Failure Analysis of Polypropylene Fiber Reinforced Concrete Two-Way Slabs Subjected to Static and Impact Load Induced by Free Falling Mass

Abstract

The impact resistance of concrete is considered as poor due to a relatively energy dissipating characteristics and tensile strength. Therefore, this paper investigates the feasibility of using polypropylene fibers PF to enhance punching shear capacity of reinforced concrete RC two-way slabs subjected to drop-weight impacts. The evaluated parameters included two slab thickness 70 mm and 90 mm , five different PF percentages 0%, 0.3%, 0.6%, 0.9%, and 1.2% , and two impact load height 1.2 m and 2.4 m . The tested slabs divided into three groups: not subjected to impact load, subjected to impact load at a height of 1.2 m, and subjected to impact load at a height of 2.4 m, resulting in a total of 25 slabs. The behavior of each two-way RC slab was evaluated in terms of the crack patterns, ultimate punching shear capacity. The present experimental data can be used for further assessment of the performance of PF reinforced concretes two-way slabs as well as providing a well-documented dataset related to the impact-resistant applications which is presently limited within the literature. The results showed that adding the PF at a dosage of 0.3 to 1.2% by volume of concrete and increasing the slab thickness from 70 mm to 90 mm leads to considerable enhancement in the overall structural behavior of the slabs and their resistance to impact loading. Interestingly, the degradation in the ultimate punching capacity of the slabs subjected to impact load at a height of 1.2 and 2.4 m is 30.5% and 34.6%, respectively. Finally, an empirical model was proposed for predicting the punching shear capacity of RC twoway slabs based on reliable experimental results available in literature

Failure Modes Behavior of Different Strengthening Types of RC Slabs Subjected to Low-Velocity Impact Loading: A Review

“…On the other hand, increasing the drop height significantly increases the damage to the RC slab. Al-Rousan [61] found that increasing the mix's PF (%) quantity increases the impact resistance and decreases the RC slab's flexural failure. PF (polymer fiber) increases the impact resistance of the RC Slab and decreases the punching shear failure damage of the structure.…”

“…Ref. [61] used a polypropylene fiber to investigate RC slab subjected to impact load with different thicknesses and subjected to different drop heights. Polypropylene fibers (PF) by volume (0.3-1.2%) effect are shown in Figure 7, indicating that increasing the PF (%) quantity in the mix increased the impact resistance; in other words, it decreased the flexural failure of the RC slab.…”

“…Several techniques have been used to increase RC slab punching shear capacities, such as bent-up bars, close stirrups, shear studs, and the utilization of high-strength concrete [61]. As summarized in Table 1, the behavior of RC slabs under impact loads was investigated experimentally, numerically, and analytically by several researchers.…”

Progressive damage in pretensioned and reinforced concrete plates against repeated impacts

“…The study also suggested to increase the amount of shear reinforcement to reduce the punching effects under impact loading. In another study (Al-Rousana, 2018; Ong et al, 1999), the impact resistance and energy absorption capacity of the slabs were increased with an increase in fibre content. In another study (Sohel and Liew, 2014), interlocking elements were used to hold steel laminates that were provided on either side of the concrete slabs for strengthening purposes.…”

“…The researchers had investigated the effects of drop height, drop mass, fibre content, type of fibre, thickness of slab, impact velocity, reinforcement ratio, composite laminate on the performance of slab/plate specimens tested against drop impact (Al-Rousana, 2018; Bhatti et al, 2011; Delhomme et al, 2007; Micallef et al, 2014; Radnić et al, 2015; Sawan and Abdel-Rohman, 1986; Sohel and Liew, 2014; Yoo and Yoon, 2013; Zineddin and Krauthammer, 2007). Radnić et al (2015) investigated the performance of conventional and CFRP strengthened reinforced concrete slabs subjected to impact load.…”