Web Shear Strengthening Technique of Deep Precast Prestressed Hollow Core Slabs under Truck Loads

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.

Shear Tests of Deep Hollow Core Slabs Strengthened by Core-Filling

“…Prestressed hollow core slabs (PHCSs) can reduce self-weight due to the presence of voids in the section, and because they are prefabricated in a factory as precast members, ensure excellent quality and reduced construction duration [1][2][3][4]. In addition, PHCSs exhibit high flexural strength and excellent deflection control performance because prestressing strands are placed in the bottom flange of the member, and consequently they are widely applied to long-span structures [5][6][7][8].…”

“…Many previous researchers [3][4][5][6][7][8][9][10][11][12][13][14] have made various attempts to increase web-shear strength without using shear reinforcement, and examined the rationality of the additional strength reduction 2 of 17 factor for deep PHCS members specified in the design code. Lee et al [5] and Park et al [6] collected many web-shear test results on PHCS, based on which they pointed out that the additional strength reduction factor (0.5) specified in ACI 318-14 [16] can provide excessively conservative design results.…”

Assessment the Shear Behavior of Sustainable Thick Hollow Core Slab Using Experimental and Nonlinear Finite Element Modelling

“…El-Arab (2017) [4] provided a description of the technique to resist the shear cracking in deep HCS specimens under uniform load. Ten HCS specimens were cast with thickness 400mm and 500mm and fill the hollow core with concrete for 1.5m at end of each side.…”