Nonlinear analysis of flat slab‐column connections to optimize the use of HPFRC under monotonic vertical loading

Abstract

Numerous studies have shown that incorporating fibers in concrete can improve its mechanical properties, including tensile strength and toughness. Due to these outstanding properties, the use of fiber‐reinforced concrete (FRC) composites has been investigated for applications in structural members subjected to shear, in which brittle failure mode may occur. An example of this type of application is the use of high/ultrahigh‐performance fiber‐reinforced concrete (HPFRC/UHPFRC) in flat slab‐column connections as an alternative to shear reinforcement. The experimental results revealed that the use of advanced concrete materials led to an increase in the punching shear and deformation capacities. Despite these advantages, the use of HPFRC/UHPFRC in practical design is somehow limited by the lack of guidelines in codes for this type of new material. Furthermore, the study of constitutive models for nonlinear finite element analysis is also necessary. In this regard, this article addresses the simulation of two‐way slabs with HPFRC, subjected to concentrated monotonic vertical loading, tested in a previous experimental study, where the HPFRC was used only in a limited slab region around the column, and the rest of the slab was cast with normal strength concrete. The numerical models were developed in the commercial finite element software DIANA. The concrete nonlinear behavior was modeled by a total strain‐based constitutive model, in which the HPFRC softening is represented by a tensile stress‐crack width (σ − w) relationship. The validity of the numerical model is checked by the comparison with the experimental results and a punching shear mechanical model, leading to the formulation of a closed‐form equation. Finally, a parametric study was conducted to extrapolate the results obtained in the experimental campaign and to optimize the use of HPFRC to obtain a more economical and sustainable solution.

Experimental investigation of innovative reinforcement method for two‐way concrete slabs using perforated steel plates

“…The slab secant stiffness is determined from the loaddisplacement diagram at the slab center. The stiffness of the sample is calculated using two steps of loading including the start of loading up to the first crack (K cr ) and the first yield (K y ), which are calculated by Equations (11) and (12), respectively.…”

“…Various reinforcement methods are used for concrete slabs. [1][2][3][4][5][6][7][8][9][10][11][12] Reinforced concrete members can become more efficient and cost-effective by improving steel performance. In some studies, profiled steel sheets have been used as an alternative to tensile reinforcements.…”

“…Concrete slabs are used as flexural members in structures such as floors, slabs on grades, bridges, and foundations. Various reinforcement methods are used for concrete slabs 1–12 . Reinforced concrete members can become more efficient and cost‐effective by improving steel performance.…”