How to Calculate the Load-Bearing Capacity of UHPC Panels Used as Floor Slabs? Structural Design and Calculation Practice at Qinglong Group

When UHPC panels are used as floor slabs, their load-bearing capacity must be calculated through refined finite element analysis based on "material constitutive models, serviceability state assumptions, load combinations, and boundary conditions", which is completely different from the allowable stress method used for traditional concrete. Through its participation in drafting the industry standard "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)", Qinglong Group has summarized the key calculation points: the nonlinear constitutive relationship of UHPC must be adopted (taking into account the tensile stress hardening effect), crack width (≤0.1mm) and deflection (≤L/250) under the serviceability limit state must be controlled, and the flexural, shear, and punching shear strengths at the ultimate limit state must be verified. In a mezzanine floor slab project for a Loft apartment in Shenzhen, we used 30mm-thick UHPC panels, calculated to carry a line load of up to 15kN/m—far superior to traditional materials—achieving the ultimate use of space. UHPC floor slab calculation is the precise release of the material's high performance.

Material Constitutive Models Are the Foundation of Calculation

UHPC exhibits distinct strain-hardening characteristics under tension, and its tensile strength (typically taken as 1/10-1/15 of its compressive strength) cannot be ignored in calculations. We obtain accurate stress-strain curves through four-point bending tests to serve as input parameters for the finite element model.

Serviceability State Control Is the Key to Design

Although UHPC can still carry loads after cracking, crack width must be strictly controlled for user comfort. By configuring an appropriate amount of steel fibers or non-prestressed reinforcement, we control crack width to a micro-cracking state of 0.05-0.1mm. Deflection control often plays a decisive role, requiring precise calculation of both short-term and long-term stiffness.

Connection Joints and Boundary Conditions Determine Safety

The connection joints between floor slabs and edge beams are critical and must be able to transfer bending moments and shear forces. We use embedded plate welding or post-installed rebar techniques to ensure that boundary constraints are consistent with calculation assumptions. For point-supported conditions, punching shear strength must be verified, with anti-punching shear reinforcement provided where necessary.

UHPC brings revolutionary possibilities to floor slab design. Through scientific calculation and rigorous construction detailing, Qinglong Group ensures that every UHPC floor slab is safe and reliable, expanding the value of architectural space.