INTERNATIONAL JOURNAL OF CIVIL AND STRUCTURAL ENGINEERING Volume 4, No 4, 2014 © Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN 0976 – 4399 Numerical study on deformation characteristics of composite slab – with and without embossments 1 Merool D. Vakil1, Japan U. Shah2, H.S.Patel3 Assistant Professor, Applied Mechanics Department, Government Engineering College, Patan, Gujarat, India. 2 P.G. Student Applied Mechanics Department, L.D. College of Engineering, Ahmedabad, Gujarat, India. 3 Professor, Applied Mechanics Department, Government Engineering College, Patan, Gujarat, India. Doi: 10.6088/ijcser.201404040001 ABSTRACT Many efforts have been made by the researchers to forecast the strength of composite slab experimentally. The experimental methods based on the full-size test are expensive, time consuming and semi-empirical. This paper describes a study on finite element modelling of composite slab numerically. The aim is to understand the deflection characteristics of steel–concrete composite deck in order to improve designs for steel decking for composite slabs. 3-D finite element slab model is built, with and without embossments on profile deck. Analysis is carried out on simply supported composite slab under two point line loads by varying parameters: concrete height and concrete grade. It has been observed that composite slab without embossment deformed more as compared to slab with embossment. Keywords: Composite slab, FEM analysis, ANSYS, Embossments, Concrete height, Grade of concrete. 1. Introduction A composite slab with profiled steel decking is considered as one of the simpler, faster, lighter and economical constructions in steel-framed building systems. The system is well recognized by the construction industry due to many advantages such as, no formwork, quick installation, and reduced dimensions and weight. Composite floors with profiled decking consist of the profiled decking, shear connectors, reinforcement for shrinkage and temperature stresses and concrete. For the steel deck and concrete to act compositely, a mechanical interlocking is needed. This is provided essentially by shear transferring mechanism such as rolled embossments, indentation, holes or by dovetail shape of the profile. Figure-1 shows schematic view of the composite slab. This paper, aims to study the deformation of composite slabs considering with embossment and without embossment profile sheetby the varying concrete height and grade of concrete numerically. 2. Description of the FEM model for composite deck slab The objective of this work is to evaluate the dependency of deflection on embossment, material and geometric parameters so; these numerical models have been parametrically built. The finite element (FE) method is one of the powerful tools to study the behaviour of the composite slabs. Total 18 models are modelled in ANSYS-15 to identify the Received on December, 2013 Published on May2014 477 Numerical study on deformation characteristics of composite slab – with and without embossments Merool D deformation of the composite slab considering different parameters. Concrete is modelled by SOLID65 element. This element can be used for the 3-D modelling of solids with or without reinforcing bars. The solid is capable of cracking in tension and crushing in compression. The element is defined by eight nodes having three degrees of freedom at each node: translations in the nodal x, y, and z directions. Profile deck is modelled with SHELL181 element. It is used for analysing thin to moderately-thick shell structures. It is a 4-node element with six degrees of freedom at each node: translations in the x, y, and z directions, and rotations about the x, y, and z-axes. Figure1: Composite floor system 2.1 Material Properties of FE Model Bilinear Isotropic property was used for profile Sheet. Multi linear Isotropic material properties were used for concrete. The material properties are listed in Table – 1 Table 1: Material property Density Poisson’s ratio Elastic modulus Yield strength Structural steel property 7850 kg/m3 0.3 2x105 N/mm2 250 N/mm2 Table 2: Material property Concrete property Density 2300 kg/m3 Poisson’s ratio 0.18 Elastic modulus 25000 N/mm2 Compressive Cube strength 25 N/mm2 2.2 Geometric parameters of FE model In this study, thickness of the profile deck 0.9 mm, the span of the composite slab 2400mm and width 450 mm is considered. The shape and dimensions of the deck sheet are shown in 478 International Journal of Civil and Structural Engineering Volume 4 Issue 4 2014 Numerical study on deformation characteristics of composite slab – with and without embossments Merool D Figure-2. Different depth of the slab like 110 mm, 120 mm, 130 mm, 140 mm and 150mm is considered in this analysis. The embossments were modelled with the help of PRO Engineer (Pro-E) software. A punch tool was modelled with exact dimensions of embossments. The same tool had been used over the sheet metal module to form the embossment over the profiled deck sheet. The model was imported into ANSYS software and the properties were assigned. Embossments were projected for 3 mm towards the concrete portion as. The embossments were spaced at 65 mm c/c and placed along the length of the sheet as shown in Figure-3. The square dimensions are 25mm x 25mm considered for embossment. By variation in concrete mix for different grade of concrete like M25, M30, M35, M40, and M45 the finite element analysis is carried out. Figure2: Trapezoidal profile sheet Figure 3: Pro-E Geometry with Embossment (sheet metal) 2.3 Loading and Boundary Condition of FE model Two wavelength of the composite slab was considered in finite element analysis. A static load of 20 kN was applied as two line load at distance of 600mm from each of the support. The standard gravity of the materials was included in the model. Mesh refinement is done to whole composite slab as shown in Figure-4. Bonded connection between profile steel sheet and concrete was considered. A simply supported boundary condition was assumed for the composite deck slab, one end considered as hinged support and other end as a roller support. Figure 4: Meshing of Composite slab 479 International Journal of Civil and Structural Engineering Volume 4 Issue 4 2014 Numerical study on deformation characteristics of composite slab – with and without embossments Merool D 3. Results and Discussion The parametric study was conducted with the different concrete height and con crete grade and the total deflection at mid-span of the composite slab has been observed. Deflection contours of profile deck with and without embossments are shown in Figure -5 for 110 mm height of slab and M25 grade of concrete. Table 2 shows deflection variation of slab with and without embossment by varying concrete height. Table 3 shows deflection variation of slab with and without embossment by varying concrete grade. Without embossment with embossment Figure5: Deflection contour of 110 mm height of slab and M25 grade of concrete Table 3: FE analysis results of deformation with a variation in concrete height Description Concrete height Without Embossment With Embossment Deformation (mm) 110 mm 13.85 8.24 120mm 10.81 6.59 130mm 140mm 8.57 6.91 5.47 4.61 150mm 5.67 3.99 Table 4: FE analysis results of deformation with a variation in concrete grade Description Deformation (mm) Concrete Grade M25 Without Embossment 13.85 With Embossment 8.24 M30 12.92 7.56 M35 M40 12.14 11.51 7.06 6.67 M50 10.98 6.36 480 International Journal of Civil and Structural Engineering Volume 4 Issue 4 2014 Numerical study on deformation characteristics of composite slab – with and without embossments Merool D 3.1 Results of various parameters are summarized as follows: 1) The concrete height has a considerable effect on the deflection of composite slab. It is observed that deflection decreases by 14% to20% as the height is increased from 110 mm to150 mm in WE Sheet. 2) In WOE composite slab deformation reduces by18% to 22% as the height is increased from 110mm to 150 mm. 3) Comparing the WOE and WE, it is observed that the WE composite slab has less deformation by almost 30% to 41 % as the concrete height is increased from 110mm to 150 mm. 4) When deformation of WE is calculated by varying different grade of concrete from M25 to M45, it is reduced by 5% to 8%. 5) In WOE slab deformation reduces by 4% to 6 % as the grade increased by M25 to M45. 6) When the deformation of WOE with WE sheet is compared by considering different grade of concrete from M25 to M45, it is reduced by 41% to 42% 4. Conclusions A parametric study of 18 composite decks with and without embossment was performed using the finite element analyses. Square shape embossment and no embossment composite deck were studied for different concrete height and concrete mix. A deflection characteristic of composite deck is studied for these variations. Deflection in slab without embossment was found higher than deflection in slab with embossment. It is observed that, while comparing WOE slab with WE slab, the WE composite slab has almost 30% to 41 % less deformation as the concrete height is increased and 41% to 42% as the concrete mix is increased. There was a significant decrease in deflection by varying concrete height rather than by varying concrete mix for WE and WOE slab. This is due to increase in moment of inertia of the section. 5. References 1. ANSYS User’s manual. 2. Chen, S., (2003), Load carrying capacity of composite slabs with various end constraints, Journal of Constructional Steel Research, 59, pp 385-403. 3. EN 1994-1-1 (2004). Euro code 4: design of composite steel and concrete structures. Part 1.1: general rules and rules for buildings. Brussels: European Committee for Standardization. 4. Euripides S. Mistakidis, (2009), Bending resistance of composite slabs made with thin-walled steel sheeting with indentations or Embossments, Thin-Walled Structures, 46, pp 192–206. 5. Johnson R. P., (2004), Composite structures of steel and concrete beams, slabs, columns, and frames for buildings, 3rd Edition Oxford, United Kingdom: Blackwell Scientific Publications. 481 International Journal of Civil and Structural Engineering Volume 4 Issue 4 2014 Numerical study on deformation characteristics of composite slab – with and without embossments Merool D 6. Marimuthu V, (2007), Experimental studies on composite deck slabs to determine the shear-bond characteristic (m-k) values of the Embossed profiled sheet, Journal of Constructional Steel Research, 63(6), pp 791–803. 7. Miquel Ferrer, (2006), Designing cold-formed steel sheets for composite slabs: An experimentally validated FEM approach to slip failure Mechanics, Thin-Walled Structures, 44, pp 1261–1271. 8. Pentti Makelainen, (1999), The longitudinal shear behaviour of a new steel sheeting profile for composite floor slabs, Journal of Constructional Steel Research, 49, pp 117–128. 9. Shiming Chen, (2011), Shear bond mechanism of composite slabs - A universal FE approach, Journal of Constructional Steel Research, 67 b, pp 1475–1484. 482 International Journal of Civil and Structural Engineering Volume 4 Issue 4 2014
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