Design of a Specimen Fixture for Mechanical Property Testing of Timber Column–Beam Joints

Abstract

This research article is part of a thesis entitled Mechanical Testing of 90-Degree Timber Joints in Structural Applications. The objective of this study is to propose a design approach for a specimen holding fixture used in the mechanical testing of timber beam–column joints. The study began with an analysis of the existing fixture system and the operating mechanism of the universal testing machine, followed by a comparison of two fixture arrangement configurations. The investigation focused on the load transfer mechanism and moment distribution acting on the test specimen.

The results indicate that the configuration in which the fixture is attached to the testing machine column is more suitable because it does not obstruct the movement of the loading head and allows easier installation. The upper beam fixture was designed to behave similarly to a hinge joint in order to reduce moment resistance, while the base support was designed based on a modified roller support to restrict horizontal movement. This configuration improves the stability of the testing system and minimizes the influence of the fixture on the experimental results.

The proposed design was fabricated and applied in a beam–column joint testing setup. Dial gauges were installed to measure fixture displacement during testing. The results showed zero displacement in both upper and lower fixtures, indicating that the fixture did not influence the deformation behavior of the specimen and can be effectively applied in timber joint testing.