Designing concrete slabs with openings
A study to the design process and structural behavior of concrete slabs with openings due to non-structural elements
N. Dubbeldam (TU Delft - Civil Engineering & Geosciences)
M.G.C. Bosch-Rekveldt – Mentor (TU Delft - Integral Design & Management)
Y. Yang – Mentor (TU Delft - Concrete Structures)
E.J. Houwing – Mentor (TU Delft - Integral Design & Management)
Sander Vernooij – Coach
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Abstract
This research aims to improve the structural safety of wide floor slabs with openings due to embedded non-structural elements. The multidisciplinary design of these slabs has resulted in various safety issues, including errors in the design due to the absence of a calculation method and insufficient integration between designs of different disciplines. The study assesses the influence of non-structural elements on the bearing capacity of the slab, maps possible errors in the integration process, and proposes an integrated design strategy to resolve safety errors.
The structural analysis focuses on four parameters of the openings (shape, size, longitudinal placement, height placement) and their effects on three failure modes (bending moment failure, shear failure, and interface failure). A workflow of calculation methods is formed to calculate the bearing capacity of a slab with an opening and the influence of the openings are calculated with a case study.
The management analysis assesses the integration process by examining the project process used in the building industry and comparing it to a theoretical process. It was found that the integration of the designs is heavily affected by a phase shift between the structural and mechanical disciplines. This phase shift is caused by multiple disrupting events.
Using the influence of the openings and the disrupting events, an integrated design strategy is proposed, which includes design rules and an adjusted design process. The feasibility and effectiveness of this strategy were assessed by an expert panel, who found it to be feasible if applied to all structural elements, but concluded that it could only mitigate the problems caused by the design shift. Other measures, such as changing the DNR and adapting another project delivery model, may be necessary to fully solve the safety issues.