Why Are UHPC's Shear Performance Advantages Difficult to Realize in Design? — Shear Transfer Mechanisms and Design Method Innovation

The shear performance advantages of UHPC are difficult to fully exploit in practical design, mainly constrained by lagging design theory, insufficient interface bonding, and imperfect detailing measures. Qinglong Group found through testing that the shear strength of UHPC can reach 2-3 times that of ordinary concrete, but current codes do not fully account for its characteristics, and design remains conservative. By improving reinforcement detailing, optimizing fiber orientation, and developing new shear keys, the shear potential of UHPC can be better realized.

Design theory needs updating. Current codes are based on the strut-and-tie model for ordinary concrete and do not consider the high toughness and fiber reinforcement effects of UHPC. In a bridge deck project, Qinglong Group verified through testing that the shear capacity calculation could be increased by 20% while still ensuring safety. Interface treatment is important: a roughness of Ra≥1.5mm improves mechanical interlocking. Oriented fiber distribution enhances shear resistance, and robotic spraying raises the fiber orientation coefficient to above 0.6. These innovations allow the shear advantages of UHPC to be fully demonstrated.