Designing new pre-tensioned hollow core slabs for heavy duty loads
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Insinööritieteiden korkeakoulu |
Master's thesis
Ask about the availability of the thesis by sending email to the Aalto University Learning Centre oppimiskeskus@aalto.fi
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Mcode
ENG30309
Language
en
Pages
276
Series
Abstract
Hollow core slabs are the most popular product of the precast industry and has been used worldwide as a load bearing structure such as roofs, floors and occasionally as walls in various construction projects. There are no shear reinforcement inside the hollow core slab which makes it vulnerable to shear failure. The goal of the research is to focus on the shear capacity of the element and to study and analyze the number of ways to increase the capacity under the influence of heavy duty loads (30 - 50 kN/m^2). For this purpose, the analytical approach has been used, thus, determining and evaluating the behavior of hollow core slabs in shear using expressions and formulas in accordance with the standards and research papers. EC 1992-1-1, Finnish National Annex, the Product Standard of hollow core slabs EN 1168 and the research papers mentioned in the bibliography have been used as a reference for this study. The results show that the hollow core slab fail in shear such that the critical point of shear failure does not lie at the neutral axis, but in the lower region of web where tensile principal stresses are maximum and exceeds the tensile strength of concrete. The research also included the study of effectiveness of adding shear reinforcement inside the hollow core slab to increase the shear capacity. It has been concluded that the shear reinforcement are only effective in the region cracked in bending but not in uncracked region. If a shear crack is assumed to appear in the uncracked region near the support, the shear reinforcement becomes less effective as the anchorage failure tends to be the prevailing mode of failure. So, unless the issue of anchorage failure of pre-tensioned tendons is resolved, the use of shear reinforcement inside the hollow core slab is not effective. A 500 mm deep and 10 meters long, hollow core slab has been designed by modifying the cross-section to resist 35 kN/m^2 of surface loading. The calculation models and results have been discussed in detail in the thesis.Description
Supervisor
Puttonen, JariThesis advisor
Nokelainen, TeroRajala, Lasse