Hamid Reza Valipour

Conventional steel‐concrete composite floors comprising of steel sections and sheeting, cast in situ concrete and embedded stud shear connectors are made from energy‐ and carbon‐intensive construction materials, viz. concrete and steel. Replacing conventional reinforced concrete floors with solid timber, in particular cross‐laminated timber (CLT) with improved stability and structural characteristics, can significantly increase the speed of construction, reduce the need for rigging and craneage and also lower the self‐weight of the building, the size of the columns and foundations and therefore the overall carbon footprint of the building. However, experimental data on the short‐ and long‐term structural performance of steel‐timber composite (STC) floors under service loading conditions are scarce and no long‐term theoretical analyses of steel‐timber composite floors have been reported hitherto in the literature. Accordingly, non‐linear 1‐D frame finite element models are developed in this paper, and validated against experimental data on timber and hybrid timber composite beams. The numerical tool is then employed to predict the long‐term stiffness and load‐deflection response of STC floors under service loading conditions. A parametric study is carried out and the influence of the stiffness of the shear connectors, timber shrinkage, creep, hydro‐expansion and mechano‐sorptive effect on the long‐term behaviour of the STC beams are investigated.

The enhanced loading capacity of transversely confined concrete deck slabs has been demonstrated through different studies, but the available transverse confining systems used in conjunction with cast in situ concrete deck slabs are not conducive to deconstruction. This paper presents the results of an experimental study on precast slabs attached to girders using bolted shear connectors. Ten half-scale precast slabs are tested under a monotonically increasing force applied at the mid-span. The configuration and proportion of the reinforcing steel bars and types of transverse confining system (cross-bracings or ties) are the main test variables. The experimental results demonstrate the efficiency of the proposed system for mobilising arching action in the precast concrete deck slabs. Also, it is shown that the location of reinforcing bars in single-span concrete slabs with transverse confinement can significantly influence the load capacity and ductility, but the top reinforcing steel bars have negligible influence on the peak load and ductility. In addition, detailed finite-element models of the specimens are developed and verified against test results and it is shown that the adopted finite-element models can adequately capture the local and global response of the transversely confined deconstructable precast concrete deck slabs.