This study aims to evaluate energy absorption capacity of hysteretic steel damper for earthquake protection of structures. These types of steel dampers are fabricated from mild steel plate with different geometrical shapes on the side part, namely, straight, concave, and convex shapes. The performance of the proposed device was verified experimentally by a series of tests under increasing in-plane cyclic load. The overall test results indicated that the proposed steel dampers have similar hysteretic curves, but the specimen with convex-shaped side not only showed stable hysteretic behavior but also showed excellent energy dissipation capabilities and ductility factor. Furthermore, the load-deformation relation of these steel dampers can be decomposed into three parts, namely, skeleton curve, Bauschinger part, and elastic unloading part. The skeleton curve is commonly used to obtain the main parameters, which describe the behavior of steel damper, namely, yield strength, elastic stiffness, and postyield stiffness ratio. Moreover, the effective stiffness, effective damping ratio, cumulative plastic strain energy, and cumulative ductility factor were also derived from the results. Finally, an approximation trilinear hysteretic model was developed based on skeleton curve obtained from experimental results.

Experimental investigations were performed to evaluate the effect of waste Polyethylene Terephthalate (PET) fibres on the mechanical properties of Green Ultra-High Performance Cementitious Composites (GUHPCCs). Ultra-fine Palm Oil Fuel Ash (UPOFA) and Silica Fume (SF) were utilised to produce GUHPCCs that consist of up to 50% UPOFA and 20% SF as a partial replacement binder with cement. PET fibres were added to the GUHPCCs at a proportion of 1% of the total mixed volume, to produce Green Ultra-High Performance PET reinforced Cementitious Composites (GUHPPCCs). The mechanical properties and flexural performance of the resulting beams and slabs, including their stress–strain behaviour and ductility, were investigated. Results showed that addition of PET fibres increases the flexural strength of GUHPPCCs beams by approximately 63.24% compared with that of the ultra-high performance concrete control at the age of 90 days. Moreover, significant improvements in the flexural capacity and ductility index of the GUHPPCCs slabs were obtained. These findings may due to the bridging effects of PET fibres. Thus, the combination of UPOFA and SF with PET fibres can produce GUHPPCCs with superior mechanical properties and enhanced ductility.