Development of a design oriented analytical method for the reinforced concrete (RC) transfer slabs loaded with closely offset planted columns
File(s)
Author(s)
Wang, Zeyu
Type
Thesis
Abstract
Transfer slabs are often used in multistorey buildings to support columns that are stopped off, or planted, prior to reaching foundation level due to changes in column grid between floors. This thesis is concerned with the shear failure of transfer slabs with closely spaced upper and lower columns. This study combines numerical analyses, analytical modelling, and empirical testing to augment the understanding of the behaviour of transfer slabs loaded with closely offset planted columns. The research delineated herein comprises three principal sections.
First, an experimental investigation was conducted to assess the influence of various key parameters on the punching resistance of transfer slabs loaded with closely offset planted columns. A total of eight internal column flat slab specimens without shear reinforcement were tested. The slabs were loaded around their perimeter as well as through plates simulating planted columns.
Second, the tested slabs were modelled with nonlinear finite element analysis (NLFEA) using 3D solid elements. The modelling procedure was calibrated using pertinent test specimens from the literature. The NLFEA is shown to realistically reproduce the behaviour of the tested specimens including the load-displacement response, slab rotations, reinforcement and concrete strains and crack patterns. The validated NLFEA model is used to model a series of representative planted column subassemblies extracted from a full-scale building with transfer slab.
Finally, the results of the laboratory testing and the NLFEA of the subassemblies extracted from the full-scale building are used to validate a design oriented analytical method for the assessment of reinforced concrete (RC) transfer slabs loaded with closely offset planted columns. The proposed method takes account of the interaction between field shear and the upper column load. Load is assumed to be transferred from the upper to lower column through direct strut action which is modelled using a simplified strut and tie model.
First, an experimental investigation was conducted to assess the influence of various key parameters on the punching resistance of transfer slabs loaded with closely offset planted columns. A total of eight internal column flat slab specimens without shear reinforcement were tested. The slabs were loaded around their perimeter as well as through plates simulating planted columns.
Second, the tested slabs were modelled with nonlinear finite element analysis (NLFEA) using 3D solid elements. The modelling procedure was calibrated using pertinent test specimens from the literature. The NLFEA is shown to realistically reproduce the behaviour of the tested specimens including the load-displacement response, slab rotations, reinforcement and concrete strains and crack patterns. The validated NLFEA model is used to model a series of representative planted column subassemblies extracted from a full-scale building with transfer slab.
Finally, the results of the laboratory testing and the NLFEA of the subassemblies extracted from the full-scale building are used to validate a design oriented analytical method for the assessment of reinforced concrete (RC) transfer slabs loaded with closely offset planted columns. The proposed method takes account of the interaction between field shear and the upper column load. Load is assumed to be transferred from the upper to lower column through direct strut action which is modelled using a simplified strut and tie model.
Version
Open Access
Date Issued
2024-01-04
Date Awarded
01/04/2024
License URL
Advisor
Vollum, Robert
Publisher Department
Civil and Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)