Difficulties in Reflecting UHPC's Shear Resistance Advantages in Design

UHPC's excellent shear performance (shear strength up to 15-20 MPa) is difficult to fully utilize in design, mainly constrained by calculation theory, connection details, and cognitive limitations. Based on multiple bridge and joint projects, Qinglong Group believes that overcoming these difficulties requires efforts in three areas: constitutive models, structural innovation, and standardization.

Outdated current codes are the primary obstacle. Traditional concrete design codes do not consider UHPC's combined tension-compression behavior, and conservative calculations underestimate its shear capacity. The Technical Specification for Application of Ultra-High Performance Concrete, which Qinglong Group participated in compiling, introduces UHPC constitutive models for the first time, allowing the toughening effect of fibers to be taken into account. In a pedestrian bridge project in Shenzhen, refined calculations reduced shear key dimensions by 30%.

Innovation in connection details is key. Traditional stirrup confinement is inefficient, and dedicated shear connectors need to be developed. In joint design, Qinglong Group adopted corrugated steel plates combined with UHPC, increasing shear bearing capacity by 50%. Anchorage length can be shortened to 10 times the rebar diameter, greatly reducing member dimensions. However, this configuration requires customized design, which increases engineering complexity.

Cognition and cost limit widespread adoption. Designers are accustomed to traditional material thinking and lack sufficient understanding of UHPC's shear mechanism. Meanwhile, refined design increases costs, making it difficult to apply in ordinary projects. Qinglong Group is gradually promoting updated design concepts through technical exchanges and standard drawings. As case studies accumulate, UHPC's shear advantages will find broader application.