Experimental and numerical investigation on flexural performance of non-prestressed concrete precast bottom slab with a removable section steel and three ribs

Abstract

Current methods for enhancing the bending stiffness of non-prestressed concrete precast bottom slabs are constrained by the limited height of reinforcing elements, restricting their use to spans of up to 3.6 m. This study introduces the NPS-3R, an innovative precast bottom slab design that incorporates precast concrete segmental ribs and removable section steel. The design tackles common challenges such as insufficient bending stiffness and the reliance on temporary supports in large-span non-prestressed concrete precast bottom slabs (NLBS). To evaluate the bending behavior of the NPS-3R design, three full-scale precast bottom slab specimens were fabricated and subjected to static loading tests. These tests were complemented by detailed finite element (FE) simulations to analyze the stress distribution, deformation characteristics, and the interaction between the section steel and segmental ribs, providing a comprehensive understanding of the slab's flexural performance under varying loading conditions. Experimental results reveal a notable enhancement in flexural performance, with the cracking load and ultimate bearing capacity increasing by 78.9 % and 72.6 %, respectively, compared to NLBS. Although the addition of steel trusses has a limited effect on the overall bending behavior of NPS-3R, contributing only an 8.1 % increase in cracking load and a 3.9 % increase in ultimate load capacity, it significantly influences late-stage bending stiffness. The numerical model developed in this study shows high reliability, with stiffness errors in the load-mid-span deflection curves remaining below 10 % compared to experimental values. Simulation results further reveal that the length of short ribs, the section steel, and the diameter of stressed reinforcement are key factors affecting NPS-3R's bending performance. Additionally, the improved bending stiffness calculation method, based on integral and superposition techniques, demonstrates high accuracy and provides a reference for engineering design. These findings offer valuable insights for the design and optimization of precast concrete structures, providing a promising solution for improving the performance of large-span bottom slabs in both practical applications and theoretical research.