Numerical Analysis and Review of Detailing Practices of Slabless Staircase

Abstract

The analysis and detailing of the slabless staircase represent a critical factor in their limited commercial and residential usage compared to the waist slab staircase, despite their architectural attractiveness. Literature in the past and present has provided analysis and detailing of slabless staircase based on analytical and engineering judgment. Extensive knowledge of its behavior in terms of failure modes, crack patterns, and stress flow is necessary to evaluate the efficacy of these detailing practices. This paper presents the results of corresponding numerical investigations on four reinforced concrete detailing practices for single-flight slabless staircases. The study is conducted using the 3D Finite Element (FE) approach, where the constitutive law of concrete is based on the microplane model with relaxed kinematic constraints. The load was applied in a downward monotonic displacement control manner at the mid-span of each model, and the analysis results are evaluated in terms of load-displacement behavior, failure load, and failure mode. The numerical investigations provide a deeper insight into the detailed behavior of reinforced concrete slabless stairs through the visualization of crack patterns, stress flows, and strain development in concrete. The results show that slabless detailing options with stirrups formed as chains of links along the longitudinal direction serve as a conservative approach compared to other options that could serve the same purpose.