PSI - Issue 60

Swathy S et al. / Procedia Structural Integrity 60 (2024) 591–603

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Swathy S et.al / Structural Integrity Procedia 00 (2019) 000 – 000

Nomenclature ρ

Reinforcement ratio

SP1-CS SP2-SBF SP3-SBL

Specimen 1- Control Slab Specimen 2- Slab with Basalt fan Specimen 3- Slab with Basalt laminate Fibre Reinforced Polymer Carbon Fiber Reinforced Polymer

BFRP HSC UTM GFRP

Basalt Fiber Reinforced Polymer High Strength Concrete Universal Testing Machine Glass Fiber Reinforced Polymer Nominal shear strength of concrete Designed shear strength of concrete Line loading

FRP

CFRP

LL V u Ꞇ c

IS

Indian Standard Code

L 1, L 2

Span length in x and y direction

k s β c

Shear correction factor Eccentricity factor

M u A st f ck

Ultimate moment of resistance

Area of Steel

Characteristic compressive strength of concrete

b d

width of slab

Effective span depth

advantages over other types of slab that includes: (a) Flexibility in the partition walls. (b) Reduction in the floor to floor height that reduces the cost of construction. (c) Construction time is also less when compared to other type of reinforced concrete slab. Due to the shear and flexural stress around column, slab-column connections are the most critical sections. In two-way flat slabs without shear reinforcement, its behavior is highly dependent on the ratio of flexural reinforcement. Progressive failures can result from the shear failures at the slab-column connections. To overcome failure in flat slab strengthening is very much essential. Techniques for strengthening were developed to improve the overall structural stability. Strengthening is effective when there is insufficient bearing capacity of structural concrete element. Generally, literature elaborate various strengthening methods to overcome failure against vertical loading like concrete and steel jacketing but these methods increases the column size and are cumbersome. Some related studies are as follows. El- Salakawy et al [1] studied the strengthening technique for concrete slab with shear bolts installed in drilled holes. Shear bolts has increased the load carrying capacity and the ductility of the connections. Soudki et al [2] investigated on shear behaviours of both carbon and basalt FRP laminates strengthened flat slab were used. Second technique implies FRP sheets externally bonded with steel bolts. FRP sheets and the steel bolts used improved the load carrying capacity. Micael et al [3] conducted experimental studies to analyse the performance of concrete slab with the shear reinforcement. Prestressed vertical bolts, using different anchorage approaches: large anchorage on surface, small anchorage on surface and small embedded anchorage were introduced in eight specimens. Navid et al [4] examined the effect of FRP (Fibre Reinforced Polymer) in orthogonal and radial grids on shear behaviour of reinforced concrete slabs using basalt, glass and carbon FRP (BFRP, GFRP and CFRP) in twelve specimens. Results proved that the shear resistance and the ductility of the slabs were improved by providing FRP grids. Hamed et al [5] scrutinized effectiveness of vertical prestressed bolts for retrofitting flat slabs which is damaged due to punching shear. He varied the ratio of the bolts and studied the load carrying capacity, cracking behaviour and the deformation characteristic. Micael et al [6] has found punching resistance of high strength concrete slab without shear reinforcement. Three flat slab specimens were casted using HSC of compressive strength 130 MPa. The experimental results indicated that if the ratio of longitudinal reinforcement is increased then the shear resistance is also increased for the HSC with addition of basalt coarse aggregate. Hasan et al [7] analysed through experimental studies the strengthening of flat slabs with FRP string for shear. 8, 16 and 24 strengtheners were used in the above case. The results indicated that the deformation capacity and maximum loading capacity is improved by the above method. Hazem et al [8] used external steel plates to enhance the punching shear behaviour of two- way slabs. Square steel plates with steel anchor shear stud were provided to