timber joints results in sudden failure with little energy absorption. However, if the failure of a timber joint is termed ductile, large deformation occurs to the timber joint without sudden failure and this leads to absorption of large amounts of energy. The common practice in the UK is to use a seasoned European oak (Quercus robur L.) peg within a green (commonly around 60% moisture content) European oak mortice and tenon. Whilst carpenters in UK use hardwood as the material for both pegs and the mortice and the tenon connection, the US timber framers commonly use a seasoned white oak (Quercus alba L.) peg within Douglas fir (Pseudotsuga menziesii Mirb. Franko.) framing members, which means there is a hardwood peg within a softwood base material. The Japanese practice is to use a seasoned square ARTICLE IN PRESS 1537-5110/$ - see front matter & 2008 IAgrE. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.biosystemseng.2008.03.012 Ã Corresponding author. Tel.: +886 62373605; fax: +886 62374680. E-mail addresses: Jon.Shanks@BuroHappold.com (J.D. Shanks), wenshao.chang@msa.hinet.net (W.-S. Chang), kkomatsu@rish.kyoto-u.ac.jp (K. Komatsu). 1 Tel.: +44 1225 320 606; fax: +44 870 787 4148. 2 Tel.: +81 77438 3670; fax: +81 77438 3678. BIOSYSTEMS ENGINEERING 100 (2008) 562– 570