EXPERIMENTAL INVESTIGATION ON BASALT FIBRE REINFORCED POLYMER WRAPPED HOLLOW SQUARE STEEL SECTIONS WITH AND WITHOUT CASTELLATIONS

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 4, April 2018, pp , Article ID: IJCIET_09_04_190 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EXPERIMENTAL INVESTIGATION ON BASALT FIBRE REINFORCED POLYMER WRAPPED HOLLOW SQUARE STEEL SECTIONS WITH AND WITHOUT CASTELLATIONS Mohamed Haris Department of Civil Engineering, SRM Institute of Science & Technology, Kattankulathur, Chennai, Tamilnadu, India Bhuvaneshwari M Department of Civil Engineering, SRM Institute of Science & Technology, Kattankulathur, Chennai, Tamilnadu, India ABSTRACT This paper presents the results of experimental research to examine the stiffness of beams of square hollow sections and square hollow castellated sections with and without being wrapped by BasaltFibre Reinforced Polymer (BFRP). Specimens were wrapped with BFRP in Two layers, then allowed to dry and tested under two-point loading. It was found that the external bonding of BFRP with steel sections significantly increased the load carrying capacity and stiffness of hollow steel sections. This study proves that deformation of hollow steel sections can be improved by providing appropriate BFRP strengthening techniques. Ultimate load carrying capacity and stiffness of square wrapped hollow sections increased by 6.46% and 7.50% as compared to square conventional section. Ultimate load carrying capacity of square wrapped castellated section increased by 1.28% and 30.15% as compared to square castellated conventional section. Keywords: Two-point loading, hollow square steel sections, stiffness, BFRP. Cite this Article: Mohamed Haris and Bhuvaneshwari M, Experimental Investigation on Basalt Fibre Reinforced Polymer Wrapped Hollow Square Steel Sections with and without Castellations, International Journal of Civil Engineering and Technology, 9(4), 2018, pp editor@iaeme.com

2 Experimental Investigation on Basalt Fibre Reinforced Polymer Wrapped Hollow Square Steel Sections with and without Castellations 1. INTRODUCTION The structural application of hollow square sections (HSS) in offshore structures become widespread due to its numerous advantages such as light weight, high strength, large energy absorption capacity, high torsional rigidity, and adequate ductility to certain extents. And very recently, designers discovered its economical advantages as well, at the same time, aging and deterioration caused by exposure to the marine environment of tubular and metallic structures were often reported. In addition to that infrastructures concerned with metallic structures were found to be structurally unsatisfactory due to overloading and deficiency in the design phase. Hence, the engineers are constrained to implement new materials and effective strengthening technique to efficiently combat this problem [1]. The conventional method of repairing or strengthening steel structures is to cut out and replace plating or to attach external steel plates. However, such strengthening has some drawbacks due to bulky, heavy, difficult to fix and prone to corrosion and fatigue of these steel plates, Fibre reinforced polymer (FRP) is an advanced material which is increasingly being used for strengthening and repair of existing metal structures [2]. Basalt is a most commonly used extrusive igneous rock formed from cooling of lava introduced at very near the surface of the planet. It is usually very fine grained or glassy matrix scattered with observable mineral grains. The density is 3.0 g/cm³. Basalt s colour normally is grey or black, but cools down to brown or rust because of oxidation of its iron rich minerals into hematite and other iron oxides and hydroxides. 2. PAST RESEARCH Selvaraj and madhavan (2016) [3] experimentally investigatied to achieve an strengthening technique to retrofit the damaged tall steel structures using carbon fiber-reinforced polymer (CFRP). Yuguang Fu et al., (2016) [4] proposed an efficient technique of Carbon Fibre Reinforced Polymer (CFRP) to promote joint capacity of general tubular k-joints fabricated from Circular Hollow Section (CHS) members. Zahurul Islam and Ben Young (2011) [5] conducted a test programme on aluminium tubular structural members that have experienced web crippling failure due to localized concentrated loads or reactions. In the past studies, it is known that the steel structures are susceptible to damage and lose their strength under buckling failure, web crippling or corrosion. So in order to overcome this problem high strength material such as FRP which has low self-weight, minimized disturbance to the structural system is wrapped over steel sections to enhance the stiffness and strength of steel sections. 3. MATERIALS USED 5 nos of Hollow Square steel sections of size 100*100mm with 3 mm thickness, and Basalt Fibre Reinforced Polymer (BFRP) of GSM 320 with 0.3 mm thickness has been used HOLLOW SQUARE STEEL SECTION Calculation of design load for hollow square steel section To calculate the design load for hollow square steel section is M=F*Z. The load has been calculated from the permissible bending stress, which is 0.67 fy and the section modulus of the structural member. Therefore, the load is 34893N as per IS code 800:2007 [6] editor@iaeme.com

3 Mohamed Haris and Bhuvaneshwari M Figure 1 steel section Figure 2 BFRP 3.2. BASALT FIBRE REINFORCED POLYMER Hollow structural steel sections were wrapped with basalt fibre reinforced polymer 0.3 mm thickness of 300 GSM. Two layers of fibre were wrapped over structural steel sections using epoxy and hardener. Basalt fiber is a material made from extremely fine fibers of basalt. The manufacture of the basalt fiber is by melting the quarried basalt rock. The molten rock is then extruded through small nozzles to produce continuous filaments of basalt fiber. It is known that basalt fibers have better tensile strength than E-glass fibers, greater failure strain than carbon fibers as well as good resistance to chemical attack, impact load and fire with less poisonous fumes. Basalt having a high modulus of elasticity and excellent heat resistance, the fibers made of it has significant capability of heat and acoustic resistance and are outstanding vibration isolators. Basalt fibers are produced with the Junkers technology by melting the basalt rock and then forming fibers out of it [7]. Properties of basalt fiber Properties Table 1 Properties of BFRP value Tensile strength 4.84 GPa Elastic modulus 89 GPa Elongation at break 3.15 % Density 2.7 g/cm³ 3.3. EPOXY AND HARDENER Araldite LY 556 epoxy and Aradur HY 951 hardener were used. Araldite LY 556 is medium viscosity, unmodified liquid epoxy resin based on Bisphenol-A, Aradur HY 951 is a low viscosity, unmodified, aliphatic polyamine. PROPERTIES Low-viscosity system, glass fibre laminates are dimensionally stable, glass fibre laminates are practically free from internal stress and excellent water resistance. 4. DESIGN Calculation of design load for hollow square steel section as per IS 800:2007 [8] editor@iaeme.com

4 Experimental Investigation on Basalt Fibre Reinforced Polymer Wrapped Hollow Square Steel Sections with and without Castellations Table 2 design load for HSS section Material Load (kn) Hollow square steel section TEST ON STEEL BEAMS 5.1. DETAILS OF SPECIMENS A total of 5 specimens were used in this experiment, out of which 3 specimens are hollow square steel sections and other 2 are castellated hollow square steel sections. 2 conventional specimens and 1 castellated steel section were wrapped with Basalt Fibre Reinforced Polymer (BFRP) using epoxy and hardener, were allowed to dry and then tested TEST SETUP All the conventional, castellated and wrapped sections were tested for two-point bending Universal Testing Machine (UTM) with a capacity of 1000kN. The specimens are placed on two supports; the distance of support from both the edges is 10cm. Two point loads were placed on the specimens, the distance of both point loads were 35cm from the edges. An dial gauge is fitted at the center of the specimen to measure the deflection. Load is applied until the specimen reaches its maximum load carrying capacity, ultimate load and maximum deflction is noted down. Figure 3 conventional specimen setup Figure 4 wrapped specimen setup 6. RESULTS AND DISCUSSION 6.1. FAILURE MODES OF SPECIMENS All the specimens were tested till their ultimate failure. In order to evaluate the strengthening effect, failure modes of specimens were studied. It can be seen that the bare beam failed showing typical ductile manner under failure. It was also observed that the failure happened to control beams with and without embedded GFRP due to local buckling of the tubular hollow section in the compression zone near the loading points where crushing of the fibre layers was found as well. The behavior of steel beams follows the same type of failures reported by M.H. Kabir et al., [8] editor@iaeme.com

5 Mohamed Haris and Bhuvaneshwari M Figure 5 Figure 6 Figure 7 Figure LOAD CARRYING CAPACITY Load carrying capacity of a specimen depends on the type of material and strengthening technique used. Ultimate load carrying capacity and stiffness of square wrapped hollow sections increased by 6.46% and 7.50% as compared to square conventional section. Ultimate load carrying capacity of square wrapped castellated section increased by 1.28% and 30.15% as compared to square castellated conventional section. Specimen Ultimate load (kn) Average load (kn) Square conventional Square wrapped Specimen (1) Square wrapped Specimen (2) Square castellated conventional Square castellated wrapped LOAD DEFORMATION CHARACTERISTICS The load-deformation curves have been plotted. The effects of increased deflection effects on stiffness of Basalt Fibre Reinforced Polymer (BFRP) hollow steel beams with and without castellations are shown graphically. It clearly shows that the load increases with increase in editor@iaeme.com

6 Experimental Investigation on Basalt Fibre Reinforced Polymer Wrapped Hollow Square Steel Sections with and without Castellations deflection until the failure load is achieved. It is also noted that increased load with deflection has also affected the stiffness of the hollow steel beams. Figure 9 Figure CONCLUSIONS Following conclusions were made based on the results and experimental observations. Ultimate load carrying capacity of square wrapped hollow sections increased by 6.46% as compared to square conventional section. Stiffness of square wrapped hollow sections increased by 7.50% as compared to square conventional section. Ultimate load carrying capacity of square wrapped castellated section increased by 1.28% as compared to square castellated conventional section. Stiffness of square wrapped castellated section increased by 30.15% as compared to square castellated conventional section. REFERENCES [1] Balavinayagam j., Sakthieswaran N., Shiny Brintha G., Ganesh Babu O., Hollow tubular rectangular steel section wrapped GFRP A Review, International Journal for Research in Applied Science and Engineering Technology, 2016, 4(5), [2] Zahurul Islam S.M., Ben Young, FRP strengthening of lean duplex stainless steel hollow sections subjected to web crippling, Thin-Walled Structures, 2014, 85, [3] Sivaganesh Selvaraj, Mahendrakumar Madhavan, Enhancing the structural performance of steel channel sections by CFRP strengthening, Thin-walled Structures, 2016, 108, pp [4] Yuguang Fu, Lewei Tong, Lang He, Xiao-Ling Zhao, Experimental and numerical investigation on behavior of CFRP-strengthened circular hollow section gap K-joints, Thin-Walled Structures, 2016, 102, [5] Zahurul Islam S.M., Ben Young, FRP strengthened aluminium tubular sections subjected to web crippling, Thin-Walled Structures, 2011, 49, [6] IS 800:2007 General constructions in steel, Bureau of Indian standards, New delhi, [7] Hannibal Olafsson, Eypor Porhallsson, Basalt fiber bar, [8] Kabir H.M., Fawzia S., Chan T.H.T., Badawi M., Durability of CFRP strengthened steel circular hollow section member exposed to sea water, Construction and building materials, 2016, 118, editor@iaeme.com