Experimental and theoretical investigation of long-term performance of steel-timber composite beams

•Bolt in grout pocket connectors had the highest short- and long-term stiffness.•Estimated creep deformation factor was 0.29–0.39 for steel-timber composite beam.•Segmentation of CLT slabs had major impact on the short- and long-term stiffness.•In beams with segmented CLT slabs, composite action significantly reduced over time.