COMPARATIVE STUDY ON ANALYSIS OF PLAIN AND RC BEAM USING ABAQUS

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp Article ID: IJCIET_08_04_172 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed COMPARATIVE STUDY ON ANALYSIS OF PLAIN AND RC BEAM USING ABAQUS Ch. Koteswara Rao PG Student, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India P. Polu Raju Associate Professor, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India T. Naga Seshu Babu Assistant Professor, Department of Civil Engineering, KL University, Vaddeswaram, Andhra Pradesh, India ABSTRACT Reinforced concrete has become one of the most important building materials and is widely used in many types of engineering structures. To predict exact behavior of element detailed properties and behavior of RC elements under different loading conditions is needed. Experimental research supplies the basic information for finite element modelling to get reliable analytical models to do so large number of specimens is to be tested. In present study is to compare the experimental results with manual results and Finite element modelling using ABAQUS software. Laboratory tests are carried out on a beam dimension 500mm x 100mm x 100mm of M30 grade of concrete for both plain concrete beam and reinforced cement concrete beam. Finite element analysis is performed using ABAQUS software. The stress strain results from experimental and analytical study is compared. Key words: Plain concrete beam, RCC beam, direct stiffness method, finite element modelling. Cite this Article: Ch. Koteswara Rao, P. Polu Raju and T. Naga Seshu Babu, Comparative Study on Analysis of Plain and RC Beam using Abaqus. International Journal of Civil Engineering and Technology, 8(4), 2017, pp INTRODUCTION In the olden days, stones are the only scope for construction of structural members like arches but due to these failures in arched structures they are replaced by flat members (beam). Many experiments were conducted by scholars like Leonardo Da Vinci, Galileo etc. But they failed to explain the complete behaviour of a beam. Study by Leonardo Da Vinci led to many solutions for unsolved questions on behaviour of a beam [1].A beam is a structural editor@iaeme.com

2 Ch. Koteswara Rao, P. Polu Raju and T. Naga Seshu Babu element that is capable of withstanding load primarily by resisting against bending. Beams generally carry vertical gravitational forces but can also be used to carry horizontal load [2].Fig. 1 shows the statically determinate beam, bending (sagging) under a point load Figure 1 A statically determinate beam, bending (sagging) under a point load The beams are show poor behaviour when they were made using plain concrete or steel. Tensile strength of plain concrete is about one tenth of its compressive strength [2].The concrete beams are weak in tension which leads to cracks, whereas the steel beams are weak in compression which leads to buckling, compression and twisting of beams. Eventually the beam collapses due to these failures [3].To overcome these failures, the concept of Reinforced Concrete (RC) beams has been introduced from last few decades. Reinforced concrete is a composite structure which utilizes compression of concrete and tension of steel to produce a block that can take both compression and tension forces simultaneously. Reinforced concrete is cost effective and easy to use, hence it is widely used as construction material. However, the behavior of RC is still questionable under different types of loads such as static, cyclic, dynamic, etc. [4]. Reinforcing steel and concrete interact in a complex way through bond-slip and aggregate interlock [5].In order to build safe structures, it becomes very essential to predict the load deformation behavior of reinforced concrete. In this paper, the behavior of RC beam under centre point loading is studied experimentally. Further, the experimental results are validated by analytical study carried out in ABAQUS software. 2. EXPERIMENTAL PROGRAMME Concrete beams of plain and RC type was used for study. The details of the beams including section and reinforcement details are listed in Table 1. Table 1 Description of specimen Specifications Plain concrete beams Reinforced concrete beams Grade of Concrete M30 M30 Grade of steel Nil Fe 415 Dimensions of Beam 500 mm 100 mm 100 mm 500 mm 100 mm 100 mm Area of Steel Nil 8 mm Ø bars(4) Cover Nil 25 mm Stirrups size Nil 50 mm 50 mm Spacing of stirrups Nil 150 mm Figs. 2 through 5 show that the testing apparatus and specimens being tested in the laboratory. After completion of 28 days curing, the beams were subjected to center point editor@iaeme.com

3 Comparative Study on Analysis of Plain and RC Beam using Abaqus loading using UTM. Dial gauge were arranged to bottom of beam and hydraulic load is applied linearly till first crack at which load and corresponding deflection were observed. This process is done for all beams and ultimate load along with corresponding deflection for all beams. Before Loading After Loading Figure 2 Plain Concrete Beam Testing Figure 3 Reinforcement Casing Figure 4 RC Beam Figure 5 Crack Pattern editor@iaeme.com

4 Ch. Koteswara Rao, P. Polu Raju and T. Naga Seshu Babu 3. FINITE ELEMENT MODELLING On the basis of central objective in research is finite element model of plain concrete beam were developed Plain Concrete Beam A solid model of a plain concrete beam with an area 100 mm x 100 mm and depth 500 mm, and suitable material properties was developed using ABAQUS software [6]. After assembling and assigning the properties, an input file is created which is then imported to create an orphan mesh. Meshing is the process of generating nodes and elements. A mesh is generated by defining nodes and connecting them to define the elements. In order to solve any type of the finite element problem, the relevant job analysis should be established. After creating job analysis the data should be checked and submitted to get the results and visualized analytically Reinforced Concrete Beam A sketch of concrete and steel section are created separately with ABAQUS, which can be extruted in any direction. This is why a 3D solid element in modelling space using deformable type of beam was created. A solid model of a concrete beam with an area 100 mm 100 mm, depth 500 mm was developed. Steel rebars of length 450mm with stirrups 50 mm 50 mm was created. Thereinforcement for concrete beam was arranged with size 450mm rebars and placing the stirrups with spacing 150mm from centre to the both sides with effective cover 25mm to translate instance on both x, y and z directions. Assigning the steel and concrete material properties for RC beam. A tie constraints ties two separate surfaces together so that there is no relative motion between them. This type of contraint allows to fuse together two regions even though the meshes created on the surface of the regions may be dissimilar [7]. And specified load and boundary conditions of RC beam model are shown below. Giving an input file by assembling and Assigning material properties and create a Meshing part for concrete, rebars, and stirups, giving an approximate size for global seed to Assigning the mesh controls. A mesh part is generated by defining nodes and connecting them to define the elements. Field output request and historial output request should be given to establish the job analysis. In order to solve any type of finite element problem, creating a job manager for data check and submitted to get the results of full analysis in visualization. 4. RESULTS AND DISCUSSION The results from experimental and analytical study of beam under one point loading are presented here. Tables 2 and 3 shows the load and deflection values for various specimens of plain and reinforced concrete respectively. Parameter Table 2 Results of Plain Concrete Beam Specimen 1 Specimen 2 Specimen 3 Cycle 1 Cycle 2 Cycle 1 Cycle 2 Cycle 1 Cycle 2 Load(kN) Displacement(mm) Deflection(mm) editor@iaeme.com

5 Comparative Study on Analysis of Plain and RC Beam using Abaqus Table 3 Results of RC Beam Parameters Specimen 1 Specimen 2 Specimen 3 Cycle 1 Cycle 2 Cycle 1 Cycle 2 Cycle 1 Cycle 2 Load(kN) Displacement 0.3 mm 1.3 mm 0.3 mm 1.3 mm 0.1 mm 1.4 mm Deflection 0.16 mm 1.25 mm 0.2 mm 1.2 mm 0.2 mm 1.17 mm Fig. 6 shows the deformation pattern of plane concrete beam where maximum deformation Is observed at the centre of the beam under the loading. Fig. 7 shows the stress distribution at various points of beam section in a plane concrete beam. Fig. 8 shows the load deformation graph for various plain concrete beam specimens used for the study. Figure 6 Déformation of plain concrete beam Figure 7 Stress in plain concrete beam editor@iaeme.com

6 Ch. Koteswara Rao, P. Polu Raju and T. Naga Seshu Babu Stress kn/m Beam 1 Beam Strain Figure 8 Stress-Strain graph for plain concrete beam Fig. 9 shows deformation pattern of RC beam where maximum deformation is observed at the centre of the beam under the loading. Fig. 10 shows the stress distribution at various points of the beam section in the plane concrete and the steel bars.fig. 11 shows the stress in steel bar in under reinforced concrete beam. Fig. 12 shows the load deformation graph for various RC beam specimens used for the study Figure 9 Deformation of concrete beam Figure 10 Stress in concrete beam editor@iaeme.com

7 Comparative Study on Analysis of Plain and RC Beam using Abaqus Figure 11 Stress in steel bar in under reinforced concrete beam Stress (kn/m 2 ) Specimen 1 Specimen 2 Specimen Strain Figure 12 Stress-Strain graph for RC Beam Table 4 shows the comparison of results of experimental study and analytical results obtained from the ABAQUS software. The results are similar, but not same due to irregularities in the experimental studies. Name PC beam RC beam Ultimate load (kn) Deflection (mm) Table 4 Comparaison of Results Displacement (mm) Stress (kn/m 2 ) Moment (kn-m) S.F (kn) EXP FEA EXP FEA Tension Comp CONCLUSIONS The paper deals with the flexural behaviour of plain and RC beam under flexural loading. The following conclusions can be drawn from the study : The deflection and stress values from the experimental study correlates well with the analytical study carried out in ABAQUS editor@iaeme.com

8 Ch. Koteswara Rao, P. Polu Raju and T. Naga Seshu Babu Plain concrete being weak in tension, fails at lower loads and can sustain low deflections. The strength and deformability improves quite remarkably with the addition of rebars. Maximum deflection was observed at the centre of the beam. Both RC and plain concrete beams start to fail at centre of beam. ACKNOWLEDGEMENT I Sincerely Thankful to Mr. D. RAKESH, Associate Professor, Department of Civil Engineering, Dhanekula Institute of Engineering & Technology, for his Guidance and Support in Completion of this project. My Special Thanks to my Juniors D. Bharath, M. Balakrishna Reddy, P. Devi Varun, B. Augasteen, Under Graduate Students, Department of Civil Engineering, Dhanekula Institute of Engineering & Technology, for their helping me in Experimental work in Completion of this project. REFERENCES [1] Anthony J. Wolanski, B.S. (2004) Flexural Behavior of Reinforced and Prestressed Concrete Beams Using Finite Element Analysis, Master s Thesis, Marquette University Milwaukee, Wisconsin. [2] Vazirani, V.N.; Ratwani, M.M., (1995), Concrete Structures, Khanna Publishers, Delhi. [3] S. Yamini Roja, P. Gandhi, DM. Pukazhendhi and R. Elangovan (2014), Studies on Flexural Behaviour of Concrete Beams Reinforced with GFRP Bars, International Conference on Emerging Trends in Science Engineering and Technology (ICETSET- 2014) [4] Kachlakev, D., PhD., Miller, T, PhD, P Yim, S, PhD, PE; Chansawat, K. and Potisuk, T., ( 2001), Finite Element Modeling of Reinforced Concrete Structures Strengthened with FRP Laminates, Oregon Department of Transportation, Research Group [5] Saenz LP (1964), Discussion of aquation for the stress-strain curve of concrete, by Desayi and Krishnan. ACI J., 61(9): [6] Hibbitt K, Karlsson B, Sorensen P (1988), ABAQUS: User's Manual: Hibbitt, Karlsson & Sorensen. [7] Hamid Sinaei, Mahdi Shariati, Amir Hosein Abna, Mohammad Aghaei and Ali Shariati (2012), Evaluation of reinforced concrete beams behaviour using finite element analysis by ABAQUS Scientific Research and Essays Vol. 7(21), pp editor@iaeme.com