IRJET- Behaviour of Concrete Columns by using Biaxial Geogrid Encasement
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The document presents research on using biaxial geogrid encasement to reinforce concrete columns as an alternative to traditional steel reinforcement cages. Three types of column specimens were tested: 1) traditionally reinforced with rebar, 2) reinforced with geogrid and longitudinal rebar, and 3) reinforced with only geogrid. Test results showed the geogrid-reinforced columns had 5% and 29% lower load capacity than the rebar and hybrid systems, respectively. Finite element analysis found stresses in the traditional system were higher than the other systems. In conclusion, geogrid reinforcement provided some confinement and reduced construction complexity, but did not match the strength of a rebar cage.
IRJET- Behaviour of Concrete Columns by using Biaxial Geogrid Encasement
- 1. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1051 BEHAVIOUR OF CONCRETE COLUMNS BY USING BIAXIAL GEOGRID ENCASEMENT Y Narasimharao1, B Sirisha2 1M.Tech, Structural Engineering, Sri Sunflower College of Engineering and Technology, Lankapalli, Andhra Pradesh 2Assistant Professor, Sri Sunflower College of Engineering and Technology, Lankapalli, Andhra Pradesh ----------------------------------------------------------------------***--------------------------------------------------------------------- Abstract: A new reinforced system is introduced to be used in concrete columns. This new reinforcement named Geogrid reinforced steel columns (GRSC), is a little satisfactory alternative to the rebar cage used in traditional reinforced concrete, for faster and easier construction. Geogrids are an alternative tool in transportation and civil construction. They allow engineers to build where it otherwise would not be possible or would be cost prohibitive using traditional material. It is structured polymeric material usually made from polyethylene compounds. To extend the use of geogrid in civil engineering as a structural component in concrete in axial load member, with the strength comparison to traditional rebar system and geogrid encased system was done. Test results have shown that the axial load carrying capacity of specimens reinforced with two different cases geogrid encased columns. The geogrid reinforced steel columns are given strength 5 percent less strength with compare to traditional rebar system by using geogrid (50kN/m tensile strength).Axial load-displacement relations for the test column and stresses in member was observed in Finite element analysis (ANSYS12.0). Keywords: Reinforced Concrete (RC), Geogrid reinforced steel columns (GRSC) I. INTRODUCTION Reinforced concrete (RC) has been used in construction of different structures for centuries. Reinforced concrete is defined as concrete which is a mixture of cement, sand, gravel, water, and some optional other admixtures, combined with a reinforcement system, which is usually steel. Concrete is strong in compression but weak in tension, therefore may result in cracking and failure under large tensile stresses. Steel has high tensile capacity and can be used in areas with high tensile stresses to compensate for the low tensile strength of concrete. The combination of concrete, a relatively cheap material with high compressive strength, and steel, a material with high tensile strength, has made reinforced concrete a popular construction material for structural and non-structural members. Historically, steel in the form of rebar has been used as longitudinal and transverse reinforcement. Other forms of steel reinforcement systems, such as tubular and composite sections have been introduced in recent decades. Reinforced concrete columns are used to transfer the load of the structure to its foundations. These are reinforced by means of main longitudinal bars to resist compression and/or bending and transverse steel (ties) to resist the bursting forces. II. EXPERIMENTAL PROGRAM The three types of specimens were constructed and tested up to failure monotonic axial load. The strength and displacement and effect of reinforcement with rebar and polypropylene geogrid strength of the column were investigated. The results from traditional rebar, GRSC and GRC specimen with different amount of transverse and longitudinal steel were compared. The specimens were 700mm high and had 230mm X 230mm cross-sections with 40 mm clear cover the reinforcement .The specimen specification are provided in Table 1. The characteristic concrete compressive strength for tested specimen M20 grade concrete was used. Table 2 illustrates the mixture properties as well as the concrete mechanical properties for the tested specimens. The used polypropylene and high density polyethylene geo grid with opening size (25x25) mm with tensile strength 50kN/m. Gro up Column Designation Column specimens dimension Slenderne ss Ration h/D L (mm) B (mm) H (mm) C1 Traditional Rebar Columns 230 230 700 3.04 C2 Geogrid Reinforced Steel Columns 230 230 700 3.04 C3 Geogrid Reinforced Columns 230 230 700 3.04 Table 1: Details of tested column specimen Grade W/C Cement (Kg/m3) Fine Aggregate (Kg/m3) Coarse Aggregate (Kg/m3) M20 0.5 360 586.8 1195.2 Table 2: Mixture properties of concrete M20 (1:1.63:3.32)
- 2. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1052 III. ANALYTICAL MODELLING The finite element model in ANSYS (SAS 2003) there are multiple tasks that have to be completed for the model to run properly. Models can be created using command prompt line input or the Graphical User Interface (GUI). For this model, the GUI was utilized to create the model. This section describes the different tasks and entries into used to create the FE calibration model. Material Type ANSYS Element Concrete Solid65 Steel Reinforcement & geogrid Link8 Table 3: Element Type for Working Model Material Model Number Element Type Material Properties Linear isotropic 1 Solid65 EX 22360 PRXY 0.2 2 Link 8 EX 200000 PRXY 0.3 3 Link 8 EX 2500 PRXY 0.18 Table 4: Material Models for the Calibration Model Modelling: The concrete column with rebar and geogrid were modeled as volumes. Since a quarter of the beam is modeled, the model is700mm long with a cross section of 230x230mm. Meshing: Figure 1: Meshing of the concrete and rebar Figure 2: Meshing of concrete and geogrid material Loads and Boundary Conditions: Figure 3: Boundary conditions for plane of symmetry Figure 4: Boundary condition and pressure direction IV. RESULTS AND DISCUSSIONS The all three types specimens Traditional rebar column (C1),Geogrid reinforced steel column (C2) and Geogrid reinforced column (C3) was very different in strength see Table. A representative axial load- displacement is measured; typically the specimens behaved elastically without cracking until the peak
- 3. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1053 strength was almost reached .Suddenly the axial strength dropped about 1/2 of the peak strength. G r o u p Column Designatio n Column specimens dimension 1ST Crac king (KN) Peak Stren gth(K N) Disp lace men t(m m) L (mm) B (mm) H (mm) C 1 Traditional Rebar Columns 230 230 700 560 799.8 8.9 C 2 Geogrid Reinforced Steel Columns 230 230 700 520 750.6 7.84 C 3 Geogrid Reinforced Columns 230 230 700 515 500.2 7.47 Table 5: Measured load-displacement value 1000 Rebar 900 GRSC L 800 GRC O700 A 600 D 500 400 300 200 100 0 1 6 11 16 Displacement(mm) Graph 1: Load Vs Displacement Curve Tested Specimens: Rebar Column GRSC GRC Figure 5: Specimens Specime n Type Analytical Study Stress Stress at the interface Longitu dinal Bar Ties Geo grid Longit udinal Bar Ties Geogrid TRC 82.47 (comp) 25.8 …… 17.48 14.33 ……. GRSC 78.58 (comp) ……. 3.22 15.82 ……. 13.67 GRC 11.4 (comp) …… 3.22 10.71 ……… 10.20 Table 6: Stress value from analytical study Figure 6: Stress in steel bar (C1) model Figure 7: Stress in steel ties (C1) model Figure 8: Stress in steel bar (C2) model
- 4. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1054 Figure 9: Stress in geogrid (C2) model Figure 10: Stress in geogrid (C3) model Figure 11: Stress at interface in (C1) model longitudinal rebar Figure 12: Stress at interface in (C1) model rebar lateral ties Figure 13: Stress at interface in (C2) model longitudinal rebar Figure 14: Stress at interface in (C2) model geogrid lateral direction Figure 15: Stress at interface in (C3) model geogrid longitudinal direction
- 5. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1055 Figure 16: Stress at interface in (C3) model geogrid lateral direction V. CONCLUSIONS From the experimental and practical investigations carried out in the study, the following major findings can be arrived at 1. A new geogrid reinforcement termed GRSC is proposed for longitudinal reinforced members GRSC is an anticipated to be an alternative to the existing reinforcement systems and lower construction cost as it eliminates the labour cost associated with cutting, bending and tying reinforcing ties. 2. The columns with rebar gives the better confinement than the geogrid, this may be due to low tensile and compressive strength of geogrid. 3. The test results shows that the load carrying capacity of columns with geogrid and longitudinal steel reinforcement is 5% less than the load carrying capacity with traditional rebar reinforcement, so the GRSC shows a little reduction of its strength. 4. The strength reduction of two models GRSC and GRC compared with traditional rebar specimens give 5% and 29% respectively. 5. From FEM analysis it is observed that the failure stresses at the interface in traditional system with GRSC and GRC systems was compared, and found that the stresses in traditional reinforcement is more. 6. A result of analytical work, the stresses developed steel in traditional rebar column - 86.47N/mm2 (compression),Geogrid reinforced steel columns-81.53N/mm2(compression) and geogrid reinforced columns-2.37N/mm2(tension) respectively. From the above result can conclude that compression stress in GRCS is more compared to GRS. 7. This research shows that in second case with increasing the tensile strength of geogrid grade, the confinement of the concrete compressive strength of the column specimen will increase. From the experimental and analytical analysis it was observed that geogrid is a better replacement of steel ties. VI. REFERENCES 1. Bing, L., Park, R., and Tanaka, H. (2001). “Stress- strain behaviour of high-strength concrete confined by ultra-high- and normal-strength transverse reinforcements.” ACI Struct. J., 98(3), 395–406. 2. Shamsai, M., and Sezen, H. (2005). “Fast and easy concrete construction using innovative steel reinforcement.” Proc., Construction Research Congress, ASCE, Reston, Va., 317–321. 3. S, M. (2006). “Prefabricated cage system for reinforcing concrete members.” Ph.D. dissertation, Dept. of Civil and Environmental Engineering and Geodetic Sciences, Ohio State Univ., Columbus, Ohio. 4. System (2007) Halil Sezen, M.ASCE; and Mohammad Shamsai “High-Strength Concrete Columns Reinforced with Prefabricated Cage” J.Constr.Eng.Manage (2007)133:864-870 5. Shamsai, M., Whitlatch, E., and Sezen, H. (2007). “Economic evaluation of reinforced concrete structures with columns reinforced with prefabricated cage system.” J. Constr. Eng. Manage., 133(11), 864–870. 6. Joel Gniel a,1, Abdelmalek Bouazza b, “Construction of geogrid encased stone columns: A new proposal based on laboratory testing” Geotextiles and Geo membranes 28 (2010) 108– 118 7. Joel Gniel 1, Abdelmalek Bouazza ” Improvement of soft soils using geogrid encased stone columns” Geotextiles and Geomembranes 27 (2009) 167– 175 8. R.Chitra & R.Thenmozhi (2011) “Studies on prefabricated cage reinforced steel-concrete composite beams” Asian jouranal of civil engineering (building & housing) vol. 12, no. 1, Pages 27-37 9. R.Chitra, R.Thenmozhi (2011) “Strength and ductility of concrete cylinders reinforced with prefabricated steel cage” International Journal of
- 6. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395-0056 VOLUME: 06 ISSUE: 09 | SEP 2019 WWW.IRJET.NET P-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1056 Engineering Science and Technology Vol.3 No.9 pages(6931-6939) 10. Ata EI-kareim Shoeib Soliman(2011) “Behavior of long confined concrete column” Ain Shams Engineering Journal (2011) 2,141-148 11. R.Chitra, Thenmozhi, Ravathi.M.C (2012)” Ductility of Prefabricated Cage Concrete Beams: Analytical Study” International Journal of Civil and Structural Engineering Volume2, No 4. 12. Maryam Poursharifi, Yashar Yasrebi Nia, Zahra Poursharifi (2012) “Assessment of Normal Strength Concrete and High Strength Concrete on Prefabricated Cage Systems in Near-Field Earthquake”. 13. Syed Sohailuddin S S1 and M G Shaikh1 (2013) “FINITE ELEMENT MODELING OF REINFORCED CONCRETE BEAM COLUMN JOINT USING ANSYS” International Journal of Civil and Structural Engineering Volume2, No 3. 14. American Concrete Institute (ACI). (2005). “Building code requirements for structural concrete (ACI 318-05) and commentary (ACI 318R-05).” ACI Committee 318, Farmington Hills, Mich. 15. Mander, J. B., Priestley, M. J. N., and Park, R. (1988). “Theoretical stress-strain model for confined concrete.” J. Struct. Eng., 114(8), 1804–1826.