Evaluation of Characteristic Strength and Stiffness Properties of Regionally Sourced Pinus Patula Sawn Timber for Structural Application in East Africa

Abstract

This study investigates the strength and stiffness properties of Pinus patula rectangular sawn timber sourced from sawmills in Rwanda and Western Tanzania, in alignment with Eurocode guidance. The study was designed to provide reliable baseline data for structural engineers considering the use of locally sourced timber for design in the region. Recognising the limited technical information on regional timber, extensive testing was conducted on up to 40 samples from each batch of timber procured for the multi-phased Rwanda Institute of Conservation Agriculture (RICA) project. Timber was sourced from Sao Hill (Tanzania), New Forests Company (Rwanda), and Sawmill East Africa Limited (Rwanda). A custom visual grading process was employed to classify the timber before mechanical testing, and 4-point bending tests were conducted following guidance from BS EN 408 to evaluate modulus of elasticity and flexural strength.  Characteristic (5th percentile) values were determined through statistical analysis based on BS EN 14358 guidelines, with characteristic flexural strength values typically ranging between 9-12MPa and MoE averaging between 3000-4000MPa -both significantly lower than European equivalents.  This paper discusses the testing methodologies, results, and offers recommendations to enhance the East African timber supply chain. The findings demonstrate that the material is generally suitable for medium span roofs and lightly loaded structural elements, while floor systems may require shorter spans, paired sections, or closer spacing due to lower stiffness values.