Investigation on the aging performance of novel high friction polyurethane bearings

• A novel high friction polyurethane(HFPU) material was synthesized and four kinds of HFPU specimens were fabricated for accelerated aging and mechanical tests. • Aging performance of HFPU material and HFPU bearings under accelerated aging tests were evaluated at micro-scale and macro-scale level. • A newly developed constitutive model can accurately simulate the shear hysteresis behavior and friction coefficient of HFPU bearings before and after thermal aging. Abstrac t High friction polyurethane (HFPU) with selective damping and excellent deformation capacity is a novel alternate for manufacturing high-performance bridge bearings. HFPU bearings (HFPUBs) can facilitate installation and maintain stable horizontal deformation under 250% shear strain thorough self friction resistance. The superior friction performance also enabled HFPUBs to perform plump shear hysteretic curves and dissipate seismic energy. While durability issues of rubber material is a critical factor compromising bridge rubber bearings’ long-term performance, the aging mechanism of polyurethane bearings remains unclear. To address this gap, this study have performed accelerated thermal aging and UV-irradiation aging tests on HFPU specimens to examine their compression, tensile, shear and tear properties. Then Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and dynamic mechanical analysis (DMA) were utilized to investigate the micro-structural and compositional changes of HFPU post aging tests. HFPUBs’ mechanical performance under different loading conditions were also evaluated before and after accelerated thermal aging. Test results demonstrated no new functional groups were formed in HFPU after accelerated thermal aging, but hydrogen bonds formation have occurred and increased the vertical and shear stiffness of HFPU by 15.4%-28.9%. HFPUBs can provide a stable resistance to deformation across varying loading conditions, and maintain a favourable energy dissipation capacity after thermal aging test. The newly developed constitutive model can accurately simulate the shear behavior and friction coefficient of HFPUBs under different test conditions, furnishing the application for future bridge seismic analysis.