Active strengthening of reinforced concrete arch ribs using high-strength steel wire mesh: Experimental investigation and theoretical prediction

Many aging reinforced concrete (RC) arch bridges require effective retrofitting because of material deterioration and the continuous growth of traffic demand. Conventional passive strengthening techniques often exhibit stress lag and relatively low material utilization efficiency. To overcome these limitations, this study proposes an active confinement system based on high-strength steel wire mesh (HSSWM), combined with a specially-designed circumferential tension anchorage device that enables the confinement to be applied before external loading. The experimental program comprised axial compression tests on eleven square RC columns and static loading tests on two scaled RC arch ribs. The results show that the proposed HSSWM system effectively changes the failure mode of axial column specimens from brittle splitting to a more stable ductile crushing mode, while delaying premature brittle shear failure in RC arch ribs. In the column tests, raising the initial prestress level from 0% to 30% increased the peak load by up to 84%. For the arch-rib tests, the HSSWM-strengthened specimen GL02 exhibited a 60% higher yield load than the unconfined control specimen GL01 and sustained a maximum applied load of 220 kN without structural failure, whereas GL01 failed at 150 kN, demonstrating substantially enhanced load-carrying performance within the investigated loading range. In addition, active confinement alters the internal stress distribution of the arch ribs, allowing the intrados to remain in compression and expanding the plastic zone considerably. A theoretical framework was developed to predict the calculated yield load corresponding to the formation of the first plastic hinge in HSSWM-strengthened RC arch ribs by combining a prestress-dependent Mander constitutive formulation with the equivalent beam-column method. The predicted yield load agrees well with the experimental observations, indicating that the proposed approach provides a conservative basis for evaluating the design bearing capacity of retrofitted RC arch bridges.