Mechanical testing and engineering application of steel-wood composite beams string structures

Increasing the span of large wooden structures raises the risk of brittle failure in the glulam beams' tensile zone, while the compressive zone materials remain underutilized, resulting in suboptimal structural efficiency and material wastage when constructing large-span wooden roof systems solely with wooden components. The steel-wood composite beam-string structure is a suitable solution for such needs. However, there is still a gap in research regarding the overall mechanical performance of steel-wood composite beam-string structures on a larger scale, with limited attention given to studying their mechanical properties and force mechanisms comprehensively. This paper introduces a steel-wood composite beam-string structure based on a practical engineering project of the Capital Museum East Branch. It includes a detailed analysis of forces and structural calculations, along with static loading tests on a glulam curved beam roof system using beam-string structures. Structural analysis shows that, under frequently occurred earthquake, the maximum inter-story drift of the overall structure is 1/370, with the stress ratio of most components below 0.8. Experimental results indicate that when the load increases to twice the design load, there is a tendency for separation at the connection, but significant damage is not observed. The cross-section generally satisfies the assumption of a plane section. The pre-stressed strands set at the bottom of the wooden beams strengthen the tension zone of the beams, causing the neutral axis of the beams to generally shift towards the tension zone. The experimental findings will inform the museum project and provide useful design insights for similar steel-wood composite beam-string structures.