Failure behaviour and design of I-shape metal brackets for truss-out bamboo scaffolding

For many decades, truss-out bamboo scaffolding has been widely used in Hong Kong for maintaining and retrofitting structures. Yet there are major concerns about the safety of truss-out bamboo scaffoldings due to the metal brackets that support them frequently failing. This paper presents an investigation into the failure behaviour of the most commonly used support for scaffoldings: The I-shape metal bracket. Uniform distributed load (UDL) tests were performed on 39 × I-shape metal brackets to analyse their mechanical behaviour and failure mechanism in different anchorage locations. The test data obtained was used to establish a finite element model for the bracket. Criteria governing the failure of brackets were then developed and calibrated against the test data. A new set of I-shape metal brackets with redesigned dimensions were then tested to verify the proposed failure criteria. Results show that the proposed failure criteria match well with the experimental results. A set of rules is therefore recommended for the limit state design of the I-shape metal bracket. The proposed failure criteria and design rules could be used to design I-shape metal brackets for the industry that offer greater safety and reliability.