Influence of grain distribution on orientation of saw cuts: Reference to heritage structures

Abstract

Longitudinal arrangement of wood fibers are known as timber grains. It is one of the most important physical aspects of timber in applications. The properties differ along the grain and against the grain. Straight grains run parallel to the longitudinal axis of the wood. Meanwhile the cross grain deviates from the longitudinal axis as spiral and diagonal grains. This orientation has a high influence on the timber and affects physical properties during application. In order to study this, a detailed analysis was performed on Ambalam structures, a cherished heritage structure originated from the vernacular architecture in Sri Lanka. These structures are existing living proofs of vibrant construction materials with an exposed environment for more than 50 years. Badulla Ambalama,Padivitiya Ambalama, Panavitiya Ambalama, Karagahagedra Ambalama, Giruwa Ambalama and Rukula Ambalama were selected as case studies. The growth ring distribution of the exposed surfaces of the structural components were mapped using AutoCAD software. The results of overlapping and mapping the growth ring distribution of the specific timber helps to generate clues on size of the tree and sawing pattern of the wood log. The generated growth ring map revealed the sensitivity and the adequate knowledge in material manipulation utilized for specific structural components with respect to the load distribution. The Ambalam heritage structures have enlighten timber as an acceptable construction material with a respectable service life for tropical countries.