International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 11 Issue: 07 | July 2024
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p-ISSN: 2395-0072
Proposed Geometry of Standard Precast Double Tee Floor Slab Members for Indian Markets Vemuri Sitaram1, Srimaruthi Jonnalagadda 2 1 Structural Engineer, Assystem Stup
2 Structural Research Engineer, Tindall Corporation -----------------------------------------------------------------------------***------------------------------------------------------------------------Abstract: The use of precast Double Tee (DT) members for floor slabs is gaining popularity in Indian markets. However, no
efforts have been made to standardize the process of precast engineering and manufacturing as happened in advanced countries. As such not much is known about the process of engineering of these members. In a prior research that is very related, a comprehensive market survey was conducted to understand the design and construction practices of precast double tee members in India. In that study, the authors collected the practices and preferences of precast engineers, builders, and manufacturers with regards to standard design parameters of these DT members such as span, factory-topped or field-topped members, thickness of slab, and prestressing properties. When the results of the survey were analyzed, it was found that there is no standard DT member developed or designed for Indian markets yet. Precast engineers design the member geometry and reinforcement for these DT members using detailed engineering methods. No standard geometry or designs are available for precasters and designers to quickly pick a member as a baseline for design in a process like the practice in USA where Precast/Prestressed Concrete Institute (PCI) provides standard DT member geometry and design for engineers to use. This paper identified this major gap in Indian markets and hence developed a standard DT member design. A standard DT member geometry is proposed for typical application as floor slabs in residential and office buildings for Indian standard code specifications. This standardization is made keeping in mind the constraints set by precast manufacturing processes, crane capacities, truck hauling capacities and highway load limits in the context of Indian socio-economic-cultural and construction practices. The cross section of the proposed standard member along with material properties and specifications of the ingredient materials is presented. Finally, the need for developing a full set of standard member designs and guiding design tables for varying spans and loads is put forward. Keywords: Precast, Double Tee, DT, Slab, Geometry, Engineering
1. Introduction and Background To quickly introduce the readers to what inspired this research and provide a background on the work done so far, the authors walked the readers through the history of precast DT engineering and the market survey conducted to understand the precast DT trends in Indian markets. In the US, the Precast/Prestressed Concrete Institute (PCI) had been very instrumental in developing standard precast DT member designs. PCI developed their handbook [1] expanding on the research contributions of many authors in the development of precast member design and construction. The process of standardization of DT members in the US helped the precast industry flourish very rapidly. Figure 1 shows a standard 12ft wide (4m) precast DT from PCI tailored to the specifications of PCI and American Concrete Institute (ACI) [2] codes. The engineers and precast manufacturers were able to quickly design and construct these members adopting the standard DT member designs as baseline along with the supplementary design tables provided by PCI. This process made the entire process of design and construction of these DT members very smooth and streamlined. Precasters were able to automate the fabrication of these members in the plant environment with high levels of efficiency [3].
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