Abstract

Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, residential buildings, as well as, in the parking structures. This paper succeeded to present new special details for deep HCS to enhance and strengthen the web shear strength capacity of HCS 400 and 500 mm depths respectively at the open parking area. This is subjected to heavy truck wheel loads so as to achieve the LRFD Code’s requirements. However, it is noticed many web shear cracks of HCS are used at parking area at many projects in Gulf Region. On the other hand, ACI318-14 permits no shear reinforcement in prestressed HCS thickness of less than 12.5 in (320 mm). The paper presents experimental tests program, to verify the numerical finite element of deep HCS under maximum design uniform loads, in addition to the new strengthening techniques. New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for HCS 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section. Also, HCS 500 shear capacity is enhanced with different percentages of strengthening techniques by 55%, up to 197% based on the different cases of strengthening. Furthermore enhancing deep HCS shear performance; the new techniques have an advantage of an easy execution at the site; casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques.

Highlights

  • Since the early eighties of twenty century, the slab cross-sections with non-circular voids have become commonly used gradually; as an easy and quick construction technique

  • New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for Hollow Core Slabs (HCS) 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section

  • Enhancing deep HCS shear performance; the new techniques have an advantage of an easy execution at the site; casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques

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Summary

Introduction

Since the early eighties of twenty century, the slab cross-sections with non-circular voids have become commonly used gradually; as an easy and quick construction technique. There are many of deep HCS suffering shear cracks in most of the areas being exposed to heavy truck loads; especially for HCS’s with 400 and 500 mm thickness One example for this project is the parking area in Girls Campus in King Saud University (GCKSU), located in Riyadh, KSA. This type of shear failure usually occurs when a maximum principal stress results from combined effects of shear and bending exceeding the tensile strength of concrete [3] The geometric cross section of this type of European Factory of ELEMATIC precast factory technology supplier, exemplified at Table 1 with all natural properties and reinforced details, as per supplier’s stander

Shear Stress Design of Deep HCS
Experimental Program Setup
Verification of Finite Element Modeling
New Techniques of Web Shear Strengthening
Findings
Conclusions
Full Text
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