Thermo-mechanical assessment of heated bridge deck under internal cyclic thermal loading from various heating elements: pipe, cable, rebar

Heated bridge is an eco-friendly technology where embedded internal heating elements are utilized for deicing/snow melting of the bridge deck surface. A crucial factor preventing wide scale implementation of this technology is the lack of fundamental understanding of the thermo-mechanical behavior of the reinforced slab under cyclic internal thermal loads. This study presents a novel thermo-mechanical assessment of a heated bridge deck subjected to cyclic internal thermal loads implemented through three different heating elements: pipe, cable, rebar. A new finite difference based numerical model was developed and calibrated against small scale laboratory experiments; considering realistic thermal and mechanical boundary conditions, and incorporating thermal-induced degradation of the mechanical properties of concrete. Results revealed a considerably distinct thermo-mechanical response of the concrete slab under each heating system. The cable system resulted in the most substantial thermal-induced internal damage in the concrete slab. Findings indicate that the thermal conductivity and the linear thermal expansion coefficients of the heating elements are key factors governing the thermal efficiency and the extent of the internal damage in a heated concrete slab. A sensitivity analysis suggested that the thermo-mechanical performance of a heated slab can be notably enhanced through initiating heating at higher ambient temperatures, and reducing the depth of placement of the heating elements.