Punching Shear of High Strength Polypropylene Fiber Reinforced Concrete Slabs Interior Column Connection
Omar Abd El-Nasser Abdou Mansour;
Abstract
Punching shear failure is caused by the transfer mechanism of shear forces from the slab to the slab-column connection. These shear stresses are developed from gravity loads and unbalanced moments. Once these shear stresses exceed the slab’s shear capacity, punching occurs with no warning. Punching shear failures are generally brittle phenomena. Recently, using fibers has proven to give good results as a new technique to improve the punching shear resistance, and cracking control of slab-column connections. This study investigates mainly the influence of high strength crimped polypropylene fibers on the punching shear of slab interior column connection.
In the first part of the thesis, an experimental program was carried out to investigate the influence of polypropylene fibers on the properties of hardened concrete. Concrete specimens have been tested at different ages to determine the mechanical properties of concrete, namely, compressive strength, tensile splitting strength, flexural strength, and direct tensile strength. Samples with polypropylene fibers dosage of 2.5 kg/m³ showed the best results. The compressive, split tensile and flexural strengths improved significantly with an increase in strength up to 53, 45 and 40%, respectively.
The second part of the thesis employs nonlinear finite element method using ANSYS 19.0 software to investigate the punching shear strength of reinforced concrete slab-column connections focusing on four main parameters, namely, the inclusion of polypropylene fibers, flexural reinforcement ratio, column size and concrete compressive strength.
This finite element analysis comparative study includes modeling eighteen full scale slab-column connection of dimensions 3500x3500x220 mm and volumetric fiber contents 0 kg/m³ and 2.5 kg/m³. Slabs are divided into six groups and reinforced with two flexural reinforcement ratios of 0.80% and 1.27%. Compression longitudinal steel bars are of diameter 12 mm and spaced 125 mm center to center in both directions for all specimens. Columns are of size 300x300 mm and 500x500 mm, reinforced with four longitudinal steel bars of diameter 16 mm and eight longitudinal steel bars of diameter 18 mm, respectively.
The inclusion of polypropylene fibers by dosage 2.5 kg/m³ enhanced the mechanical properties of concrete which resulted in increasing the punching shear capacity ranging from 11% to 59% and the slab deflection at service loads increased ranging from 5% to 56%.
Other parameters such as increasing the flexural reinforcement ratio from 0.80% to 1.27% slightly increased the punching shear strength ranging from 6% to 11% and reduced the slab deflection at service loads ranging from 8% to 13% as the stiffness of the slabs increased.
In the first part of the thesis, an experimental program was carried out to investigate the influence of polypropylene fibers on the properties of hardened concrete. Concrete specimens have been tested at different ages to determine the mechanical properties of concrete, namely, compressive strength, tensile splitting strength, flexural strength, and direct tensile strength. Samples with polypropylene fibers dosage of 2.5 kg/m³ showed the best results. The compressive, split tensile and flexural strengths improved significantly with an increase in strength up to 53, 45 and 40%, respectively.
The second part of the thesis employs nonlinear finite element method using ANSYS 19.0 software to investigate the punching shear strength of reinforced concrete slab-column connections focusing on four main parameters, namely, the inclusion of polypropylene fibers, flexural reinforcement ratio, column size and concrete compressive strength.
This finite element analysis comparative study includes modeling eighteen full scale slab-column connection of dimensions 3500x3500x220 mm and volumetric fiber contents 0 kg/m³ and 2.5 kg/m³. Slabs are divided into six groups and reinforced with two flexural reinforcement ratios of 0.80% and 1.27%. Compression longitudinal steel bars are of diameter 12 mm and spaced 125 mm center to center in both directions for all specimens. Columns are of size 300x300 mm and 500x500 mm, reinforced with four longitudinal steel bars of diameter 16 mm and eight longitudinal steel bars of diameter 18 mm, respectively.
The inclusion of polypropylene fibers by dosage 2.5 kg/m³ enhanced the mechanical properties of concrete which resulted in increasing the punching shear capacity ranging from 11% to 59% and the slab deflection at service loads increased ranging from 5% to 56%.
Other parameters such as increasing the flexural reinforcement ratio from 0.80% to 1.27% slightly increased the punching shear strength ranging from 6% to 11% and reduced the slab deflection at service loads ranging from 8% to 13% as the stiffness of the slabs increased.
Other data
| Title | Punching Shear of High Strength Polypropylene Fiber Reinforced Concrete Slabs Interior Column Connection | Other Titles | القص الثاقب لوصلات الأعمدة الداخلية بالبلاطات الخرسانية المسلحة بألياف البولى بروبلين عالية المقاومة | Authors | Omar Abd El-Nasser Abdou Mansour | Issue Date | 2021 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| BB7314.pdf | 545.47 kB | Adobe PDF | View/Open |
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